Nutritional and antioxidant profiles of pumpkin (Cucurbita pepo Linn.) immature and mature fruits as influenced by NPK fertilizer

This study evaluated the influence of NPK fertilizer on protein, fibre, ash, fat, carbohydrate, antioxidant activities and antioxidant phenolic compounds in immature and mature fruits of pumpkin. The treatment consisted of six NPK levels (0, 50, 100, 150, 200 and 250 kg/ha), and was replicated six times in a randomized complete block design (RCBD). Proximate analysis and antioxidant assays were done using standard analytical methods. At control and lower NPK rates, the proximate compositions and antioxidant profile of pumpkin fruits decreased with increasing NPK fertilizer. Between the control and the highest fertilizer rate, proximate compositions decreased by 7–62% while the antioxidant profile decreased by 13–79% for both immature and mature fruits. Across all the measured parameters, mature fruit had higher proximate contents and higher antioxidant concentrations. For the high health value of pumpkin fruits to be maintained, little or no NPK fertilizer should be applied.

► The proximate contents of pumpkin fruits decreased with increasing NPK fertilizer.
► The carbohydrate composition analysed increased with increasing fertilizer rates.
► The antioxidant activities of the fruits reduced by 15% with increasing fertilizer rates.
► The phenolic compounds of pumpkin fruits reduced by 75% as fertilizer rates increased.
► Mature pumpkin fruit had higher proximate and antioxidant profile than the young fruit.