A breeding method of rices of the indica-japonica hybrid group and early generation regeneration force directional screening based on rices

Abstract

The application provides a kind of based on indica japonica hybrid assorting and early generation regeneration force directional screening's ratoon rice breeding method, belongs to rice breeding technical field.A kind of based on indica japonica hybrid assorting and early generation regeneration force directional screening's ratoon rice breeding method, constructs " indica japonica intermediate type x strong ratoon rice" three hybrid system is screened after the first season harvest, obtains the strain of sprouting fast, ratoon shoot is more, after the screening of recovery rate, accumulated temperature loss and yield, obtains a kind of ratoon rice strain.The breeding cycle of the method is shortened by 3-4 years compared with the traditional method, and the screened ratoon rice strain has the characteristics of strong regeneration capacity, high yield and lodging resistance, and can realize "one-time sowing two-season mechanical harvesting" full-process mechanized production.

Description

Technical Field

[0001] This invention belongs to the field of rice breeding technology, specifically relating to a method for breeding ratooning rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening. Background Technology

[0002] Traditional ratooning rice breeding faces three major technical bottlenecks: narrow parental genetic base, with most existing ratooning rice varieties originating from a single indica germplasm; delayed screening of regeneration traits, with conventional methods requiring evaluation of regeneration ability only after the F5 generation; and difficulty in synergistic improvement of traits, making it difficult to simultaneously enhance high-yield characteristics and strong regeneration ability. Current technologies show that conventional breeding methods have a breeding cycle of 8-10 years, and the yield in the ratoon season is generally lower than that in the first season. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method for breeding ratooning rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening, which can greatly shorten the breeding cycle and increase the yield of ratooning rice.

[0004] This invention provides a method for breeding ratooning rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening, comprising the following steps:

[0005] Using "Jia 58" as the female parent and "Shunda 135" as the male parent, the F1 generation was obtained by crossbreeding. The F1 generation was then crossbred with the indica rice "Huang Huazhan" to obtain the F2 generation.

[0006] After the first harvest of the F2 generation, the F3 generation was selected according to the following criteria: basal node wound flow >1200mg / h, number of regenerated tillers ≥5 / plant, SPAD value of regenerated tillers >38, and ear formation rate of regenerated tillers ≥70%;

[0007] The F3 generation was planted and tested in several regions. Seeds with a recovery rate of more than 70% within two weeks after the first harvest and an accumulated temperature loss of less than 15% with no significant difference in yield were selected as the F4 generation.

[0008] The F4 generation and the harvested F5 generation are planted together to harvest the F6 generation;

[0009] The F6 generation was selected to obtain the F7 generation according to the criteria for retaining the F3 generation;

[0010] The F7 generation was selected based on the criteria of early maturity, first-season yield of more than 8 tons, and ratooning season yield of more than 5 tons to obtain ratooning rice lines.

[0011] Preferably, the basal joint damage flow is measured 7 to 8 days after the first harvest.

[0012] Preferably, the statistical time for the number of regenerated tillers, the SPAD value of regenerated tillers, and the ear formation rate of regenerated tillers is 21 to 22 days after the first harvest.

[0013] Preferably, the selection criteria for F3 generation also include calculating the tiller germination rate 14-15 days after the first harvest; the selection criterion for the tiller germination rate is ≥4 tillers / plant.

[0014] Preferably, at the time of the first harvest, the stubble height of the plant is 28-32cm.

[0015] Preferably, the formula for calculating the recovery rate is shown in Formula I;

[0016] Recovery rate = (Number of buds sprouting in the compacted area / Number of buds sprouting in the uncompacted area) × 100% Formula I.

[0017] Preferably, the formula for calculating the accumulated temperature loss is shown in Formula II;

[0018] Accumulated temperature loss = (1 - actual accumulated temperature / demanded accumulated temperature) × 100% (Formula II)

[0019] The required accumulated temperature for the F3 generation regeneration season is 1300 degree-days.

[0020] Preferably, the planting area for the F3 generation regeneration season includes areas with 1150 to 1450 degrees per day.

[0021] Preferably, the first harvest of the F2, F3 and F6 generations is completed by mechanical harvesting.

[0022] Preferably, the standard for early maturity is that it is more than 3 days earlier than the maturity period of Zhongzao 39 regeneration planting.

[0023] This invention provides a method for breeding ratooning rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening. The invention uses heat-resistant indica rice with high regeneration rate and high dormant bud survival rate as the male parent, and japonica rice germplasm with strong lodging resistance as the woody plant to obtain the F1 generation. The F1 generation is then recrossed with indica rice with strong regeneration capacity to construct a "middle type indica-japonica × strong regeneration indica rice" ternary hybrid system as F2. Dynamic screening of regeneration capacity is conducted in the F2 generation using a "simulated harvest in the first season - follow-up evaluation in the ratoon season" method, resulting in an F3 generation with rapid germination and numerous regenerated buds. The F3 generation is then subjected to multi-environment verification, and lines with strong self-healing ability and yield unaffected by accumulated temperature deficit of less than 15% are selected as the F4 generation. After two generations of planting, the F6 generation undergoes dynamic screening of regeneration capacity again. The resulting F7 generation is then screened for yield in the first and ratoon seasons, yielding a new ratooning rice germplasm with increased yield, strong regeneration capacity, and lodging resistance. This invention advances the screening of regeneration traits to F2-F3, significantly shortening the breeding cycle by 3-4 years compared to traditional methods. Through the interaction of indica and japonica subspecies, this invention enables the yield in the regeneration season to reach 55%-63% of the first season's yield. The method described in this invention successfully creates new germplasm that combines lodging resistance (lodging index <10) with strong regeneration ability (regeneration rate >90%). Furthermore, the method described in this invention enables fully mechanized production of "one sowing, two harvests," greatly simplifying the screening workload. Detailed Implementation

[0024] This invention provides a method for breeding ratooning rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening, comprising the following steps:

[0025] Using "Jia 58" as the female parent and "Shunda 135" as the male parent, the F1 generation was obtained by crossbreeding. The F1 generation was then crossbred with the indica rice "Huang Huazhan" to obtain the F2 generation.

[0026] After the first harvest of the F2 generation, the F3 generation was selected according to the following criteria: basal node wound flow >1200mg / h, number of regenerated tillers ≥5 / plant, SPAD value of regenerated tillers >38, and ear formation rate of regenerated tillers ≥70%;

[0027] The F3 generation was planted and tested in several regions. Seeds with a recovery rate of more than 70% within two weeks after the first harvest and an accumulated temperature loss of less than 15% with no significant difference in yield were selected as the F4 generation.

[0028] The F4 generation and the harvested F5 generation are planted together to harvest the F6 generation;

[0029] The F6 generation was selected to obtain the F7 generation according to the criteria for retaining the F3 generation;

[0030] The F7 generation was selected based on the criteria of early maturity, first-season yield of more than 8 tons, and ratooning season yield of more than 5 tons to obtain ratooning rice lines.

[0031] This invention uses "Jia 58" as the female parent and "Shunda 135" as the male parent to cross and obtain the F1 generation. The F1 generation is then crossbred with the indica rice "Huang Huazhan" to obtain the F2 generation.

[0032] In this invention, "Jia 58" is a japonica rice variety with lodging resistance. "Shunda 135" is an indica rice variety with high regeneration rate and high dormant bud survival rate. This invention does not impose any special restrictions on the hybridization; hybridization methods well-known in the art can be used. The first crop seeds from the F1 generation are harvested and used for subsequent generations, then recrossed with the strongly regenerating indica rice variety "Huang Huazhan" to harvest the F2 generation in the same year.

[0033] After obtaining the F2 generation, the present invention selects the F3 generation according to the following criteria after the first harvest of the F2 generation: basal joint injury flow rate >1200mg / h, number of regenerated tillers ≥5 tillers / plant, SPAD value of regenerated tillers >38, and ear formation rate of regenerated tillers ≥70%.

[0034] In this invention, the determination of basal node wound flow is preferably performed 7-8 days after the first harvest. Screening based on basal node wound flow helps to eliminate plants with poor root development and low vigor, while selecting plants with well-developed and vigorous root systems. The selection criteria for F3 generation preferably also include calculating the tiller germination rate 14-15 days after the first harvest; the selection criterion for the tiller germination rate is ≥4 tillers / plant. The statistical time for the number of regenerated tillers, the SPAD value of regenerated tillers, and the ear formation rate of regenerated tillers is preferably performed 21-22 days after the first harvest. The calculation method for the ear formation rate of regenerated tillers is preferably shown in Formula I.

[0035] The ear formation rate of regenerated tillers = (number of effective ears of regenerated tillers / number of highest regenerated tillers) × 100% Formula I.

[0036] The effective number of panicles in ratooning rice refers to the number of panicles that can produce more than 5 full grains per panicle under normal grain filling conditions, while the maximum number of ratooning tillers refers to the highest number of ratooning tillers.

[0037] The SPAD value of the regenerated tillers is preferably measured using a chlorophyll meter. This invention, through double-season tracking and dynamic screening, facilitates the acquisition of strains with numerous buds, rapid germination, and fast growth. At the first harvest, the stubble height is preferably 28-32 cm, but can be 30 cm. Mechanical harvesting is preferred for the first harvest.

[0038] After obtaining the F3 generation, the present invention will plant and test the F3 generation in several regions, and select the material seeds with a recovery rate of more than 70% within two weeks after the first harvest and an accumulated temperature loss of less than 15% with no significant difference in yield as the F4 generation.

[0039] In this invention, the planting areas for the F3 generation are preferably in the range of 1150-1450 degree-days, such as areas with 1150-1250 degree-days, 1250-1350 degree-days, and 1350-1400 degree-days. The preferred planting areas are Huzhou, Shaoxing, and Wenzhou.

[0040] In this invention, the formula for calculating the recovery rate is preferably found in Formula III. Screening for the recovery rate helps to eliminate strains with poor self-healing ability and helps to obtain strains with strong vitality and lodging resistance.

[0041] Recovery rate = (Number of buds sprouting in the compacted area / Number of buds sprouting in the uncompacted area) × 100% Formula III.

[0042] In this invention, the formula for calculating the accumulated temperature deficit is preferably found in Formula III; the screening of the accumulated temperature deficit is beneficial for exploring the environmental adaptability of the plant and laying the foundation for subsequent large-scale promotion and planting.

[0043] Accumulated temperature loss = (1 - actual accumulated temperature / demanded accumulated temperature) × 100% (Formula IV);

[0044] Among them, the accumulated temperature requirement for the F3 generation during the regeneration season is defined as 1300 degree-days, which ensures early maturity and high yield during the regeneration season, improves economic value, and ensures the arrangement of subsequent crop rotation.

[0045] In this invention, the first harvest of the F3 generation is preferably completed by mechanical harvesting.

[0046] After obtaining the F4 generation, the present invention will plant the F4 generation and the harvested F5 generation together to harvest the F6 generation.

[0047] In this invention, the term "multi-generation planting" refers to planting F4 and F5 generations in the same year. In this embodiment, the F4 generation is planted in Shaoxing, and the seeds harvested in the first season are planted in Lingshui, Hainan, in the winter of the same year, thereby achieving rapid propagation and shortening the selection cycle.

[0048] After obtaining the F6 generation, the F6 generation of the present invention is screened according to the standard of selecting the F3 generation to obtain the F7 generation; the F7 generation is screened according to the standard of early maturity, first season yield of more than 8 tons and ratooning season yield of more than 5 tons to obtain ratooning rice lines.

[0049] In this invention, the standard for early maturity is preferably more than 3 days earlier than the early rice variety Zhongzao 39 when it is regenerated.

[0050] In this invention, the screening cycle of the method is 6 years, which significantly shortens the breeding cycle by 3-4 years compared to conventional breeding methods. The method yields a new ratooning rice variety with a first-season yield of over 8.72 t / ha and a ratooning-season yield of over 5.13 t / ha, achieving 55%-63% of the first-season yield in the ratooning season, greatly increasing both the ratooning-season yield and the total annual yield; simultaneously, the number of effective panicles in the ratooning season exceeds 3.21 million panicles / ha. Compared to conventional year-round rice cultivation, the ratooning rice variety screened in this invention shortens the entire growth period by 17 days, significantly improving production efficiency.

[0051] The following detailed description, in conjunction with embodiments, illustrates a method for breeding regenerated rice based on indica-japonica hybridization and early-generation regeneration capacity directional screening provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] Step 1: Germplasm Creation

[0054] In 2017, the japonica rice variety "Jia 58" was used as the female parent and the strongly regenerating indica rice variety "Shunda 135" was used as the male parent to obtain the F1 generation hybrid. The F1 generation hybrid was then crossbred with the widely adaptable indica rice variety "Huang Huazhan" to construct the A / B / / C population, resulting in a "Japonica-indica intermediate type × strongly regenerating indica rice" ternary hybrid system, which was designated as the F2 generation.

[0055] Step 2: Early screening to eliminate unsuitable groups.

[0056] In 2018, the F2 population was planted in paddy fields in Shaoxing, a region characterized by alternating wet and dry seasons. Forty days after the first heading, the rice was mechanically harvested at a 30cm stubble depth. Seven days after the first harvest, plants within the population were randomly selected to measure basal node wound flow. The screening criterion was >1.2 g / h. Plants meeting the screening criteria were retained, while those not meeting the criteria were discarded. On the 14th day, the number of regenerated tillers sprouting from the selected plants was counted, and the average value was calculated. Plants with ≥4 tillers / plant were retained, while others with less than 4 tillers / plant were discarded. On the 21st day, the SPAD value of the regenerated tillers was measured, and the average value was calculated. Plants with a SPAD value >38 were retained, while others with ≤38 were discarded. Additionally, plants with more than 5 regenerated tillers / plant were also selected. Plants with a regenerated tiller panicle formation rate (see Formula I) ≥70% after maturity were retained.

[0057] The SPAD values ​​were measured using a SPAD-502 chlorophyll meter, and the specific method was as follows:

[0058] Select the last healthy, intact leaf, avoiding the main vein, lesions, and areas of mechanical damage. Pinch the leaf and insert the measuring probe, ensuring it completely covers the receiving window (2mm × 3mm) without gaps. Press the measuring probe down and hold for 2-3 seconds. Release after hearing the beep; the screen will directly display the SPAD value. Measure 3-4 different sites on the same leaf, discard outliers, and calculate the average. Avoid measurements during periods of strong sunlight (midday) and before morning dew dries. Measurement times are 9:00-11:00 or 15:00-17:00 daily. The temperature range for measurement is 25℃~35℃. Temperatures exceeding this range require SPAD value correction; otherwise, the value may be artificially inflated. Selected plants from suitable lines are harvested and planted using a mixture of seeds.

[0059] The method for determining the base joint damage flow rate is completed by the following steps:

[0060] 1) Plant preparation: Stop watering the evening before sampling, keep the soil moist but not waterlogged (avoid water stress affecting root pressure).

[0061] 2) Stem treatment

[0062] At the second internode at the base (approximately 5-10 cm from the ground), use an alcohol-sterilized blade to horizontally cut the stem. Quickly blot away any excess liquid from the cut surface with absorbent paper. Begin collecting liquid in the early morning (6:00-8:00 AM, during peak root pressure) and continue for 1 hour.

[0063] 3) Collection device

[0064] You can hang a pre-weighed cotton ball directly over the cut (it needs to be replaced and weighed regularly). Then wrap and seal it with plastic wrap.

[0065] 4) Flow calculation

[0066] Weigh the cotton balls before and after collection using the cotton ball weighing method, and calculate the weight according to Formula II:

[0067] Base joint damage flow rate (mg / h) = (final weight of cotton ball - initial weight) / time Formula II.

[0068] Step 3: Multi-environment verification

[0069] In 2019, the F3 generation underwent multi-site testing: the individual seeds selected in step 2 were planted in Wenzhou, Shaoxing, and Huzhou. The recovery rate of mechanical damage to the rice stubble within two weeks after the first harvest of ratooning rice was measured. Comparing the data with data from uncompacted areas, the recovery rate was calculated using Formula III, and plants with a 14-day recovery rate greater than 70% were selected.

[0070] Recovery rate (%) = (Number of buds sprouting in the compacted area / Number of buds sprouting in the uncompacted area) × 100% Formula III.

[0071] Three locations with accumulated temperature conditions meeting the experimental requirements were selected to test the regeneration seasonal temperature and light response characteristics. The accumulated temperature loss was required to be <15%, meaning that there was no significant difference in yield within an accumulated temperature loss of 15%.

[0072] Accumulated temperature loss = (1 - actual accumulated temperature / demand accumulated temperature) × 100% Formula IV.

[0073] The required accumulated temperature for the regeneration season is 1300℃, but the accumulated temperature in the planting area is only 1150℃, resulting in a temperature deficit of 14.9%. If the yield differs significantly from that under normal accumulated temperature conditions, the materials that do not meet the temperature deficit requirements will be eliminated, and F4 generation seeds will be obtained.

[0074] Next, F4 and F5 generations were planted. Specifically, F4 generation rice was planted in Shaoxing from May to November 2020, and the first crop seeds were planted in Lingshui, Hainan from December 2020 to April of the following year to obtain F5 generation plants. The seeds harvested from the F5 generation plants were then planted in Shaoxing from May to November 2021 to obtain F6 generation seeds.

[0075] Step 4: Assessment of Advanced Generation Recycling Production Capacity

[0076] In 2022, F6 generation plants were planted in paddy fields with alternating wet and dry conditions and managed conventionally. Seven days after the first harvest, 10 plants were randomly selected from the population to measure basal node wound flow, and plants with a flow rate >1.2 ml / h were retained. On day 14, the number of regenerated tillers from the selected plants was counted, and plants with ≥4 tillers / plant were retained. On day 21, the SPAD value of the regenerated tillers was measured using the same method, and plants with a SPAD value >38 were retained.

[0077] All F7 generation plants meet the requirements. Planting is done by selecting early-maturing strains with a first-season yield of over 8 tons and a second-season yield of over 5 tons.

[0078] Using the above method, the "Shaozaiyou 3" strain was developed over six years. This strain yielded 8.72 t / ha in the first season and 5.53 t / ha in the second season; the effective panicle number in the second season was 2.73 million panicles / ha. The entire growth period lasted from April 10th to October 1st, with a total growth cycle of 177 days across both seasons.

[0079] Example 2

[0080] In 2023, “Shaozaiyou No. 3” and “Zhongzao 39” were planted in Shaoxing. The early-season seeds were soaked on April 10, sown on April 15, and transplanted on May 15. The experimental results are shown in Table 1 below.

[0081] Table 1. Record of Regeneration Test of Shaozaiyou No. 3

[0082]

[0083] The results showed that the entire growth period of the “Shaozaiyou 3” strain screened in this invention was shortened by 4 days compared with the control strain Zhongzao 39. The average yield in the early season was 8.54 t / ha, and the average yield in the regenerating season was 5.38 t / ha, both of which were higher than the control strain. The yield variation of “Shaozaiyou 3” between different years was also smaller than that of the control strain, and its stable yield performance in the regenerating season was better than that of the control strain.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A breeding method of rices based on indica-japonica hybrid grouping and early generation regeneration power directional screening, characterized in that, The method comprises the following steps: F1 generation is obtained by crossing "Jia 58" as the female parent and "Shundada 135" as the male parent, and the F1 generation and indica rice "Huanghuazhan" are cross-pollinated to obtain F2 generation; The F3 generation is selected according to the following standards after the first season harvest: base node injury flow > 1.2 ml / h, regenerative tiller number ≥ 5 tillers / plant, regenerative tiller SPAD value > 38, and regenerative tiller earing rate ≥ 70%; The F3 generation is planted in several regions for testing, and the seeds of the materials with a recovery rate greater than 70% and accumulated temperature loss < 15% within two weeks after the first season harvest and without significant yield difference are selected as F4 generation; The F4 generation and the harvested F5 generation are planted to obtain F6 generation; The F6 generation is screened according to the F3 generation selection standard to obtain F7 generation; The F7 generation is screened according to the standards of early maturity, first season yield of more than 8 tons and regenerative season yield of more than 5 tons to obtain a regenerative rice line.

2. The method for breeding ratooning rice according to claim 1, characterized in that, The determination time of the base node injury flow is 7-8 days after the first season harvest.

3. The method for breeding ratooning rice according to claim 1, characterized in that, The statistics time of the regenerative tiller number, regenerative tiller SPAD value and regenerative tiller earing rate is 21-22 days after the first season harvest.

4. The method for breeding ratooning rice according to claim 1, characterized in that, The F3 generation selection standard also includes the tiller germination rate on the 14th-15th day after the first season harvest; the selected standard of the tiller germination rate is ≥ 4 tillers / plant individual.

5. The method for breeding ratooning rice according to claim 1, characterized in that, The plant height of the line is 28-32 cm at the time of the first season harvest.

6. The method of claim 1, wherein the rice is japonica. The first season harvest of the F2 generation, F3 generation and F6 generation is completed by mechanical harvesting.

7. The method of claim 1-6, wherein, The standard of early maturity is that the maturity period of the line is more than 3 days earlier than that of Zhongzao 39.

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