Preharvest melatonin application mitigates arsenic-induced oxidative stress and improves vase life of tuberose (Polianthes tuberosa L.) cut flowers

Abstract

Arsenic (As) stress severely hinders the growth of ornamental cut flowers. Melatonin (MLT) as a biostimulant protects plants from various abiotic stresses including As stress. However, its protective roles are not well understood in ornamental cut flowers especially tuberose. This research investigated the effects of exogenous melatonin supplementation on alleviating As stress damage in tuberose plants. In As-treated plants, growth traits and leaf chlorophyll contents markedly decreased, while application of MLT, alleviated the inhibitory effect of As on plant growth and chlorophyll content in As-treated plants. Melatonin application considerably increased the vase life of cut tuberose flowers and also improved the protein as well as proline contents in leaf tissues. Level of oxidative markers including electrolyte leakage (EL), malondialdehyde (MDA) and hydrogen peroxide (H2O2) increased in As-treated plants. Upon application of MLT, this trend was alleviated; however, the activities of enzymatic antioxidants increased when plants were subjected to As stress in combination with MLT. Results obtained in the present study suggest that exogenous MLT could alleviate negative effects of As stress on tuberose plants stimulating of oxidative defense related antioxidants. These results are beneficial to improve ornamental tuberose cut flowers production in heavy metal polluted soils or irrigation water.