Effects of four potassium doses on six sprinkler irrigated rice upland cultivars. I. Yield and yield components.

Abstract

The effects of four potassium rates (0, 20, 30, and 40 kg/ha of K2O ) on yield components and grain yield of six upland rice cultivars (IAC-20, Carajás, Caiapó, Canastra, Araguaia, and Cirad 4) were studied. Half the dose of potassium was applied at sowing and the other half at flowering onset (50% of the plants starting panicle emission). All plots received a basic fertilization of 40 kg/ha of P2O5 (simple superphosphate), 0 kg/ha of N (ammonium sulphate) and 60 kg/ha of N (urea) 30 days after seedling emergence. Plants were irrigated with a central pivot. Potassium increased panicle length, weight of 00 grains, number of filled grains/panicle, number of empty grains/panicle, number of grains/panicle, number of panicles/m2, spikelet fertility and grain yield.Additional keywords: dryland rice; supplementary irrigation; fertilization.