Efficient breeding method for high-quality millet

Abstract

The invention discloses an efficient breeding method for high-quality millet, which aims at solving the problems of traditional millet breeding and comprises the steps of parent selection and matching, planting layout, spike cutting and size thinning, bagging and pollination, generation selection and the like. The parent selection follows the principle of matching and complementation of recessive and dominant characters, a planting mode of'double male parents and female parents' is adopted, and the sowing time is adjusted. Middle grain sizes are reserved by cutting ears and thinning, and flapping pollination is performed at a specific time period after bagging. And performing rice color quantitative selection by combining generation selection with phenotype observation and ABL value measurement by a colorimeter. The multi-generation selection strategy covers from the F1 generation to the F5 generation, and all the generations are screened according to character characteristics. According to practice, the pollination success rate of the method is larger than or equal to 80%, the rice color quantitative selection accuracy rate exceeds 90%, 22 high-quality varieties such as' Jinzhu K1 'and the like are bred, the popularization benefit reaches 18.24 billion yuan, and the method has the advantages that time and labor are saved, the quality identification cost is low, the breeding period is short and the like, and is suitable for large-scale high-quality millet breeding.

Description

Technical Field

[0001] The invention belongs to the technical field of crop genetic breeding, and in particular relates to a high-efficiency breeding method for high-quality millet. Background Art

[0002] Millet (Setaria italica) is an important grain crop in my country. Its processed grains are rich in protein, vitamins and minerals, and have high nutritional and economic value. Traditional millet breeding methods mainly include systematic breeding, hybrid breeding, backcross breeding and mutation breeding. Among them, hybrid breeding has become the mainstream breeding method because it can integrate the excellent traits of parents, break the unfavorable gene linkage, and create genetic diversity. However, there are many bottleneck problems in the existing technology: Hybridization operation is inefficient: millet has tiny inflorescence organs, with a single flower diameter of about 2-3mm. Traditional methods of emasculation, such as warm water emasculation, require precise control of the water temperature at 44-45°C and soaking time of 8-10 minutes, which is cumbersome and easily damages the pistil; although the emasculation method can avoid heat damage, it requires cutting the inner and outer lemma of each flower, which is time-consuming and labor-intensive. The emasculation of a single ear takes more than 30 minutes, resulting in a hybridization success rate of less than 50%.

[0003] Offspring selection relies on experience and lacks accuracy: Important millet traits, such as yield, quality, and stress resistance, are mostly controlled by multiple genes, and the phenotype is easily affected by environmental factors. The traditional pedigree method requires the selection of individual plants from generation to generation, but due to limited manpower and resources, the size of the F2 generation population is often insufficient, usually only 100-200 plants are planted, making it difficult to fully separate the target genotype, which in turn leads to the loss of excellent genotypes.

[0004] Quality evaluation is delayed and highly subjective: The evaluation of high-quality millet is usually carried out through cooking and tasting or chemical analysis, such as protein content determination. These methods are time-consuming, with a single sample test taking 2-3 days and high costs. The cost of chemical analysis is about 200 yuan per sample, and it is impossible to achieve early large-scale screening. In addition, sensory evaluation is highly subjective and easily affected by human factors, resulting in selection bias.

[0005] In recent years, although the improved pedigree method has partially alleviated the above problems by optimizing the offspring selection process, it still has defects such as complex procedures and high resource consumption. For example, the F3 generation needs to be planted and screened line by line, which has high field management costs; beige quantitative selection relies on visual comparison, which makes it difficult to quantify the difference in goldenness, affecting the efficiency of high-quality material screening. Therefore, a breeding method that integrates efficient pollination technology, accurate phenotypic identification and optimized selection strategy is urgently needed to accelerate the breeding of high-quality millet varieties. Summary of the invention

[0006] The invention aims to solve the difficult problems in the millet hybrid breeding process and provide a time-saving, labor-saving and easy-to-operate high-quality millet efficient breeding method, especially the quality identification link in the method has low cost and high efficiency.

[0007] The object of the present invention is achieved in this way: a high-efficiency breeding method for high-quality millet, which comprises the following steps: S1. Parent selection and planting layout: The female parent uses recessive trait materials, and the male parent uses dominant trait materials. Planting is carried out in accordance with the "double male parent sandwiched with the female parent" mode, and the sowing period is adjusted to ensure that the flowering period coincides. Among them, parent selection follows the following principles: the female parent uses recessive trait materials such as green leaf sheaths, yellow seedlings, and no resistance to sethoxydim, and the male parent uses dominant trait materials such as purple leaf sheaths, green seedlings, and resistance to sethoxydim. This ensures that the F1 generation can quickly identify true hybrid plants through dominant and recessive phenotypes. The seedlings are identified by spraying sethoxydim. Plants that are not successfully hybridized are directly removed, and those that are successfully hybridized are retained. Yellow seedlings with green leaf sheaths that are not successfully hybridized are pulled out, and green seedlings with purple leaf sheaths that are successfully hybridized are retained. At the same time, the parents must have complementary traits. For example, the female parent focuses on high quality, with characteristics such as beige golden color and good taste, and the male parent focuses on stress resistance, with advantages such as drought resistance and disease resistance. The planting pattern adopts the layout of "two male parents sandwiching female parents", that is, two rows of female parents are planted in the middle, and two rows of different male parents are planted on both sides, with the row spacing controlled at 35-50cm. The sowing period is adjusted according to the difference in the flowering period of the parents, so that the heading period of the female parent overlaps with the flowering period of the male parent, thereby improving the pollination success rate.

[0008] S2. Cutting and thinning the ears and bagging for pollination: At the beginning of the flowering period of the ears, cut off the upper and lower 1 / 3 of the ears, keep the middle ears, put on the cellophane bag, and pat for pollination every day for 6-10 days. The specific operation is as follows: Cutting and thinning the ears should be carried out when the lower ears of the ears of the female and male parents begin to open, that is, when the first flower opens. Use sterilized scissors to cut off 1 / 3 of the ears at the top and bottom of the ears, keep the middle ears, and thin out the overcrowded ears so that the distance between the ears is ≥2cm to reduce invalid pollen competition. In terms of the bagging pollination process, the bagging material is a cellophane bag with a light transmittance of ≥90% and a size of 25cm×40cm to avoid mildew caused by excessive humidity. When bagging, put the ears of the male and female parents that have been cut and thinned together in a cellophane bag. Every morning after the dew has dispersed and the paper bag is relatively dry, use a bamboo pole or your hands to pat the glass paper bag covering the ears of grain. Pat the paper bag 10-15 times a day for 6-10 consecutive days to promote pollination, so that the pollen is evenly scattered on the female stigma. After the grains are ripe, open the glass paper bag, harvest the female ears and the male ears separately, and clearly mark the parents of the hybrid combination.

[0009] S3. Generation selection method: Phenotypic selection and beige quantitative selection are carried out according to the breeding goals. Phenotypic selection screens materials by direct observation, and beige quantitative selection uses 3nh colorimeter to measure ABL value, and selects materials with high golden color and uniform color. Among them, when using 3nh colorimeter to measure ABL value, select materials with L≥75, a≥5, and b≥20, which meet the "golden high quality" standard.

[0010] S4, multi-generation selection strategy: F1 generation: Identify true hybrid plants based on dominant and recessive phenotypes, and eliminate weak and deformed seedlings; harvest individual ears and retain seeds as the basis for F2 generation planting.

[0011] F2 generation: construct a large-scale separation population, plant 100-1000 plants per F1 ear, and the planting pattern can be 5m×16 rows or 2m×50 rows with a plant spacing of 10cm to ensure sufficient separation of the target traits, and then screen the individual plants according to the generational selection method.

[0012] F3 generation: Select F2 single ear division lines for planting and screen according to the generation selection method. Among them, those with plant height variation coefficient <5% are neat lines, and 3-5 ears are selected; those with plant height variation coefficient >15% are separated lines, and 10-30 ears are selected. Priority is given to retaining lines with significant differences from the parents, such as those with ear shape changing from cylindrical to spindle-shaped.

[0013] F4 generation: The offspring of the same F3 strain are sister lines. The disease resistance and yield potential between system groups are compared. Those with trait consistency > 90% are stable groups, and mixed harvests are upgraded to identification nurseries. For unstable groups, single plant selection continues according to the generational selection method.

[0014] F5 generation: Stable lines were subjected to variety comparison test to measure yield, thousand-grain weight, rice yield and rice color index. Those with excellent comprehensive performance entered the regional test. The variety comparison test was repeated 3 times and the randomized block design was adopted.

[0015] Method for measuring the ABL value of millet using a colorimeter: Use a 3nh colorimeter, with D65 standard light source and 10° observation angle. The white board needs to be calibrated before measurement, and the calibration values ​​are L=94.3, a=0.3, and b=4.2. The operation process is as follows: After rice milling, spread the sample on a black background board to avoid reflection interference, measure 5 sites for each sample, and take the average as the ABL value.

[0016] Advantages of the invention The pollination efficiency is significantly improved: the natural out-pollination rate of millet is generally 2-3%. By reducing ineffective pollen competition through ear pruning and thinning technology, and using bagging and patting pollination to simulate natural wind, the natural out-pollination rate can be increased to 8-10%, and the pollination success rate can be increased from the traditional 50% to 82.5%, saving 320 yuan in labor costs per mu.

[0017] Quality selection is more scientific and accurate: The colorimeter quantifies the beige standard and eliminates materials that deviate from the ABL threshold. The accuracy of early selection of high-quality materials is increased to 92%, which is 58% more efficient than traditional sensory evaluation.

[0018] The breeding cycle is greatly shortened: the optimized pedigree method enables stable strains to be obtained in the F5 generation, while the traditional method requires the F7-F8 generation, saving field management costs of approximately RMB 1,500 per mu.

[0019] Significant economic benefits: This method has been used to breed 22 high-quality varieties such as "Jinmiao K1" and "Chiyou No. 2", 18 of which have passed provincial registration. The cumulative promotion area is 5.026 million mu, and the new social and economic benefits are 1.824 billion yuan. For example, the price of "Jinmiao K1" millet is 0.8-1.2 yuan / kg higher than that of ordinary varieties, and the willingness of processing companies to purchase has increased by 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flow chart for multi-generation selection of Jinmiao K1; Figure 2 This is a table showing the relationship between the dominant and recessive sex of millet phenotypes; DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: Example 1: See Figure 1 and Figure 2 , a high-efficiency breeding method for high-quality millet, which comprises the following steps: S1. Parent selection and planting layout: Strictly follow the principle of parent selection and select parents with complementary traits that meet the requirements of dominant and recessive. For example, when breeding "Jin Miao K1", the female parent "Huang Miao A" (recessive traits: green leaf sheath, yellow seedling, not resistant to fenthion) is a recessive trait material, which has the characteristics of beige golden yellow but easy to lodging; the male parent "Zi Ye Sheath B" (dominant traits: purple leaf sheath, green seedling, resistant to fenthion) is a dominant trait material, resistant to lodging but beige light yellow. Adopt the "double male parent sandwiched female parent" planting mode, arrange the row spacing reasonably, and accurately adjust the sowing period according to the difference in the flowering period of the parents to ensure that the flowering period meets.

[0022] S2. Trimming and bagging for pollination: When the grains at the bottom of the ear of millet begin to open, use sterilized scissors to accurately cut off 1 / 3 of the grains at the top and bottom of the ear of millet, and remove the overcrowded grains. Use appropriate cellophane bags for bagging, and tap the paper bags for pollination during the peak period of natural pollen shedding of millet, that is, every morning after the dew has dispersed and the paper bags are relatively dry, and continue the operation for 6-10 days. After the grains are ripe, open the cellophane bags, harvest the female and male ears separately, and clearly mark the parents of the hybrid combination. For example, in the breeding process of "Jin Miao K1", the heading period of the female parent is 3 days later than that of the male parent. By delaying the sowing period of the male parent, the flowering period is met, and the upper and lower 1 / 3 of the grains are cut off. After bagging, tap the paper bags 12 times a day for 7 consecutive days, and the pollination success rate reaches 85%.

[0023] S3, generation selection method: According to the breeding objectives, phenotypic selection and beige quantitative selection were carefully carried out. A 3nh colorimeter (model NR10QC) was used to measure the ABL value and select materials that met the "golden high quality" standard.

[0024] S4, multi-generation selection strategy: F1 generation: Accurately identify true hybrid plants based on dominant and recessive phenotypes, and eliminate weak and deformed seedlings. Harvest individual ears and keep number records. For example, when breeding "Jin Miao K1", in the F1 generation, spray sethoxydim at the seedling stage to remove false hybrid plants, pull out false hybrid plants with yellow seedlings and green leaf sheaths, and retain true hybrid plants with green seedlings and purple leaf sheaths, with an elimination rate of 30%. Figure 1 In the 10 districts, all the true hybrids identified by dominant and recessive traits were harvested individually. The identification was mainly based on the length of bristles, seedling color, leaf sheath color, etc. (see Figure 2 ).

[0025] F2 generation: large-scale segregation population construction, segregation population is constructed according to the specified planting scale to ensure sufficient separation of target traits, and then single plants are selected strictly according to the generation selection method. For example, in the breeding of "Jin Miao K1", 800 F2 plants were planted, and 8 single ears were selected according to the bristle length > 5cm, white husk color, and ABL value (L=78, a=6, b=22).

[0026] Figure 1 Among the 20 zones, those with a coefficient of variation of traits related to the maternal parent of less than or equal to 5% are neat strains, indicating that hybridization was unsuccessful, and 3-5 ears can be selected and can continue to be used as parents; those with a coefficient of variation of traits related to the maternal parent of more than 15% are separated strains, indicating that hybridization was successful, and 10-30 ears can be selected. After selection, each ear is threshed separately, and a small amount of single ear seeds (about 3g) are taken out and milled with a small rice hustle. S3 are selected and eliminated according to generations, and finally the target F2 generation ears are selected to enter the F3 generation, with priority given to retaining strains with significant differences from the parents, such as the change of ear shape from cylindrical to spindle.

[0027] F3 generation: Select F2 for single ear division and plant, accurately judge the neat and separated plant, select ears as required, and give priority to the plant with significant difference from the parent. In the breeding of "Jin Miao K1", the F3 generation was planted in 8 plant lines, of which 3 plant lines had high uniformity (plant height CV=4.2%), and 5 ears were selected from each; 5 plant lines had obvious separation (CV=18%), and 20 ears were selected from each.

[0028] Figure 1 In areas 30, 31, 32, 34, 35, and 37, those with a coefficient of variation of traits related to the maternal parent greater than 15% are isolated strains, and 10-30 ears are selected according to the selection criteria for the F2 generation, and the homozygous generations are continued; No. 33, 36, and 38 are preliminary stable strains, and the main identification criteria are neat groups, good plant shape, and strong stress resistance. 3-5 ears with consistent phenotypes are selected and harvested as single ears. Among the separate harvests, those identified as true hybrids by dominant and recessive traits are harvested as single ears.

[0029] F4 generation: Classify by system group, carefully compare the disease resistance and yield potential between system groups, accurately select stable groups for mixed harvest and upgrade to the identification nursery, and continue to select individual plants for unstable groups. When breeding "Golden Seedling K1", 3 stable system groups entered the identification nursery, and the per-acre yield increased by 12.7% compared with the control "Golden Seedling".

[0030] Figure 1 The coefficient of variation of the traits related to the maternal parent in the 40, 41, 42, 47, and 48 regions is greater than 15%, which is considered as the segregating strain. 10-30 ears are selected according to the selection criteria of the F2 generation, and the homozygous strains are added. Figure 1 The 43, 44, 45, and 46 zones are stable strains. The main identification criteria are neat population, good plant shape, and strong stress resistance. 3-5 ears with the same phenotype are selected, mixed and harvested, and then entered into the F5 generation for verification. Figure 1 Areas 43, 44 and 45 are sister systems.

[0031] F5 generation: Stable lines are subjected to standardized variety comparison tests, and various indicators are measured. After comprehensive evaluation, those with excellent performance will be sent to regional trials. For example, in the variety comparison test, the average yield of "Jinmiao K1" was 318kg per mu, the thousand-grain weight was 3.2g, the rice yield was 78%, and the ABL value was stable (L=79±1.2, a=6.3±0.5, b=23±1.1), and it finally passed the provincial variety registration.

[0032] Figure 1 Areas 54 and 55 can be used for strain comparison tests. Figure 1 Areas 51 and 57 need to be further upgraded. Figure 1 Areas 52, 53, and 58 need to continue to be selected.

[0033] Test data and verification results: 1. Parent selection and F1 hybridization verification: After the female parent "Huangmiao A" (recessive traits: green leaf sheath, yellow seedling, no resistance to fenthion) was crossed with the male parent "Ziyeshe B" (dominant traits: purple leaf sheath, green seedling, resistance to fenthion), the phenotypic characteristics of the F1 generation plants were green seedlings and purple leaf sheaths, which was consistent with the dominant and recessive inheritance law, and the true hybridization rate was ≥95%. Field observations showed that the lodging resistance of the F1 generation plants was 42% higher than that of the female parent, verifying the effective integration of the male parent's stress resistance traits.

[0034] 2. F5 generation stability verification: Through multi-generation selection strategies, the stability of the F5 generation strains reached 93% (trait consistency > 90%). Comparison tests with traditional pedigree methods showed that: Traditional method: It takes F7-F8 generations to reach stability, and the average field management cost is 1,800 yuan / mu; The method of the present invention: the F5 generation can be stable, and the field management cost is reduced to 1,200 yuan / mu, saving 33.3% of the cost.

[0035] Data support: Field observations were conducted on the "Jinmiao K1" F5 generation strain for three consecutive years (2016-2018), with a plant height variation coefficient of less than 3%, an ear shape consistency of 97%, and a yield fluctuation rate of less than 5%.

[0036] 3. Verification of the accuracy of beige quantification selection: The ABL values ​​of F3 to F5 generation materials were measured using a 3nh colorimeter (model NR10QC): The materials that met the “golden high quality” standard (L≥75, a≥5, b≥20) in the F3 generation screening accounted for 82%; The proportion of materials that meet the F5 generation screening standards increased to 98%, and the color uniformity increased to 95%.

[0037] Comparative tests between sensory evaluation and instrumental measurement showed that the colorimeter screening accuracy reached 92%, an increase of 48% compared with traditional visual evaluation (accuracy 62%).

[0038] 4. Yield and resistance data: Yield: In the regional trials of 2016-2017, the average yield of "Jinmiao K1" was 318kg per mu, an increase of 12.7% over the control variety "Chigu No. 8"; Resistance: The artificial inoculation test of leaf rust showed that the disease index was 32 (the control variety was 78), and the resistance level was "medium resistance"; Drought resistance: Under drought stress (soil moisture content ≦40%), the green rate increased by 28% compared with the control, and the yield loss rate was reduced to 15%.

[0039] 5. Quality test results: After testing: crude protein content is 10.30%, crude fat content is 2.25%, and branched starch accounts for 77.20%; beige ABL value is stable (L=79±1.2, a=6.3±0.5, b=23±1.1).

Claims

1. A high-efficiency breeding method for high-quality millet, characterized in that: The following steps are involved: S1. Parent selection and planting layout: The female parent should use recessive trait materials, and the male parent should use dominant trait materials. Plant them in the "two male parents sandwiching the female parent" mode, and adjust the sowing time to ensure that the flowering period coincides; S2. Trimming and thinning the ears and bagging for pollination: When the ears first bloom, cut off the upper and lower 1 / 3 of the ears, keep the middle ears, put them in cellophane bags, and pat them every day for pollination for 6-10 days; S3. Generation selection method: Phenotypic selection and beige quantitative selection are carried out according to the breeding objectives. Phenotypic selection is to screen materials by direct observation, and beige quantitative selection is to measure the ABL value with a colorimeter to screen materials with high golden color and uniform color. S4, multi-generation selection strategy: (1) F1 generation: Identify true hybrid plants based on dominant and recessive phenotypes and eliminate weak and deformed seedlings; Harvest a single ear and save the seeds as the basis for F2 generation planting; (2) F2 generation: screening of individual plants according to the generation selection method; (3) F3 generation: Select the single ear ramet lines from F2 and plant them according to the generation selection method. Select 3-5 ears for the neat lines and 10-30 ears for the segregating lines. (4) F4 generation: The offspring of the same F3 strain are sister lines. The disease resistance and yield potential between system groups are compared. The stable groups are selected for mixed harvest and upgraded to the identification nursery. The unstable groups continue to be selected individually according to the generational selection method. (5) F5 generation: Stable lines are subjected to variety comparison tests to measure yield, 1000-grain weight, rice yield and rice color index. Those with excellent overall performance will enter regional trials.

2. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S1: (1) Principles of parent selection: The female parent is selected from recessive trait materials, including green leaf sheaths, yellow seedlings, and no resistance to sethoxydim; the male parent is selected from dominant trait materials, including purple leaf sheaths, green seedlings, and resistance to sethoxydim, to ensure that the F1 generation can identify true hybrid plants through dominant and recessive phenotypes; the parents must have complementary traits, with the female parent focusing on high quality and the male parent focusing on stress resistance; (2) Planting pattern: Adopt the "two male parents sandwiched between female parents" layout, with two rows of female parents planted in the middle and two rows of different male parents planted on both sides, with a row spacing of 35-50 cm; adjust the sowing time according to the difference in flowering period of the parents to ensure that the heading period of the female parent overlaps with the full flowering period of the male parent.

3. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S2: (1) Trimming and thinning: This should be done when the lower grains of the ears of the female and male parents begin to open. The method is to use sterilized scissors to cut off 1 / 3 of the grains at the upper and lower parts of the ears, retain the grains in the middle, and thin out the overcrowded grains. The spacing between grains should be ≥ 2 cm. (2) Bagging pollination process: The bagging material is a glass paper bag with a light transmittance of ≥90% and a size of 25 cm × 40 cm. The bagging method is to use a glass paper bag to put the cut and sparse ears of the male and female parents together. After the dew has dissipated in the morning every day and the paper bag is relatively dry, use a bamboo pole or your hands to pat the glass paper bag covering the ears of grain. Pat the paper bag 10-15 times a day, and continue to pat the bag for pollination for 6-10 days.

4. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S3: the beige quantitative selection is to use a 3nh colorimeter to measure the ABL value and select materials with L≥75, a≥5, and b≥20.

5. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S4: a large-scale segregating population is constructed for the F2 generation, with a planting scale of 100-1000 plants per F1 ear, a planting pattern of 5 m×16 rows or 2 m×50 rows, and a plant spacing of 10 cm.

6. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S4: in the F3 generation, those with a plant height variation coefficient of less than 5% are neat strains, and those with a plant height variation coefficient of more than 15% are segregated strains. Strains with significant differences from their parents are preferentially retained, and the significant differences include ear shape changing from cylindrical to spindle-shaped.

7. The high-efficiency breeding method for high-quality millet according to claim 1, characterized in that: In step S4: the F4 generation with a neutral trait consistency greater than 90% is a stable group, and the mixed harvest is upgraded to the identification plot.

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