Effect of Ammonium Sulphate Incorporated with Calcium Nitrate Fertilizers on Nutritional Status, Fruit Set and Yield of Pomegranate Trees cv. Wonderful

Abstract

The effect of (NH4)2SO4:Ca(NO3)2 ratios applied by fertigation on nutritional status, fruit set, yield, and marketable yield of pomegranate trees cv. Wonderful was evaluated. The trees were provided with five nutrient solutions with the same total nitrogen level (200 units/ha) but with different (NH4)2SO4:Ca(NO3)2 ratios (100:0, 90:10, 80:20, 70:30, and 60:40). Increasing the (NH4)2SO4 ratio from 60 to 100% significantly reduced the nitrogen (N), magnesium (Mg), calcium (Ca), and potassium (K) concentrations while significantly increasing P and Fe concentrations in pomegranate leaves. The highest (NH4)2SO4 proportion (100%) induced a reduction in both chlorophyll content and dry matter values in pomegranate leaves. The maximum fruit set (33.65% and 31.40%) and the minimum fruit drop (6.74% and 6.25%) were recorded at the applied ratio of 60% of (NH4)2SO4:40% of Ca(NO3)2. The applied proportion of 70% of (NH4)2SO4:30% of Ca(NO3)2 provided the minimum fruit sunburn (9.54% and 9.74%) and fruit cracking (6.45% and 5.64%), maximum yield (33.62 and 33.00 kg/tree), and marketable yield (27.41 and 27.93 kg/tree) in the 2019 and 2020 seasons, respectively. Our results provide valuable information about the effects of partial replacement of nitrogen fertilizer from (NH4)2SO4 with nitrogen fertilizer from Ca(NO3)2 on the growth characteristics of pomegranate trees cv. Wonderful.