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.

No abstract

An investigation of the proximate composition and antioxidant profile of pumpkin seeds obtained from different levels of NPK 15 : 15 : 15 compound fertilizer application at the Obafemi Awolowo University, Ile-Ife, Nigeria was carried out. Pumpkin seeds were grown in 2010 for two cropping seasons (May to August and August to November), and the following fertilizer rates were applied: 0, 50, 100, 150, 200, and 250 kg/ha. Standard analytical methods were used to determine protein, crude fibre, ash, fat, carbohydrate, antioxidant activities, phenol, flavonoid, proanthocyanidin, and anthocyanin. The highest concentrations of the proximate and antioxidants analysed were found from the seeds of control and those treated with lower NPK rates. The mean protein, ash, crude fibre, and carbohydrate values of pumpkin seeds at zero to 100 kg NPK/ha were 27%, 1.56%, 0.56%, and 11.7% respectively. At these same levels of fertilizer, pumpkin seed oil yield was 59%. Antioxidant activities ranged from 89.9 to 90.4% while total phenol was 47 mg/100 g. Except for carbohydrate, the % concentration of nutrients and antioxidants in pumpkin seeds was significantly (P = 0.05) depressed with fertilizer rates above 100 g/ha.

There were significant differences between hybrids for number of bunches (NB), mean bunch weight (MBW) and fresh fruit bunch yield (FFB). For the hybrid population as a whole, significant hybrid X year (environment) effects were also observed for the two yield components and for yield per se. The linear component of the hybrid X year effect was also significant. There were highly significant and positive correlations between FFB, NB and MBW hybrid means and the regression co-efficients of the hybrid means on the environmental index. There were no significant associations between these means and mean square deviations from regression (s(2)d) for these traits.

Pumpkin (Cucurbita pepo L.) young leaves and vines are consumed as vegetables among the rural dwellers in Southwest Nigeria. It is a cheap source of protein, vitamins, fibres and antioxidants in their diet. Due to the intensive cultivation of available lands which affects the nutrient status of most soils and their productivity, the need to apply fertilizer on pumpkin became pertinent. Therefore, nitrogen, phosphorus and potassium (NPK) fertilizer influence on biomass accumulation in pumpkin was investigated for two consecutive seasons in 2010 at the Research Farm of Obafemi Awolowo University, Ile-Ife, Nigeria. NPK (15:15:15) compound fertilizer was applied at the rates of (0, 50, 100, 150, 200 and 250 kg ha-1) to C. pepo at 2 weeks after planting (WAP). At 8 WAP, the following morpho-physiological traits: vine length, vine diameter, number of internodes, internodes length, vine weight, number of leaves, total fresh and dry biomass assessed were significantly influenced by season and fertilizer effects. The combined analysis of variance (ANOVA) results showed that the effects of season (S) and fertilizer (F) are significant effect on all the traits. Season effect showed that the early season was better (p = 0.05) while the application of fertilizer beyond 100 kg of NPK per hectare was not statistically beneficial for biomass yield and its components. However, the significant S X F interaction on the total dry matter fitted well into a quadratic equation with significant R 2 values. The response curves showed higher response to fertilizer in the early than late planting season and a maximum biomass yield was attained at the application of 205 kg and 244 kg ha-1 of NPK (15-15-15) for early and late season cultivations, respectively.