Comprehensive Assessment of Drought Resistance of BILs Population Derived from Dongxiang Wild Rice(Oryza rufipogon Griff.) at Seedling Stage and Its Genetic Analysis

66 rice(Oryza sativa L.)materials,including four upland rice,the backcross inbred lines(BILs)derived from the combination R974//R974/Dongxiang wild rice(Oryza rufipogon Griff.,Hereafter DXWR),and their parents,were employed for evaluation of drought resistance and screening of drought resistance index at seedling stage.Nine traits were monitored for assessment of drought resistance,including maximum root length(MRL),number of root(NR),stem length(SL),dry root weight(DRW),fresh root weight(FRW),root relative water content(RRWC),leaf relative water content(LRWC),level for rolling leaf(LRL),and seedling survivability under repeat drought(SSRD),respectively.Comprehensive assessment of drought resistance based on the principal component analysis(PCA)indicated the line 1949 showed the strongest drought resistance.Analysis on the stepwise regression equation and correlation demonstrated that MRL,RN,FRW,and RRWC significantly influenced the drought resistance,thus could be used as comprehensive index for identification of drought resistance at the seedling stage.The genetic mechanism of drought resistance at the seedling stage in the BILs population was controlled by two independent genes and polygenes,based on comprehensive drought resistance value(CDRV).As a result,the DXWR could be precious resources for genetic improvement of drought resistance in cultivated rice.