Study area
Ambatofitorahana, Region Amoron'i Mania, Madagascar
Objectives
To determine the optimal planting density for green bean that maximizes yield, pod quality, and land-use efficiency. Specific objectives: (1) compare the effect of different planting spacings on vegetative growth (plant height, leaf count, stem diameter, biomass); (2) assess the impact on yield components (pods per plant, pod weight and length, total yield); (3) analyze the influence of plant density on crop health status and inter-plant competition.
Methodology
Completely Randomized Block Design (CRBD); 4 treatments × 4 blocks = 16 experimental plots of 4 m² (2 m × 2 m). Treatments differ only in planting spacing: T1 (farmer's practice/control), T2 (20 cm × 40 cm), T3 (5 cm × 50 cm), T4 (30 cm × 60 cm). Direct seeding; fertilization and crop management are uniform across all treatments.
Monitored parameters
Vegetative growth (at 21, 35, and 50 days after sowing – DAS): plant height, leaf number, stem diameter at collar, fresh and dry aboveground biomass. Yield components (at harvest): pods per plant, average pod length and weight, plot yield and extrapolated yield in kg/ha. Plant health: disease incidence and severity (0–5 scale), pest presence, plant mortality rate.