Influence of graded levels of potassium fertilizer on growth, yield, and economic parameters of potato

In a field experiment, four genotypes of potato were grown with graded levels of potassium (K) (0, 75, 150, and 225 kg K2O ha(-1)) with a uniform dose of nitrogen (N) (200 kg ha(-1)) and phosphorus (P) (100 kg P2O5 ha(-1)) to study their performance with regard to growth, yield, and economic parameters. Growth parameters (above ground plant biomass and tuber bulking rate), tuber yield, and the yield components (tuber population, average tuber weight), as well as economic parameters (net return, return per rupee invested and net production value) were significantly affected by increasing K application rates. Potassium application at 150 kg K2O ha(-1) proved to be optimum dose for most parameters studied. Progressive application of K significantly increased the aggregate as well as large and medium grade tuber yields, with concomitant decrease in the yield of small grade tubers. The highest contribution of large grade tubers (> 75 g) to the aggregate yield was found to be mainly due to the large size of the tuber; while medium grade tubers contributed it through size as well as number of tubers. Genotypes differed in optimum and maximum yield. Agronomic efficiency of all the genotypes had maximum value at 75 kg K2O ha(-1), which decreased with increase in K dose. The yield performance of the genotypes was truly reflected in the net economic returns, with 150kg K2O ha(-1) proving the optimum K level. However, return per rupee invested and net production value showed a reverse trend, with 75 kg K2O ha(-1) proving as the best K application rate. Genotypic differences, with regard to the parameters studied and the interaction between K levels and the genotypes, were significant for most parameters.