Growth Gas Exchange Parameters of Maize with Elevated Atmospheric Carbon Dioxide and Temperature

Abstract

Temperature and carbon dioxide (CO₂) are two important parameters related to climate change, which affect gaseous exchange and yield parameters of many cereal food crops. In this study, an experiment was conducted growing maize (Zea mays L.) in open top chambers (OTCs) to determine the effects of elevated CO₂ and temperature on gaseous exchange parameters (leaf photosynthetic rate (PN), stomatal conductance (gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr) and water use efficiency (WUE) of maize crop in Indian Agricultural Research Institute (IARI), New Delhi, India. Maize (var. PEHM 5) was grown with two levels of CO₂ ambient (400 ppm) and elevated (550 + 20 ppm) and three levels of temperature i.e., ambient, ambient +1.5 ^oC and ambient +3.0 ^oC during (July–October) seasons of 2013 and 2014. The two years average data indicated that the interactive effects of elevated CO₂ with 1.5 and 3.0^oC  temperature rise increased photosynthetic rate by 24.32 & 37.5%, stomatal conductance by 50.0% & 87.5%, intercellular CO₂ concentration by 55.0% &77.16%, transpiration rate by 44.0% & 102.16%, but decreased intrinsic water use efficiency by 7.46% & 28.7%, respectively. On the contrary, elevated CO₂ with 1.5 and 3.0 ^oC temperature rise decreased photosynthetic rate by 4.67 & 8.34%, stomatal conductance by 34.78% & 43.48%, transpiration rate by 25.17% & 20.52%, but increased intrinsic water use efficiency by 28.6% & 17.23%, respectively. The interactive effects of elevated CO₂ with 1.5 ^oC temperature rise resulted in 10.81% decrease and elevated CO₂ with 3.0 ^oC temperature rise resulted in a 14.47% increase in intercellular CO₂ concentration as compared to ambient CO₂ and temperature. Elevated temperature by 1.5^oC and 3.0 ^oC at elevated CO₂ had no effect on photosynthetic rate and intercellular CO₂ concentration. In addition, elevated temperature by 3.0 ^oC at elevated CO₂ had no effect on intrinsic water use efficiency as compared to ambient CO₂ and temperature treatment. From this study it can be concluded that elevated levels of both temperature and CO₂ have significant effects on maize growth gas exchange parameters.