Evaluation of Rice line and mapping quantitative trait loci for heat stress tolerance

Abstract

Intergovernmental Panel on Climate Change (IPCC) predicted a rise in global mean temperatures up to 2 - 40C by the end of 21st century. Rice is sensitive to high temperatures mostly during reproductive stage of development. Significant yield losses were already observed in major rice growing regions of China, Japan, Philippines and across South and Southeast Asia because of intense and long lasting heat waves. Most of the cultivated mega varieties of rice are found to be vulnerable to high temperatures. Moreover, most of the heat tolerance studies in rice so far are not field based. Hence, the identification of heat tolerant genotypes which can perform well in field conditions can help adapt rice to the effects of warmer temperatures. In the present study, the goal was to identify high yielding rice lines which are tolerant to heat stress in field conditions so that they newlinecan be used as varieties or donors in breeding programs and to identify important chromosomal regions which confer heat tolerance. The experiments were conducted in natural environmental conditions in pots as well as in field. Initially, a set of stable and high yielding introgression lines developed from elite variety x wild species crosses newline(Swarna x O. nivara and KMR3 x .rufipogon) and EMS induced mutants (N22) along with parents were screened for heat stress newlinetolerance during reproductive stage under six different temperature regimes in four experiments.