Mapping QTLs for morpho-physiological traits related to grain yield under late sown conditions in wheat (Triticum aestivum L.)

The elevating temperature makes heat stress one of the major issues for wheat production globally. To elucidate genetic basis and map heat tolerance QTLs for agroecology of the State of Bihar under NEPZ, a set of 166 doubled haploid lines (DHLs) derived from the cross between PBW343/IC252874 was used. The population was evaluated under normal sown (NS) and late sown (LS) conditions for two cropping seasons. The canopy temperature (CT) showed positive correlations with grain yield, whereas Soil Plant Analysis Development (SPAD) chlorophyll meter value was not significantly correlated and associated with grain yield (GY) in both the normal and late sown conditions. Composite interval mapping identified a total of 12 quantitative trait loci (QTLs) viz., 2 (NS), 10 (LS) mapped on linkage groups 1A, 1D, 2B, 2D, 3B, 4D, 5B, and 6D, during both the crop seasons 2017-18 and 2018-19. Combining the results of these QTLs revealed a major stable QTL for GY on chromosome 3B which explained 11.84% to 21.24% of phenotypic variance under both sowing conditions. QTL for CT and SPAD was detected on chromosome 1A, while QTL for GY on chromosome 3B and 5B. The identified QTLs could be targeted for genetic improvement and marker-assisted selection for heat tolerance in wheat. The tools like SPAD and CT could be exploited to screen a large number of breeding lines.