Abstract

Onion is a vital spice crop in the Bangladeshi diet; however, its average yield remains low. This low productivity is primarily attributed to various constraints, including suboptimal nutrient management. Therefore, this study was conducted to determine how nitrogen (N) and potassium (K) affected the growth and yield attributes of onions and to determine the optimum doses of these two macronutrients to get maximum output using the bulb-to-bulb method. The treatments consisted of a factorial combination of four different doses of N 0, 50, 100 and 150 kg ha-1 and four K doses 0, 30, 60 and 90 kg ha-1 and their combination. The analysis of variance showed that the individual application of nitrogen and their interaction with 150 kg N ha-1 and 90 kg K ha-1 significantly (P < 0.05) affected plant height, number of leaves per plant, bulb length, blub diameter, single weight of bulb, yield per plot, and yield per hectare. The highest bulb yield (12.66 t ha−1) of onion was obtained from the combined application of 150 kg N ha-1 + 90 kg K ha-1 while the lowest bulb yield was found from the control plot. Moreover, a positive correlation was found between different N and K fertilizer levels with yield. Thus, the findings indicated the potential application of N and K fertilizer to the combined application methods for getting maximum production.