RICE KERNEL MOISTURE CONTENT VARIATION AT HARVEST

Abstract

ABSTRACT Previous research has shown that harvesting rice while the kemels are immature (high moisture contents) results in low total and head rice yields. As the rice continues to mature (decreasing moisture content), the head rice yield reaches a maximum and then decreases. Other research has shown significant reductions in head rice yield from rapid moisture adsorption by rice at moisture contents lower than the safe rewetting threshold. One variety of rice ('Katy') with three replications for each of three seeding dates was used in this study. Ten panicles were harvested from each replication approximately three times per week as the average rice moisture content (MG) decreased from approximately 24 to 14%. The moisture contents of the individual kemels were measured and the distribution of the kernel moisture contents was studied. The kernel moisture content distributions later in the harvest season were skewed with the majority of kemels at moisture contents lower than the mean. Thus, as the rice matures, the average moisture content can be very misleading for persons accustomed to assuming the mode of this population is nearly the same as the mean. A linear function of the average moisture content explained about 72% of the variance in individual kernel moisture contents. Kernel moisture content variance decreased as the average moisture content decreased. The percentage of kernels at moisture contents below the assumed safe rewetting threshold increased significantly as the average moisture content decreased below 18%.