Individual Heat and Combined Heat Drought Stresses in Wheat: Variation in NDVI and Canopy Temperature

Abstract

The present study was conducted to determine genotypic variations for normalized difference vegetation index (NDVI) and canopy temperature (CT) in wheat under terminal heat and combined heat and drought stresses. Forty-four wheat genotypes were evaluated under late sown with irrigation (heat stress) and without irrigation (combined heat and drought stress) in an environment with average temperatures of 28.6°C during the growing season and 30.62°C during the grain filling stage. Moisture under heat stress range from 14.84 to 19.12 % whereas under combined stress it was 5.08 to 10.49 %. The mean grain yield was 106.7 and 123.4 gm/ plot under heat stress and combined stress respectively. The mean CT 24.1 and 29.4 0 C was under heat stress and combined stress respectively. The mean NDVI 0.57 and 0.50 under heat stress and combined stress respectively. Overall, under combined stress there was a 13 %decrease in NDVI, 18% increase in the CT and 13.5% increase in the yield than the heat stressed genotypes. The negative correlation between NDVI and yield whereas positive correlation between CT and grain yield under combined stress. The NDVI and CT are the two physiological traits to measure high yielding genotypes under combined stress.