EVALUATION OF SPRING WHEAT GENOTYPES FOR TOLERANCE TO HEAT STRESS BASED ON YIELD AND RELATED TRAITS

Abstract

The prevalence of high temperature stress, a significant constraint on agricultural productivity, including wheat, is expected to intensify with climate evolution. Heat stress can affect any crop development stage depending on the region; however, the reproductive and grain filling stages are the most sensitive. Reproductive heat stress may cause pollen sterility, infertile ovules, reduced fertilization, and aborted florets, ultimately decreasing grain number and yield. An experiment conducted at Bahauddin Zakariya University, Multan, aimed to identify heat-tolerant wheat genotypes. Ten commercial wheat varieties were screened at two different sowing dates, October 15th and December 5th, 2023. Results indicated that Bhakkar Star produced a high grain yield of 6966.6 kg/ha under the first sowing date. In contrast, Fakhr e Bhakkar yielded the highest grain yield of 3351.8 kg/ha under the second sowing date. Phenological traits, including days to heading and days to maturity, were longer in the normal sowing date but shortened in the late sowing date. Plant height significantly reduced in late sowing, and the NDVI value was high in the normal sowing date and low in the late sowing date. The selected line can be further utilized in breeding programs.