Combined effects of magnesium and micronutrients on growth, yield, quality, and nutrient use efficiency of bitter gourd in terrace soils

Combined effects of magnesium (Mg), zinc (Zn), and boron (B) on bitter gourd ( Momordica charantia L.) under terrace soils are not well documented. Therefore, a study was conducted to assess the combined effect of Mg, Zn, and B fertilization on bitter gourd growth, yield, nutrient use efficiency (NUE), postharvest quality, and profitability. Nine treatment combinations, based on varying levels of Mg, Zn, and B were tested in a RCBD with three replications. Treatments were T 1 (Mg 0 Zn 0 B 0 kg ha −1 ), T 2 (Mg 4 Zn 3 B 1.5 kg ha −1 ), T 3 (Mg 4 Zn 3 B 2 kg ha −1 ), T 4 (Mg 4 Zn 4 B 1.5 kg ha −1 ), T 5 (Mg 4 Zn 4 B 2 kg ha −1 ), T 6 (Mg 8 Zn 3 B 1.5 kg ha −1 ), T 7 (Mg 8 Zn 3 B 2 kg ha −1 ), T 8 (Mg 8 Zn 4 B 1.5 kg ha −1 ) and T 9 (Mg 8 Zn 4 B 2 kg ha −1 ). The combined application of Mg 8 Zn 4 B 2 kg ha −1 (T 9 ) significantly increased marketable fruit yield (14.8 t ha −1 ), which was 98% higher over control (T 1 ). T 9 demonstrated superior growth, yield attributes, and quality. This treatment produced maximum vitamin C (64.9 mg/100 g) and beta-carotene (151 mcg/100 g). T 9 reduced postharvest weight loss during the 4-day storage period. Furthermore, T 9 maximized the accumulation and uptake of N, P, K, S, Ca, Mg, Zn, and B; despite inconsistent apparent recovery efficiency for Mg, Zn, and B. T 9 also generated the highest gross margin (2405 US$ha −1 ). Post-harvest soil analysis indicated slightly improved chemical properties relative to initial conditions. These results suggest that the combined application of Mg 8 Zn 4 B 2 kg ha −1 is an optimal strategy for improving bitter gourd yield, quality, nutrient use efficiency (NUE), and profitability.