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 applied foliarly to pepper plants and water use was monitored. Peppers were grown in pots in growth-chambers, where transpiration was measured by weighing pots. In an accompanying field study, water use was determined by monitoring soil moisture depletion with time domain reflectometry. An automated irrigation system replenished the water used each day, Plant biomass and yield were determined to calculate biomass-to-water ratios. Differences in canopy resistance between control and chitosan treated plants were analyzed with the aid of the Penman-Monteith equation. Scanning electron microscopy (SEM) and histochemical analyses demonstrated that chitosan induced closure of the plant's stomata, resulting in decreased transpiration. Foliar application of chitosan reduced water use of pepper plants by 26-43% while maintaining biomass production and yield. We suggest that chitosan might be an effective antitranspirant to conserve water use in agriculture. (C) 2001 Elsevier Science B.V. All rights reserved.