103(1)_str3

ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 103, No. 1 (2016), p. 21–28
DOI 10.13080/z-a.2016.103.003

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

Jurga MILIAUSKIENĖ, Sandra SAKALAUSKIENĖ, Sigitas LAZAUSKAS, Virmantas POVILAITIS, Aušra BRAZAITYTĖ, Pavelas DUCHOVSKIS

Abstract

The aim of this study was to estimate the effects of drought stress under elevated CO₂ 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, CO₂ – 350 ppm (CO₂ T), and enhanced environment conditions – day/night temperature 30/23°C, CO₂ – 700 ppm (+CO₂ T). Maize (C₄) grown in mixture with winter rape (C₃), had significantly smaller assimilating leaf area and produced less fresh mass at CO₂ T and +CO₂ T, as compared to monoculture, and water deficit strengthened the negative effect. Comparison of the data obtained for monoculture revealed that elevated CO₂ 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 CO₂ T and +CO₂ T. Water shortage had a stimulating effect on chlorophylls in leaves of winter rape in monocultures and mixtures. At +CO₂ 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 +CO₂ 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 CO₂ T. However, a significant decrease in carotenoids was determined in rape leaves under +CO₂ T. The elevated contents of ascorbic acid, total phenolics and antioxidant potential indicate high capacity of winter rape to counter oxidative stress.

Key words: antioxidants, Brassica napus, growth indices, photosynthetic pigments, Zea mays.

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