Harvest Location and Moisture Content Effects on Rice Kernel-to-kernel Breaking Force Distributions

One medium-grain rice variety, six long-grain varieties, and two long-grain hybrids, harvested from 13.4% to 26.0% moisture content (MC) from Keiser, Arkansas, Stuttgart, Arkansas, and Alvin, Texas, were used to determine the influence of harvest location and MC on kernel-to-kernel breaking force distributions (BFDs). Harvest moisture content (HMC) affected BFDs, however, a greater influence was imposed by the growing location. Breaking force distributions were generally characterized by primary and secondary modal populations, although in many instances a clear demarcation between these populations was not apparent. Head rice yield (HRY) was plotted against the percentage of kernels in a sample having breaking forces greater than 20 N, which was used as an estimate to define “strong” kernels. The strongest correlations between HRY and the percentage of strong kernels were found for growing location/variety lots having HRYs of 45% to 65%. Little to no correlation was observed for groups of samples having HRYs greater than 65%. One of the issues preventing a better HRY versus strong kernel percentage correlation was that the force level separating “weak” from “strong” kernels could not be accurately and consistently identified due to a lack of clear delineation between the modal populations.