Phenotypic and genetic analysis of RILs for drought resistance in rice (Oryza sativa L.)

Drought is one of the abiotic stresses limiting yield both in lowland and upland rice ecosystem. Varietal development through conventional breeding is slow due to poor understanding of genetic control of drought resistance. Identification of quantitative trait loci (QTLs) associated with drought resistance traits will provide an opportunity for breeding of rice varieties for drought prone areas. Forty drought resistant and susceptible recombinant inbred lines (RILs) derived from IR 64 and lalankada 41 were phenotypically screened under no stress, lowland stress and upland stress conditions for drought and genotyped with 53 polymorphic simple sequence repeat (SSR) markers covering 12 chromosomes. Two QTLs for ear bearing tillers per plant co-segregating with markers RM 202 (chromosome 11) and RM 19382 (chromosome 6), 1 for SPAD at drought recovery at RM 280 on chromosome 4 and 1 for leaf drying at RM 14565 on chromosome 3 were identified using composite interval mapping which explained individually 19.2 to 26.8% phenotypic variation. These traits correlated with yield enhancement coupled with high heritability. QTLs associated with these traits may be useful for indirect selection for grain yield under drought through marker assisted selection.