CLUSTER BEAN INTERCROPPING WITH OKRA AND CHILI: AGRONOMIC RESPONSES AND ECONOMIC PERFORMANCE UNDER ARID CONDITIONS

Abstract

Smallholder agricultural systems across arid and semi-arid zones of the Global South face mounting systemic risks stemming from land fragmentation, climatic anomalies, groundwater depletion, and escalating costs of synthetic chemical inputs. In response to these vulnerabilities, intercropping drought-hardy legumes with high-value horticultural cash crops represents a vital agro-ecological mechanism to maximize land-use efficiency, conserve soil capital, and enhance farm enterprise resilience. This two-year field investigation (conducted during 2023 and 2024 at Multan, Pakistan) evaluated the agronomic performance, biological efficiencies, allometric growth parameters, and economic viability of cluster bean (Cyamopsis tetragonoloba L.) cultivated in sole stands and intercropped with two morphologically contrasting horticultural companion crops: okra (Abelmoschus esculentus L.) and chili (Capsicum frutescens L.). The experiment was arranged in a Randomized Complete Block Design (RCBD) with three replications across five distinct cropping treatments: sole cluster bean (T₁), sole okra (T₂), sole chili (T₃), cluster bean intercropped with okra (T₄), and cluster bean intercropped with chili (T₅). Interspecific competition for spatial and nutritional resources significantly altered vegetative and reproductive allometric. Cluster bean vegetative development was highest in sole stands 19.77 cm plant height at first picking, 79.57 cm final plant height), but experienced significant suppression when intercropped with okra 16.72 cm and 69.68 cm, respectively and chili 16.35 cm and 68.72 cm, respectively. Leaf count per cluster bean plant was significantly restricted by okra competition 5.53 relative to chili intercropping 6.32 and sole stands 6.23. For companion vegetables, sole okra produced significantly more pods per plant 12.40 than intercropped okra 11.17, though cumulative pod yield of 14.85 t ha⁻¹ vs. 13.57 t ha⁻¹ was statistically maintained. Conversely, chili displayed pronounced competitive sensitivity: fruit count per plant dropped from 44.65 to 36.22, fruit fresh weight declined from 62.46 g to 47.56 g, and cumulative cumulative fruit yield suffered a statistically significant reduction from 3.49 t ha⁻¹ in monoculture to 2.65 t ha⁻¹ in intercropping (p = 0.0151). Despite individual yield trade-offs, comprehensive partial budget analysis revealed substantial economic premiums for polyculture diversification. Intercropping cluster bean with okra achieved the highest enterprise profitability, delivering a net financial return of PKR 573,450 ha-1, a marginal net benefit of PKR 474,950 ha-1, a marginal rate of return (MRR) of 1,922.87%. Cluster bean intercropped with chili also yielded positive financial margins (net benefit of PKR 204,500 ha-1; MRR of 476.83%, outperforming sole cluster bean monoculture (PKR 98,500 ha-1. These empirical findings demonstrate that integrating low-water, nitrogen-fixing legumes with heavy-feeder horticultural vegetables stabilizes agrarian income and provides an adaptable polyculture model for climate-vulnerable smallholder farms.