Combined Effects of Nitrogen, Mulch and Gibberellic Acid on Postharvest Physiology of Multi-Purpose Pumpkin Leaves and Fruits

Abstract

The leaves, fruits and seeds of multi-purpose pumpkin (Cucurbita moschata Duch.) species are consumed as vegetables, snacks and blended dishes to boost household health, food and nutritional security. However, cultivation without using inputs leads to poor postharvest physiological attributes. Consequently, a study was conducted to assess the effects of combined nitrogen, mulch and gibberellic acid(GA3) on postharvest physiology of pumpkin. The treatments comprised fourN rates (0, 50, 100 and 150 kg N/ha)supplied as CAN, three mulch types (none, unpainted, andblack-painted rice straws) and three GA3rates (0, 40 and 80 mg/L). Experimentation was done in two seasons using split-split plots arranged in randomized complete block design with three replications,and2 m x 2 m plant spacing. Nitrogen occupied main plots, mulch sub-plots, and GA3split plots. Post-harvest measures reported in this paper were harvested edible leaf weight, leaf and fruit moisture losses. Data values were subjected to analysis of variance using SAS Version 9.3. Separation of significant means was done using the least significant difference test at α=0.05.Nitrogen fertilizer did not significantly (P>0.05) affect leaf weight and physiological weight loss, but it significantly (P<0.05) increased fruit physiological weight loss. Mulch had no significant effect on leaf weight and physiological weight loss, but it significantly increased fruit physiological weight loss. The effect of GA3 on leaf weight and physiological weight losses was not significant, although the trend was positive in fruits. Similarly, combined nitrogen, mulch and GA3 did not significantly affect leaf weight and physiological weight losses in both seasons. Thus, the increase of weight loss in pumpkin fruits produced using high nitrogen, mulch or GA3 application should be counteracted by taking appropriate postharvest deterrent measures. On the other hand, the influence of combined nitrogen, mulch and GA3 on multi-purpose pumpkin performance cannot be entirely depicted by analysing postharvest physiology.