Optimal Harvest Moisture Contents for Maximizing Milling Quality of Long- and Medium-Grain Rice Cultivars

Abstract

The objective of this study was to determine the harvest moisture contents (HMCs) at which rice milling quality peaked for various rice lots. Multiple samples per field of cultivars Bengal, Cypress, and Drew were harvested at northeast and southeast Arkansas locations in 1999 and 2000. Additional field sample sets of multiple cultivars were collected in 2004, 2005, and 2006 at various locations in Arkansas, Mississippi, and Missouri. Head rice yields (HRYs) were described by a quadratic equation with HMC as the independent variable. Peak HRYs varied from 63.8% to 70.6%. Optimal HMCs, determined as the MC at which HRY peaked, varied from 18.7% to 23.5% for long-grain cultivars and 21.5% to 24.0% for medium-grain Bengal. The general range of optimal HMCs was 19% to 22% for long-grains and 22% to 24% for medium-grain Bengal. For rice lots with HMCs less than the optimal HMC, the amount of HRY reduction from peak values was strongly correlated to the percentage of fissured kernels at harvest; fissured kernel percentage accounted for 77% of the variation in HRY reduction from peak HRYs.