Inheritance And Identification Of Dormancy At Harvest (Resistance To Pre-Harvest Sprouting) And Application In Rice (Oryza Sativa L.) Breeding

Dormancy at harvest (DAH) of 33 maintained lines and 40 restorer lines successfully chosen or often used in practice were identified and screened; The basic characters of 4 rice varieties with heavy dormancy introduced from IRRI were researched; Materials with different dormancy screened from the maintained lines and restorer lines crossed with the 4 heavy dormancy rice varieties, and the expression of dormancy at harvest (DAH) in seed F2 population were researched; Effect of hull on seed germination were also researched in these materials;6 rice varieties with different DAH were completely diallel crossed as 6X6, the additive and dominant effects of major loci groups in DAH trait were analyzed ;Gang46A, II-32A and their corresponding maintained lines Gang46B, II-32B, crossed with the 4 rice varieties from IRRI, the inheritance of DAH in segregation population were analyzed and progenies were screened in breeding procedure. Results were as follows:1. Significant difference in seed germination percentage was only seen at 40d and 30d after heading; The correlation coefficient of seed germination percentage between complete ear method and kernel method was max at 35d. It was easy to discriminate weak and heavy dormant varieties after soaked 24h and germinate in incubator at 30 C for 3 days.2. No heavy dormant materials were found in 33 maintained lines; and few heavy dormant materials was selected although most of the restorer lines had no or weak dormancy. Generally analysis, no significant difference at DAH between MS lines and restorer lines.3. The dormancy in FI population was secund to the heavy dormant parents in"heavy dormancy X heavy dormancy " combinations, while, it was secund to the weak dormant parents in "medium dormancy X heavy dormancy " combinations, in "weak dormancy X heavy dormancy " combinations, some were secund to the heavy dormant parents and some were secund to the weak dormant parents. It wasdeduced that the dominance/recessive of DAH trait in F| population was different according to materials and combinations.4. The inheritance of DAH was not the same in different materials and combinations. The distribution frequency of F3 and BC|F2 came from Gang46B, II-32B crossed with the 4 rice varieties from IRRI demonstrated that, in most cases, DAH was mainly inherited as a quantitative trait controlled by micro-effect multi-genes, while major gene effects were also observed in II-32B /IR112 combinations.5. But the diallel cross results showed that DAH trait was controlled by two major loci groups (MLGs) and minor loci groups. The genetic variation was mainly explained by major loci groups,.6. Germination of F2 populations in 9 NILs of 9311 varieties and 2 NILs in jonpanic rice and 15 pairs of mutant crosses was identified, the results showed no cytoplasm effect was found in DAH trait in rice.7. In general, great potential of breeding for resistance to pre-harvest spouting (PHS) was found in II-32B /IR112 combination. Now the transient materials with higher resistance to PHS but without restorer genes were obtained.