Seeding rates for stale seedbed rice production in the Midsouthern United States

The establishment of an adequate and uniform rice (Oryza sativa L.) stand is critical to achieve high grain yields. The literature is extensive for older cultivars planted in conventional tillage and/or water-seeded systems; however, there are no published data for current cultivars grown in stale seedbed systems. Six of the cultivars most commonly grown in the Midsouth rice production area of the USA were drill seeded at densities of 108, 215, 323, 430, and 538 seeds m(-2) into a stale seedbed at Crowley, LA, from 2002 to 2004, and in Clarksdale, MS, in 2003 and 2004. Established plant densities responded linearly to seeding rate for all cultivars except Cocodrie, which responded quadratically. Rough rice yields were not affected by seeding rate for Cheniere, but followed a quadratic relationship for the cultivars CL161, Cocodrie, and Priscilla. A location X seeding rate interaction was detected for yield of Wells. Seeding rate did not affect rough rice yields for Wells in Mississippi, while in Louisiana, yields responded quadratically. Francis rough rice yields increased linearly with increased seeding rates. Optimal rough rice grain yields can be achieved in Mississippi and Louisiana with a seeding rate of 323 seeds m(-2) for cultivars that are currently grown across the Midsouth rice-producing area in the USA. Furthermore, depending on the cultivar, when plant densities are uniform and range from 50 to 70 plants m(-2), the resulting rice grain yields may offset the cost of terminating the stand and replanting.