Ozone and future climate effect on interspecific competition between summer rapes and wild mustard

Abstract

Weeds are accepted to be the most important pests in agriculture. Increased spread or aggressiveness of invasive and native weeds due to climate change and other anthropogenic activities have been evidenced in many scientific researches. Therefore the aim of this study was to evaluate an effect of climate change (elevated air CO2 concentration and temperature) and O3 treatment on mono- and mixed-culture summer rape and wild mustard. A pot experiment was carried out in phytotron chambers. Summer rape (Brassica napus L.) and wild mustard (Sinapis arvensis) were grown in mono- and mixed-cultures under current climate (CC) (400 μmol mol−1 of CO2, 21/14 °C day/night temperature) or future climate (FC) conditions (800 μmol mol−1 of CO2, 25/18 °C day/night temperature) with and without O3 treatment (180 μg m-3). Competition with wild mustard had relatively low effect on rape’s growth at current climate, both with and without ozone treatment. Climate change positively affected crop’s growth; however, weed competitive effect increased at FC conditions. The most drastic changes was detected under combined impact of ozone and future climate (FC+O3). Rape competitive effect on wild mustard also significantly increased under FC+O3 treatment. In must be emphasized, that stronger competition-induced reduction in dry biomass was detected for wild mustard (up to 80 %) than for summer rape (up to 40%), indicating increased rape’s competitiveness under FC+O3 conditions. Better antioxidative protection was found to be the main reason for improved rapes growth at FC. Whereas stronger oxidative damage and lower pool of soluble sugars in wild mustard determined its sharply reduced competitiveness under FC+O3 conditions. However, in spite of improved competitiveness of rape, competition with weeds strongly interfered with crops growth, indicating increased yield losses due to the climate change, especially with concomitant intensification of O3 pollution.[...]