Effect of Spacing on Growth Response and Pest Incidence in Coffea canephora

Abstract

Coffee tree density optimization can improve fortunes of stakeholders, especially smallholder farmers who dominate the sub-sector at production level. An attractive example is with highly productive countries where high plant densities do increase area yield but across board recommendations are illogical especially with variety and agroecological variations. We aimed to compare two spacing regimes for growth response and pest incidence using Uganda’s unique C. canephora. Randomized complete block designs with three replications and eight plants per plot were established at four locations. Eleven growth variables namely stem girth (STG), number of internodes on stem, plant height (PH), canopy height, canopy diameter, number of primaries, number of active bearing primaries, length of longest primary (LLP), number of internodes on primary, leaf blade length and leaf blade width (LBW) were measured. Incidences of black coffee twig borer (BCTB), leaf eating beetles (LEB), leaf miners (LM), skeletonizers (SKL) and tailed caterpillars (TC) were also assessed. Highly significant differences between spacing regimes (p<0.01) were obtained for majority of variables, locations, and crop ages. Higher mean growth response was generally higher under 3 m x 1 m (high density) than 3 m x 3 m (low density) with most suitable variables as STG, PH, LLP and LBL. Conversely, pest incidence (BCTB, LEB, LM and TC, except SKL) was higher under high than low plant densities. The findings provide a first stage guide on implications of high plant densities for growth robustness which is translatable into yield potential; amidst a pest prevalence dilemma in studied type of C. canephora.

Keywords

• Coffee tree density; stable growth traits; plant population; pest dynamics; Xylosandrus compactus