Development and evaluation of Pusa 44 backcross derived lines possessing QDTY2.1, qDTY3.1 and their combinations indicate differential yield response under severe reproductive stage drought stress

Reproductive stage drought stress (RSDS) tolerance in rice with higher productivity is very important in the context of climate change. With increasingly fluctuating rainfall distribution, maintaining higher productivity in the niche areas of rice production such as northern-western India is a challenge. Pusa 44 has been one of the most popular high yielding cultivars of northern-western India especially in the states of Punjab and Haryana. A medium duration rice variety with long slender grains, Pusa 44 is highly sensitive to drought and can lose up to 65% yield when exposed to the unexpected RSDS. To address this challenge, marker-assisted backcross breeding was adopted to introgress two QTLs governing yield under RSDS namely, qDTY2.1 and qDTY3.1 from the donors, IR81896-B-B-195 and IR81896-B-B-142 possessing both the QTLs. Through marker assisted foreground and phenotypic selection several backcross derived inbred lines (BILs; BC₃F₄) were developed, out of which Pusa 1823-12-31-12-12 (qDTY3.1), Pusa 1823-12-62 (qDTY2.1+qDTY3.1), Pusa 1823-12-82 (qDTY2.1+qDTY3.1), Pusa 1823-12-55 (qDTY2.1+qDTY3.1), and Pusa 1969-13-2110-24 (qDTY2.1) were found to significantly out-yield Pusa 44 to the tune of 2.0 to 2.5 times under RSDS. Lines possessing qDTY2.1 were found relatively less stable for drought response, than those possessing both the QTLs. These improved BILs are important genetic resource for further genetic studies as well as donors for improving rice yields under RSDS.