Genetic Dissection Of Yield Related Source And Sink Traits In A Set Of Hhz Selective Introgression Lines Under Drought Stress And Irrigation In China And Vietnam

Development of cultivar with relatively high yield potential under both stress and irrigation condition is an effective way to insure the food safety in the regions threatened by seasonal drought stress, such as the coastal area of North-western and Eastern of Vietnam. A population of selective introgression lines in BC1F6generation using Huang-Hua-Zhan, an indica cultivar with high yielding and wide-adaptability developed in Southern China, as recurrent parent and four cultivars (OM1723, Teqing, CDR22and PSBRC28) as donor, from a two-cycle cross screening with SNP genotype were used as materials for the phenotype assessment of source and sink related traits under both drought stress and irrigation in China and Vietnam. The major results from this research were shown in following:Results from three way (genotype (G), environment (E) and treatment (T)) ANOVA for the fifteen traits investigated in HHZ-ILs showed that the E factor affected all traits except PN highly significantly (P<0.0001); and HD was the one mostly affected (R2=86.9%). T affected all the traits very significantly (P<0.0001), except for GW. GY is the top one (R2=62.2%) being affected by the treatment factor. Of the two-way interactions, G×E affected five traits (HD, PH, PL, GL and GW) significantly; G×T significantly affected six traits including HD, PH, PL, FLW, TGW, and GY. No trait was affected by the three-way interaction (GxExT). According to the heritability (H2) estimated based on ANOVA results, the averaged value of H2was75.9%. Top seven heritable traits with H2more than80%in HHZ-IL are PL(89.0%), FLL(8.0%), FLW(83.1%), SLL(82.7%), PH(82.1%), GNP(81.8%), and GL(81.6%). Among them, three control leaf size which belongs to the source trait, and the other four are associated with plant type and seed density per panicle. Heritability is relatively low (<70%) in four traits of PN (68.3%), GT (66.2%), SF (62.5%) and GY (59.2%).Based on the yield per plant, a series of superior lines were found in comparing with HHZ by t-test, which belongs to IT1-2(ie, GY under irrigation is improved in at least one environment and is not decreased in another environment in comparing with HHZ) and DTI-2(ie, GY under stress conditions is improved with no yield penalty in comparing with HHZ). DTI-2lines behaved better than HHZ in GY under stress at Vietnam while indifferent from HHZ in GY at Hainan. Total of28of four types could be directly or indirectly applied in breeding programs for the corresponding ecological conditionsWith ICIMapping, a total of219regions were found to be significantly associated with the leaf and yield related traits under drought stress/irrigation. Among them, fourteen were expressed under two environments (stably expressed loci, SE-QTL) and fifteen were functioning under both stress and irrigation.