Irrigation is an important aspect of successful rice (Oryza sativa, L.) production in the Southern U.S. Due to reduced water availability and demand for water for other crops, interest has been expressed in determining the optimum time for terminating irrigation in rice. Previous studies suggest that the flood may be removed 14 d after 50% heading, but this study only considered the effects of one cultivar. Therefore, a study was initiated during 2004 at two locations to determine the optimum timing for irrigation termination on two medium grain rice cultivars (‘Medark' and ‘Bengal') and two long grain rice cultivars (‘Cocodre' and ‘Wells'). The rice was seeded into 9-row plots 4.88 m long and managed according to recommended production practices for Arkansas. Irrigation treatments imposed were draining the flood 14, 21, 28, or 35 days after 50% heading. Soil moisture readings were conducted with a soil resistance probe every 2 d after flood removal. Grain yield and milling yields were determined at maturity. Terminating irrigation 14 days after 50% heading resulted in significant yield reduction compared to the recommended 28 days after 50% heading at both locations. However, it appears that Wells and Cocodrie may be drained 21 d after 50% heading without reducing grain yields. Milling yields were not affected by timing of irrigation termination.
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See more of The ASA Southern Regional Branch (June 19-21, 2005)