Effect of time and level of potassium application on tuber yield and K composition of plant tissues and tubers of two potato cultivars*

Field experiment was conducted on alluvial soil of Jalandhar with sixteen combinations of 4 rates of K applied at planting and earthing and 2 potato cultivars. Kufri Jyoti and Kufri Chandrarnukhi Late maturing cv. Kufri Jyoti responded to 66 kg K ha⁻¹ applied either at planting or at earthing, 30 days after planting while early maturing cv. Kufri Chandrarnukhi responded to 33 K at ha⁻¹ applied at planting and did not respond to K at earthing. Kufri Jyoti produced 59.1 kg of potato tubers per kg of K applied at planting or at earthing and Kufri Chandramukhi produced 48.5 kg K applied at planting.

K application decreased dry matter percentage of tubers and increased K concentration and size of tubers. K also increased its concentration in petioles and leaflets of recently matured leaves, sampled at 29, 40, 50 and 60 days after planting. K in petioles and leaflets upto 60 days was correlated with tuber yield. The results indicate that K can be applied successfully at earthing to late maturing cv. Kufri Jyoti which produces large grade tubers but not to early maturing cv. Kufri Chandramukhi which produces predominantly small grade tubers. Optimum dose of K at earthing and its likely response can be calculated based on K concentration in petioles or leaflets sampled at 29 days after planting.