Effect of Cultivars, Fertilizers, and Plant Hormones on Chalkiness in Rice Grain.

Rice marketability is dictated by two traits- proportion of broken grains after milling and amount of chalkiness or opaque spots in whole grains. Both traits are the result of uneven packing of amyloplasts in the rice seed endosperm which causes weak and brittle grains. Broken grains in cooked rice detract from its aesthetic value and chalkiness hurts the taste. The most valuable rice grains are translucent. The objective of this study was to compare grain chalkiness from 11 rice cultivars and hybrids. Nutrient and hormone programs were also evaluated to reduce chalkiness. At maturity, panicles from CL151 cultivar were cut and milled from three sections-top, middle, and bottom. Milled samples were tested with an MBZ-2 electronic grain whiteness meter (Limeria, Brazil). The first grain to mature were in the top of the panicles. Transparency was highest in grains in the top>middle>bottom. Laskast cultivar from the University of Arkansas produced grains with significantly higher transparency than other cultivars or hybrids. Treatment applications made at internode elongation growth stage with potassium chloride, calcium silicate, gibberellic acid, and kinetin did not significantly impact chalkiness. However, potassium fertilization decreased plant lodging and increased yield in CL151 cultivar.