MEETING ABSTRACT
P-257
Effects of nighttime temperature during grain-filling on rice processing quality
Presenter: N. Watson, Department of Food Science, University of Arkansas, Fayetteville, Arkansas
Co-Author(s): T. Siebenmorgen, Department of Food Science, University of Arkansas, Fayetteville, Arkansas; P. Counce, Rice Research and Extension Center, Stuttgart, Arkansas
Rice is a grain that is primarily consumed as a whole kernel, and therefore quality is largely measured by head rice yield (HRY), which is the mass percentage of rough rice kernels that remain as head rice (kernels that are 3/4 of a whole kernel or longer) after milling. HRY can vary inexplicably from year to year and often from field to field, and can be uniform in one cultivar of rice and yet variable in another cultivar, leading to the suspicion that some cultivars are more susceptible to quality variation. Preliminary historical data analyses indicated that the ambient nighttime temperature during the grain-filling stage of rice kernel development could be affecting the processing quality of certain rice cultivars. A controlled temperature study was conducted in four phytotrons (large-scale growth chambers) in the fall and winter of 2004. Tested cultivars were chosen based on their observed milling and processing quality: Cypress (long-grain, consistent miller), Lagrue (long-grain, variable miller), M-204 (medium-grain, consistent processing quality), Bengal (mediumgrain, variable processing quality), XL8 (hybrid, consistent miller), and XP710 (new hybrid cultivar). Plants were grown in greenhouses until flowering, and then transferred into nighttime temperature treatments of 18°C, 22°C, 26°C, and 30°C until harvest. Results indicated that as nighttime temperature during the grain-filling stage of rice development increased, kernel thickness and HRY variability increased.