Breeding technology of rice blast resistant hybrid rice combination

Abstract

The invention relates to the technical field of rice breeding, and discloses a breeding technology of a rice blast-resistant hybrid rice combination, which comprises the following steps: screening parent materials: screening male parent and female parent materials with strong rice blast resistance and excellent agronomic traits from rice varieties with different genetic backgrounds, the rice blast resistance is determined in a mode of combining indoor seedling stage inoculation identification and field adult-plant stage natural induction identification, in the indoor seedling stage inoculation identification, spray inoculation is carried out by adopting a rice blast bacteria suspension with the concentration of 5 * 10 < 4 > cfu / mL, and culture is carried out for 14-21 days under the conditions that the relative humidity is not lower than 90% and the temperature is 25-30 DEG C after inoculation. Plants with lesion types of grade 3 and below are screened out. By accurately screening parent materials with high rice blast resistance and applying a mode of combining indoor inoculation and field identification, the disease resistance of parents is guaranteed from the source, and stable inheritance of disease-resistant genes in offspring is guaranteed by means of a molecular marker-assisted screening technology.

Description

Technical Field

[0001] The present invention relates to the technical field of rice breeding, in particular to a breeding technology for a blast-resistant hybrid rice combination. Background Art

[0002] Rice blast, a fungal disease caused by the rice blast fungus (Magnaporthe oryzae), is one of the most devastating diseases in rice production worldwide. It is widespread and devastating, affecting nearly all rice-growing regions. Once it breaks out, it can cause a yield reduction of 10%-20% at best, or even 50% or more, or even total crop failure. The numerous and frequently mutating physiological races of the blast fungus make it easy for rice varieties to lose their resistance, posing a significant challenge to blast prevention and control.

[0003] In existing technologies for breeding hybrid rice resistant to rice blast, traditional hybrid breeding methods are mostly used, relying mainly on the natural disease resistance of the parental materials, and screening disease-resistant varieties through field observation and simple indoor inoculation identification. However, these methods have many limitations. First, traditional indoor inoculation identification often uses a single concentration of rice blast fungus suspension, and the culture conditions are not strict enough, resulting in unstable disease resistance of the selected disease-resistant plants in actual field planting. Secondly, field identification is mostly carried out in ordinary field, lacking targeted research on historical rice blast outbreak areas, and it is impossible to accurately assess the actual disease resistance of the parental materials under natural disease conditions. Furthermore, in the process of screening hybrid offspring, the existing technology is not precise enough in the selection of agronomic traits, and lacks full tracking and observation of key agronomic traits, resulting in the hybrid combinations selected being difficult to achieve ideal levels in terms of yield and rice quality.

[0004] Furthermore, existing technologies for breeding and promoting blast-resistant hybrid rice varieties lack standardized breeding procedures, inadequate isolation measures for seed production fields, unreasonable planting ratios of male and female parents, unscientific regulation of flowering periods, and inadequate pollination management, making it difficult to ensure seed yield and quality. Furthermore, in areas with a high incidence of rice blast, the limited number of existing blast-resistant hybrid rice varieties makes it difficult to meet local planting needs. Furthermore, their ecological and social benefits need further improvement. Existing varieties are not sufficiently effective in reducing the spread of rice blast, reducing pesticide use, and improving the ecological environment of rice fields.

[0005] In summary, the existing breeding technology for blast-resistant hybrid rice has shortcomings in terms of the accuracy of disease resistance screening, the precision of offspring screening, the standardization of seed breeding, and ecological and social benefits. It is difficult to effectively cope with the variable physiological races of rice blast fungus and complex field disease conditions. There is an urgent need for a combination breeding technology for blast-resistant hybrid rice that can accurately screen disease-resistant parents, optimize the agronomic traits of hybrid offspring, ensure seed quality, and have significant ecological and social benefits. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a breeding technology for a blast-resistant hybrid rice combination, which solves the problems raised in the above-mentioned background technology.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A breeding technology for blast-resistant hybrid rice combinations, comprising the following steps:

[0008] Screening of parental materials: Male and female parent materials with strong resistance to rice blast and excellent agronomic traits were screened from rice varieties with different genetic backgrounds. The resistance to rice blast was determined by combining indoor seedling inoculation and field natural induction. The indoor seedling inoculation was performed with a concentration of 5×10 4 The plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus, and then cultured for 14-21 days under conditions of relative humidity not less than 90% and temperature of 25-30°C. Plants with lesion type 3 or below were screened. Natural induced identification during the field mature stage was conducted in areas with a history of rice blast. The disease situation was investigated during the heading and grain filling stages of rice. The diseased ear rate and disease index were calculated, and plants with a diseased ear rate less than 5% and a disease index less than 20 were screened.

[0009] Hybrid combination configuration: The selected male and female parent materials are hybridized in an isolated area. Specifically, during the rice flowering period, when the female parent flower opening degree reaches more than 70% and the stigma is well exposed, the male parent pollen is collected and immediately pollinated on the female parent stigma. Each hybrid combination is configured with 3-5 replicates. After each pollination, it is marked and recorded to ensure uniform pollination and no hybrid contamination;

[0010] Progeny screening: The F1 generation seeds obtained from the hybridization are planted in the field and field observed and selected at the seedling, heading, and maturity stages. During the seedling stage, plant growth, leaf color, and leaf morphology are observed; during the heading stage, ear shape, number of grains per ear, and lodging resistance are examined; and during the maturity stage, 1000-grain weight, fruit set rate, and total growth period are measured. Simultaneously, blast resistance is identified under natural blast disease conditions. Molecular marker-assisted screening technology is used to detect molecular marker loci closely linked to blast resistance genes to screen for plants carrying the target blast resistance gene.

[0011] Multi-site trials: Selected superior hybrid combinations will be tested regionally at multiple test sites with different ecological environments. The test sites cover areas with low, moderate, and high incidence of rice blast. The test period for each test site is one growing season. A comprehensive evaluation will be conducted on agronomic traits such as yield, rice quality, and blast resistance of the hybrid combinations. The planting area of each test site should be no less than 100 square meters, and the number of replications should be no less than three. A randomized block design will be used, and the local main cultivated variety will be set as a control.

[0012] Breeding and promotion of improved varieties: Hybrid rice combinations that have undergone multi-site trials and have performed well are bred into improved varieties using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, flowering period regulation, pollination management, seed harvesting and processing, etc.

[0013] Preferably, the male parent material needs to meet the requirements of tall plants, large ears, strong lodging resistance, and good compatibility under multiple different ecological environments. The female parent material has a moderate growth period, strong tillering ability, developed root system, and coordinated ear-grain structure.

[0014] Preferably, during the hybrid combination configuration process, 1-2% gibberellin solution is used to regulate the flowering period of the male and female parents 3-5 days before flowering to ensure that the male and female parents' flowering periods coincide and improve the hybrid fruit setting rate.

[0015] Preferably, in the multi-point test, under the natural occurrence conditions of rice blast at each test point, a standardized disease investigation method is used to investigate the incidence of leaf blast and ear blast at the rice blast stage and the full heading stage, respectively, to screen out hybrid combinations that show high resistance to rice blast at multiple test points.

[0016] Preferably, during the breeding process of improved varieties, the isolation distance of the seed production field is not less than 500 meters, the planting row ratio of male and female parents is 1:2-4, the planting density is 12,000-15,000 plants per mu, and artificial assisted pollination is combined with natural pollination to improve seed yield and quality. The specific method of artificial assisted pollination is to use a bamboo pole to gently shake the male parent plant during the peak period of male parent pollen shedding so that the pollen is evenly scattered on the female parent stigma, and this is done 1-2 times a day for 3-5 consecutive days.

[0017] Preferably, the method further comprises the step of treating the bred blast-resistant hybrid rice seeds, wherein the seed treatment comprises processes such as sun drying, disinfection, soaking and germination, wherein the disinfection is carried out by treating with 500 times diluted 25% 100g emulsifiable concentrate for 4-6 hours, and the soaking is carried out by soaking in warm water at 30-32°C for 48-60 hours.

[0018] A breeding technology for a blast-resistant hybrid rice combination is applied to large-scale planting in areas with a high incidence of rice blast, and the planting method comprises the following steps:

[0019] Land preparation and sowing: Select a field with medium fertility and good drainage, plow and prepare the land, and apply base fertilizer. The base fertilizer dosage is 1500-2000 kg of decomposed farmyard manure, 30-40 kg of compound fertilizer, and 1-1.5 kg of zinc fertilizer per mu. Sow in late March to early April. Use the dry seedling raising method and sow 100-120 grams per square meter. Cover with plastic film after sowing to keep warm and moist.

[0020] Transplanting and field management: Transplant the rice seedlings when they have 3-4 leaves. The transplanting density is 18,000-20,000 stalks per mu, with 2-3 plants planted per stalk. Irrigate promptly after transplanting, maintaining a shallow water layer of 3-5 cm. During the tillering stage, maintain a shallow water layer of 2-3 cm to promote tillering. Maintain moist irrigation from the panicle differentiation stage to the filling stage, alternating dry and wet seasons to increase the fruit set rate. During the rice growth period, timely disease and insect pest control should be carried out, focusing on the prevention and control of rice blast, rice planthoppers and rice leaf rollers. Use high-efficiency, low-toxicity, and low-residue pesticides for prevention and control.

[0021] Fertilization and harvesting: Topdressing should be carried out during the tillering stage, panicle differentiation stage and filling stage respectively. The amount of topdressing is 5-8 kg of urea and 3-5 kg of potassium fertilizer per mu. After the rice matures, it should be harvested in time. Choose a sunny day for harvesting and use mechanized or manual harvesting to ensure that every grain is stored in the warehouse.

[0022] The present invention provides a breeding technology for a blast-resistant hybrid rice combination. It has the following beneficial effects:

[0023] 1. This invention precisely screens parental materials for strong resistance to rice blast, employing a combination of indoor inoculation and field testing to ensure parental disease resistance from the source. Molecular marker-assisted screening ensures the stable inheritance of disease-resistance genes in subsequent generations. Multi-site trials have demonstrated that the resulting hybrid rice combinations exhibit significant resistance in areas with a high incidence of rice blast, significantly reducing the incidence and the impact of the disease on plant growth and yield, thereby establishing a strong defense against disease and ensuring stable and high rice yields.

[0024] 2. This invention improves rice blast resistance while optimizing rice yield and quality. By rigorously screening the agronomic traits of parental materials, tracking and observing the key agronomic traits of hybrid offspring, and combining multi-site testing and comprehensive evaluation, high-yield, high-quality hybrid combinations are precisely selected. These selected combinations can achieve yield increases of over 10% compared to existing major varieties, meeting market demand for high-quality rice and enhancing the economic value and market competitiveness of rice.

[0025] 3. This invention provides a practical solution for areas with a high incidence of rice blast, with significant ecological and social benefits. Promoting the cultivation of selected blast-resistant hybrid rice varieties can reduce the spread of rice blast and pathogen spores, improve the paddy field ecosystem, and reduce the risk of soil and water pollution. Furthermore, it reduces the use of chemical pesticides and the harm of pesticide residues to rice quality and human health, aligning with the concepts of green and ecological agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart for configuring the hybrid combination from parent screening of the present invention;

[0027] Figure 2 A multi-point test flow chart was obtained for the offspring screening of the present invention;

[0028] Figure 3 This is a flow chart of the improved variety breeding, promotion and planting application of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Please see the attached Figure 1 -Attached Figure 3 The present invention provides a breeding technology for a blast-resistant hybrid rice combination, which specifically includes:

[0031] Example 1

[0032] Parent screening

[0033] From multiple rice varieties, we screened male and female parent materials with high resistance to rice blast and excellent agronomic traits. Male parents were required to have tall plants, large panicles, strong lodging resistance, and good compatibility in various ecological environments. Female parents were required to have a moderate growth period, strong tillering ability, a well-developed root system, and a well-balanced panicle-grain structure. Blast resistance was determined through a combination of indoor seedling inoculation testing and field testing during the mature plant stage. Indoor seedling inoculation testing used a concentration of 5×10 4 Plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus. After inoculation, the plants were cultured for 14-21 days at a relative humidity of no less than 90% and a temperature of 25-30°C. Plants with lesion grade 3 or lower were selected. Field blast identification was conducted in areas with a history of rice blast. Disease activity was investigated during the heading and grain-filling stages, and the diseased ear rate and disease index were calculated. Plants with a diseased ear rate below 5% and a disease index below 20 were selected.

[0034] Hybrid configuration

[0035] In the isolation area, during the rice flowering period, when the female flower opening degree reaches more than 70% and the stigma is well exposed, the male pollen is collected and immediately conferred to the female stigma. Each hybrid combination is configured with 3 replicates, and the pollination is marked and recorded after pollination to ensure uniform pollination and no hybrid contamination.

[0036] Offspring screening

[0037] The F1 generation seeds obtained from hybridization were planted in the field, and field observation and selection were carried out at the seedling stage, ear stage and maturity stage respectively, focusing on the plant growth potential, leaf color, leaf morphology, ear shape, number of grains per ear, etc., and rice blast resistance was identified under the conditions of natural occurrence of rice blast, and plants carrying the target rice blast resistance gene were screened out.

[0038] Multi-point test

[0039] Regional trials were conducted at multiple test sites in different ecological environments, covering areas with light, moderate and heavy rice blast incidence. The planting area of each test site was no less than 100 square meters, with no less than 3 repetitions. A randomized block design was adopted, and local main cultivated varieties were set as controls.

[0040] Breeding and promotion of improved varieties

[0041] Hybrid combinations with excellent performance are bred into high-quality varieties using standardized breeding technology processes. The isolation distance of seed production fields is no less than 500 meters, the planting row ratio of male and female parents is 1:2, the planting density is 12,000 plants per mu, and a combination of artificial assisted pollination and natural pollination is used.

[0042] Example 2

[0043] Parent screening

[0044] On the basis of Example 1, the stress tolerance screening of the male and female parents was added to select varieties with stronger cold and drought resistance.

[0045] Hybrid configuration

[0046] The male and female parents were treated with 1.5% gibberellin solution for flowering regulation 4 days before flowering to ensure that the male and female parents' flowering periods coincided and to increase the hybrid fruit setting rate.

[0047] Offspring screening

[0048] Increase the screening of cold resistance during the seedling stage to select plants that grow normally in low temperature environments.

[0049] Multi-point test

[0050] Regional trials were conducted at multiple test sites in different ecological environments, covering areas with light, moderate and heavy rice blast incidence. The planting area of each test site was no less than 100 square meters, with no less than 3 repetitions. A randomized block design was adopted, and local main cultivated varieties were set as controls.

[0051] Breeding and promotion of improved varieties

[0052] We breed high-quality hybrid combinations with excellent performance using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, flowering period regulation, pollination management, seed harvesting and processing, etc.

[0053] Example 3

[0054] Parent screening

[0055] From rice varieties with different genetic backgrounds, male and female parent materials with strong resistance to rice blast and excellent agronomic traits were selected. Male parent materials were required to have tall plants, large panicles, strong lodging resistance, and good compatibility in multiple ecological environments; female parent materials had a moderate growth period, strong tillering ability, a well-developed root system, and a well-balanced panicle and grain structure. Indoor seedling inoculation was performed using a concentration of 5×10 4 Plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus. After inoculation, the plants were cultured for 14-21 days at a relative humidity of no less than 90% and a temperature of 25-30°C. Plants with lesion grade 3 or lower were selected. Field blast identification was conducted in areas with a history of rice blast. Disease activity was investigated during the heading and grain-filling stages, and the diseased ear rate and disease index were calculated. Plants with a diseased ear rate below 5% and a disease index below 20 were selected.

[0056] Hybrid configuration

[0057] The selected male and female parent materials were hybridized in an isolated area. During the rice flowering period, when the female flower was more than 70% open and the stigma was well exposed, pollen from the male parent was collected and immediately transferred to the female parent's stigma. Three replicates were configured for each hybridization combination, and each pollination was marked and recorded to ensure uniform pollination and the absence of hybrid contamination.

[0058] Offspring screening

[0059] The F1 generation seeds from the hybridization were planted in the field and observed and selected at the seedling, heading, and maturity stages. During the seedling stage, plant growth, leaf color, and morphology were observed. At the heading stage, panicle shape, number of grains per panicle, and lodging resistance were examined. At maturity, 1,000-grain weight, seed set rate, and overall growth period were measured. Simultaneously, blast resistance was identified under natural blast-infecting conditions. Molecular marker-assisted screening (MACS) was used to identify molecular markers closely linked to blast-resistance genes, allowing plants carrying the target blast-resistance gene to be identified.

[0060] Multi-point test

[0061] Selected hybrid combinations were regionally tested at multiple sites across diverse ecological environments, encompassing areas with minimal, moderate, and severe rice blast infestation. Each site underwent a full growing season, during which a comprehensive evaluation of agronomic traits such as yield, rice quality, and blast resistance was conducted. Each site had a planting area of at least 100 square meters, with at least three replicates. A randomized block design was employed, with the dominant local variety serving as a control.

[0062] Breeding and promotion of improved varieties

[0063] Hybrid rice combinations that have undergone multi-site trials and performed well are bred for improved varieties using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, flowering period regulation, pollination management, seed harvesting and processing. The isolation distance of seed production fields is no less than 500 meters, the planting row ratio of male and female parents is 1:3, and the planting density is 13,000 plants per mu. A combination of artificial assisted pollination and natural pollination is used to improve seed yield and quality. The specific method of artificial assisted pollination is to use a bamboo pole to gently shake the male parent plant during the peak pollen shedding period of the male parent so that the pollen is evenly distributed on the female parent's stigma. This is done once a day for four consecutive days.

[0064] Example 4

[0065] Parent screening

[0066] Paternal and maternal materials with strong resistance to rice blast and excellent agronomic traits were selected from rice varieties with different genetic backgrounds. Paternal materials were required to have tall plants, large panicles, strong lodging resistance, and good compatibility in multiple ecological environments; maternal materials were required to have a moderate growth period, strong tillering ability, a well-developed root system, and a well-balanced panicle-grain structure. Blast resistance was determined through a combination of indoor seedling inoculation testing and field testing at the mature plant stage. Indoor seedling inoculation testing used a concentration of 5×10 4 Plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus. After inoculation, the plants were cultured for 14-21 days at a relative humidity of no less than 90% and a temperature of 25-30°C. Plants with lesion grade 3 or lower were selected. Field blast identification was conducted in areas with a history of rice blast. Disease activity was investigated during the heading and grain-filling stages, and the diseased ear rate and disease index were calculated. Plants with a diseased ear rate below 5% and a disease index below 20 were selected.

[0067] Hybrid combination configuration

[0068] The selected male and female parent materials were hybridized in an isolated area. During the rice flowering period, when the female flower was more than 70% open and the stigma was well exposed, pollen from the male parent was collected and immediately transferred to the female parent's stigma. Each hybridization combination was configured with four replicates, and each pollination was marked and recorded to ensure uniform pollination and no hybrid contamination.

[0069] Offspring screening

[0070] The F1 generation seeds from the hybridization were planted in the field and observed and selected at the seedling, heading, and maturity stages. During the seedling stage, plant growth, leaf color, and morphology were observed. At the heading stage, panicle shape, number of grains per panicle, and lodging resistance were examined. At maturity, 1,000-grain weight, seed set rate, and overall growth period were measured. Simultaneously, blast resistance was identified under natural blast-infecting conditions. Molecular marker-assisted screening (MACS) was used to identify molecular markers closely linked to blast-resistance genes, allowing plants carrying the target blast-resistance gene to be identified.

[0071] Multi-point test

[0072] Selected hybrid combinations were regionally tested at multiple sites across diverse ecological environments, encompassing areas with minimal, moderate, and severe rice blast infestation. Each site underwent a full growing season, during which a comprehensive evaluation of agronomic traits such as yield, rice quality, and blast resistance was conducted. Each site had a planting area of at least 100 square meters, with at least three replicates. A randomized block design was employed, with the dominant local variety serving as a control.

[0073] Breeding and promotion of improved varieties

[0074] Hybrid rice combinations that have undergone multi-site testing and have performed well are bred for improved varieties using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, adjusting the flowering period, pollination management, seed harvesting and processing, etc. The isolation distance of seed production fields is no less than 500 meters, the planting row ratio of male and female parents is 1:4, and the planting density is 15,000 plants per mu. A combination of artificial assisted pollination and natural pollination is used to improve seed yield and quality. The specific method of artificial assisted pollination is to use a bamboo pole to gently shake the male parent plant during the peak pollen shedding period of the male parent to evenly distribute the pollen on the female parent's stigma. This is done twice a day for three consecutive days.

[0075] Example 5

[0076] Parent screening

[0077] From rice varieties with different genetic backgrounds, male and female parent materials with strong resistance to rice blast and excellent agronomic traits were selected. Male parent materials were required to have tall plants, large panicles, strong lodging resistance, and good compatibility in multiple ecological environments; female parent materials had a moderate growth period, strong tillering ability, a well-developed root system, and a well-balanced panicle and grain structure. Indoor seedling inoculation was performed using a concentration of 5×10 4 Plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus. After inoculation, the plants were cultured for 14-21 days at a relative humidity of no less than 90% and a temperature of 25-30°C. Plants with lesion grade 3 or lower were selected. Field blast identification was conducted in areas with a history of rice blast. Disease activity was investigated during the heading and grain-filling stages, and the diseased ear rate and disease index were calculated. Plants with a diseased ear rate below 5% and a disease index below 20 were selected.

[0078] Hybrid combination configuration

[0079] The selected male and female parent materials were hybridized in an isolated area. During the rice flowering period, when the female flower was at least 70% open and the stigma was well exposed, pollen from the male parent was collected and immediately transferred to the female parent's stigma. Each hybridization combination was configured with five replicates, and each pollination was marked and recorded to ensure uniform pollination and the absence of hybrid contamination.

[0080] Offspring screening

[0081] The F1 generation seeds from the hybridization were planted in the field and observed and selected at the seedling, heading, and maturity stages. During the seedling stage, plant growth, leaf color, and morphology were observed. At the heading stage, panicle shape, number of grains per panicle, and lodging resistance were examined. At maturity, 1,000-grain weight, seed set rate, and overall growth period were measured. Simultaneously, blast resistance was identified under natural blast-infecting conditions. Molecular marker-assisted screening (MACS) was used to identify molecular markers closely linked to blast-resistance genes, allowing plants carrying the target blast-resistance gene to be identified.

[0082] Multi-point test

[0083] Selected hybrid combinations were regionally tested at multiple sites across diverse ecological environments, encompassing areas with minimal, moderate, and severe rice blast infestation. Each site underwent a full growing season, during which a comprehensive evaluation of agronomic traits such as yield, rice quality, and blast resistance was conducted. Each site had a planting area of at least 100 square meters, with at least three replicates. A randomized block design was employed, with the dominant local variety serving as a control.

[0084] Breeding and promotion of improved varieties

[0085] Hybrid rice combinations that have undergone multi-site trials and performed well are bred for improved varieties using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, flowering period regulation, pollination management, seed harvesting and processing. The isolation distance of seed production fields is no less than 500 meters, the planting row ratio of male and female parents is 1:2, and the planting density is 12,000 plants per mu. A combination of artificial assisted pollination and natural pollination is used to improve seed yield and quality. The specific method of artificial assisted pollination is to use a bamboo pole to gently shake the male parent plant during the peak pollen shedding period of the male parent so that the pollen is evenly distributed on the female parent's stigma. This is done once a day for 5 consecutive days.

[0086] 2. Comparative Example

[0087] Comparative Example 1

[0088] Parents were screened only through indoor seedling inoculation identification, without combining natural induction identification during the field adult stage.

[0089] Comparative Example 2

[0090] Parents were selected only through field identification, without combining indoor seedling inoculation identification.

[0091] Comparative Example 3

[0092] During the progeny screening process, molecular marker-assisted screening technology was not used.

[0093] Comparative Example 4

[0094] During the breeding process of improved varieties, no seed treatment was carried out.

[0095] 3. Test Examples

[0096] Evaluation of rice blast resistance

[0097] Planting trials were carried out in fields in areas with a high incidence of rice blast, and the diseased ear rate and disease index were recorded.

[0098]

[0099]

[0100] Table 1

[0101] As can be seen from Table 1 above, the hybrid combinations of Examples 1-5 showed significant disease resistance in areas with a high incidence of rice blast, with diseased ear rates below 5% and disease indexes below 20, while the combinations of Comparative Examples 1-4 showed poor disease resistance at some test sites.

[0102] Yield Assessment

[0103] By comparing the yield data of each combination, the average yield of the hybrid combinations of Examples 1-5 is significantly higher than that of the existing main varieties, with an increase of more than 10%.

[0104] Group Yield (kg / mu) Example 1 620 Example 2 630 Example 3 610 Example 4 615 Example 5 625 Comparative Example 1 550 Comparative Example 2 560 Comparative Example 3 570 Comparative Example 4 580 Local main varieties 560

[0105] Table 2

[0106] The average yield of the combination of Example 1 in the areas with light, moderate and heavy rice blast incidence was 620 kg, 580 kg and 540 kg per mu respectively, which were 11%, 12% and 10% higher than those of the main local varieties.

[0107] Rice quality assessment

[0108] The rice quality of each combination was tested, and the combination of Examples 1-5 performed well in terms of rice quality, meeting the market demand for high-quality rice.

[0109] Group Rice quality rating Example 1 90 Example 2 92 Example 3 88 Example 4 89 Example 5 91 Comparative Example 1 80 Comparative Example 2 82 Comparative Example 3 83 Comparative Example 4 85

[0110] Table 3

[0111] It can be seen from the above test examples that the breeding technology of the blast-resistant hybrid rice combination of the present invention shows significant advantages in improving the rice blast resistance, yield and rice quality, and has high application value and promotion prospects.

[0112] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A breeding technology for blast-resistant hybrid rice combinations, characterized in that: The following steps are involved: Screening of parental materials: Male and female parent materials with strong resistance to rice blast and excellent agronomic traits were screened from rice varieties with different genetic backgrounds. The resistance to rice blast was determined by combining indoor seedling inoculation and field natural induction. The indoor seedling inoculation was performed with a concentration of 5×10 4 The plants were spray-inoculated with a suspension of rice blast fungus containing 100 cfu / mL of rice blast fungus, and then cultured for 14-21 days under conditions of relative humidity not less than 90% and temperature of 25-30°C. Plants with lesion type 3 or below were screened. Natural induced identification during the field mature stage was conducted in areas with a history of rice blast. The disease situation was investigated during the heading and grain filling stages of rice. The diseased ear rate and disease index were calculated, and plants with a diseased ear rate less than 5% and a disease index less than 20 were screened. Hybrid combination configuration: The selected male and female parent materials are hybridized in an isolated area. Specifically, during the rice flowering period, when the female parent flower opening degree reaches more than 70% and the stigma is well exposed, the male parent pollen is collected and immediately pollinated on the female parent stigma. Each hybrid combination is configured with 3-5 replicates. After each pollination, it is marked and recorded to ensure uniform pollination and no hybrid contamination; Progeny screening: The F1 generation seeds obtained from the hybridization are planted in the field and field observed and selected at the seedling, heading, and maturity stages. During the seedling stage, plant growth, leaf color, and leaf morphology are observed; during the heading stage, ear shape, number of grains per ear, and lodging resistance are examined; and during the maturity stage, 1000-grain weight, fruit set rate, and total growth period are measured. Simultaneously, blast resistance is identified under natural blast disease conditions. Molecular marker-assisted screening technology is used to detect molecular marker loci closely linked to blast resistance genes to screen for plants carrying the target blast resistance gene. Multi-site trials: Selected superior hybrid combinations will be tested regionally at multiple test sites with different ecological environments. The test sites cover areas with low, moderate, and high incidence of rice blast. The test period for each test site is one growing season. A comprehensive evaluation will be conducted on agronomic traits such as yield, rice quality, and blast resistance of the hybrid combinations. The planting area of each test site should be no less than 100 square meters, and the number of replications should be no less than three. A randomized block design will be used, and the local main cultivated variety will be set as a control. Breeding and promotion of improved varieties: Hybrid rice combinations that have undergone multi-site trials and have performed well are bred into improved varieties using standardized breeding technology processes, including the selection and isolation of seed production fields, the planting ratio of male and female parents, flowering period regulation, pollination management, seed harvesting and processing, etc.

2. The breeding technology for a blast-resistant hybrid rice combination according to claim 1, characterized in that: The male parent material must meet the requirements of tall plants, large ears, strong lodging resistance, and good compatibility under multiple different ecological environments. The female parent material must have a moderate growth period, strong tillering ability, a developed root system, and coordinated ear-grain structure.

3. The breeding technology for a blast-resistant hybrid rice combination according to claim 1, characterized in that: During the hybrid combination configuration process, 1-2% gibberellin solution is used to regulate the flowering period of the male and female parents 3-5 days before flowering to ensure that the male and female parents have the same flowering period and improve the hybrid fruit setting rate.

4. The breeding technology for a blast-resistant hybrid rice combination according to claim 1, characterized in that: In the multi-point test, under the natural occurrence conditions of rice blast at each test point, a standardized disease investigation method is used to investigate the incidence of leaf blast and ear blast at the rice blast stage and the full heading stage, respectively, to screen out hybrid combinations that show high resistance to rice blast at multiple test points.

5. The breeding technology for a blast-resistant hybrid rice combination according to claim 1, characterized in that: During the breeding process of the improved varieties, the isolation distance of the seed production field is not less than 500 meters, the planting row ratio of the male and female parents is 1:2-4, the planting density is 12,000-15,000 plants per mu, and artificial assisted pollination is combined with natural pollination to improve seed yield and quality. The specific method of artificial assisted pollination is to use a bamboo pole to gently shake the male parent plant during the peak period of male parent pollen shedding so that the pollen is evenly scattered on the female parent stigma. This is done 1-2 times a day for 3-5 consecutive days.

6. The breeding technology for a blast-resistant hybrid rice combination according to claim 1, characterized in that: The method also includes the step of treating the bred blast-resistant hybrid rice seeds, wherein the seed treatment includes seed sun-drying, disinfection, seed soaking and germination. The disinfection step is performed by treating the seeds with a 500-fold dilution of 25% 100g emulsifiable concentrate for 4-6 hours, and the seed soaking step is performed by soaking the seeds in warm water at 30-32°C for 48-60 hours.

7. A breeding technology for blast-resistant hybrid rice combinations for large-scale planting in areas with high incidence of rice blast, wherein the breeding technology for blast-resistant hybrid rice combinations according to any one of claims 1 to 6 is characterized in that: The planting method includes the following steps: Land preparation and sowing: Select a field with medium fertility and good drainage, plow and prepare the land, and apply base fertilizer. The base fertilizer dosage is 1500-2000 kg of decomposed farmyard manure, 30-40 kg of compound fertilizer, and 1-1.5 kg of zinc fertilizer per mu. Sow in late March to early April. Use the dry seedling raising method and sow 100-120 grams per square meter. Cover with plastic film after sowing to keep warm and moist. Transplanting and field management: Transplant the rice seedlings when they have 3-4 leaves. The transplanting density is 18,000-20,000 stalks per mu, with 2-3 plants planted per stalk. Irrigate promptly after transplanting, maintaining a shallow water layer of 3-5 cm. During the tillering stage, maintain a shallow water layer of 2-3 cm to promote tillering. Maintain moist irrigation from the panicle differentiation stage to the filling stage, alternating dry and wet seasons to increase the fruit set rate. During the rice growth period, timely disease and insect pest control should be carried out, focusing on the prevention and control of rice blast, rice planthoppers and rice leaf rollers. Use high-efficiency, low-toxicity, and low-residue pesticides for prevention and control. Fertilization and harvesting: Topdressing should be carried out during the tillering stage, panicle differentiation stage and filling stage respectively. The amount of topdressing is 5-8 kg of urea and 3-5 kg of potassium fertilizer per mu. After the rice matures, it should be harvested in time. Choose a sunny day for harvesting and use mechanized or manual harvesting to ensure that every grain is stored in the warehouse.

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