The competition between winter rape (C3) and maize (C4) plants in response to elevated carbon dioxide and temperature, and drought stress

Abstract

© 2016, Lithuanian Institute of Agriculture. All rights reserved. The aim of this study was to estimate the effects of drought stress under elevated CO 2 and temperature on the competition between winter rape and maize plants. The experiment was conducted in a controlled-environment growth chamber at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Plants grown in monoculture (100:0) or in mixture (winter rape:maize, 50:50) irrigated and non-irrigated (drought stress), were exposed to ambient environment conditions - day/night temperature 21/14°C, CO 2 - 350 ppm (CO 2 T), and enhanced environment conditions - day/night temperature 30/23°C, CO 2 - 700 ppm (+CO 2 T). Maize (C 4 ) grown in mixture with winter rape (C 3 ), had significantly smaller assimilating leaf area and produced less fresh mass at CO 2 T and +CO 2 T, as compared to monoculture, and water deficit strengthened the negative effect. Comparison of the data obtained for monoculture revealed that elevated CO 2 and temperature in the conditions of sufficient moisture supply had significantly positive effect on maize assimilating leaf area (increased ~21%) and fresh mass accumulation (increased ~22%). Assimilating leaf area and fresh mass of winter rape and maize monocultures significantly decreased in response to water deficit both at CO 2 T and +CO 2 T. Water shortage had a stimulating effect on chlorophylls in leaves of winter rape in monocultures and mixtures. At +CO 2 T and sufficient water supply, maize in monoculture and mixture with rape significantly reduced the content of chlorophyll a. Carotenoid content significantly decreased in maize leaves (monoculture and mixture) under +CO 2 T in both irrigated or non-irigated substrates. Winter rape, in monoculture and mixture, accumulated significantly higher content of carotenoids under water deficit and ambient CO 2 T. However, a significant decrease in carotenoids was determined in rape leaves under +CO 2 T. The elevated contents of ascorbic acid, total phenolics and antioxidant potential indicate high capacity of winter rape to counter oxidative stress.