Chitosan effects on physiochemical indicators of drought-induced leaf stress

Authors: FAROUK, SAAD - Mansoura University; RAMADAN, AMANY - Mansoura University; Showler, Allan

Submitted to: Journal of Plant Production Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2013
Publication Date: 3/1/2013
Citation: Farouk, S., Ramadan, A.A., Showler, A. 2013. Chitosan effects on physiochemical indicators of drought-induced leaf stress. Plant Knowledge Journal. 2(4):135-144.

Interpretive Summary: Drought stress in plants is accompanied by leaf senescence, which can reduce plant productivity. We assessed the effects of different rates of the polysaccharide chitosan, sprayed on the foliage of cowpea plants under different levels of water deficit stress, on accumulations and activities of biochemicals that are associated with inducing stress-related plant injury and other biochemicals that protect against such injury. We found that low and moderate rates of chitosan reduced amounts of injurious biochemicals and increased amounts of protective biochemicals, while a high rate had little or no effect on either. Chitosan, when used at appropriate rates, might prove useful for crop production in situations where water availability is limited.

Technical Abstract: Water deficit stress in crops is associated with leaf senescence, a damaging oxidative process that is irreversible once it is initiated. This study was conducted to assess the effect of chitosan, a marine polysaccharide with unique bioactive properties that scavenges for reactive oxygen species; hence, chitosan application to plants has been suggested as an aid for reducing oxidative injury caused by water deficit stress. In our study, using cowpea, Vigna unguiculata (L.) Walp. (var. Cream 7), chitosan application reduced hydrogen peroxide accumulation, lipid peroxidation, and membrane permeability. The application of chitosan also elevated antioxidant enzyme activities, such as superoxide dismutase and catalase, and accumulations of ascorbate, calcium, carotenoids, magnesium, and phenolic compounds were observed in mature plants. Under moderate and severe water deficit, chitosan, particularly at a concentration of 250 ml/liter water, alleviated the injurious effects of the consequent stress, including leaf senescence. The greater levels of antioxidants and low hydrogen peroxide concentration in the chitosan-treated cowpea leaves suggest that chitosan delays senescence. Chitosan might be useful for crop production in situations where water availability is limited, and to make crop plants less attractive to pests that are favored by water-deficit-stressed plants.