2017 ASHS Annual Conference

Chitosan, the deacetylated form of chitin, has become of interest as a crop biostimulant suitable for use in sustainable agriculture since it is biocompatible, biodegradable, environmentally-friendly, and readily available. Short-term (35-days) effects of chitosan, applied as soil amendment at 0.00, 0.05, 0.10, 0.15, 0.20 or 0.30% by weight, on romaine lettuce plants (Lactuca sativa L. cv. Heart’s Delight) were evaluated in a growth chamber. Chitosan treatments, with appropriate application rates, increased leaf number, area, fresh and dry weight. It also enhanced leaf succulence as indicated by decreased ratio of leaf dry and fresh weight. As application rate increases, chitosan enhanced leaf chlorophyll index, photochemical efficiency, yield, electron transport rate, photosynthetic rate, stomatal conductance and transpiration. However, the highest application rate of 0.30% resulted in the lowest fresh and dry weight due to less leaf number and area. The results indicated that chitosan, applied as soil amendment at appropriate rates, could not only enhance lettuce growth but also improve its physiological properties and quality by increasing leaf succulence.