Effect of Excess Application of Nitrogenous Fertilizer on Postharvest Quality of Spinach during Storage

The quality of vegetables depends upon the preharvest and postharvest practices. The preharvest practices include type, amount, form of fertilizers, harvesting period, growing season, and conditions that influence the yield of the crop and affect its chemical, biochemical, and mechanical properties. Moreover, postharvest practices such as storage conditions and processing methods also affect the quality of vegetables. Therefore, the present study was conducted to study the effect of different doses of nitrogen fertilizer (0–400 kg·N/ha) and storage conditions on the quality attributes of spinach leaves such as respiration rate, physiological loss in weight (PLW), chromatic properties, chlorophyll, puncture strength, TSS, pH, and nitrate during the storage studies. The respiration rate of leaves decreased with an increase in fertilizer dose. The a^∗and ΔE values of spinach leaves significantly (p < 0.01) increased with an increase in storage temperature (T) and storage time (t) and decreased significantly (p < 0.01) with an increase in fertilizer dosage (F). The puncture strength (PS) of leaves significantly (p < 0.01) decreased with an increase in F, T, and t. The T, t, and their interaction had a significant (p < 0.05) negative effect on the chlorophyll content of spinach leaves for all treatments. However, the T, t, and their interaction had a significant (p < 0.01) positive effect on pH and PLW and a negative effect on the nitrate content. The colour change, nitrate, and chlorophyll degradation were higher with storage time for leaves which have a higher amount of nitrate content initially. The TSS, pH, PLW, and mechanical properties degradation were higher with storage time for leaves that initially had a lower amount of nitrate content. Therefore, application of the recommended dosage (as per the soil nutrient status) of nitrogen fertilizer can produce leaves with minimum nitrate content, and storage of leaves under refrigerated conditions can enhance the shelf life.