EFFECTS OF NUTRIENT SOURCE AND LEAF HARVESTING INTENSITY ON PUMPKIN (Cucurbita moschata Duch.): 1. VEGETATIVE AND REPRODUCTIVE GROWTH COMPONENTS

Abstract

Multi-purpose pumpkin is an important vegetable that has gained popularity in Kenya. It is rich in mineral nutrients and antioxidant properties. The crop is sensitive to management practices, including defoliation that removes photosynthetic machinery. For better growth and development, balanced leaf removal and re-growth are necessary. Severe harvest of leaves compromises physiological functions that influence yields. Farmers in Kenya harvest the leaves indiscriminately and leave the plants to grow without any improvement in agronomic practices. As a result, the yields experienced remain suboptimal and poor in quality. To address this problem, an experiment was conducted at two sites in Kakamega and Nyeri Counties to elucidate the impact of varied leaf harvesting intensity and nutrient sources on vegetative and reproductive growth components that impact subsequent leaf and fruit yields and quality. The experimental design was Randomized Complete Block Design, with four replications. The factorial arrangement treatments were nutrient source (0, 4 g 10N:10P:10K, 5 and 10 t/ha farmyard manure) by leaf harvesting intensity (0, 1, 2 and 3 leaves per vine per week). Plants were spaced at 2 m x 4 m, with one plant per experimental unit. Data values were collected and subjected to analysis of variance. Means were separated using the Tukey’s HSD test at P = 0.05. Results showed that leaf harvesting intensity and nutrient source had significant (P<0.05) effects on number of vines, leaf area and chlorophyll content index. The treatments did not significantly influence male to female flower ratio and mineral nutrient contents in leaf tissue, except phosphorous that significantly affected by nutrient source in Kakamega. The number of vines and leaf area increased with decrease in leaf harvest intensity and increase in FYM. The CCI increased with increase in FYM, but was constant for leaf harvesting intensity. The sex ratio ranged from 1 to 3 male flowers per 1 female flower, and was highest for no leaf harvesting and lowest for 3 leaf harvesting. The trends observed in these vegetative and reproductive growth components end up impacting edible leaf and fruit yields and quality either positively or negatively, depending on the function they perform in plants.