Genetic variability in Wheat (Triticum aestivum L.) accession for heat tolerance during seed germination

Abstract

Heat stress drastically reduces the production of cool season crops including wheat (Triticum aestivum L.). Seed germination of cool season crops is most sensitive to high temperature and reduced germination led to decrease in plant density and yield. Therefore, present study was aimed to identify the heat tolerant and heat sensitive wheat accessions to improve the yield under heat stress by wheat breeders. Four wheat cultivars (Anmol_90, Chkwal_50, Moomal_2002 and Sindh_8) were evaluated at six temperature (25ºC, 30ºC, 35ºC, 37ºC, 40ºC, and 45ºC) regimes and 37ºC was defined as an appropriate screening temperature for seed germination. Diverse wheat germplasm (n = 50) from National Agriculture Research Center (NARC) Pakistan were evaluated under control (25ºC) and heat stress (37ºC) treatments. Heat tolerance potential of wheat accessions during seed germination was measured by using absolute decrease in seed germination (AD), inhibition index of seed germination (II), relative heat tolerance (RHT), and heat tolerance index (HTI). WB_4721 (winter, 1.21), WB_4515 (winter, 1.09), and WB_6341 (spring, 1.05) are most heat tolerant whereas, WB_4792 (winter, 0.04), WB_6121 (spring, 0.006), and WB_1376CLP (winter, 0.008) are most heat sensitive accessions during seed germination stage.