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

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.