Effects of fertilizer and irrigation on the growth and yield of bush pepper (piper nigrum L.) intercropped under coconut

Abstract

This research was conducted at the Intercropping and Betel Research Station of the Department of Export Agriculture, Sri Lanka, to assess the impact of different irrigation levels (6 L or 8 L per day) and amounts of inorganic fertilizer mixture (660 kg, 1320 kg, or 1980 kg per ha) consisting of Urea, MOP, and Eppawala Rock Phosphate, on the growth and yield of bush pepper planted under coconut. The study was a factorial experiment in a randomized complete block design with three replicates. Data on growth and yield were collected for five years. The findings didn’t reveal significant differences in canopy diameter or branching. However, after 20 months, plants irrigated with 8 L per day exhibited a higher percentage of flowered plants, indicating that increased irrigation can accelerate flowering. Nevertheless, more spikes were observed under low fertilizer application, suggesting that low nutrient supply positively influences the anthesis of bush pepper. Although the increased irrigation and fertilizer application improved the spike filling rate, it showed a decrease in spike production. Nonetheless, no interaction between the two factors has been identified. Moreover, the decline in yield from the third to the fifth year was observed which can be attributed to the mutual shading of growing plants. However, these results do not support the feasibility of field cultivation of bush pepper, as the dry yield achieved in this experiment (maximum 660 kg/ha/year) falls short when compared to traditional climbing pepper.