Effects of pre-harvest desiccants on rice yield and quality

Field studies were conducted from 2000 to 2003 to determine the effect of paraquat and sodium chlorate applied as pre-harvest desiccants on rice yield and quality. In these trials, paraquat and sodium chlorate were applied 7 and 3 d prior to main-crop rice harvest (pre-harvest). In the first study, the rice cultivars Cocodrie, Cypress, and Wells responded differently to desiccants. Paraquat could be an effective desiccant for rice, but dose, application timing, and cultivar must be taken into account prior to its use. In the second study, both doses of sodium chlorate applied 7 d pre-harvest reduced head rice yield, but only the dose of 6.7 kg/ha reduced head rice yield when applied 3 d pre-harvest. Sodium chlorate should be applied to rice as a desiccant at 4.5 kg/ha no earlier than 3 d pre-harvest to avoid losses in grain yield and quality.