Interactive effects and competitive shift between Triticum aestivum L. (wheat) and Chenopodium album L. (fat-hen) under ambient and elevated ozone

Abstract

The aim of this study was to evaluate the impact of ambient and elevated O3 (ambient+20 ppb) under the competition between a crop plant Triticum aestivum L.cv. HD 2967 and a weed, Chenopodium album L. (fat-hen) grown singly and in mix-culture (1:1) using open-top chambers. The competition posed a relatively lesser effect on the growth of fat-hen as compared to the wheat under ambient O3 at both the sampling time, however, the effects of stress factors (competition and O3) were more pronounced at the reproductive stage on both the plants. Fat-hen possess a stronger antioxidative potential against elevated O3 (eO3), irrespective of competition, making it more resistant against the existing stress factors. Significant stimulation in the activities of CAT, POX, GR and SOD in fat-hen and non-enzyme antioxidants (AsA, thiols, and total phenolics) might have helped the plants to pose a superior ROS scavenging potential under competition + O3. Strong stimulation of flavonols (kaempferol and quercetin) and phenolic acid (p-coumaric acid and ferulic acid) in fat-hen not only helped the plants to withstand the oxidative damage under eO3 but also might have influenced the allelopathic interaction (competition + O3). Yield loss in wheat was observed to be larger under competition + O3 (33.1%) followed by O3 (20.5%) than only under competition (16.3%). The study suggests stringent weed management strategies to be established recognizing the existing threat from O3 to the productivity of a staple crop-wheat.