Evaluation of Spring Wheat Genotypes for Climatic Adaptability using Canopy Temperature as Physiological Indicator

Abstract

Temperature and drought stresses are generally considered main wheat yield limiting factors in rainfed environment, especially during reproductive growth stages. However, variability might exist among wheat genotypes in response to stressful conditions. The objective of the study was to test the climatic adaptability potential of the wheat genotypes using canopy temperature measurement as physiological indicator. The trial was comprised of forty spring wheat genotypes which were sown on normal and late planting dates to create variable growing environments under field conditions. Wheat genotypes showed significant variation (p<0.05) under both normal and late planting dates. The genotypes showed a strong correlation among canopy temperature, spike sterility and grain yield under both planting dates. The canopy temperature and grain yield correlated negatively under both normal (r2 = -0.943) and late planting (r2 = -0.957). However, the canopy temperature and spike sterility showed strong positive correlations under both normal (r2 = 0.920) and late (r2 = 0.937) plating dates, respectively. The results indicate that genotypes viz; Pakistan-2013, DN-93, SRN-09111, PR-103, NR-409, NR-421 (now approved wheat variety in the name of Zincol-2016), Galaxy and NARC-2011 maintained low crop canopy temperature during grain filling period showed lower spike sterility and produced higher grain yields. The genotypes with higher canopy temperature during grain filling period showed higher spike sterility which is linked to lower grain yield. The wheat genotypes identified with better climatic adaptability are potentially useful sources for improving drought and heat tolerance in wheat. Moreover, canopy temperature measurement proved to be a useful phenotyping tool in selection of drought and heat tolerant wheat germplasm under field conditions.