Interactive effects of chitosan and cadmium on growth, secondary metabolism, oxidative defense, and element uptake in pea (Pisum sativum L.)

Chitosan is an important mediator of plant stress tolerance due to its ability to promote antioxidant system. In the present research, we appraised the effects of chitosan supplemented as foliar or seed priming methods to circumvent cadmium (Cd) effects on pea plants. Cd stress significantly reduced plant biomass, yield attributes, chlorophyll, and carotenoid contents. Antioxidant compounds, namely flavonoids and anthocyanins, decreased whereas there was more significant accretion in phenolics and ascorbic acid in Cd-stressed plants. Antioxidant enzyme activities were higher in Cd-administered plants. The accumulation of calcium (Ca), potassium (K), and phosphorous (P) decreased in plants subjected to Cd stress. Cd toxicity produced conspicuous oxidative damage measured as malondialdehyde and hydrogen peroxide accumulation. Exogenous chitosan as foliar spray notably promoted antioxidant defense system with concomitant decrease in oxidative damage. Under both modes of chitosan application, lower doses (0.05 and 0.1%) were more effective than higher (0.5 and 1%). Cadmium contents in different plant parts decreased when chitosan was applied at 0.05 and 0.1% concentration. The present study revealed that chitosan is an essential plant growth regulator at low concentrations to mitigate Cd effects on pea plants.