Influence of elevated CO2 and temperature on physiological traits and yield attributes of heat tolerant wheat genotype Halna grown inside open top chambers

Abstract

Both CO2 and temperature caused significant changes in crop productivity. An experiment was conducted wherein wheat was grown inside open top chambers (OTCs) in order to determine the effects of elevated atmospheric carbon dioxide (CO2) and temperature on physiology and yield attributes of wheat genotype Halna. Halna was grown with two levels of carbon dioxide, i.e., ambient (400 ppm) and elevated (500 ± 20 ppm) and two levels of temperature, i.e., ambient, and ambient +2 °C during the Rabi (November–April) season of 2014–2015 at ICAR-RCER, Patna, India. The study revealed that elevated CO2 improved water use efficiency by 26.3%, photosynthetic rate by 14.6%, relative water content (RWC) by 15.9%, membrane stability index (MSI) by 6.6%, leaf area (LA) by 4.6%, plant height by 2.53% and grain yield by 26.9% as compared to ambient, while the activity of antioxidant enzymes were decreased, i.e., catalase by −12.59% and peroxidase by −21.04%. However, elevation of temperature by 2 °C decreased the photosynthetic rate by 15.9%, LA by 8.7% and grain yield by 11.7% but activity of CAT (+64.8%), and POX (+7.2%) were increased as compared to ambient condition. Simultaneous elevation of both (CO2 and temperature) caused non-significant increase in leaf area, number of grains ear−1, 1000 grain weight and grain yield as compared to ambient condition. The results indicated that elevated CO2 had positive effects, whereas elevated temperature had negative effects and with simultaneous elevation of CO2 and temperature, elevated CO2 nullified the negative effects of elevated temperature on photosynthetic characteristics and yield components of Halna.