Potassium nitrate sprays improved potato tuber size and yields

A field experiment was conducted to evaluate the response to foliar potassium nitrate in terms of vegetative growth, yield and tuber size of potato grown in a sandy loam soil in the semi-arid environment of East Central Tunisia. The experimental setup was a completely randomized block designed with 4 treatments and 3 replications. The four treatments were: 0, 0.5, 1 and 2 g _KNO3/L and were supplied as foliar spray at 45, 55 and 70 days after planting. Incremental doses of potassium nitrate resulted in a significant increase (P<0.05) in plant height, leaf number, leaf area, relative leaf water content and chlorophyll concentration.

All potassium nitrate treatments showed significant increases in average tuber weight and diameter (Table 1). Foliar sprays of _KNO3 increased tuber yield compared to the control, however not statistically significant (Table 1). Treatments were applied early in the growing season, so that possibly more pronounced effects on yield could be obtained with late applications during the tuber growth or maturation stages.

Table 1. Effect of foliar applications of potassium nitrate on potato tuber quality and yield.