Effects of Molecular Weight of Chitosan on Yield Potential of Rice Cultivar Suphan Buri 1

Abstract

Chitosan is a natural polymer extracted from chitin. It can be applied to plants in order to increase yield. The aims of this study were to determine the effective type of chitosan and the appropriate method for increasing rice yield. The experimental design was 3 x 3 factorial in RCB with one control and replicated four times. The factor A was seed soaking, seed soaking + foliar spraying and foliar spray; the factor B was polymeric chitosan, oligomeric chitosan and monomeric chitosan. The mixed chemical fertilizer between 46-0-0 and 16-20-0 ( ratio 1:1w/w) at the rate of 50 kg/rai was applied to the rice plants of all treatments, but without chitosan in the control treatment. This study was conducted in pot experiment in a greenhouse at Rajamangala University of Technology Suvarnabhumi during January to April 2005. The results indicated that application of polymeric chitosan by seed soaking before planting followed by four foliar sprayings throughout cropping season significantly increased (P<0.05) the tiller numbers per plant and dry matter accumulation but decreased unfilled grains. However, the application of chitosan with different molecular weights and different application methods did not affect plant height, thousand-grain weight and filled grains. Focusing on the rice yield, there was a tendency to achieve higher yield when polymeric chitosan was applied by seed soaking before planting followed by foliar spraying but it did not show any significant difference from the other treatments.