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Effect of Cultural Management Practices on Grain Quality of Two Rice Cultivars

¹USDA-ARS, Dale Bumpers National Rice Research Center, 2890 Hwy 130 E., Stuttgart, AR 72160. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 870-672-9300 Ext. 227. Fax: 870-673-7581. E-mail: rolfe.bryant@ars.usda.gov ³University of Arkansas Rice Research and Extension Center, 2900 Hwy 130 E., Stuttgart, AR 72160.

To reduce fuel and labor costs and increase profits, farmers are trying new ways of growing rice (Oryza sativa L.). This includes changing crop rotations, tillage systems, and fertilization levels. There is little information on how these changes affect the cooking quality of rice. We therefore looked at the parameters associated with cooking and processing quality (apparent amylose, gelatinization temperature, lipid and protein contents, and pasting properties) of two U.S. long grains (Cybonnet and Wells) that were grown using two different tillage systems, standard rate and high rates of fertilization, and different crop rotations (continuous rice R-R, rice after soybeans R-SB, and rice after corn R-C). No differences in quality traits were observed among any of the tillage systems. Rice grown in continuous rice rotation had the lowest protein content of brown and milled rice (8.6 and 8.1%, respectively) as compared to the highest levels observed in the rice-soybean rotation (9.3 and 8.6%, respectively). Rice grown in continuous rice rotation also had higher peak viscosity than other crop rotations. Increasing the fertilization rate increased the protein content of brown rice and decreased peak, trough, and final viscosities. Apparent amylose content, gelatinization temperature, and lipid content were not affected by crop rotation or fertility; however, they were influenced by cultivar. Although the results indicated statistical differences for some quality parameters, the differences were small enough that they are unlikely to have a major impact on processing quality of long grain rice if co-mingled.