Because of the financial investment, producers have expressed interest in agronomic differences that may exist when rice (Oryza sativa L.) is seeded on 18-cm row spacing compared to 25-cm row spacing. A study was initiated in 2004 to examine the effect of drill row spacing and seeding rates on three cultivars (‘Francis', ‘Banks', and ‘Cybonnet') at two locations on a silt loam soil (Lake Hogue and RREC), and one location on a Perry clay (SEREC). Each cultivar was seeded at rates of: 50, 76, 101, 126, or 151 kg ha-1 into 4.88 m-long plots with either 18- or 25-cm drill row spacing. Grain yield was significantly higher for 18-cm row spacing versus 25-cm row spacing at all locations during 2004. The yield difference ranged from 320 kg ha-1 to 1,100 kg ha-1. On the clay at SEREC ‘Francis' and ‘Banks' had significantly greater grain yield with 18-cm row spacing than 25-cm row spacing. However, ‘Cybonnet' was not affected by row spacing at this location. For the silt loam locations, the data suggests that the optimum seeding rate for these three rice cultivars is 76 kg ha-1 compared to the current recommended rate of 101 kg ha-1. It also appears that if weather conditions are favorable, reduced seeding rates may also be feasible on clay soils as well.
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See more of The ASA Southern Regional Branch (June 19-21, 2005)