Comparative Study on Backcross Inbred Lines of IR64 Rice (Oryza sativa L.) Introgressed with Drought QTLs under Varied Moisture Regimes over Different Seasons

Abstract

Among the abiotic stresses, drought is the major factor for heavy yield losses in rice production. The present study was undertaken with an aim of understanding the effect of mega QTLs of Apo controlling yield under drought. The BILs viz., CB 229 and CB 193-3 were evaluated for their drought responses under green house conditions along with the parents Apo, IR64 and check Norungan during Summer 2015, Kharif 2015, Rabi 2015-16. The results from this study reported that, Apo and BILs had higher photosynthetic rate when compared to IR64 under drought. CB 229 had low reduction per cent of photosynthesis (45.25%), Ci/Ca (23.88%), conductance (52.38%) and RWC (25.72%) compared to susceptible parent IR64. Number of filled grains was much higher in Apo, CB229 and CB 193-3 when compared to IR64 under stress condition. The significant reduction in single plant yield under moisture stress condition was observed in all the genotypes especially in IR64 (65.15%). Reduction was relatively less in the donor Apo and BILs. CB 229 showed a greater RWC, conductance, moderate transpiration rate, increased water uptake, a higher assimilation rate and a higher grain yield under the moisture stress condition compared to the other BIL and IR64. It was found that CB 229 with three QTL, i.e., qDTY2.2, qDTY3.1 and qDTY8.1, showed better performance than CB 193-3 with two QTL, qDTY3.1 and qDTY8.1, under severe stress while in irrigated condition CB 229 was onpar with IR64.