Studies on response to drought susceptibility index and grain yield in early backcross generation lines in rice (Oryza sativa L.)

Abstract

Rice under rainfed condition faces frequent moisture stress. Recent studies at IRRI have shown moderate to high heritability of grain yield under stress. Evaluation was done for reproductive stage moisture stress tolerance in severe moisture stress and well irrigated condition to study the effect of the introgressed QTLs in BILs. QTLs were introgressed through backcrossing of Apo (donor) and IR 64 (recipient) lines and Set of 81 backcross inbred lines (BILs) at BC1F3 generations developed through MAS (Marker Assisted Selection) bearing one at a time, two and three DTY (yield under drought) QTLs (Quantitative Trait Loci) for yield under stress donated by Apo. Single QTLs DTY2.2 performed best for grain yield and also showed least drought susceptibility index (DSI). Two and three QTL combination in the background of IR 64 viz., [DTY (3.1+8.1)] and [DTY (2.2+3.1+8.1)] QTL combinations recorded lesser DSI (Drought Susceptible Index) values than their parents and check DSI values. DTY (2.2 + 8.1) performed better in traits like grain yield than expected three QTL line. QTLs bearing BILs were advantageous over IR 64 under severe moisture stress with respect grain yield and direct us to further studies regarding QTLs effect on drought susceptibility index and its relationship with grain yield.