Agronomic Agronomic Technical Study of the Hedge Row System: Optimization of Plant Spacing and Pruning in Robusta Coffee Plantations in Bengkulu

Abstract

Bengkulu Province is part of the Coffee Triangle Region alongside Lampung and South Sumatra; however, robusta coffee productivity in Bengkulu remains low (0.67 tons/ha) and suboptimal. The hedge row system is an innovation that can increase plant population to 4,000 trees/ha with a production potential of 4 tons/ha, but its adoption in Bengkulu is still limited. This study aimed to examine the optimization of plant spacing and pruning techniques in robusta coffee plantations using the hedge row system in Bengkulu. The research employed a factorial Randomized Complete Block Design with two factors: plant spacing (J1=2.5×1.25 m, J2=2.0×1.5 m, J3=2.5×1.5×1.5 m) and pruning methods (P1=standard pruning at 180 cm, P2=layered pruning at 120 cm). The study was conducted at a demonstration plot in Batu Bandung Village, Kepahiang Regency, from July to December 2025. Parameters observed included vegetative growth (plant height, stem diameter, number of primary branches, canopy width), production (number of fruits per plant, fresh fruit weight, productivity per hectare), and bean quality (weight of 100 beans, yield percentage, moisture content). Results showed that plant spacing significantly affected growth and production. J3 produced the highest yield (3.2 tons/ha) with a population of 4,000 trees/ha, but did not differ significantly from J1 (2.8 tons/ha) with a population of 3,200 trees/ha. The highest stem diameter was obtained in J1 (28.4 mm) and the lowest in J3 (25.1 mm), indicating competition among plants at dense populations. Layered pruning (P2) resulted in higher numbers of primary branches (9.4) and production per plant (1.4 kg) compared to P1 (8.7 branches; 1.2 kg/plant). There was no significant interaction between plant spacing and pruning. The J1P2 combination gave the highest production numerically. Technical recommendations include J1 or J3 plant spacing and layered pruning integrated with GAP, as well as the establishment of demonstration plots in Bengkulu's production centers. Further research with broader location coverage is needed for result generalization.