Agronomic Evaluation of Lowland Rice Genotypes for Potassium-Use Efficiency

Lowland rice is an important crop for humans, and information on potassium (K)-use efficiency for this crop is limited. A greenhouse experiment was conducted to evaluate agronomic characteristics of 12 lowland rice genotypes for K utilization. The K levels used were 0mgkg(-1) (low, natural level of soil) and 300mgkg(-1) (high). Plant height, straw yield, grain yield, panicle number, grain harvest index, 1000-grain weight, and spikelet sterility were significantly affected by K and genotypes treatments. The K x genotype interactions were significant for most of these growth, yield, and yield components, indicating that genotypes responded differently under two K rates. Furthermore, selection is possible for low as well as high K rates for lowland rice genotypes. Contribution of growth and yield components and agronomic efficiency in improving grain yield was in the order of agronomic efficiency > grain harvest index > 1000-grain weight > panicle number > shoot dry weight. There was significant decrease in soil K at harvest at low as well as at high K levels, indicating greater K requirements for lowland rice genotypes. Further, rice genotypes were significantly different in uptake and utilization of P, K, Al, and H+Al, as indicated by soil analysis at harvest.