Growth, Yield, and Economics of Potato in Relation to Progressive Application of Potassium Fertilizer

ABSTRACT

Four genotypes of potato (Solanum tuberosum L.), namely Kufri Satluj, Kufri Badshah, Kufri Bahar, and Kufri Kuber, were field grown to study the effect of application of four levels of potassium (K) fertilizer (0, 75, 150, and 225 kg (K₂O) ha⁻¹) on growth, yield, and economic parameters. A fertilizer dose of 200 kg nitrogen (N) and 100 kg phosphorus (P₂O₅) ha⁻¹ was applied uniformly in the form of urea and diammonium phosphate, respectively. During the growth period, parameters, viz plant height, shoot biomass, tuber biomass, tuber bulking rate, tuber population, and average tuber weight, were determined at 65 and 90 days after sowing (DAS). Yield parameters, viz aggregate and grade-wise tuber yield (large, medium, and small grade, weighing >75g, 30–75 g, and <30 g, respectively), tuber population, and average tuber weight as well as economic parameters, viz gross return, net return, return per rupee invested, and net production value, were recorded at harvest. All the parameters were significantly affected by increasing K application rates, with potassium application at 225 kg K₂O ha⁻¹ resulting in the highest value for the growth parameters. Progressive application of potassium fertilizer up to 225 kg K₂O ha⁻¹ significantly increased the yield of aggregate and large-grade tubers. The optimum K dose for the yield of medium-grade tubers was 150 kg K₂O ha⁻¹, while that for small-grade tubers was 0 kg K₂O ha⁻¹ (no K application) as the former reached a plateau at 225 kg K₂O ha⁻¹ and the latter decreased with increasing K application rates. Large-grade tubers offered the highest contribution to the aggregate yield. The growth and yield performance of the genotypes was truly reflected in the gross and net economic returns, with 225 kg K₂O ha⁻¹ proving the best K level. However, return per rupee invested and the net production value showed a different trend, with 75 kg K₂O ha⁻¹ giving the highest value for Kufri Satluj and Kufri Badshah, and 150kg K₂O ha⁻¹ proving the best K level for Kufri Bahar and Kufri Kuber. Genotypic differences and the interaction between genotypes and K levels were significant for most parameters studied.