| A recombinant inbred lines (RILs) population of 248 lines derived from a cross of Jiucaiqing (japonica)/IR26 ( indica) was used to construct a molecular linkage map consisiting of 94 SSR markers was employed to identify the quantitative trait loci(QTLs) and genetic analyses of nitrogen-absorbing ability and nitrogen-utilizing efficiency of rice at the seedling stage.1.Construction of molecular linkage map530 SSR markers covering with all chromosome of rice were choiced to screening parent plant. 160 markers screened haved polymorphic in parent plant,and polymorphic ratio was 30%.94 of 160 markers were choiced to construct molecular map. A molecular map comprised of 94 markers was constructed using RILs population containing 248 indibiduals derived from Jiucaiqing (japonica)/IR26 (indica) ,convering 2477.2 cM on all chromosomes with 26.3 cM.2.Detection of distorted segregation in the linkage mapAnalysis genotype frequency of SSR markers was conducted based on molecular linkage map from RILs population derived from Jiucaiqing (japonicd)/IR26 {indica), and consisiting of 94 SSR markers,to detect distorted segregation. The results show that:65 markers fell into distorted segregation in RILs population and distributed on all chromosome.RILs was population intercross of japonica and indica.The population had some traits:(l) purification slower, so ratio of hybrid genotype was higher;(2) genotype of RILs population was partial indica, genotype ratio of IR26(indica,)was higher than genotype ratio of jiucaiqing(japonica);(3) in the study, the rate of distorted segregation in the RILs was 69.15%, the rate was more bigger than other population.3.Genetic analyses of nitrogen-absorbing ability and nitrogen-utilizingefficiency of rice at the seedling stageOne RILs population with 248 lines (F8) derived from the cross between Jiucaiqing (japonica) and IR26 (indica) was evaluated for analyzing inheritance of traits: nitrogen-absorbing (NA) ability and physiological use efficiency(NUE) of rice seedling. The results showed that the inheritance of NA and NUE of the rice were under the major gene plus polygene mixed inheritance model. NO3-absorbency , NH4- absorbency and nitrogen physiological use efficiency of rice seedlings were genetically controlled bygenetic mode of two major genes plus polygenes .The heritability values of major genes of NO3-absorbency , NH4- absorbency and nitrogen physiological utilizing efficiency was 79%, 55.67% and 19.47% respectively,and the heritability values of polygene of three traits was 6.68%,0.033% and 67.46% respectively . Between two major genes there are respectively additive and epistasis effect for the NO3-absorbency , epistasis effect for the NH4- absorbency and accumulative effect for the physiological use efficiency of nitrogen.4.QTLs mapping and genetic analyses of nitrogen-absorbing ability andnitrogen -utilizing efficiency of rice at the seedling stageA recombinant inbred lines (RILs) population of 248 lines derived from a cross of Jiucaiqing (japonica)/IR26 ( indica) by the single seed descent method was used to construct a molecular linkage map of RILs population consisiting of 94 SSR markers was employed to identify the quantitative trait loci(QTLs) by QTL Cartographer software,which control the abilities of rice root to uptake NO3-N and NH4-N and N use efficiency at seedling stage in a hydroponic experiment. Two QTLs linked with ability to uptake NO3-N were detected.One of QTLs located on chromosome 5 and another on chromosome 10,individual QTL accounted for 3.27 % ~ 3.28 % of the phenotypic variance in the RILs population.Two QTLs associated with ability to uptake NH4-N were identified.One of the QTLs located on chromosone 6 and another on chromosome 10 ,each QTL explained for 42.06 % ~ 10.54 % of the phenotypic variance in the population.Two QTLs was found to underlying N use efficiency, One QTL located on chromosome 5 and another on chromosme 12, which explained for 6.31 %~8.87% of the phenotypic variance in the population.
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