Effects of irrigation rate and leaf harvest intensity on growth, yield and quality components of multi-purpose pumpkin (Cucurbita moschata duch.)

Abstract

Pumpkin (Cucurbita moschata Duch.) is a multi-purpose fruit and leaf vegetable that is rapidly gaining popularity in urban, peri-urban and rural areas in Kenya. The fruits and leaves are rich in vital vitamins and minerals. The seeds are becoming popular as a snack for their nutritional and medicinal properties. However, water stress during dry periods and irregular leaf harvesting are some of the constraints largely affecting optimal fruit and leaf yields. This study was carried out both in Nairobi and Embu Counties from June 2012 to April 2013 to determine the effects of irrigation water rate and leaf harvest intensity in enhancing fruit, seed and leaf yields. A split-plot experiment embedded in a Randomized Complete Block Design with four replications was used. A rain shelter was used to block rain water from the experimental plot. Irrigation was applied to main plots and leaf harvest intensity to split-plots. The treatments included four irrigation rates (1, 2, 3 and 4 litres applied once per week through drip tubes) and four leaf harvest intensities (0, 1, 2 and 3 leaves harvested once per fortnight per branch). One plant spaced at 2 m x 2 m and replicated four times was used per treatment. The parameters studied were: number and fresh biomass of edible leaves; sex ratio; number of male and female flowers; number, size, weight and quality of fruits; number and weight of seeds; germination percentage and seedling vigor. Data obtained were subjected to analysis of variance using JMP IN 5.1 statistical package software. Mean separation for all significant variables was conducted using the Tukey’s Studentized Range Test at P = 0.05. Results showed that leaf harvest intensity had a significant (P < 0.05) decreasing effect on flowers, leaf vegetables, fruit yields and quality. Irrigation rate had a significant (P < 0.05) increasing effect on the number of branches. Interaction between irrigation rate and leaf harvest intensity had a significant (P < 0.05) increasing effect on number of leaves, seeds and male flowers. Irrigating with three litres of irrigation water once each week recorded the best performance in most treatments and is recommended for pumpkin plant growth and production. The highest yields were 4.7 t/ha edible leaves for 3-LHI and 22.7 t/ha of fruits for no leaf harvest intensity. Harvesting one leaf or none per branch per week recorded the best results in most treatments Harvesting two leaves per branch once per week is recommended for farmers interested in edible leaves and one leaf per branch or none for farmers interested in fruits and seeds.