Reduction of transpiration through foliar application of chitosan

In this study, we investigate the potential of chitosan, a natural beta-1-4 -linked glucosamine polymer, to reduce plant transpiration. Chitosan was ap plied foliarly to pepper plants and water use was monitored. Peppers were g rown in pots in growth-chambers, where transpiration was measured by weighi ng pots. In an accompanying field study, water use was determined by monito ring soil moisture depletion with time domain reflectometry. An automated i rrigation system replenished the water used each day, Plant biomass and yie ld were determined to calculate biomass-to-water ratios. Differences in can opy resistance between control and chitosan treated plants were analyzed wi th the aid of the Penman-Monteith equation. Scanning electron microscopy (S EM) and histochemical analyses demonstrated that chitosan induced closure o f the plant's stomata, resulting in decreased transpiration. Foliar applica tion of chitosan reduced water use of pepper plants by 26-43% while maintai ning biomass production and yield. We suggest that chitosan might be an eff ective antitranspirant to conserve water use in agriculture. (C) 2001 Elsev ier Science B.V. All rights reserved.