Pepino melon (Solanum muricatum Ait.) is an exotic vegetable whose consumption is on the increase in Kenya due to its health and nutritional benefits. A study was conducted at Egerton University, Kenya in 2018-2019 to investigate the effect of NPK fertilizer rates (0, 100, 200. 300 and 400 kg ha-1) on growth and yield of field and greenhouse grown pepino melons. The experiment was laid in a randomized complete block design with three replications. Data was recorded on plant height, stem diameter, number of leaves per bush, number of branches, days to 50% flowering, fruit weight and total yield. Data were analyzed using analysis of variance with the SAS statistical package. Significant means were separated using Tukey’s Honestly Significant Difference at p ≤ 0.05. Results indicated that NPK fertilizer rates and growing environment influenced growth and yield of pepino melon. At 100 DAP plants grown in the greenhouse and supplied with 200 kg NPK ha-1 had a stem diameter of 14.01 mm which was significantly bigger p ≤ 0.05 compared to those grown in the field and supplied with 300 kg NPK ha-1 with a stem diameter of 11.71 mm in trial two. Application of 300 kg NPK ha-1 for field grown pepino melons gave the highest yield of 1102.48 kg ha-1 and 1060.55 kg ha-1 in trial one and two respectively. In conclusion, application of 300 kg ha-1 of NPK fertilizer for field grown pepino melon is recommended.

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The present study evaluated the effect of NPK fertilizer (17:17:17) rates (0, 100, 200, 300 and 400 kg ha-1) on the postharvest quality of field and greenhouse grown pepino melons (Solanum muricatum Ait.) stored at room temperature (15-22°C) and at low temperature (7°C). The study was carried out in randomized complete block design with fruits from the field and greenhouse, five NPK fertilizer rates as treatments and the two storage temperatures replicated three times. Data were collected on percentage fruit weight loss (PWL), total soluble solids (TSS), firmness and shelf life. Results indicated that greenhouse and field grown fruits from the control and plants supplied with 100 kg NPK ha-1 had low PWL at both storage temperatures. Field grown fruits from the control stored at room temperature had the highest TSS and were firmer after 28 days of storage. Field grown fruits not supplied with fertilizer and stored at low temperature had a shelf life of 27 and 26 days in trial one and two respectively. Application of 100 kg NPK ha-1 and storage of pepino melon fruits at low temperature can be used to enhance quality and shelf life.

Secondary metabolites are bioactive compounds which are synthesized naturally in all plant parts. The quality and quantity of secondary metabolites produced by plants differ depending on the plant and environmental conditions under which they are produced. The purpose of the study was to investigate the effects of nitrogen, phosphorous and potassium (NPK) fertilizer (17:17:17) rates (0, 100, 200, 300 and 400 kg ha-1) on the production of secondary metabolites in field and greenhouse grown pepino melons (Solanum muricatum Aiton). The experimental design was randomized complete block design with five NPK fertilizer treatments replicated three times. Results indicated that an increase in NPK fertilizer rate led to an increase of carotenoids (lutein, lycopene and β-carotene) up to a maximum at 200 kg NPK ha-1 after which the contents decreased in both growing environments and trials. The control (no fertilizer application) favored the accumulation of total phenolic content (TPC) in both growing environments and trials. Greenhouse grown pepino melon fruits which were not supplied with fertilizer (control) had a TPC content of 174.3 and 145.5 mg GAE 100g-1 fresh weight (FW) in trial one and two, respectively. Fertilizers could not enhance production of TPC in pepino melon fruits and application of 200 kg NPK ha-1 is recommended for maximum accumulation of carotenoids (lycopene, lutein and βcarotene).