Modified Canopy Architecture Enhanced Yield of Black Pepper (Piper nigrum L.) through High Absorption and Distribution of Photosynthetically Active Radiation (PAR)

Abstract

Black pepper (Piper nigrum L.), is a woody perennial climbing plant belonging to family Piperaceae and the most consumed spice in the world. Although the support tree Gliricidia (Gliricidia sepium) is pruned 3 to 4 times per year, pepper vines are not annually pruned in Sri Lanka. The characteristic cylindrical compact canopy of pepper is inefficient in intercepting solar radiation compared to most other vine crops. Therefore, this study was conducted to investigate the effect of different canopy pruning practices on the Photosynthetically Active Radiation (PAR) interception efficiency of the plant canopy and its effect on the yield. Four treatments on pruning practices were compared to each other. Treatments were, T1 – Control (no pruning); T2 - maintaining cone-shaped canopy by pruning only the plagiotropic branches; T3 - partial pruning of lateral branches of only the upper half (layer 1 and layer 2) of the canopy; and T4 - removal of 25% of lateral branches allowing uniform distribution of sunlight all over the canopy (loose canopy). The results revealed that T2 and T4 pruning methods significantly improved the yield (P<0.05) compared to T1 and T3. Hence, both modifying the cone-shaped canopy and maintaining a loose canopy all over the plant are better pruning practices to maximize yield through efficient PAR absorption. Therefore, adopting either of these pruning methods can be recommended as better practices for farmers to maximize their crop yield.