A Rice Cultural Management Study.

The growth, development, grain yield, and yield components of rice (Oryza sativa L. cultivar Mars) were compared under different cultural and fertilization practices at three locations in Louisiana. Locations and soils were: Northeast Research Station, Sharkey clay; Macon Ridge Branch of the Northeast Research Station, Gigger silt loam; and the Rice Research Station, Crowley silt loam. The influence of cultural system was variable over the locations and years. However, the cultural system with the larger means for dry matter, concentration and uptake of N at mid-tillering and panicle differentiation tended to have larger grain yields. Nitrogen uptake at mid-tillering and panicle differentiation were positively correlated with grain yields. Regression analysis indicated that more variation in grain yield could be accounted for by N uptake at mid-tillering. Nitrogen rate and application time influenced grain yields. Grain yields were generally maximized when N was applied as a single preplant or preflood application. Yield components were influenced by N rates and application times. The number of florets per panicle and the one thousand grain weight tended to be larger when N was applied as a three-way split application. In general, panicle density and floret sterility was larger when N was applied as a single preplant or preflood application. There was a general decrease in the one thousand grain weight as N rates were increased. Multiple regression analysis indicated that up to 43% of the total variation in grain yield could be accounted for by panicle density, the number of grains per panicle and the one thousand grain weight. Drill-seeded rice produced taller plants and more lodging. Nitrogen rate and application time significantly increased plant height and lodging. Plant height and lodging were greatest when N was applied as a single preplant or preflood application. The water-seeded rice required significantly fewer days to 50% heading. The number of days to 50% heading was decreased when N was applied as split applications in relation to a single preplant or preflood N application