Strawberry cultivation methods

Abstract

To provide a strawberry cultivation method capable of increasing a yield in an early stage.SOLUTION: There is provided a strawberry cultivation method configured so that: to strawberry stocks of strawberry of one season growing type, whose apical buds differentiated to flower buds, long day treatment in which a day length is 16 hours or more, is performed for 7 days to 28 days, the long day treatment being started within 21 days after differentiation of the apical buds to the flower buds.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for cultivating strawberries. [Background technology]

[0002] Because strawberries command a high price in the early season, increasing initial yield (also known as early yield) is crucial. Conventional cultivation techniques involve long-day treatment in the main field during winter to maintain plant vigor and increase yield, thereby increasing yield from early spring onward (Non-Patent Literature 1, Figure 1). However, this cultivation technique has had limited effect in increasing initial yield from December onward. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Yoshida, Yuichi “Strawberry Production in Japan:History and Progress in Production Technology and Cultivar Development”, International Journal of Fruit Science (2013) Volume 13, Issue 1-2: Proceedings of the 2011 North American Strawberry Symposium [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a method for cultivating strawberries to increase early yield. [Means for solving the problem]

[0005] In early autumn, strawberry plants should be kept under short-day conditions as much as possible to stabilize flower bud differentiation, and long-day treatment is not performed during this period. Furthermore, it is standard practice to transplant the plants promptly after confirming flower bud differentiation, and it is said that each day of delay in transplanting can reduce the yield by 1%.

[0006] Contrary to this finding, the inventors have surprisingly discovered that initial yields can be increased by applying long-day treatment of a specific length at a specific timing to strawberry plants in early autumn, and have completed the present invention.

[0007] In other words, the present invention provides, for example, the following: [1] This includes applying a long-day treatment of 16 hours or more for 7 to 28 days to a single-fruiting strawberry plant whose apical bud has differentiated into a flower bud. A strawberry cultivation method in which long-day treatment is initiated within 21 days after the differentiation of the apical bud into a flower bud. [2] The method according to [1], further comprising transplanting strawberry plants after the completion of the long-day treatment. [3] The method of [2] is used to transplant strawberry plants, which is done within 7 days after the end of the long-day treatment. [4] The method according to any of [1] to [3], wherein the length of daylight for long-day treatment is 18 hours or more. [Effects of the Invention]

[0008] According to the present invention, it is possible to increase the early yield of strawberry fruit, which has a high unit price. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a conceptual diagram comparing the strawberry cultivation method of this embodiment with the conventional method. [Figure 2]Figure 2 is a graph showing the effect of long-day treatment on pre-planting seedlings on the marketable fruit yield (g / plant) from December to May of the once-a-year cropping variety (‘Tochiotome’, ‘Fukuoka S6’ (described as ‘Amao’ (registered trademark) in the figure. The same applies hereinafter), ‘Koinori’). ND indicates the results of the plot cultivated under natural day length, and LD indicates the results of the plot with end-of-night lighting using incandescent bulbs for two weeks starting from September 26th. [Figure 3] Figure 3 is a graph showing the effect of long-day treatment on pre-planting seedlings on the leaf area of ‘Koinori’ at the time of seedling raising. The estimated leaf area was calculated as 1.74 × length of the apical leaflet × width of the apical leaflet - 3.49 (referenced from ‘Examination of a regression model for non-destructive and simple estimation of individual leaf area using seed-propagated strawberries Takuji Hata, Zenichi Ito (Faculty of Agriculture, Meiji University) 2019. Hort. Res. (Japan) (Separate) 1:311’). The leaf position was set to ‘0’ for the latest fully expanded leaf at the end of the long-day treatment. The bar of the marker indicates the standard deviation. ※Significant at the 1% level [Figure 4] Figure 4 is a graph showing the effect of long-day treatment on pre-planting seedlings on the petiole length of ‘Koinori’ at the time of seedling raising. The leaf position was set to ‘0’ for the latest fully expanded leaf at the end of the long-day treatment. The bar of the marker indicates the standard deviation. ※Significant at the 1% level [Figure 5] Figure 5 is a graph showing the effect of long-day treatment on pre-planting seedlings on the leaf area of ‘Tochiotome’ and ‘Amao’ (registered trademark) at the time of seedling raising. The estimated leaf area was calculated in the same way as ‘Koinori’ and represented by the total of the estimated leaf areas of the 2nd to 5th leaves (cm2 / individual). ND indicates the results of the plot cultivated under natural day length, and LD indicates the results of the plot with end-of-night lighting using incandescent bulbs for two weeks starting from September 26th. [Figure 6] Figure 6 is a graph showing the effect of long-day treatment on pre-planting seedlings on the petiole length of ‘Tochiotome’ and ‘Amao’ (registered trademark) at the time of seedling raising. The petiole length was represented by the average petiole length (cm) of the 2nd to 5th leaves. ND indicates the results of the plot cultivated under natural day length, and LD indicates the results of the plot with end-of-night lighting using incandescent bulbs for two weeks starting from September 26th. [Figure 7] Figure 7 is a graph showing the effect of long-day treatment and planting time on the monthly marketable fruit yield (g / plant) of ‘Amao’ (registered trademark) seedlings.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] In this specification, "strawberry" means a plant of the scientific name Fragaria×ananassa of the genus Fragaria in the Rosaceae family.

[0011] In this specification, "seedling" means a young plant body among the stocks, especially in the state just grown from seeds and before being planted in the main field, unless otherwise particularly limited.

[0012] In this specification, the target strawberry stock is a once-bearing strawberry stock. In contrast to the ever-bearing strawberries that bear fruits throughout the four seasons, the once-bearing strawberries bear fruits once a year. The once-bearing strawberries are short-day plants, and flower bud differentiation is promoted under short-day conditions. The once-bearing strawberry stocks may be cultivated varieties. Examples of Japanese varieties of once-bearing strawberry stocks include, for example, 'Koi Mirori', 'Fukuoka S6' (hereinafter, also described as "Amaou" (registered trademark)), 'Toriotome', 'Sachinoka', 'Oyama', 'Benihoppo', 'Akihime', 'Amaotome', 'Toyonoka', 'Amaekubo', etc. However, since the effect of the present invention is presumed to be due to the increase in the light-receiving area from the increase in the leaf area and the extension of the petiole by long-day treatment, the effect is considered to be more remarkable in varieties with a compact plant form. Such varieties include, for example, 'Tochiotome', 'Fukuoka S6', 'Sachinoka', 'Toyonoka', 'Amaekubo', 'Oyama', etc. Examples of US varieties of once-bearing strawberry stocks include, for example, 'Fronteras', 'Strawberry Festival', and 'Florida Radiance', etc. Examples of Korean varieties of once-bearing strawberry stocks include, for example, 'Solhyang' and 'Mehyang', etc.

[0013] As one embodiment, the present invention provides a method for cultivating strawberries, which includes applying a long-day treatment of 16 hours or more for 1 to 4 weeks to a single-fruiting strawberry plant whose apical bud has differentiated into a flower bud, wherein the long-day treatment is started within 21 days after the differentiation of the apical bud into a flower bud.

[0014] Using the conceptual diagram in Figure 1, the differences between the strawberry cultivation method of this embodiment and the conventional method will be explained. Both are forced cultivation methods in which harvesting begins around December. For single-season strawberry plants, "cuttings" are usually made in mid-to-late June by extending runners from the planted parent plant, separating the seedlings from the runners, and planting them in pots or the like. After that, they are cultivated in a nursery until flower bud differentiation occurs. In the conventional method, once flower bud differentiation is confirmed, the plants are promptly transplanted to the main field and cultivated. On the other hand, in this embodiment, after confirming flower bud differentiation, long-day treatment (approximately 2 weeks of continuous nighttime lighting) is performed for 1 to 4 weeks within 21 days. In this case, as shown in the figure, transplanting is not done immediately after confirming flower bud differentiation, but long-day treatment is performed before transplanting to the main field, or, although not shown in the figure, the same long-day treatment is performed after transplanting following confirmation of flower bud differentiation. Cultivation after transplanting (excluding the period when long-day treatment is performed after transplanting) is the same between the conventional method and the method of this embodiment and can be carried out similarly. Long-day treatment may be applied from winter to spring to maintain plant vigor, but it is unnecessary for varieties that grow to sufficient height even with natural day length (for example, 'Koiminori' and 'Benihoppe'). Unless otherwise specified in this specification, "long-day treatment" refers to the long-day treatment performed in early autumn after the differentiation of the terminal bud into a flower bud, not the long-day treatment performed from winter to spring.

[0015] In this embodiment, long-day treatment is applied to a single-fruiting strawberry plant whose apical bud has differentiated into a flower bud. In this specification, "plant (seedling) whose apical bud has differentiated into a flower bud" is used synonymously with "plant (seedling) whose flower bud has differentiated," "plant (seedling) after flower bud differentiation," and "plant (seedling) in which flower bud differentiation is sufficiently stable," and "after apical bud has differentiated into a flower bud" is used synonymously with "after confirmation of flower bud differentiation."

[0016] Strawberry plants that bear fruit only once a year are short-day plants, and flower bud differentiation is promoted under low temperature and short-day conditions. Under normal natural conditions, the day length after flower bud differentiation in early autumn is usually less than 16 hours. Therefore, by artificially extending the continuous light period (light period) to 16 hours or more, for example, by providing artificial lighting during the period before sunset or after sunset, it is possible to achieve a long-day treatment of 16 hours or more. If artificial lighting is provided all night from sunset to sunset (i.e., all night), the day length for the long-day treatment will be 24 hours. When cultivating by completely artificially controlling the day length rather than the natural day length, it is sufficient to provide a continuous light period of 16 hours or more, regardless of the time of day. The day length for the long-day treatment may be 16 hours or more, or it may be between 16 hours and 24 hours, for example, 17 hours or more, 18 hours or more, 19 hours or more, 20 hours or more, 21 hours or more, 22 hours or more, 23 hours or more, or 24 hours.

[0017] The long-day processing period in this embodiment (including the processing start date) may be 7 to 28 days, for example, 10 to 25 days, 12 to 21 days, 13 to 16 days, 13 to 15 days, 8 days or more, 9 days or more, 11 days or more, 12 days or more, 13 days or more, or 14 days or more, and may be 25 days or less, 24 days or less, 23 days or less, 22 days or less, 21 days or less, 20 days or less, 19 days or less, 18 days or less, 17 days or less, 16 days or less, or 15 days or less.

[0018] In this embodiment, it is important to perform long-day treatment on plants where the apical bud has differentiated into a flower bud, within 21 days after the apical bud differentiates into a flower bud, and it is not necessary to start the long-day treatment immediately after the apical bud differentiates into a flower bud. After the apical bud differentiates into a flower bud, the long-day treatment may be started, for example, within 20, 19, 18, 17, 16, 15, or 14 days (including the treatment start date).

[0019] Whether the apical bud has differentiated into a flower bud can be confirmed by methods known to those skilled in the art, such as microscopic examination of flower buds. For example, one can observe the apex of a strawberry stem with a stereomicroscope and peel off the internal leaves to confirm whether the growing point has differentiated into a flower bud. The more plants there are, the more difficult it becomes to confirm that the apical bud has differentiated into a flower bud on every single plant. However, starting long-day treatment on plants where the apical bud has not differentiated into a flower bud is expected to have the adverse effect of delaying bud formation. The timing of stable flower bud differentiation varies depending on the variety, but most single-fruiting cultivated varieties stabilize flower bud differentiation by the end of September. Therefore, it can be done after the period when flower bud formation is known to be stable for the cultivated variety. Alternatively, for example, long-day treatment may be started after confirming that the apical buds of a certain percentage of multiple plants have all differentiated into flower buds. Furthermore, in this embodiment, it is not necessary to immediately start long-day treatment on plants whose apical buds have differentiated into flower buds. For example, after confirming that a certain percentage of multiple plants have differentiated into flower buds, it is possible to wait for a certain period (e.g., one week) before starting long-day treatment. This allows long-day treatment to be started after almost all of the multiple plants being cultivated have differentiated into flower buds. Also, for reference in subsequent years, in order to determine when to start long-day treatment on multiple plants, for example, long-day treatment may be performed at a specific time, and the percentage of plants that have sprouted by the end of November may be calculated. If the percentage of plants that have sprouted reaches 80% or more, 90% or more, 95% or more, or 100%, it may be decided to start long-day treatment at that time.

[0020] In this embodiment, seedlings may be planted after the long-day treatment is completed. When planting after the long-day treatment, it is preferable to plant them as soon as possible after the treatment, considering the growth of the plants. Planting may be done, for example, within 7 days, 5 days, 3 days, 2 days, or 1 day after the completion of the long-day treatment. Alternatively, it may be done within 6 weeks, 5 weeks, or 4 weeks from the day the apical bud differentiates into a flower bud. Since the main field is usually larger than a nursery field, the cost of artificial lighting can be reduced by performing the long-day treatment in the nursery field before planting. Also, while the peak planting period is in mid-to-late September in conventional methods, shifting the planting time from such methods allows for the distribution of labor for planting.

[0021] In this embodiment, long-day treatment may be performed after planting the strawberry plants (seedlings), as long as it is started within 21 days after the differentiation of the apical bud into a flower bud.

[0022] The cultivation of strawberry plants in nurseries and main fields should be carried out appropriately using methods suitable for the strawberry variety being cultivated, but the following is an example of general cultivation. The examples of timing and natural conditions for general cultivation are based on the climate of Kurume City, Fukuoka Prefecture, Japan.

[0023] A nursery primarily refers to a cultivation area where plants (seedlings) are grown from cuttings until transplanting. Nurseries may employ either open-field cultivation or greenhouse cultivation. Open-field cultivation is a method of cultivation that utilizes the natural environment in an outdoor field, and includes, for example, greenhouses without covering materials or greenhouses with only shading nets (which allow rain to pass through). Open-field cultivation is not limited to planting directly in the ground; it also includes raising seedlings on benches placed inside the greenhouse. Greenhouse cultivation includes, for example, greenhouse cultivation using covering materials that allow the use of natural light, and greenhouse cultivation using closed facilities where the growing environment can be artificially controlled. Greenhouses also include solar-powered plant factories that produce plants in a semi-closed environment such as a greenhouse, primarily using sunlight. In indoor facilities where the growing environment can be artificially controlled, it is possible to manage temperature, humidity, CO2 concentration, and lighting suitable for the strawberry variety being cultivated. Long-day treatment may be performed in the seedling nursery, in a separate facility, or in the main field as described later.

[0024] The main field refers to the cultivation area where strawberry plants (seedlings) are primarily planted and then strawberry fruit is harvested. In the method of this embodiment, planting may be performed in the main field after long-day treatment, or long-day treatment may be performed after planting in the main field. In particular, in forced cultivation, greenhouse cultivation is more common than open-field cultivation. Greenhouse cultivation includes, for example, greenhouse cultivation using covering materials that allow natural light to be used, and greenhouse cultivation using closed facilities where the growing environment can be artificially controlled. In the case of indoor facilities where the growing environment can be artificially controlled, management appropriate to the strawberry variety being cultivated should be carried out. It is preferable to perform soil analysis before planting and determine the amount of basal fertilizer to be applied. Cultivation after planting includes ground bed cultivation and elevated cultivation. Ground bed cultivation is a method in which the ground is tilled, ridges are made, and plants are planted there, while elevated cultivation is a method in which benches are assembled using pipes, etc., and strawberry plants are placed in a position that is easy to work with. Cultivation methods should be tailored to each strawberry variety. For example, in ground-level cultivation with out-bearing plants, the spacing between plants can be about 19-25 cm, the spacing between rows about 25 cm, and the plants can be planted in a staggered pattern in two rows. The ridges can be shaped into a semi-circular shape at a height of about 30 cm or more, and the plants can be planted so that the fruit sets on the ridges. Alternatively, in elevated cultivation, for example, the spacing between plants can be about 19-25 cm, and the plants can be planted in a staggered pattern in two rows.

[0025] The light irradiated during the light period when cultivating plants in the nursery and main field may be natural light (sunlight), artificial light, or a combination thereof. The light source is not particularly limited and includes forms that can be used in the long-day treatment described later. The light source may be used alone or in combination with other light sources. Furthermore, for example, if the intensity of natural light is insufficient, it may be supplemented with artificial light, and conversely, if the intensity of natural light is too high or the duration is too long, the intensity can be adjusted by shading or other means.

[0026] Cultivation in both the nursery and main fields may, in principle, be carried out according to natural day length, with temperature control being performed by ventilation when it is hot and by insulation or heating when it is cold. In that case, the nursery may be set to the day length and temperature of June to September, i.e., a day length of 12.5 to 15 hours and an air temperature of 18 to 38°C, and the main field may be set to the day length and temperature of late September to May, i.e., a day length of 10.5 to 14.5 hours and an air temperature of 6 to 38°C. In the main field during the low-temperature period, for example, insulation or heating may be performed to maintain a temperature of 5 to 7°C or higher, with an upper limit of one of the temperatures between 20 and 26°C.

[0027] In general strawberry cultivation, mulching is performed around mid-to-late October. Also, when the average temperature falls below 16°C (around late October), the greenhouse roof is covered with plastic sheeting for rain protection and insulation, and the temperature is controlled to suit the strawberry variety being cultivated. In the case of indoor facilities where the growing environment can be artificially controlled, management should be carried out according to the strawberry variety being cultivated. As shown in Figure 1, long-day treatment may be performed from winter to spring to maintain plant vigor. Under natural conditions, if forced cultivation is performed in a greenhouse or other facility with insulation around October, before dormancy, harvesting will be possible from around December. In the method of this embodiment, normal forced cultivation can be performed except during long-day treatment. In forced cultivation of single-season strawberries, the optimal method varies somewhat depending on the variety and region, but typically seedlings collected around June to July are planted in September to early October, and the fruit is harvested from mid-November to around June of the following year.

[0028] Examples of the light source used for long-day treatment include, for example, incandescent lamps, fluorescent lamps, and LED lamps. For example, three-wavelength fluorescent lamps, red LEDs, far-red LEDs, etc. can also be used. The light source may be used alone or in combination with a plurality of light sources. The horizontal illuminance at the top of the stock (or community if there are multiple stocks) is considered to have no physiological upper limit, but for example, it may be 50 lux to 35000 lux, 60 lux or more, 70 lux or more, 75 lux or more, 80 lux or more, and may also be 32000 lux or less, 30000 lux or less, 10000 lux or less, 1000 lux or less, 180 lux or less, 170 lux or less, 160 lux or less. The photosynthetic photon density is also considered to have no physiological upper limit, but for example, it may be 0.6 to 475 μmolm -2 ·s -1 and may be 0.6 μmolm -2 ·s -1 or more, 0.8 μmolm -2 ·s -1 or more, 0.9 μmolm -2 ·s -1 or more, 1.0 μmolm -2 ·s -1 or more, and may also be 435 μmolm -2 ·s -1 or less, 405 μmolm -2 ·s -1 or less, 135 μmolm -2 ·s -1 or less, 13.5 μmolm -2 ·s -1 or less, 2.5 μmolm -2 ·s -1 or less, 2.3 μmolm -2 ·s -1 or less, 2.2 μmolm -2 ·s -1 or less.

[0029] During the autumn season (late September to mid-October), when long-day treatment is performed, the minimum temperature in the morning is usually around 18°C, and the maximum temperature is around 35°C. Therefore, the cultivation temperature during long-day treatment may be, for example, between 18°C ​​and 35°C. The temperature during long-day treatment may be carried out under natural conditions, for example, in a cultivation facility with windows left open and fixed for ventilation, and without heating. Alternatively, the temperature may be adjusted as needed by ventilation, evaporative cooling, heating, and additional heating.

[0030] In this embodiment, fertilization may be carried out during the long-day treatment period. The fertilizer used may be liquid fertilizer or solid fertilizer. It may also be a compound fertilizer or an organic fertilizer. Examples of fertilizers used at this time in strawberry cultivation include slow-release compound fertilizers containing nitrogen, phosphorus, and potassium. When fertilizing, use the appropriate amount of each fertilizer. Fertilization is not limited to the long-day treatment period, but may also be carried out after planting. Furthermore, if long-day treatment (early autumn) is carried out after planting, fertilization may also be carried out after planting.

[0031] Most single-fruiting cultivars achieve stable flower bud differentiation by late September under natural conditions. For example, 'Fukuoka S6' belongs to the group with the latest flower bud differentiation. However, this does not prevent controlling the timing of flower bud differentiation through low temperature and short-day treatment as needed.

[0032] According to this embodiment, it is possible to increase the early yield of strawberries, which have a high unit price. This effect is presumed to be due to the increase in leaf area and elongation of petioles due to long-day treatment, which increases the light-receiving area and thus increases the amount of photosynthesis. As an indicator of the increase or decrease in strawberry yield, marketable fruit yield (g / plant) can be used. Marketable fruit yield is the weight of fruit per plant that meets the sales standard and can be harvested. In this context, "early" mainly means from the start of harvesting until the end of February. For example, the increase in early marketable fruit yield (g / plant) of strawberries cultivated using the method of this embodiment may be 30%, 50%, or 80% or more compared to strawberry plants cultivated under the same conditions except that long-day treatment is not performed in early autumn.

[0033] The method of this embodiment also includes applying a long-day treatment of 16 hours or more for 7 to 28 days to a single-fruiting strawberry plant whose apical bud has differentiated into a flower bud, and the long-day treatment may be started within 21 days after the differentiation of the apical bud into a flower bud, thereby improving the initial yield of strawberries. [Examples]

[0034] [Example 1] The cultivation trials were conducted in a nursery and main field in Kurume City, Fukuoka Prefecture. Seedlings of 'Tochiotome', 'Fukuoka S6' (Amaou® registered trademark), and 'Koiminori' (all single-season varieties) were used after flower bud differentiation (after the apical bud differentiated into a flower bud) in connected nursery containers with a root diameter of approximately 5.5 cm. The nursery (a glass room with a skylight and side windows kept open at all times, where the temperature was generally within the range of the outside daily minimum temperature of 20°C to the daytime maximum temperature of 35°C) was illuminated with incandescent light bulbs for two weeks from the night of September 26th to the morning of October 10th (horizontal illuminance at the top of the canopy: 80 lux (photosynthetic photon flux density: approximately 1.1 μmolm)). -2 ·s -1 The plants were continuously lit from sunset to sunrise, and on the last day of treatment, they were transplanted to elevated benches in a solar-powered plant factory with a spacing of 20 cm between plants. After transplanting, cultivation was carried out using natural day length with ventilation, aiming for a temperature of 26°C or lower during the day. During the cold season, heating was maintained with a maximum temperature of 26°C, and heating was added to ensure that the minimum daily temperature was 6°C or higher. Fertilization was carried out during the long-day treatment period. Seedlings in the control group were managed in the same way as the long-day treatment group under natural day length. The most recently developed leaf on the last day of long-day treatment was set as "0," and the size of the leaves up to the 5th leaf, the petiole length, the monthly plant height, and the yield were investigated. The test scale was 6 plants for each variety and treatment, with 2 replications. Long-day treatment was not performed from winter to spring.

[0035] The results are shown in Figures 2 to 6. In the long-day treatment plots, early yields (from the start of harvesting until the end of February) increased for all three varieties (Figure 2). The increase in yield was mainly due to an increase in the number of harvested fruits for 'Tochiotome' and 'Amaou' (registered trademark), and an increase in the weight of a single fruit for 'Koiminori' (data omitted). The leaf area, estimated from the leaf length and width of the central leaflet, increased for all three varieties with long-day treatment, and for 'Koiminori', it increased in the 2nd and 4th leaves that unfolded after the end of long-day treatment (Figure 3). Similarly, for 'Tochiotome' and 'Amaou' (registered trademark), it increased in the 2nd to 5th leaves (Figure 5). Petiole length also increased with long-day treatment (Figures 4 and 6), and the area of ​​leaf growth expanded overall.

[0036] These factors likely increased the light-receiving area per plant, leading to increased early yields. Budding tended to occur slightly earlier with the long-day treatment (data omitted). Generally, in strawberries, yields decrease if planting is not done promptly after flower bud differentiation is confirmed. However, since the yield of 'Koiminori' in other trials where planting was done at the appropriate time was similar to that in the natural day length control in this trial, it is estimated that the impact of delayed planting was small.

[0037] [Example 2] The cultivation trials were conducted in a nursery and main field in Kurume City, Fukuoka Prefecture. The optimal timing for long-day treatment of seedlings was investigated using seedlings of 'Fukuoka S6' (Amaou® registered trademark). Specifically, Amaou® seedlings cultivated in a nursery facility (a solar-powered plant factory where the minimum daily temperature is about the same as the outside temperature, and the maximum daily temperature is generally below 35°C due to ventilation and evaporative cooling, and cultivation is performed with about 40% of the amount of light received from the outside) were transported to the glasshouse described in Example 1, and long-day treatment was started at 4-day intervals for 2 weeks from September 10 to October 4. On the same day that the long-day treatment ended, the seedlings were promptly transplanted to the main field facility (elevated benches in the solar-powered plant factory described in Example 1) and cultivated. The long-day treatment was performed by continuous lighting with incandescent light bulbs from sunset to sunrise, as in Example 1. Cultivation after transplanting was carried out in the same manner as in Example 1, with ventilation aimed at keeping the daytime temperature below 26°C, and cultivation under natural day length conditions. During low-temperature periods, heating was maintained with a maximum temperature of 26°C, and heating was added to ensure that the minimum daily temperature was above 6°C. In addition, to determine only the effect of long-day treatment, a comparative example was established in which long-day treated seedlings ("LD section") and seedlings cultivated for the same period under natural day length conditions as the facility where long-day treatment was performed were cultivated ("ND section"). The treatment schedule for this example is shown in Table 1 below. The test scale was 12 plants per section (6 plants in 2 replicates). Long-day treatment was not performed from winter to spring.

[0038] [Table 1]

[0039] The conventional method involved raising seedlings in a nursery facility under natural day length conditions and transplanting them on September 24th. While Maru 1 was transplanted on September 24th, for the two weeks prior to that, it was cultivated in a separate facility under long-day conditions or natural day length. From there, transplanting was set every four days until Maru 6 was transplanted on October 18th (excluding the transplanting on October 14th). Fertilization involved diluting a comprehensive liquid fertilizer containing trace elements and calcium (nitrogen-phosphorus-potassium: 15-8-17) and applying it five times a day at a concentration of approximately 0.7 mS / cm, combined with irrigation. The daily liquid fertilizer application rate was approximately 300 ml / plant, the maximum amount in spring. Fertilization in the main field began on September 30th. Fertilization also began on September 30th for seedlings that had not yet been transplanted. The long-day treatment was carried out in a separate facility from the seedling nursery, but to eliminate the influence of the cultivation location, seedlings in the natural day length plot were also managed in the same facility for the same period (the conventional plot was in the seedling nursery). Compared to a typical facility, the seedling nursery had less incident light (about 40% of the outside light), a high ceiling, and good ventilation, resulting in a lower temperature environment. The facility where the long-day treatment was performed was a glass room with all windows open, and the amount of light and temperature were similar to that of a typical facility. Yield data was collected until the end of May 2022.

[0040] Figure 7 shows the results of the effects of long-day treatment on seedlings and planting time on monthly marketable fruit yield (g / plant). The "budding rate" represents the percentage of plants out of 12 tested in which buds could be seen with the naked eye from the outside by the end of November. Generally, plants that budded by the end of November can be judged to have differentiated into flower buds at the appropriate time.

[0041] When long-day treatment was started too early, before flower bud differentiation was stable (approximately 3 in the right graph, i.e., before September 18th), bud formation was delayed and yield decreased. Although delayed transplanting resulted in a slight decrease in yield, seedlings treated with long-day treatment at a later stage when flower bud differentiation was sufficiently stable (4-6 in the right graph) actually saw an increase in yield. In this case, yield increased particularly in the first half of the harvest season (December-February).

[0042] These results suggest that it is important to wait until flower bud differentiation is sufficiently stable (the time when the apical bud differentiates into a flower bud) before applying long-day treatment.

Claims

1. This includes applying long-day treatment of 16 hours or more for 7 to 28 days to single-fruiting strawberry plants whose apical buds have differentiated into flower buds, and transplanting the strawberry plants after the long-day treatment is completed. A strawberry cultivation method in which long-day treatment is started within 21 days after the differentiation of the apical bud into a flower bud.

2. The method according to claim 1, wherein the strawberry plants are transplanted within 7 days after the completion of the long-day treatment.

3. The method according to claim 1 or 2, wherein the length of the day for long-day treatment is 18 hours or more.

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