EFFECT OF INSECT POLLINATORS ON YIELD AND YIELD RELATED PARAMETERS OF WATERMELON (Citrullus lanatus thunb) IN THE NIGERIAN SOUTHERN GUINEA SAVANNAH

Abstract

Watermelon (Citrullus lanatus Thunb.) is a significant horticultural crop grown worldwide, prized for its sweet, juicy and nutritious value. As with many flowering plants, watermelons depend on pollinators for fruit set. Insect pollinators are essential in increasing seed set of many pollination-dependent fruit crops, as well as the quality of seed or fruit in terms of nutrient and mineral composition. This study was conducted at Federal University Wukari during 2024 late planting season and 2025 early planting season to determine the impact of insect pollinators on yield and fruit quality of watermelon across the seasons. The study was carried out on six 5 x 3 m = 15 m² plots demarcated on a 0.108 ha land. The plots were grouped into two with three replications. The first group was covered with net mesh for insect pollination exclusion at 50% flowering stage while the second group was left open to allow for insect pollination. There was a significantly (p < 0.05) higher number of fruits in the insect-visited plots (16.33 ± 0.76) compared to insect-excluded plots (1.67 ± 0.62), across both planting seasons. Similarly, fruit weight was markedly increased by insect visitation (7.82 ± 0.40 kg against 2.77 ± 0.73 kg). Fruit length (31.67 ± 1.40 cm against 13.98 ± 3.41 cm) and diameter (19.60 ± 1.20 cm against 8.30 ± 2.07 cm) followed the same trend across the planting seasons. Rind thickness was significantly greater in fruits from insect-visited plots during the late season (1.67 ± 0.67 cm against 0.98 ± 0.17 cm) and pooled means of early and late planting season (1.54 ± 0.06 cm against 0.94 ± 0.20 cm), though this difference was not significant (p > 0.05) in the early season. Total Soluble Solids (TSS), were also elevated in late season fruit from insect-visited plot (10.00 ± 0.12 °Brix against 6.63 ± 0.22 °Brix) and pooled means of early and late planting season (10.37 ± 0.17 °Brix against 8.58 ± 0.88 °Brix). The finding showed that insect pollinators have significant role in enhancing the yield and fruit quality of watermelon, underscoring the necessity of conservation of insect diversity.