Evaluation of foliar application of zinc at different doses on potato (<i>Solanum tuberosum</i> L.) growth, yield, and economic feasibility in Dolpa of Nepal

Improper nutrient management has limited potato production in Nepal's mountainous region. Farmers prioritize macronutrients but neglect essential micronutrients like zinc (Zn), which are crucial for potato growth and enzymatic functions. However, Zn deficiency is prevalent in these regions and very few studies have highlighted its role in potato production. A field experiment with seven different concentrations of Zn-EDTA was conducted at three different locations with three replications to assess the effect of foliar application of Zn on growth, yield, and economic aspects of potatoes. The treatments were: control, single foliar spray (SS) of Zn at 50, 100, and 150 ppm, and double foliar spray (DS) at 50, 100, and 150 ppm. Results showed that the foliar application of Zn at the highest concentrations (DS-100 and DS-150) increased plant height, leaf number, and canopy diameter. Maximum tuber yield (29.99 t·ha⁻¹), tuber number (51.00), tuber diameter (1.44 cm), and B:C ratio were found with DS-150 ppm followed by DS-100 ppm. The maximum marketable tuber number (47.00) and marketable tuber weight (2,973.67 g) were found with the highest Zn concentration of DS-150 ppm whereas the maximum non-marketable tuber number (10.67) and non-marketable tuber weight (82.33 g) were obtained with control. All DS treatments produced higher yields and B:C ratios. However, DS-100 and DS-150 showed greater profitability due to marginal cost rise and higher income. Therefore, either DS-100 or DS-150 ppm Zn spray can be used. However, further research is needed to establish the threshold levels of Zn foliar application and micronutrient recommendations.