Method for sowing hybrid cereal parent seeds in an agricultural field, corresponding seed sowing device and use

Abstract

The invention relates to a method for sowing hybrid cereal parent seeds in an agricultural field, the method comprising sowing at least one pair of male-sterile female seed strips, each strip containing several female seed rows, wherein the female seed rows are spaced apart from one another and are planted with a first seed density, wherein the female seed rows cover a first surface area on the agricultural field, sowing a male seed row with a second seed density in between the pair of female row strips, wherein the male seed row covers a second surface area on the agricultural field. According to the invention, the second seed density of the male row is lower than the first seed density of the female rows, wherein the first surface area and the second surface area form a total surface area, an wherein said second surface is less than 30 % of the total surface area, preferably less than 27,5 % of the total surface area, more preferably less than 25 % of the total surface area.

Description

[0001] BASF SE

[0002] Carl-Bosch-StraBe 38, 67056 Ludwigshafen am Rhein Germany

[0003] Method for sowing hybrid cereal parent seeds in an agricultural field, corresponding seed sowing device, use and agricultural field

[0004] The invention relates to a method for planting / sowing hybrid cereal parent seeds in an agricultural field, a corresponding seed sowing device, use and agricultural field.

[0005] Background

[0006] Essentially self-fertilizing (autogamous) crops need male sterile lines for hybrid seed production, as cross-pollination between 2 hybrid parent lines (namely a male sterile female line and a fertile male line) is required. While in some autogamous crops male-sterile plants (genetically, chemically or mechanically made male-sterile) and commercial hybrid seed production methods were developed, in some other crops, like wheat, only very few commercial hybrids are on the market, and efforts are ongoing to improve hybrid seed production to make it economically viable and sustainable. Particularly grain cereals like wheat, barley, rye, or triticale that have bisexual or hermaphroditic flowers (male and female organs in the same flower), and are not pollinated by insects, are challenging for hybrid seed production. While some published documents are discussed herein, this is not to be taken as any admission that any of these forms part of the common general knowledge of the person of ordinary skill in the art.

[0007] WO 2012038350 describes that a major shortcoming of traditional hybrid seed production systems is the need to plant separate rows, strips or blocks of the male and female parent lines (in wheat hybrid production also known as bay-planting system). In such system, low efficiency pollination is an especially acute problem in crop species such as wheat and barley that release small amounts of pollen which does not travel far on the wind and only remains viable for a very short period of time. In such crops, as much as two / thirds of the hybrid-producing field needs to be dedicated to male pollen-donor plants and then hybrid seed production becomes uneconomic. In orderto achieve a more economic seed production in wheat and barley crops it is necessary to move male and female plants closer together for more efficient pollen transfer, most efficiently by inter-planting males and females within centimetres of each other in the same rows. WO2012038350 describes that the male and female plants are planted as such that upon harvest, the seed will comprise a mixture of the hybrid seed and the inbred (male) seed. Since in this system it is impractical to harvest only the hybrid seed from the (male-sterile) female parents, it is suggested to sort inbred seed from the (hybrid and inbred) seed harvested using a device that separates the BASF SE 241312 241312 inbred seed from the hybrid seed on the basis of a difference which is detectable via the use of near infrared light.

[0008] WO 2015135940 A1 describes a method of producing hybrid cereal seeds comprising crossing a stand of shorter female (male sterile) plants with a stand of taller male fertile plants and limiting the proportion of self-fertilized male seed in the produced seed stock, by passing a tool extending above the height of the shorter female plants between anthesis and harvest, which tool contacts the male fertile plants standing above this height and causes preventing or reducing normal development thereof. In this method, male and female plants are sown as a mixture, or are drilled in close rows. Female (male sterile) and male fertile plants are sown in close proximity in order to ensure a high level of crosspollination, either by sowing as a mixture, or drilled in close rows. In one embodiment, male and female seeds can be sown using several rows or lines of one type of seed, then several lines or rows of the othertype of seed, and so on, with “several” being preferably maintained at a low level to ensure "close proximity", in particular comprised of 2 or more lines of the same seed type.

[0009] CN 107637514 apparently discloses a mechanically efficient seed production and sowing method for hybrid wheat. The method comprises the following steps: sowing seeds into a male parent zone and a female parent zone in sequence according to a ratio of 1 to 2, wherein the sowing width in the male parent zone is 1 m, and the sowing width in the female parent zone is 2 m; during sowing, sowing the seeds into the male parent zone by using a narrow-width sowing machine capable of sowing at least 4 lines, and sowing the seeds into the female parent zone by using a sowing machine capable of sowing at least 8 lines, wherein the line spacing is 0.25 m, and no sowing is carried out in a gap of 0.4 m reserved between the male parent zone and the female parent zone. The mechanically efficient seed production and sowing method for the hybrid wheat can realize mechanical operation for sowing and harvesting in combination with the harvesting width of a wheat mainstream harvester in this region according to a landform for wheat planting in the southwest wheat region; the method is simple, normal and efficient, and is small in labour investment, high in seed production yield and high in seed production benefit.

[0010] WO 2022 / 090373 describe several different “planting schemes” for plant hybrid cross testing in wheat, referring to number of rows, distance between rows, length of rows, distance between plants / seeds in a row, plant density in each row / area, number of plants per row, number of total plants, and combinations thereof, for each a first and second plant or plant population (see pages 65 to 81), in particular for evaluating heterosis and / or (general and / or BASF SE 241312 241312 specific) combining ability. In the examples, 697 unique spring wheat hybrids were produced by drilling the lines using a 6-row Hege-drill, drilling 6m rows with two male sterile female rows in the center and two male rows on either side. The examples of WO 2022 / 090373 conclude that hybrid test seed can be generated from combinations in which male and female plants differ in heading date, anther extrusion and plant height, and even with very poor anther extrusion and with large (>2 days) differences in flowering time and low anther extrusion it is still possible to produce useful amount of F1 seed for testing, so that good seed production is observed even when flowering was not completely synchronized. WO 2022 / 090373 describes that this can be explained by the abundance of males over females (ratio 2:1), the close proximity and the drilling with row spacing which encourage tillering and hence prolonging the time in which both males and female plants have actively flowering florets in the exemplified hybrid cross testing method. No specific planting scheme suitable for (commercial) hybrid seed production is disclosed in this filing.

[0011] US 2024 / 0016153 describes that establishing more efficient pollen transfer is necessary to achieve greater success and more economic hybrid seed production in wheat. A major disadvantage of conventional hybrid seed production systems is the need to plant the male and female parent lines in separate rows, strips or blocks. These sections are separated so that the entire female section can be harvested without contamination with any male inbred seeds. However, this separation of males and females results in inefficient pollination in cereal crop species such as wheat. The small amounts of pollen released are not spread far with the wind and remain viable for only a very short period of time. In such crops, up to two-thirds of a hybrid production field is planted with the pollen donor male plant resulting in an inefficient and costly hybrid seed production process. In order to achieve more economical seed production in wheat and other cereal crops, it is necessary to move male and female plants close to each other to facilitate more efficient pollen transfer; most effectively, by interplanting the males and females within a few centimeters of each other in the same row. However, it is not practical to harvest only seed from the male sterile female parent in such a system, as the harvested seed contains both the hybrid seed from the fertilized male sterile female and the inbred seed from the self-fertilized male. In addition, there are set standards as to how much contamination of the inbred seed is allowable within the harvested seed (e.g., 95 % hybrid seed from the female and 5 % inbred seed contamination from the male).

[0012] US 2024 / 0016153 further describes that the contamination of harvested seed with inbred seed originating from the male parent can be minimized by using as low a percentage of such male parent plants in the planting mix as possible. However, the low number of male parents planted in combination with the low pollination efficiency described above, may BASF SE 241312 241312 result in a portion of the female plants that will not be pollinated, and therefore, will not produce any grain. This affects the total yield of the seed production field and represents a significant obstacle affecting the efficiency of the interplanting hybrid system. Consequently, most wheat seed production fields are not interplanted with males and females.

[0013] US 2024 / 0016153 then described a method of increasing wheat hybrid seed production in a field comprising the steps of (a) interplanting male and female parent wheat plants in a field; and (b) quantifying hybrid seed production; wherein hybrid seed production is increased with respect to a control planting wherein the male and female parents are not interplanted. US 2024 / 0016153 also describes a method of improving wheat hybrid seed production, by, amongst others, using a topical treatment (such as MCPA (2-methyl-4-chlo- rophenoxyacetic acid)) on male plants to limit tillering thereby reducing late emerging spikes in the wheat canopy and shortening the flowering window, and also by application of a desiccant or reducing the seeding rate of the male plants in a seed production system to delay male flowering. US 2024 / 0016153 says that when male flowering is delayed so that it minimizes overlap with flowering in the female plant, the opportunity for the male plants to self-fertilize is reduced, thereby reducing the production of male inbred seed and contamination of hybrid seed production. It is also said that reducing seeding rate of the male plants in a seed production system can delay male flowering by as much as 2.5 days, which is enough to decrease contamination of (hybrid) seed from self-pollinated males.

[0014] Description of the Invention

[0015] In view of the above there still is a need for improving hybrid seed production, particularly in cereals, such as wheat, particularly winter wheat. Thus, it was an object of the invention to provide an improved method for planting / sowing or cultivating hybrid cereal parent seeds in an agricultural field.

[0016] In mixed planting, due to the vicinity of males and females and the requirement of a low percentage of males; the yield of hybrid seeds per acreage can be good under good pollination conditions and a good nicking between male and female. However, mixed planting bears the risk of a low seed set under less optimal conditions and / or nicking, since a high seeding density as required for good yields, leads to low tillering and the formation of a very low (typical 1-3) number of spikes per plant. These spikes form simultaneously and hence the resulting pollination window is short (typically about 3-5 days) and in consequence the risk of low seed set due to imperfect nicking or adverse weather conditions is high. Mixed planting also has the concern of harvesting male seed with the hybrid seed, BASF SE 241312 241312 so that hybrid seed purity may not meet the expectations of customers and / or the requirements of authorities. Also, solutions to overcome this concern come with additional costs which increase the cost of goods for hybrid seed production.

[0017] The invention attains the aforementioned object by suggesting a method for planting or sowing hybrid cereal parent seeds according to claim 1. In one embodiment of the invention, the method comprises planting / sowing at least one pair of male-sterile female plant / seed strips, each strip containing more than one female seed row, wherein the female plant / seed rows are spaced apart from one another and are planted / sown with a first seed density, wherein the female seed rows cover a first surface area on the agricultural field, planting / sowing a male seed row with a second seed density in-between the pair of female row strips, wherein the male seed row covers a second surface area on the agricultural field, wherein the second seed density of the male row is lower than the first density of the female rows, wherein the first surface area and the second surface area form a total surface area, and wherein said second surface is less than 30 % of the total surface area, preferably less than 27,5 % of the total surface area, more preferably less than 25 % of the total surface area, or said second surface is less than or equal to 30 % of the total surface area, preferably less than or equal to 27% of the total surface area, more preferably less than or equal to 25 % or less than or equal to 20 % of the total surface area. As used herein, “a male seed row” refers to one (1) male seed row. In one embodiment of the invention, particularly when the second surface area is < 30 % of the total surface area, is < 27% of the total surface area, is < 25 % of the total surface area, or is < 20 % of the total surface area, the male plants of the invention get more space to grow by having a bigger distance to neighbouring female plant rows, and the seed density of the male rows is the same as that in the female rows (row spacing between female rows is significantly shorter than between male and female row, e.g., the row spacing between adjacent female rows is < 15 cm or < 10 cm, and the row spacing between a male row and the adjacent female row (or the 2 adjacent female rows as the case may be) is 20-35 cm, such as 20-25 cm, 20-30 cm, 25-30 cm, 25-35 cm or 30-35 cm).

[0018] The second surface may for example be less than or equal to 30 % or 29 % or 28 % or 27,5 % or 27 % or 26 % or 25 % or 24 % or 23 % or 22 % or 21 % or 20 % or 19 % or 18 % or 17 % or 16 % or 15 % or 14 % or 13 % or 12 % or less than or equal to 10 % of the total surface area, such as 20-30 % of the total surface area.

[0019] By planting / sowing the interplanted male rows at a significantly lower seed density, or otherwise providing more space to male plants to grow, a significantly higher tillering of the BASF SE 241312 241312 male plants is achieved. The enhanced tillering leads to a broader window of pollen shedding due to a sequential formation of productive tillers (that will flower later than the main tiller) which increases the chance of successful cross-pollination. In one embodiment, the male seed row is a first male seed row and wherein the method comprises planting / sowing at least one or more further male seed rows spaced apart from one another, wherein between each pair of adjacent male seed rows, 3-10, 3-9, 3-8, 3-7, 3-6, 3-5 or 3-4 of the female seed rows are planted. In one embodiment of the invention, male and female rows of the cereal plants of the invention are preferably obtained by sowing (non-germinated) seeds in a field, not by planting plants or seedlings. In one embodiment of the invention, male and female rows are sown parallel to each other (if the rows are drawn as lines on a scheme / drawing they are parallel, not oblique or perpendicular, and do not cross each other, as illustrated in Figs. 5 and 6 herein).

[0020] In one embodiment, the second seed density of one or more male seed rows is 10 % - 50 %, 12.5 %- 50 %, 15 % - 50 %, or 20 %- 50 %, preferably 10 % - 40 %, 12.5 % - 40 %, 15 % - 40 %, 20 % - 40 %, more preferably 10 % - 30 %, 12.5 % - 30 %, 15 % - 30%, 20 % - 30 % or 10 % - 20 % or 15 % - 20 % or 10 % - 25 % or 15 % - 25 % of the first seed density of the female rows, such as when the second seed density of the male rows is 50 % or less, 45 % or less, 40 % of less, 35 % or less, 30 % or less, 25 % or less, 20 % or less, or 15 % or less of the first seed density of the female rows. In one embodiment of the invention, the second seed density is 50 %, 49 %, 48 %, 47 %, 46 %, 45 %, 44 %, 43 %, 42 %,

[0021] 41 %, 40 %, 39 %, 38 %, 37 %, 36 %, 35 %, 34 %, 33 %, 32 %, 31 %, 30 %, 29 %, 28 %,

[0022] 27 %, 26 %, 25 %, 24 %, 23 %, 22 %, 21 %, 20 %, 19 %; 18 %, 17 %, 16 %, 15 %, 14 %,

[0023] 13 %, 12 %, 11 %, or 10 % of the first seed density, or is 15-35 %, 20-35 %, 25-35 %, of the first seed density.

[0024] The male plants may produce significantly more spikes than the female plants as a consequence of lower planting density. In particular, the male plants may produce 30% to 100 % more spikes, or the male plants may produce 1-3 more spikes than the female plants, such as at least 1 , or at least 2, or at least 3 more spikes per male plant than the female plants. Hence, in one embodiment of the invention, the agricultural field as described herein contains male plant rows that contain male plants producing 30 % to 100 % more spikes than the female plants in said field, such as male plants with at least 1 or at least 2 or at least 3 more spikes than the female plants in said field.

[0025] In one embodiment, the female rows are planted at a seed density between 100 seeds / m2and 400 seeds / m2, preferably between 120 seeds / m2and 300 seeds / m2, more preferably between 200 and 266 seeds / m2or between 200 and 220 seeds / m2. Depending on the BASF SE 241312 241312 purpose and seed availability, e.g., seed density can be different (planting / sowing for commercial seed production when high seed quantity is available and maximum yield is key vs. planting / sowing for breeding or seed production research purposes when more limited seed quantity is available). In one embodiment of the invention, when the male and female rows of the invention are grown on smaller fields of around 10 to 40 square meter, or fields of < 1 or < 0.5 acre, or fields of < 1 .000 m2, < 500 m2or < 50 m2(such as for breeding or hybrid parent combining ability test fields, or for seed production research purposes), the female rows are planted at a seed density between 50 seeds / m2and 400 seeds / m2, preferably between 100 seeds / m2and 300 seeds / m2, more preferably between 111 and 266 seeds / m2or between 120 and 220 seeds / m2.

[0026] In one embodiment, the planting / sowing is for (commercial) hybrid seed production (in large fields, such as fields larger than 1 ha, or fields > 1 hectare, or > 1 acre, such as for ((precommercial) hybrid seed production, and then a seed density for the female rows is more in the range of 150-400 seeds / m2, such as 200-350, 200-300, or 200-250 seeds / m2, or 150- 350, 150-300, 150-250, or 150-200 seeds / m2. In another embodiment, the planting / sowing is for breeding or seed production research (in smaller fields, such as fields of typically around 10 to 40 square meter, or fields of < 1 or < 0.5 acre, of fields of < 1 .000 m2or < 500 m2or < 50 m2), and then the seed density for the female rows is more in the range of 80- 150 seeds / m2, 90-150 seeds / m2,100-150 seeds / m2, 110-150 seeds / m2, or 80-140 seeds / m2, 90-140 seeds / m2, 100-140 seeds / m2, or 80-130 seeds / m2, 90-130 seeds / m2, 100-130 seeds / m2, or 100-120 seeds / m2. In one embodiment, the seed density for the female rows, as used herein, particularly for field > 1 hectare or > 1 acre, is > 80, > 85, > 90, > 95, > 100, > 105, or > 110 seeds / m2and is < 250, < 300, < 350, < 400 or < 450 seeds / m2.

[0027] These measures help the male plants to obtain more space so that they will generally form more tillers. This will result in a more asynchronous and staggered development of spikes and hence a broadened pollination window. This in turn mitigates the risk of insufficient pollination due to imperfect nicking and detrimental weather conditions during pollination.

[0028] Preferably, a spacing between adjacent male and female rows is less than 35 cm, in particular less than 30 cm, less than 29 cm, less than 28 cm, less than 27 cm, less than 26 cm, or less than 25 cm, and at least is 15 cm or at least 20 cm. In one embodiment, the row spacing between the male and female rows, such as between a male row and the adjacent female row, is 15-30 cm, 15-29 cm, 15-28 cm, 15-27 cm, 15-26 cm, 15-25 cm, 15- 24 cm, 15-23 cm, 15-22 cm, 15-21 cm, 16-30 cm, 17-30 cm, 18-30 cm, 19-30 cm, 20-30 cm, 21-30 cm, 22-30 cm, 23-30 cm, 24-30 cm, 25-30 cm, or is 15-25 cm, 16-25 cm, 17-25 cm, 18-25 cm, 19-25 cm, 20-25 cm, 21-25 cm, 22-25 cm, 23-25 cm, or 24-25 cm. Of BASF SE 241312 241312 course, due to the available sowing equipment, or the need to have space for the wheels of the sowing equipment, it can be that some male rows are further away from a female row, but most of the male rows should have the above distance from an adjacent female row. Hence, the above distance between male and female rows applies to most of the adjacent male and female rows, so that for some female rows (e.g., < 30 %, < 25 %, < 20 %, < 15 %, < 10 % of the female rows adjacent to a male row (to the left or the right of that female row, when you stand at the end of the row)), the distance can be larger than indicated above (e.g., for a field with 8 male and 28 female rows as in Fig. 6 (36 rows in total, and starting with a male row), where there are in total 15 female rows adjacent to a male row, at most 4 female rows can have a distance larger than indicated above from the adjacent male row, if < 30 % of the female rows adjacent to a male row can have a distance from the adjacent male row that is larger than indicated above).

[0029] In one embodiment, a spacing between adjacent female rows is less than 15 cm, in particular less than 10 cm. In one embodiment, the spacing between adjacent female rows is 10-25 cm, such as 10-20 cm, 15-25 cm, or 15-20 cm, or is 20 cm or less, or 15 cm or less, or 10 cm or less, or is less than 20 cm, less than 15 cm, in particular less than 10 cm. Of course, due to the available sowing equipment, or the need to have space for the wheels of the sowing equipment, it can be that some female rows are further away from an adjacent female row, but most of the female rows should have the above distance from a female row. Hence, the above distance between adjacent female rows applies to most (or at least 80 %, at least 85 %, at least 87,5 %, at least 90 %, at least 92,5 %, or at least 95 %) of the female rows, so that for some female rows (e.g., < 20 %, < 15 %, < 12,5 %, < 10 %, < 7,5 %, < 5 % of the female rows), the distance to an adjacent female row can be larger than indicated above.

[0030] Preferably, a maximum distance of any female plant / seed row to a male plant / seed row, such as from a female row to the closest male row (either to the left / West or right / East of that female row), is 90 cm, 85 cm or 80 cm, preferably 75 or 70 cm, more preferably 65 cm, most preferably 60 cm, or can be 55, 50 or 45 cm. In other words, the distance of any female plant / seed row to its closest male plant / seed row is < 90 cm, < 85 cm, < 80 cm, < 75 cm, < 70 cm, < 65 cm, < 60 cm, < 55 cm, < 50 cm, or < 45 cm, or < 40 cm, or the maximum distance from any female row to its closest male row is below 90, 85, 80, 75, 70, 65, 60, 55, 50, or is below 45 cm. In one embodiment, < 20 %, < 15 %, < 10 % or < 5 % of the female rows in a field have a maximum distance from the female row to the closest male row of > 40 or > 50 cm or > 60 cm, such as < 15 % of the female rows in a field have a maximum distance of > 50 cm from the closest male row, or < 5 % of the female rows in a field have a maximum distance of > 60 cm from the closest male row. E.g., in the first BASF SE 241312 241312 block of 6 rows in Fig. 6, the maximum distance of a female row to its closest male row is 40 cm (2 x 20 cm), but the first female row in the second 6-row block in Fig. 6 has a maximum distance from its closest male row of 50 cm. In one embodiment, the maximum distance from any female row to its closest male row is < 60 cm, < 50 cm, < 45 cm, or < 40 cm for at least 70 %, at least 75 %, at least 80 %, at least 90 %, or at least 95 % of all female rows in a plot / field, or for all (100 %) female rows. In one embodiment, the maximum distance from any female row to its closest male row is < 60 cm in all or at least 95 % of all female rows, < 50 cm in at least 80 %, at least 85 %, at least 90 %, or at least 95 % of all female rows, < 40 cm in at least 75%, at least 80 %, at least 85 %, or at least 90 % of all female rows. In one embodiment, the above maximum distance of any female plant / seed row to the closest male plant / seed row, is the maximum distance from a female row to the closest male row in the direction of the prevailing wind in that area (or the closest up-wind male row), so that the closest male row is at the West of that female row if the prevailing wind in that area is coming from the West (and is blowing to the East).

[0031] According to one embodiment, the female plant / seed rows are planted / sown with a first within row spacing and the male seed rows are planted with a second within row spacing, wherein the second within row spacing of the male rows is 1.5 - 10 times larger than the first within row spacing of the female rows. In an embodiment where (for security purposes, e.g., with lower seed emergence) two male seeds are sown at a location (wherein said two male seeds at a location are sown close to each other, such as 1-5 cm apart (such as 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 cm apart), the within row spacing of the male rows, as used herein, refers to the distance between the two male seeds sown at a location to the two male seeds sown at the next location (so when looking at a male row planted from left to right, from the right seed of the two seeds planted at a first location to the left seed of the seeds planted at the next / second location within the same row). In the current invention, only 1 or 2 seeds, or no more than 2 seeds, are sown close to each other, such as 1 -5 cm apart, or in the same hole, in a seed row, particularly in the male seed row, to provide male plants with sufficient space (in case not all seeds emerge). In one embodiment of the invention, particularly when seed emergence of a certain seed batch is very good (e.g., at least 90 %), only 1 cereal seed is sown at each sowing position (in a male or female) row.

[0032] In one embodiment, a within row distance between a single or two male seeds sown at a location (wherein two male seeds at a location are sown close to each other, such as 1-5 cm apart (such as 1 , 1 .5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 cm apart)) to the next within row single or two male seeds sown at a location is 10 to 30 cm, 15 cm to 25 cm, or 10 to 20 cm, such as 12 to 24 cm. BASF SE 241312 241312

[0033] Again, by implementing one or more or all of these measures, the space for the male plants is increased resulting in a broadened pollination window and a mitigation of the risk of insufficient pollination due to imperfect nicking and detrimental weather conditions during pollination. In one embodiment, the male plant selected for the invention is a very productive, vigorously growing male plant, that can occupy the more space it gets in the field.

[0034] According to one embodiment, planting / sowing the male and female rows with the first seed density and second seed density and / or first within row spacing and second within row spacing is achieved by at least one of the following: utilizing (modified) seeding disks ((allowing) for planting / ) sowing the male seed rows with different seed density compared to the female rows, planting / sowing the male and female seed rows in two separate passes at two different seeding densities into the same field, utilizing precision planting / sowing equipment configured to sowing male and female seeds at a different seed density in different rows, mixing viable male seeds with non-germinating, devitalized seeds at the proper relative amount to get the intended seed density / within row spacing.

[0035] By utilizing (modified) seeding disks allowing for planting / sowing the male seed rows with different seed densities, established row planting / sowing devices can be utilized to reduce the seed density of the male rows compared to the female rows. The seeding disks may be modified by blocking certain channels of the seeding disk, or by using adapted seeding disks with less channels to get the intended reduced male seed density. By blocking certain channels or using adapted seeding discs, per rotation of the seeding disk, less seeds are provided to the respective row in the agricultural field.

[0036] The male and female rows may also be planted in separate passes, wherein for example in a first pass the female rows are seeded with a higher density and in a second pass the male rows are seeded with a reduced seed density. As an alternative, precision planting / sowing equipment may be utilized which allows for individually defined seed densities for individual rows. For a scenario, in which the planting / sowing device cannot be modified with regard to the seeding density, the intended result may also be achieved by mixing viable male seeds with non-germinating devitalized seeds at the proper relative amount to get the intended seed density / within row spacing.

[0037] In one embodiment, the male rows are sown before the female rows, so as to further increase tillering of the male plants. In one embodiment, male and female rows are sown at the same time or on the same day, and anyhow any later sowing of male or female seed rows (in a field with already sown female or male rows, respectively) is to be done before BASF SE 241312 241312 any seedling emerges from the cereal seeds sown in the field (i.e., all sowing is before any seed that was sown in the field has emerged). Also, in the current invention, the male and female cereal plants of the invention are not purposefully grown with their roots and the base of the stem under water for major parts or most of their growing cycle, as the cereal plants of the invention will typically be lost (i.e., die) when they stand in water for longer times (such as more than 3-4 days during growth (and warmer temperatures, like in the European summer time), or more than 7 days during dormant stage (colder temperatures, such as in European winter time)).

[0038] Preferably, the method further comprises at least one or any combination of two or more of the following steps: applying fertilization (such as nitrogen fertilizer), preferably only to the male rows, in order to promote male tillering, applying a seed treatment containing gibberellic acid to the male seeds before sowing or to the male seed rows after sowing to accelerate germination and ground cover, applying gibberellic acid (“GA”) over the male plant rows between Zadoks stage Z25 and Z50, e.g., after Z25 and before Z50, to increase the height of the male plants and improve cross-pollination, if the male plants increase in plant height after application of gibberellic acid, applying gibberellic acid over the male and female plant rows, if the male plants increase in plant height after application of gibberellic acid (the male plants are GA respon- sive / sensitive) and the female plants do not increase in plant height after application of gibberellic acid, or the female plants increase significantly less in plant height after application of gibberellic acid compared to the male plants (the female plants are not or low GA responsive / sensitive), applying plant growth regulator (PGR), in particular only to the female rows, in order to cause shorter female plant heights and prevent lodging, applying herbicide, in particular to the female rows, in order to reduce or prevent weed pressure, wherein the herbicide is preferably a selective herbicide (for cereals), selective application of a solution reducing tillering on the female plant rows, selective application of a solution stimulating tillering on the male plant rows, planting / sowing the female plant rows with a seed mixture containing up to 5 % of male seeds randomly mixed with the female seed, or using female (male-sterile) plants shorter (such as at least 5, 10, 15 or 20 cm shorter) than the male plants at or before pollination / flowering, in the absence of any treatments to make female plants shorter or male plants taller, such as the shorter mutants described in WO2014 / 028980 (incorporated herein by reference), including any of the mutant Rht-B1 c alleles / genes described in WO2014 / 028980 with a mature plant height that is 1) higher than BASF SE | 241312 241312 the mature plant height of a plant with the Rht-B1 c allele, and 2) lower than 75 % of the mature height of that plant with the native (wild-type) Rht-B1 a allele (e.g., any one of the EMS mutant genes Rht-B1 c.3, Rht-B1 c.4, Rht-B1 c.5, Rht-B1 c.6, Rht-B1 c.8, Rht-B1 c.1 O, Rht-B1 c.12, and Rht-B1 c.21 described in WO2014 / 028980). Herein, the Rht-B1 c.3 mutant gene is a gene encoding the A271T mutant of the protein of SEQ ID NO: 3 in W02014 / 028980 (the A amino acid at position 271 in SEQ ID NO: 3 is replaced by amino acid T in that mutant protein), the Rht-B1 c.4 mutant gene is a gene encoding the G298D mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the G amino acid at position 298 in SEQ ID NO: 3 is replaced by amino acid D in that mutant protein), the Rht-B1 c.5 mutant gene is a gene encoding the A299T mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the A amino acid at position 299 in SEQ ID NO: 3 is replaced by amino acid T in that mutant protein), the Rht-B1 c.6 mutant gene is a gene encoding the A305T mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the A amino acid at position 305 in SEQ ID NO: 3 is replaced by amino acid T in that mutant protein), the Rht-B1 c.8 mutant gene is a gene encoding the P344S mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the P amino acid at position 344 in SEQ ID NO: 3 is replaced by amino acid S in that mutant protein), the Rht-B1 c.1 O mutant gene is a gene encoding the G377R mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the G amino acid at position 377 in SEQ ID NO: 3 is replaced by amino acid R in that mutant protein), the Rht-B1 c.12 mutant gene is a gene encoding the P394L mutant of the protein of SEQ ID NO: 3 in WO2014 / 028980 (the G amino acid at position 377 in SEQ ID NO: 3 is replaced by amino acid R in that mutant protein), and the Rht-B1 c.21 mutant gene is a gene encoding the V286M mutant of the protein of SEQ ID NO: 3 in W02014 / 028980 (the V amino acid at position 286 in SEQ ID NO: 3 is replaced by amino acid M in that mutant protein). As used herein, the protein of SEQ ID NO: 3 in WO2014 / 028980 as used above, includes proteins with some amino acid differences (keeping the mutated amino acid as described above), such as a protein with at least 95 %, at least 96 %, at least 97 %, at least 98 %, or at least 99 % sequence identity to the protein of SEQ ID NO: 3 in WO2014 / 028980, including a protein combining 2 or more of the above mutated amino acids in the same protein. To optimally determine the percent sequence identity between two amino acid / nucleic acid sequences in a first step a pairwise sequence alignment is generated between those two sequences, wherein the two sequences are aligned over their complete length (i.e., a pair- wise global alignment, also called an optimal alignment herein - see WO2023 / 118541 for details). The optimal alignment is generated with a program implementing the Needleman and Wunsch algorithm (J. Mol. Biol. (1970) 48, p. 443-453), preferably by using the program “NEEDLE” (The European Molecular Biology Open Software Suite (EMBOSS), see, e.g., www.ebi.ac.uk / jdispatcher / psa / emboss needle on the world wide web, with the programs BASF SE 241312 241312 default settings / parameters (gapopen=10.0, gapextend=0.5 and matrix=BLOSUM62 for proteins, and matrix DNAFULL for DNA).

[0039] In other words, the pollen-producing (male) cereal plants, such as wheat plants, can be made taller by application on said pollen-producing cereal plants of plant height promoting factors or hormones such as gibberellic acid (“GA”) or compounds with the same plant height effect as gibberellic acid (including but not limited to GA1 , GA3, GA4, GA7 or mixtures thereof), because the pollen-producing (male) plants are GA-responsive. Pollination of the male-sterile female plants can be improved if the fertile male plants are at least as tall as or taller than the female plants just before the start of flowering, such as at Zadoks stage Z59. Since the application of said plant height promoting factors or hormones such as GA can be done selectively on the male plant rows, the pollen-receiving (female) plants do not need to be GA-non-responsive (but they can be) in this embodiment. In one embodiment of the invention, if the female plants do not or hardly respond to GA application with a height increase (not or low GA-responsive), optionally the GA solution can be applied over the entire field, and only the GA-responsive male plants will significantly increase in plant height. This method also has the benefit that the spikes / ears of the taller pollen-producing male plants (either in the male rows or interplanted at max. 5 % between the female plants in the female rows) can be more easily removed before harvest of the hybrid seeds from the female rows (e.g., mechanically, by cutting above the height of the pollen-receiving (female) plants, or chemically, by applying herbicide to the pollen-producing (male) plants (e.g., by herbicide wicking)). A benefit of this method is that pollen-producing hybrid parent (male) plants can be made taller by application of GA and that no genetically taller male plants need to be used, so that the hybrid plants have the appropriate height and there are less concerns with lodging of resulting tall hybrid plants. When using a genetic basis to get a height difference, such as using (semi-)dwarf female plants and tall male plants, the downside is that the hybrid plants become tall, and will have a higher risk to lodge than (semi-dwarf) cereal, such as wheat, plants.

[0040] Similarly, one can envisage a method wherein the female plants are selectively made shorter by selective application of a plant growth inhibitor (like any plant growth regulator applied to prevent lodging) to the female plant rows, while using male plants that are responsive to a plant growth promoting agent like GA, and selective application of that growth promoting agent on said male plant rows in a field.

[0041] In traditional cereal, such as wheat, cultivation, often plant growth regulators (“PGR”) are used (often Gibberellin / GA(pathway)-inhibitors, so as to reduce plant height and improve BASF SE 241312 241312 yield) so as to prevent tall plants (that can lodge and cause severe harvest losses and / or losses in seed quality).

[0042] As used herein, “GA” or “gibberellic acid”, refers to GA3 and any gibberellin that gives a height increase in (GA-responsive) cereals, such as (GA-responsive) wheat plants, such as GA1 or GA4 or GA7 or mixtures of GA1 and / or GA3 and / or GA4 and / or GA7. This includes naturally existing plant hormones or synthetic growth factors derived from or based on a gibberellin. In one embodiment, GA as used herein refers to GA3 or to a mixture of GA4 and GA7.

[0043] As used herein, “GA-responsive plants”, when referring to plants in a field, refers to plants treated with GA in the field having at least a 10 % or a 12 % (or at least 13 %, at least 14 %, or at least 15 %, at least 20 %, or at least 25 %) increase in plant height at the start of flowering, or just before flowering, such as at Z59, compared to said plants at said (same) stage when not treated with GA. In one embodiment, GA-responsive male plants refers to the plants in the preceding sentence that are at least 4 cm, at least 5 cm, at least 10 cm, or at least 15 cm taller (after GA application from Z25 to Z50) at the start of flowering, or just before flowering, such as at Z59 (or at the end of flowering), than the matching female (male-sterile) plant used to produce hybrid seed with said male plant in a hybrid seed production field. In one embodiment, the majority of the main spikes of the said GA-responsive plants stick out by at least 1 / 3rd or at least half of their length (or at least 2 / 3 of their length, or with their entire length) above the layer formed by the tip of the female main spikes within a plot or production area. In one embodiment, the majority of said GA-responsive male plants become at least 4 cm, at least 5 cm, at least 10 cm, or at least 15 cm taller at the start of flowering, or just before flowering, such as at Z59, upon the application of gibberellic acid between Z25 and 250, than the majority of the female plants. In one embodiment, the male plants are shorter than the female plants at Z59 in absence of GA treatment, and pollination of the female rows by said male plants can already be improved when the male plants are GA-responsive and become as tall as the female plants after application of gibberellic acid on said male plant rows. If the female plants are not or low responsive to GA, then the GA can be applied over the entire field, and only the GA-responsive male plants will significantly increase their plant height, but the GA can then also only be applied on the male rows to reduce costs and amount of GA solution needed. In one embodiment of this invention, the GA application as described herein is applied / sprayed only on the male plant rows, or the GA application is selectively done on the male plant rows, so that GA is applied on the male plant rows and not on the female plant rows. BASF SE 241312 241312

[0044] As used herein, not or low GA-responsive when referring to plants in a field, refers to plants treated with GA in the field having less than 12 % (or less than 10 %, less than 9 %, less than 8 %, less than 7 %, or less than 6 %) increase in plant height at the start of flowering, or just before flowering, such as at Z59, compared to said plants when not treated with GA. In one embodiment, not or low GA-responsive female (male-sterile) plants refers to the plants in the preceding sentence that are at least 5 cm, at least 10 cm, or at least 15 cm shorter (after GA application from Z25 to Z50) at the start of flowering, or just before flowering, such as at Z59 (or at the end of flowering), than the matching GA-treated GA- responsive male plant used to produce hybrid seed with said female plant in hybrid seed production field.

[0045] The selective elongation of the GA-responsive male plant line by means of foliar application of GA, allows better cross-pollination on the female plants rows.

[0046] In one embodiment, GA application causes a height increase of the male plants so that the heads of the male plants are at a higher level when compared to untreated male plants, and cross-pollination is improved. If GA application causes a height increase of the main tiller of the male plants so that the main tiller heads stand out above the female heads by 5 to 15 or 10 to 15 cm, cross-pollination will be further improved, as then several male anthers will be above the female flowers. In one embodiment, GA application causes a height increase of the male plants so that the majority of the main tiller spikes of the male plants stand out above the majority of the main tiller spikes of the female plants by at least 5 cm, by at least 10 cm, or by 10 to 30 cm (such as by 15 to 30 cm, by 20 to 30 cm, by 10 to 20 cm, or by at least 15, by at least 20 cm; or by (at least) 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29 or 30 cm), such as at or (just) before pollina- tion / flowering and / or at or just before harvest. The row planting / sowing of the current invention allows easy selective removal, destruction or harvesting of the male plants.

[0047] In one embodiment the seeds are sown using a smart / precision planting / sowing equipment, wherein the preferred sowing pattern of the invention is obtained.

[0048] In one embodiment, separate bags or containers are attached to a smart planter or emptied in separate channels of a smart planter so that each male and female seed can be sown at a pre-set location and seed density in the field by said planter.

[0049] In one embodiment, the (male-sterile) female or A line used herein is a dwarf or semi-dwarf line. BASF SE 241312 241312

[0050] In one embodiment, the male sterility is based on cytoplasmic male sterility (CMS), chemically-induced male sterility (using a CHA or chemical hybridisation agent) or genic male sterility. An embodiment of genic male sterility is one wherein the male sterility is a recessive gene, and the restorer gene is linked to a phenotypic marker gene, such as a color gene. In one embodiment, the male sterility is not transgenic, in another embodiment the male sterility system was produced using genome editing, such as gene knock out of a critical male fertility gene (typically in all functional versions of that gene in the plant genome).

[0051] Purity of hybrid seeds and the (cost) efficiency of both hybrid seed production and efficient A line maintenance (in systems where this is done using fertile maintainer (B line) plants that are very similar to the male-sterile A line (but are fertile), such as in a CMS hybrid system) are key factors for commercial success of cereal, such as wheat, hybrids. These aspects are expected to be significantly improved by the current invention. In one embodiment of the invention, the female plants are male-sterile A line plants (such as CMS A line plants with a cytoplasm causing sterility), and the male plants are the fully fertile B-line maintainer plants (near-isogenic or very similar to the A-line plants but with a normal cytoplasm), that will pollinate the A line plants so as to produce sterile seed and maintain the male-sterile female plant. In another embodiment of the invention, the female plants are any type male-sterile plants (such as CMS A line plants with a cytoplasm causing sterility, or plants made sterile by a CHA treatment, or 2-line genic male-sterile plants), and the male plants are plants selected to produce good hybrid seed with that female plant, and that male will restore the male sterility so that fertile hybrid seed is produced on the female plants. For CHA-treated or 2-line genic sterile plants, any normal cross-pollinating fertile plant will typically restore the male sterility, for the CMS sterile plant, the male plant will typically need one or more restorer (normally 2-3) genes. Hence, the agricultural field or methods of the invention, as described herein, can relate to hybrid seed production (from matching fertile male and male-sterile female parent lines) or to male-sterile (A line) seed production (such as in a 3-line hybrid system, like the Triticum timopheevii (Tti) CMS system) (from matching A-line and it’s maintainer or B-line parent lines).

[0052] Gibberellins which may be useful in the present invention include gibberellins GA1 , GA3 (= gibberellic acid), GA4 and GA7, in one embodiment this is gibberellic acid or GA3 (also known as Gibberellin A3 or GA3). Gibberellins are well known in the art (e.g., Yamaguchi, Ann. Rev. Plant Biology 59:225-251 (2008); Gao and Chu, Plant and Cell Physiology, 61 :1902-1911 , world wide web at: doi.org / 10.1093 / pcp / pcaa104 (2020)). BASF SE 241312 241312

[0053] In one embodiment, testing if a plant is GA-responsive, as used herein with respect to plant height increase, is easily done by foliar application of GA in the field and by later checking or measuring plant height (such as just before flowering (e.g., at Z59)), when compared to the same plants when not treated with GA. Also, height difference between GA-treated male and (GA-treated or untreated) female plants can be measured before pollination, and compared to untreated plants or to a control treatment without GA (such as water or the same solution as the GA treatment including any solvents, adjuvants or surfactants used, but without the GA). Checking if a fertile male parent plant is taller than a female (male- sterile) parent plant after GA application is easily done, as it can immediately be seen if the male heads are at the same height as the female heads, or if and how much the male plant heads stand above the height of the female heads.

[0054] An initial test to determine GA-responsiveness of a plant line in accordance with the invention, and which can be used to pre-select candidate male and female plants to be used in the invention is checking if a significant height difference is measured in the length of the coleoptile and / or the first leaf of the seedling in a seedling growth assay, between seeds of that plant line treated with water (or the same solution as the GA treatment, but lacking the GA) and seeds of that plant line treated with a GA-containing solution, where the length measurement is several days after the GA application. E.g., seeds can be dipped in water (or control solution without GA) or GA solution for some minutes, air dried, and then sown at the same depth in soil, and grown as usual, and then the height from the soil to the tip of the seedling can be measured after several days (e.g., after a week or 10 days) - if a significantly taller seedling is measured after GA application compared to the control, the plant line is GA-responsive. In one embodiment, the method as described herein is used (essentially treating seeds with either GA or control solution, stratifying or pre-germinating the seeds, then planting / sowing them in soil, and measuring the height of the seedling that has grown from the seeds, and checking if there is a significant height difference between control and GA treatment), but in another embodiment published GA seedling growth tests such as those described by Pavlista et al. (2013, American Journal of Plant Sciences 4, pp. 2015-2022) or Chen et al. (PLoS ONE 9: e86431 (2014), world wide web at: doi:10.1371 / journal. pone.0086431) can be used. Seeds of plants that show a significant increase in seedling height when treated with GA in this seedling growth assay (compared to untreated seeds) are candidate male parent plants for use in the invention. In one embodiment this increase is expressed as % height increase compared to untreated control, since the absolute height can be different in different seedlings. BASF SE 241312 241312

[0055] In one embodiment, the desired difference in GA responsiveness between a particular male and a female parent combination depends on the height of the male and female plant without the application of GA. The primary goal of the GA application in the context of this invention is to create a situation in which the majority of the male main spikes are at the height of the female spikes or at least stick out by half of their length (or 2 / 3 or entirely) above the layer formed by the majority of the tips of the female main spikes within a plot or production area. Therefore, in case where the male of two particular hybrid parents is intrinsically shorter than the female a higher GA dose may be required, as compared to a situation where the male is of approximately the same height as the female.

[0056] The presence of GA-sensitive Rht (reduced height) alleles allows a height response if GA is applied, whereas plants carrying GA-insensitive Rht alleles do not respond to GA. In this regard, this application refers to the term as used in the literature that refers to Rht al- leles / genes as either being “GA-insensitive” or “GA-sensitive”, when referring to Rht al- leles / genes. If none of the (semi-)dwarf Rht genes is present in a plant, so that no reduced height is obtained, the plant is GA-responsive. Wheat plants that have both a GA-sensitive and a GA-insensitive Rht allele (so-called sesqui dwarfs) are GA-insensitive. Known Rht genes said to be GA-sensitive in wheat include Rht4, Rht5, Rht7, Rht8, Rht9, Rht12, Rht13, Rht14, Rht15, Rht16, Rht18, Rht20, Rht24 and Rht25. Known Rht genes said to be GA- insensitive in wheat include Rht-B1 , Rht-D1 , Rht-B1 c, Rht-B1 c semi-dwarf mutants like Rht-B1 c.21 , Rht-B1 c.23 or Rht-B1c.26 described in WO2014 / 028980, Rht10, and Rht11 . In one embodiment the wheat genotypes in the GA-responsive (male) plants of the invention mostly contain Rht24 (and no GA-insensitive Rht gene).

[0057] Also some other genes are known to reduce plant height in wheat, and are independent of the GA pathway, and hence should be GA-sensitive, such as ZnF deletion / inactivation resulting in semi-dwarf wheat plants (see, e.g., Song et al. Nature 617, 1 18-124 (2023), world wide web at: doi.org / 10.1038 / s41586-023-06023-6). Hence, GA-responsive semi-dwarf wheat plants with ZnF deletion or inactivation (and without any GA-insensitive Rht genes) can also be used in male plants of the invention.

[0058] In one embodiment of the invention, the male parent plants contain no known Rht gene causing reduced height (such as wild-type tall Rht gene like Rht-B1 a or Rht-D1 a), or contain Rht8, Rht13, Rht18, Rht25, or contain Rht24 as height reduction gene. In one embodiment the cereal plants of the invention are wheat plants (including common / bread wheat (Triticum aestivum), durum wheat (Triticum durum), einkorn (Triticum monococcum), Khorasan wheat (T. turgidum ssp. turanicum), spelt (Triticum spelta), or emmer (T. tur- gidum subsp. dicoccum )), such as hexapioid spring or winter wheat, or are the closely BASF SE 241312 241312 related barley (Hordeum vulgare), rye (Secale cereale) or Triticale plants (Triticale is a cross between wheat (Triticum durum or Triticum aestivum) and rye). In one embodiment of the invention, the cereal plants of the invention are plants sown or planted in the fall and harvested in the spring or summer in the next year (they need a colder period (vernalization) to flower), such as winter wheat, winter durum wheat, winter einkorn, winter spelt, winter barley, winter rye, winter Triticale, etc..

[0059] In one embodiment, in a hybrid parent pair for hybrid seed production, the male plants are taller than the female plants in the field (at the start of flowering) and this height difference is caused by GA application in the field over said male plants, and does not exist or is significantly less pronounced in absence of any GA application in the field or over the male plant rows.

[0060] In one embodiment, the GA solution contains one or more auxiliaries or surfactants. Suitable auxiliaries include solvents, liquid carriers, solid carriers or fillers, surfactants, dispersants, emulsifiers, wetters, adjuvants, solubilizers, penetration enhancers, protective colloids, adhesion agents, thickeners, humectants, repellents, attractants, feeding stimulants, compatibilizers, bactericides, anti-freezing agents, anti-foaming agents, colorants, tackifiers and binders.

[0061] Suitable surfactants include surface-active compounds, such as anionic, cationic, non-ionic and amphoteric surfactants, block polymers, polyelectrolytes, and mixtures thereof. Such surfactants can be used as emusifier, dispersant, solubilizer, wetter, penetration enhancer, protective colloid, or adjuvant. Examples of surfactants are listed in McCutcheon’s, Vol.1 : Emulsifiers & Detergents, McCutcheon’s Directories, Glen Rock, USA, 2008 (International Ed. or North American Ed.).

[0062] Suitable anionic surfactants or (ammonium) salts of sulfonates, sulfates, phosphates, carboxylates, and mixtures thereof. Examples of sulfonates are alkylarylsulfonates, diphenylsulfonates, alpha-olefin sulfonates, lignine sulfonates, sulfonates of fatty acids and oils, sulfonates of ethoxylated alkylphenols, sulfonates of alkoxylated arylphenols, sulfonates of condensed naphthalenes, sulfonates of dodecyl- and tridecylbenzenes, sulfonates of naphthalenes and alkyhnaphthalenes, sulfosuccinates or sulfosuccinamates. Examples of sulfates are sulfates of fatty acids and oils, of ethoxylated alkylphenols, of alcohols, of ethoxylated alcohols, or of fatty acid esters. Examples of phosphates are phosphate esters. Examples of carboxylates are alkyl carboxylates, and carboxylated alcohol or alkylphenol ethoxylates. BASF SE 241312 241312

[0063] Suitable nonionic surfactants include alkoxylates, N-subsituted fatty acid amides, amine oxides, esters, sugar-based surfactants, polymeric surfactants, and mixtures thereof. Examples of alkoxylates are compounds such as alcohols, alkylphenols, amines, amides, arylphenols, fatty acids or fatty acid esters which have been alkoxylated with 1 to 50 equivalents. Ethylene oxide and / or propylene oxide may be employed for the alkoxylation, preferably ethylene oxide. Examples of N-subsititued fatty acid amides are fatty acid glucamides or fatty acid alkanolamides. Examples of esters are fatty acid esters, glycerol esters or monoglycerides. Examples of sugar-based surfactants are sorbitans, ethoxylated sorbi- tans, sucrose and glucose esters or alkylpolyglucosides. Examples of polymeric surfactants are home- or copolymers of vinylpyrrolidone, vinylalcohols, or vinylacetate.

[0064] Suitable cationic surfactants include quaternary surfactants, for example quaternary ammonium compounds with one or two hydrophobic groups, or salts of long-chain primary amines. Suitable amphoteric surfactants include alkylbetains and imidazolines. Suitable block polymers include block polymers of the A-B or A-B-A type comprising blocks of polyethylene oxide and polypropylene oxide, or of the A-B-C type comprising alkanol, polyethylene oxide and polypropylene oxide. Suitable polyelectrolytes include polyacids or polybases. Examples of polybases are polyvinylamines or polyethyleneamines.

[0065] Examples of adjuvants or surfactants that can be used in a GA solution are Mero® (an emulsifiable concentrate containing rapeseed fatty acids esters and ethoxy (7) tridecanol, see world wide web at: assets.ctfassets.net / l2hapltrg3cz / 3owDAX- TrHeGTHmnE81 P2C1 / 4de0957699e32094a7a50740e6a296b8 / mero_gb_ra6a.pdf) or Actirob® (an emulsifiable concentrate containing rapeseed oil methyl ester, see world wide web at: www.edppiveteau.fr / files / notices / actirob-b-securite-52ecbb172af4a.pdf), or any emulsifiable concentrate containing plant fatty acid esters, such as oilseed rape oil fatty acid esters. In one embodiment, the GA solution is neutral or weakly acidic. In one embodiment, the GA solution is a solution containing GA3, optionally containing a surfactant, that has been registered for use on wheat or cereals, particularly wheat, barley, rye, ortriticale. In one embodiment, the adjuvant or surfactant is Heliosol® (Terpineol (CAS n°8000-41-7) emulsifiable concentrate, from Action Pin (world wide web at: agriculture. actionpin. com / en / produit / adjuvants / heliosol)), or Gondor® (lecithin emulsifiable concentrate, from De Sangosse (world wide web at: www.desangosse.fr / produit / gondor / ), or Exsentia® (methyl esters + ammonium sulphate, from De Sangosse (world wide web at: www.desan- gosse.fr / produit / adjuvant-exsentia-in-tech / )), or any other adjuvant authorized / registered for use with a PGR. BASF SE 241312 241312

[0066] In one embodiment, the GA solution of the invention includes a surfactant to increase uptake of the GA by the plant.

[0067] In one embodiment, a seed treatment is applied on the male and female seeds as used herein. In one embodiment, seed treatments with different color are used so that the male seeds have a different color from the female seeds after application of said seed treatment, and can be readily distinguished in a seed bag containing a mix of male and female seeds.

[0068] In one embodiment, the first GA application to the cereal, such as wheat, plants of the invention in the field is done after sowing or after seed germination, particularly after / at growth stage Z25 on the Zadoks growth scale and before heading, particularly before growth stage Z51 , such as before growth stage Z50 on the Zadoks growth scale.

[0069] In one embodiment, in jurisdictions where such processes are excluded from patent protection, any of the methods or uses described herein is not an essentially biological process for the production of plants. In one embodiment, in jurisdictions where such processes are excluded from patent protection, any of the methods or uses described herein does not contain a step of sexual crossing or selfing of plants (in one embodiment, such method or use is before the first spike starts flowering, or after the last spike ends flowering, such as when all plants are fully mature and ready for harvest). In another embodiment, in jurisdictions where such processes are not excluded from patent protection, included herein are methods or uses including the pollination of (male-sterile) female plants by (fertile) male plants to produce hybrid seed, and the selfing of male plants.

[0070] In one embodiment, the GA treatment of the invention to the male plants of the invention is an application of GA between stages Z25 to Z59, such as between Z25 and Z50, between Z25 and Z49, between Z25 and Z48, or before heading or before Z50, which can be followed by a second later application on said male plants of GA (as needed) between stages Z30 to Z59, such as between Z40 and Z50. In one embodiment, the GA treatment of the invention is an application of GA between stages Z30 to Z36, which can be followed by a second application of GA (as needed) between stages Z37 to Z59, Z38 to Z59, Z39 to Z59, or Z38 to Z59, so as to sufficiently increase male plant height. In one embodiment, the GA treatment of the invention is an application of GA at stage Z30, at stage Z31 , at stage Z32, at stage Z33, at stage Z34, at stage Z35, or at stage Z36, which can be followed by a second application of GA (as needed) at stage Z37, at stage Z38, at stage Z39, at stage Z40, at stage Z41 , at stage Z42, at stage Z43, at stage Z44, at stage Z45, at stage Z46, at stage Z47, at stage Z48, at stage Z49, at stage Z50, at stage Z51 , at stage Z52, at stage Z53, at stage Z54, at stage Z55, at stage Z55, at stage Z57, at stage Z58, or at stage Z59 BASF SE 241312 241312 so as to sufficiently increase male plant height in hybrid seed production, particularly in the current scheme of planting / sowing of female male-sterile plants and fertile male plants. In one embodiment, a third GA application can be envisaged if insufficient male height increase was obtained with the above two GA applications in a certain field (e.g., due to unfavorable environment), and that third GA application is between stages Z40 and Z59, or between Z40 and Z50. In one embodiment, that third GA application is between Z40 and Z60. In one embodiment, the third GA treatment of the invention is an application of GA at stage Z40, at stage Z41 , at stage Z42, at stage Z43, at stage Z44, at stage Z45, at stage Z46, at stage Z47, at stage Z48, at stage Z49, at stage Z50, at stage Z51 , at stage Z52, at stage Z53, at stage Z54, at stage Z55, at stage Z55, at stage Z57, at stage Z58, or at stage Z59, or at stage Z60, or between Z41 and Z59. A later GA application such as a second and / or third GA application is an option, and depends on the height difference caused by the earlier GA application, and the intended height difference at anthesis. In one embodiment of the invention, the GA application over the male plants (either selectively on the male plant rows or over the entire field of (GA-responsive) male and (nor or low GA- responsive) female plants) as described herein is after sowing and before heading, or is after sowing and before the start of anthesis.

[0071] In one embodiment, the GA treatment is an early application at (around) Z30, leaving the option later in the season (e.g. at around Z48 or even later), to apply GA a second time in case the first GA application fails due to environmental effects (such as drought and or too much rain) or due to insufficient difference in responsiveness of the male to obtain the desired height increase with respect to the female (and similarly a 3rd GA application may be done when there is insufficient effect from a 1st and / or 2nd GA application).

[0072] Z stages as used herein refer to the Zadoks cereal growth staging scales (“Zadoks growth scales” herein, see Zadoks et al., Weed Research 14:415-421 (1974), world wide web at: / / en.wikipedia.org / wiki / Cereal_growth_staging_scales). A comparison to other ce- real / wheat growth stage scales (such as Feekes and BBCH scales) and figures and terms for plant parts at several growth stages can be found in Celestina et al. (Eur. J. Agronomy 147(2023)126824:1-22, world wide web at: doi.org / 10.1016 / j.eja.2023.126824), or can be found at the world wide web at: en.wikipedia.org / wiki / Cereal_growth_staging_scales, or can be found at the world wide web at: www2. ca . u ky . ed u / ag co m m / pu bs / ag r / ag r224 / ag r224. pdf . BASF SE 241312 241312

[0073] In one embodiment, the GA application on said cereal, such as wheat, plants can be combined with a herbicide or fungicide active ingredient (as tank-mix or application from separate tanks on the same tractor), for example an early GA application (around Z30) with a herbicide and a later GA application (e.g. Z37 to Z50) with a foliar fungicide.

[0074] In one embodiment, the GA-responsive male plant of the invention has no known GA- insensitive allele resulting in (semi-)dwarf growth in wheat, or has no known GA-insensitive allele and has a GA-sensitive (semi-)dwarf Rht gene which can be a native gene or a mutated gene, including but not limited to an Rht gene such as Rht8, Rht13, Rht18, Rht25, or Rht24, or has no known GA-insensitive allele and has a non-Rht GA-sensitive gene causing (semi-)dwarf growth, such as a deleted / inactivate ZnF gene (Song et al. Nature 617, I I S- 124 (2023), world wide web at: doi.org / 10.1038 / S41586-023-06023-6).

[0075] In one embodiment of the invention, if there is an application of GA, then:

[0076] -any GA, such as GA3, applied on female plants (not or low GA responsive) will not cause a significant hybrid seed yield loss (while males can have a significant seed yield loss after GA application),

[0077] -the male flowering period is not reduced or is enlarged by application of GA, such as GA3, on the male plants (there is no delay in male flowering, and no shortening of the pollination period of the male plants, after application of GA on male plant rows),

[0078] -ideally, the male plants / heads are removed / cut after pollination or before harvest of hybrid seed, or the male plant seeds are separately harvested from the male plant rows before the hybrid seed is harvested.

[0079] According to one embodiment, the male is a strong tillering male, and the female a reduced tillering female, as there is genetic diversity in this phenotype. The female can have the “tiller inhibition” or “tin” gene, that causes less tillering, as for example described in: P.W. Hendriks, J.A. Kirkegaard, J.M. Lilley, P.J. Gregory, G.J. Rebetzke, A tillering inhibition gene influences root-shoot carbon partitioning and pattern of water use to improve wheat productivity in rainfed environments, Journal of Experimental Botany, Volume 67, Issue 1 , January 2016, Pages 327-340, world wide web at: doi.org / 10.1093 / jxb / erv457.

[0080] In one embodiment, the method further comprises the step of: BASF SE 241312 241312 pushing down the male plant rows when harvesting the hybrid seeds from the female plant rows, so that the male seeds are not harvested with the hybrid seeds (but can be separately harvested afterwards, if desired), in particular by using a device attached to the harvesting machine, treating the male rows, in particular mechanically (like cutting) or chemically (like by herbicide treatment (e.g., herbicide wicking)), after flowering to prevent seed set or prevent seed set of fully developed seeds so as to increase hybridity or hybrid seed purity, in particular by either not harvesting any male seeds or sorting out shrivelled (chemically (such as herbicide)-treated) male seeds from the harvested seeds. Pushing down the male plant rows when harvesting the hybrid seeds from the female plant rows can ensure that primarily the female plant rows are harvested.

[0081] According to one embodiment, the method further comprises the step of: planting / sowing at least one additional male seed border row around the male and female rows, wherein the at least one additional male seed border row preferably surrounds the male and female rows; or ensuring that the outer rows sown / planted in the field are male (seed / plant) rows. In one embodiment, a male border row is added to a field not having a male row as outer row on one or both sides of the field, such as in a field with rows sown perpendicular to the prevailing wind direction in the area, (if the extreme left row is a female row, a male row is sown at the left of that female row, if the extreme right row is a female row, a female row is sown at the right of that female row, and if the extreme left and the extreme right row are a female row, then a male row is sown at either side of the field). In one embodiment, a male border row can also be sown around the entire field, so that also at the top and the bottom of each row there is a male border row, e.g., the outside row in any direction is a male row.

[0082] By planting / sowing at least one additional male seed border row around the male and female rows (such as perpendicular to the prevailing wind direction), the prevailing direction of the wind may blow pollen from that male border row to the female rows. In one embodiment of the invention, it is preferred that the outer rows of a field (at the West and East side of the field, if the prevailing wind direction in that field is West-East, with the rows perpendicular to the prevailing wind direction) are a male row (at least one male row). In one embodiment of the current invention, no devices are used to artificially stimulate pollination during flowering, such as mechanically touching / shaking plants (by rope, stick or chain, etc. to release pollen from male flowers), and / or by blowing wind using a blowing device, a helicopter, drone, etc. (causing movement of pollen from male to female flowers) - a tractor driving through a field for standard agronomy practices, like spraying a fungicide or herbicide, is not considered a device to artificially stimulate pollination. BASF SE 241312 241312

[0083] Preferably, the seed is selected from at least one of the following: wheat (including common / bread wheat (Triticum aestivum), durum wheat (Triticum durum), einkorn (Triticum monococcum), Khorasan wheat (T. turgidum ssp. turanicum), spelt (Triticum spelta), or emmer (T. turgidum subsp. dicoccum), such as hexapioid spring or winter wheat), rye (Secale cereale), barley (Hordeum vulgare), triticale (a cross between wheat and rye).

[0084] In another aspect, the invention relates to a seed sowing device for sowing hybrid cereal parent seeds in an agricultural field, the seed sowing device comprising a sowing arrangement, wherein the sowing arrangement is configured for sowing at least one pair of male- sterile female seed strips, each strip containing several female seed rows spaced apart from one another, wherein the female rows are planted / sown with a first seed density, sowing a male seed row in-between the pair of the female seed strips with a second seed density, wherein the sowing arrangement is configured to plant / sow the male seed row with a lower seed density than the female seed rows and wherein a second surface area of the male row is smaller than a first surface area of the female rows, wherein the device is adapted to sow and / or plant according to the method of any one of the preceding embodiments. The seed sowing device takes advantage of the same benefits and preferred embodiments as the method according to the invention and vice versa. In this regard and in order to avoid unnecessary repetitions, reference is made to the above explanations and their content is included herein.

[0085] In another aspect, the invention relates to a use of a seed sowing device according to the previous embodiment in order to conduct a method according to any one of the previous embodiments. Also the use takes advantage of the same benefits and preferred embodiments as the method and the seed sowing device and vice versa. In this regard and in order to avoid unnecessary repetitions, reference is made to the above explanations and their content is included herein.

[0086] In yet another aspect, the invention relates to a hybrid (or male-sterile) seed (produc- tion / breeding / testing) agricultural field. According to the invention, the hybrid (or male-sterile) seed agricultural field is obtained by a method according to any one of the previous embodiments. Also the hybrid (or male sterile) seed agricultural field takes advantage of the same benefits and preferred embodiments as the method, the seed sowing device and BASF SE 241312 241312 the use according to the invention and vice versa. In order to avoid unnecessary repetitions, reference is made to the above explanations and their content is included herein.

[0087] For a more complete understanding of the invention, the invention will now be described in detail with reference to the accompanying drawings. The detailed description will illustrate and describe what is considered as a preferred embodiment of the invention. It should of course be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention may not be limited to the exact form and detail shown and described herein, nor to anything less than the whole of the invention disclosed herein and as claimed hereinafter. Further, the features described in the description, the drawings and the claims disclosing the invention may be relevant for the invention considered alone or in combination. In particular, any reference signs in the claims shall not be construed as limiting the scope of the invention. The wording “comprising” does not exclude other elements orsteps. The wording “a” or “an” does not exclude a plurality. In one embodiment of the invention, “a male row”, as used herein, mostly refers to one male row (a single male row, bordered by adjacent female rows)).

[0088] This invention will now be described with reference to the accompanying drawings, which illustrate, by way of example and not by way of limitation, one of several possible embodiments of the method and device as proposed herein, and wherein:

[0089] Fig. 1 : shows an embodiment of an agricultural field comprising a planting / sowing scheme to illustrate the benefit to be obtained by reducing male seed density (large boxes with M15 represent the male row plots, small boxes represent 3 different male-sterile female plant plots (flowering at different times));

[0090] Fig. 2a: shows the results of a field trial with regard to the yield of hybrid seed produced on different females pollinated by the same male planted at different seed densities (as in the scheme in Fig. 1); the 3 A lines shown are from left to right: F3 (late flowering female), F2 (mid flowering female), and F1 (early flowering female);

[0091] Fig. 2b: shows the contrast (in %) for hybrid seed yield forthree different female plants for different seed densities; the 3 A lines shown are from top to bottom; F3 (late flowering female), F2 (mid flowering female), and F1 (early flowering female); BASF SE 241312 241312

[0092] Fig. 3a: shows an embodiment of a modified seeding disk for planting / sowing the male rows with a reduced seed density (the lines in bold are open seed channels, the normal lines indicate where normally other seed channels are but those are closed or not existing / manufactured seed channels, this disk will sow 2 seeds close by (1 .5 or 3 cm apart depending on the speed) and then the next 2 seeds will be at 12 or 24 cm from those 2 seeds (depending on speed);

[0093] Fig. 3b: shows an embodiment of rows planted with different seed densities, wherein the male rows (left) have a lower seed density than the female rows (right) (again, lines in bold are the open seed channels);

[0094] Figs. 4a, 4b: show alternative embodiments of modified seeding disks;

[0095] Figs. 5a, 5b: show embodiments of hybrid seed agricultural fields obtained by a method according to the invention.

[0096] Fig. 6: shows an alternative embodiment of a hybrid seed agricultural field plot according to the invention.

[0097] Fig. 7: shows the overall lay-out of an alternative embodiment of a hybrid seed agricultural field according to the invention.

[0098] The figures will now be described with reference to the following examples:

[0099] EXAMPLES

[0100] 1 . Concept testing for low density male planting

[0101] 1A. Low density male planting concept testing

[0102] As initial test to check the effect of planting male parent lines at lower seed density towards the pollination window, a test was set up in Belgium, where a male wheat parent plant (here M15, genotype PMWH84562645) was planted either at 250 plants / m2or at 75 plants / m2, and the number of spikes produced was analyzed. As seen in Table 1 below, it was noted that male plants growing at 250 plants / m2had on average 2.2 spikes per plant, while male plants growing at 75 plants / m2had on average 4.5 spikes per plant. Also, it was noted that spikes on higher order tillers (on tertiary and later tillers) develop later than on the initial | BASF SE | 241312 | 241312 spikes. Hence, this suggested that sowing / planting plants at lower density enlarged the pollination window, though it was also noted that (later) tillers were shorter and less pollen is produced at a given time.

[0103] Table 1 .

[0104] 1 B. Low density male planting yield test in AxR row planting in the field

[0105] A field trial was done in Belgium, wherein rows of fertile male (restoring Tti CMS) wheat plants (also M15 male) were planted in rows of 19 m long with 9 rows of male plants forming the male bay, planted at either 300 seeds / m2or at 150 seeds / m2(at a row spacing of 12,5 cm, 150 seeds / m2is eguivalent to an average within row distance of 4.7 cm). The planting scheme is shown in Fig. 1. Next to the long male row blocks were smaller blocks of 3 different female (male-sterile) plants (with Tti CMS), with one female line F1 being early flowering (genotype PMWH140333311), one female line F2 mid flowering (genotype PMWH153972629), and one female line F3 late flowering (genotype PMWH125377677). Female blocks were 2 m long, with 6 rows of female plants per block.

[0106] The results of the field trial are shown in Figs. 2a and 2b, with Fig. 2a showing the yield (in tons / hectare) of hybrid seed produced on the different females by the M15 male planted at 150 or 300 seeds / m2, and Fig. 2b showing the % contrast for hybrid seed yield for the 3 different female plants when comparing 300 versus 150 seeds / m2.

[0107] Clearly, lower male plant density significantly improved the cross-pollination of A lines (see Figs. 2a and 2b). The difference was biggest for late or mid-flowering female, which might be in part explained by the fact, that the seed set of the early flowering female with the high density planting of the male, was already high. Beyond, this strongly indicates that the pollen production window was enlarged mainly in the direction of later pollen release with the BASF SE 241312 241312 lower seeding density of the male, as would be expected from additional and later formed productive tillers.

[0108] 2. Lower male seed density using Wintersteiqer Triplot Dynamic Plus

[0109] To implement a lower seed density of male plant seeds in an existing sowing equipment, a Wintersteiger Triplot Dynamic Plus seeder was equipped with modified seeding discs for the male rows. Different sets of discs were produced with limited amount of channels to increase the distance between the seed planted in the male plant rows, while keeping normal high seed density for the female plant rows.

[0110] In one setup, the male plant seed disc was constructed, so that only 2 times 2 adjacent channels were constructed at opposing sides of the seeding disk in comparison to 18 equally spaced channels for the female disk. The 2 adjacent channels are manufactured with the same distance as in the 18 channel disk, so that 2 seeds were planted close together (e.g. 1 ,5 cm apart) when the distance between female seeds was set at 1 .5 cm (by adapting the rotation speed of the seed disc), and at such female seed distance there will be 12 cm distance between the 2 male seeds and the next 2 male seeds in the male row, while there would be 24 cm between the 2 male seeds and the next 2 male seeds in the male row when the distance between female seeds is set at 3 cm (see Fig. 3a and 3b). Distance between male and female rows is fixed at 20 cm.

[0111] Since the discs can be used at different rotation speeds, different within row planting distances can be obtained. In this example, the female plant distance was set at 1 .5 cm (high density) or 3 cm (low density), which then ensured a higher or lower male seed density, respectively. The low female seed density equals approximately 130 female plants per square meter, the high female seed density approximately 260 female plants per square meter. It is preferred that female seed density is high so tillering is low and yield per area is high, while for the male row it is preferred that tillering is high so that the pollination window is extended. Under circumstances were amount of seeds are limiting, a lower seeding density might be preferred, since the amplification rate is usually maximized as compared to higher density planting.

[0112] In a second setup shown in Fig. 4a, the male plant seed disc was manufactured with only 6 equally spaced channels so that each male seed is planted at 1 / 3 of the density of a female seed, if the normal seeding disk (containing 18 evenly distributed channels) is used for the female rows. This results into 4,5 cm distance of male seeds when the distance BASF SE 241312 241312 between female seeds was set at 1 .5 cm (high female seed density, by adapting the rotation speed of all seed discs), and the male seed is planted at 9 cm distance when the distance between female seeds is set at 3 cm.

[0113] In a third setup, the male plant seed disc was manufactured in a way that 3 times 2 adjacent channels were placed in equal distance across the disk and the adjacent channels were made at the same distance as in the 18 channel disk, (see Fig. 4b). This resulted in a planting pattern in which 2 male seeds were planted close together (1 ,5 cm apart) when the distance between female seeds was set at 1 .5 cm (by adapting the rotation speed of the seed disc), and at such female seed distance there will be 7.5 cm distance between the 2 male seeds and the next 2 male seeds in the male row, while there will be 15 cm distance between 2 male seeds and the next 2 male seeds in the male row when the distance between female seeds is set at 3 cm. The choice for 2 adjacent seeding channels in the manufactured seeding disks shown in Fig 3a and 4b was guided by the fact that in case of failures of plant(emergence)s, the resulting holes in the row, would lead to an undesired low number of males in that row.

[0114] Of course, when you have good seed quality and do not expect loss of seed viability or non-emergence, etc., only 1 male seed can be sown at a time (then using 1 open channel instead of 2 next to each other).

[0115] Fig. 5a and 5b show how the field design can look like in this example, for this specific seeding equipment (planting 6 rows with every pass). The distance between rows is 20 cm, except between different passes where it is 50 cm (to allow space for the wheels).

[0116] In this modified planting scheme, a single male row is planted next to 2 or 3 adjacent female rows, and the maximum distance between male and female rows is 60 cm. Male rows have one or 2 male seeds with a within row distance of 4.5, 7.5, or 12 cm when the female seed density is high (within row distance set at 1 .5 cm) and at 9, 15 or 24 cm when the female seed density is low (within row distance set at 3 cm).

[0117] In Fig 5b, again a single male row is planted next to 2 or 3 adjacent female rows, and the maximum distance between male and female is 60 cm. Male rows have one or 2 male seeds with a within row distance of 4.5, 7.5, or 12 cm when the female seed density is high (within row distance set at 1 .5 cm) and at 9, 15 or 24 cm when the female seed density is low (within row distance set at 3 cm). In addition, at the outer edges of the field, male border rows are planted. BASF SE 241312 241312

[0118] 3. Alternative field trials using lower male seed density

[0119] In another field trial in France, 2 combinations of a male-sterile female wheat parent and a fertile male wheat parent were sown in a modified scheme in accordance with the invention, using a TriPlot Wintersteiger Dynamic Plus seeder (sowing 3 x 6 rows in 3 microplots, each microplot 150 cm wide (20 cm between the rows in each microplot, so 120 cm from 1stto 6throw in each plot, 50 cm between the 6throw in one microplot, and the 1strow in the adjacent microplot) - see Fig. 5a). Lines used were a combination of a male-sterile female line (PMWH140333311 , abbreviated as F1 herein, with Triticum timopheevii CMS (“Tti CMS”)) and a fertile (fertility restoring) male line (PMWH131094139, abbreviated as M9 herein) on the one hand, and a combination of a male-sterile female line (PMWH 166930426, abbreviated as F6 herein, with Tti CMS) and a fertile (restoring) male line (PMWH95085005, abbreviated herein as M5 herein) on the other hand. Both female plants are not or low GA-responsive as described herein, and both males are GA- responsive plants.

[0120] Female seed density was 111 seeds / m2, with a spacing between seeds in a female row of 3 cm (one seed is sown per hole / sowing position, the same spacing between seeds is used in male rows with the difference that in some male row plots a % of de-vitalized seeds were mixed with viable seeds). In this trial, 3 or 4 female rows were sown between 2 (single) male rows, as indicated in Fig. 6 (sown so that the main wind direction is from left to right (West to East) in Fig. 6, with the outer left / West row a male row (the distance between most female rows is 20 cm, the distance between the outer rows in 2 adjacent plots of 6 rows is 50 cm, the length of the rows was 9 m). The ratio male:total rows in each plot was 8:36, or the male rows represent 22,2 % of the total rows per plot, and the total surface occupied by male plants here is 22,2 %. The maximal distance between most female rows and its closest male row (at the West or East side) was 40 cm (24 females in the plot in Fig. 6 are at a maximum distance of 40 cm from their closest male row), with 2 female rows in the plot in Fig. 6 being at a maximum distance of 60 cm form their closest male row, and the extreme right / East female row in Fig. 6 (in absence of a male border row at its right / East) being at a maximum distance of 80 cm from its closest male (with a male border row added 20 cm to the right / East from the extreme right / East female in Fig. 6, the maximum distance from a female to its closest male row is 60 cm (for one female row), and for a male border row sown 50 cm from the extreme right female in Fig. 6, the maximum distance from a female to its closest male row is 60 cm (then for 2 female rows)). For the male rows, 3 different seed densities were used for male sowing : 1) at the same seed density as the female (111 seeds / m2, or at 100% of the female seed density), and 2) at 50 % and 3) at 33 % of the female seed density. This male seed density was achieved by partial male BASF SE 241312 241312 seed deactivation, so that when 50 % seed density was planted, half of the male seeds were devitalized / inactivated (using heating at 120 °C for 8 hrs), and mixed with 50% viable seeds, so that 50 % of the male seed will germinate. Male and female rows were sown at the same time, using the same seed discs for male and female rows (no channels blocked).

[0121] In some plots, GA3 (300 ppm (300 l / ha)) is applied on the male and female plant rows between stage Z45 and Z50 by hand sprayer (“GA3” in Fig. 7), while in other plots, no GA3 is applied (“no GA3” in Fig. 7).

[0122] Harvesting of individual male rows is done by hand, after pollination, and before the overall harvesting of the hybrid seeds from the female plants in the field.

[0123] As control, also a mixed planting plot was included with the same parent lines as above, but where 10 % of the total seeds were male seeds that were mixed with the female seeds, and that mixture was sown.

[0124] The field trial setup as indicated in Figure 6 and 7.

[0125] In Fig. 6, the sowing scheme for one of the plots used in Example 3 is shown, wherein the bolder dashed rows represent the male seed rows, with in between 3-4 female (male- sterile) seed rows. The prevailing wind normally comes from the left side (West) in the Figures.

[0126] In Fig. 7 (not drawn to scale), the overall field scheme with all plots (each 9x9 m, two sowings with the Triplot Wintersteiger Dynamic Plus seeding device (each sowing sows 3 blocks of 6 rows, each 1 .5 m wide (hence the line in the middle of each plot in Fig. 7, to show the 2 sowings), both sowings in the same plot get the same treatment (and the same parent lines)) with the different treatments, for one combination of parent lines M 9 x F1 (plots at the top), and for another combination of parent lines M5 x F6 (plots at the bottom), with (“GA3”) and without (“no GA3”) GA application, with a mixed planting check (10 % male seeds were mixed with female seeds and then sown, so that male plants are randomly growing between female plants), and plots with male seed rows with a seed density 33 %, 50%, and 100 % of the seed density of the female seed rows (which was 111 seeds / m2) obtained by male seed de-activation (hence, respectively 67 %, 50 % and 0 % of the male seed sown is de-activated / non-viable)). BASF SE 241312 241312

[0127] Also, in one field, the same as above is planted, but with a single male row sown as border row at the right / East of the last female in Fig. 6.

[0128] 4. Alternative sowing scheme

[0129] In this scheme, single male rows surround several female rows, with a row spacing of 20- 30 cm between the male and female rows (providing more space for each male plant, so it produces more tillers), and a row spacing of 10-15 cm between the female rows. Seed density of the male rows is 100%, 50 %, or25 % ofthat in the female rows in different plots. The maximum distance of each female to the closest male row is 1 m, such as a maximum distance between each female row and its closest male row of 60-90 cm. E.g., one male row (20-30 cm from the adjacent female row), followed by several female rows (each I Q- 15 cm apart) so that the maximum distance of each female to the closest male row is 1 m or is 60-90 cm, and then one male row (20-30 cm from the adjacent female row), which can be followed by another set of several female rows and one other male row, and this scheme can be repeated to fill an available field, so that the start and end row is a male row, and each male row is a single male row bordered by female rows).

[0130] The distance between seeds in the male row is 10-20 cm (providing more space for each male plant, 1 seed is sown per hole / sowing position), and between seeds in the female row is 1 .5 - 3 cm. Ideally, the male plants are GA-responsive and the female plants are not or low GA-responsive, and GA3 can be applied on the entire field, or GA3 can be applied only on the male plants (then the female plants can be GA-responsive). Harvesting of individual male rows is done after pollination, and before the overall harvesting of the hybrid seeds from the female plants in the field.

Claims

BASF SE241312241312Claims1 . Method for planting or sowing hybrid cereal parent seeds in an agricultural field, the method comprising: planting or sowing at least one pair of male-sterile female seed strips, with each strip containing several female seed rows, wherein the female seed rows are spaced apart from one another and are planted with a first seed density, wherein the female seed rows cover a first surface area on the agricultural field, planting or sowing a male seed row with a second seed density in between the pair of female strips, wherein the male seed row covers a second surface area on the agricultural field, characterized in that the second seed density of the male row is lower than the first seed density of the female rows, wherein the first surface area and the second surface area form a total surface area, and wherein said second surface is less than or equal to 30 % of the total surface area, preferably less than or equal to 27,5 % of the total surface area, more preferably less than or equal to 25 % or less than and equal to 20 % of the total surface area, and wherein the cereal seed is selected from at least one of the following:- wheat (including common / bread wheat (Triticum aestivum), durum wheat (Triticum durum), einkorn (Triticum monococcum), Khorasan wheat (T. turgidum ssp. turanicum), spelt (Triticum spelta), or emmer (T. turgidum subsp. dicoccum ), such as hexapioid spring or winter wheat),- rye (Secale cereale),- barley (Hordeum vulgare),- triticale (a cross between wheat and rye).

2. Method according to claim 1 , wherein the male seed row is a first male seed row and wherein the method comprises: planting / sowing at least one or more further male seed rows spaced apart from one another, wherein between each pair of adjacent male seed rows, strips of 3 - 10 of the female seed rows are planted.

3. Method according to claim 1 or 2, wherein the second seed density of one or more male seed rows is 12,5 % - 50 %, preferably 20 % - 40 %, more preferably 20 % - 30 % of the first seed density of the female rows.

4. Method according to any one of the preceding claims,BASF SE241312241312wherein the female rows are planted at a seed density between 100 seeds / m2and 400 seeds / m2, preferably between 120 seeds / m2and 300 seeds / m2, more preferably between 200 seeds / m2and 266 seeds / m2.

5. Method according to any one of the preceding claims, wherein a spacing between adjacent male and female rows is at least 15 cm or at least 20 cm and is less than 35 cm, less than 30 cm, or less than 25 cm, such as 15-30 cm or 20-30 cm, and / or wherein a spacing between adjacent female rows is less than 15 cm, in particular less than 10 cm.

6. Method according to any one of the preceding claims, wherein a maximum distance of any female plant row to the closest male plant row is 90 or 85 cm, preferably 70 cm, more preferably 65 cm, most preferably 60 cm.

7. Method according to any one of the preceding claims, wherein the female seed rows are planted with a first within row spacing and wherein the male seed rows are planted with a second within row spacing, wherein the second within row spacing of the male rows is 1 .5 - 10 times larger than the first within row spacing of the female rows.

8. Method according to any one of the preceding claims, wherein a within row distance between a single or two male seeds sown to the next within row single or two male seeds sown is 10 cm to 30 cm or 15 cm to 25 cm.

9. Method according to any one of the preceding claims, wherein sowing the male and female rows with the first seed density and second seed density and / or first within row spacing and second within row spacing is achieved by at least one of the following: utilizing seeding disks sowing the male seed rows with different seed density compared to the female rows, sowing the male and female seed rows in two separate passes at two different seeding densities into the same field, utilizing precision sowing equipment configured to sowing male and female seeds at a different seed density in different rows, mixing viable male seeds with non-germinating, devitalized seeds.

10. Method according to any one of the preceding claims,BASF SE241312241312wherein the male rows are sown before the female rows, so as to further increase tillering of the male plants.11 . Method according to any one of the preceding claims, further comprising at least one, or any combination of two or more, of the following steps: applying fertilization, preferably only to the male rows, in order to promote male tillering, applying a seed treatment to the male seeds or male seed rows containing gibberellic acid, applying gibberellic acid over the male plant rows to increase the height of the males and improve cross-pollination, if the male plants increase in plant height after application of gibberellic acid, applying gibberellic acid over the male and female plant rows, if the male plants increase in plant height after application of gibberellic acid (the male plants are GA respon- sive / sensitive) and the female plants do not increase in plant height after application of gibberellic acid or the female plants increase significantly less in plant height after application of gibberellic acid compared to the male plants (the female plants are not or low GA responsive / sensitive), applying plant growth regulator (PGR), in particular only to the female rows, in order to cause shorter female plant heights, applying herbicide, in particular to the female rows, in order to reduce or prevent weed pressure, wherein the herbicide is preferably a selective herbicide, selective application of a solution reducing tillering on the female plant rows, selective application of a solution stimulating tillering on the male plant rows, planting / sowing the female plant rows with a seed mixture containing up to 5 % of male seeds randomly mixed with the female seed.

12. Method according to any one of the preceding claims, further comprising the step of: pushing down the male plant rows when harvesting the hybrid seeds from the female plant rows, so that the male seeds are not harvested, in particular by using a device attached to the harvesting machine, or treating the male rows, in particular mechanically or chemically, after flowering to prevent seed set, or prevent seed set of fully developed seeds, to increase hybridity (hybrid seed purity), in particular by either not harvesting any male seeds or sorting out shrivelled male seeds from the harvested hybrid seeds.BASF SE24131224131213. Method according to any one of the preceding claims, further comprising the step of: planting / sowing at least one additional male seed border row around the male and female rows, wherein the at least one additional male seed border row preferably surrounds the male and female rows.

14. Method according to any one of the preceding claims, wherein the cereal seed is winter wheat, winter barley, winter rye, or winter triticale.

15. Seed sowing device for planting / sowing hybrid cereal seeds in an agricultural field, the seed sowing device comprising a sowing arrangement, wherein the sowing arrangement is configured for planting / sowing at least one pair of male-sterile female seed strips, each strip containing several female seed rows, spaced apart from one another, wherein the female rows are planted with a first seed density, planting / sowing a male seed row in between the pair of the female seed row strips with a second seed density, wherein the sowing arrangement is configured to plant the male seed row with a lower seed density than the female seed rows and wherein a second surface area of the male row on the field is smaller than a first surface area of the female rows, wherein the device is adapted to sow and / or plant according to the method of any of the preceding claims.

16. Use of a seed sowing device according to claim 15 to conduct a method according to anyone of claims 1 - 14.

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