Effect of timing of nitrogen top-dressing on yield and yield components of direct-seeded wetland rice
1987
Keisers, J.T. (Agricultural Experiment Station, Nickerie (Suriname). Rice Dept.)
Field experiments were conducted to study the response of wetland rice to timing of nitrogen top dressings. Experiments were performed on Eenheid clay soils (fine-clayey, mixed, isohyperthermic Typic Tropaquept) using the standard Surinam cultivar SML Eloni. Nitrogen treatment affected number of days from seeding to heading, plant height, dry matter production, straw weight, harvest index, number of spikelets per panicle, number of spikelets per unit area, grain weight and grain yield. A nitrogen top dressing at mid tillering was a prerequisite for obtaining high grain yields. A second top dressing early in the reproductive period was required for maximum spikelet differentiation, which appeared to be a major determinant of storage capacity and grain yield. Late top dressings only resulted in a slight increase in grain weight. Grain yield was closely related to the number of spikelets per unit area, while filled-spikelet percentage and grain weight remained relatively constant irrespective of spikelet number or crop season.
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