Assessment of water productivity and phenological characteristics of cowpea plants in the highlands of Colombian Orinoquia

ABSTRACT Cowpea (Vigna unguiculata (L.) Walp.) is a strategic crop for the Colombian Highlands of the Orinoquia Region (CHOR) due to its tolerance to water stress, nitrogen-fixing capacity, and high nutritional value. This study, conducted at the AGROSAVIA La Libertad Research Center from December 2024 to April 2025, evaluated water productivity (WP) under controlled greenhouse conditions using four irrigation treatments based on crop evapotranspiration (ETc): 50% (160.8 mm), 75% (200.4 mm), 100% (240.1 mm), and 125% (289.4 mm). Grain yield ranged from 0.96 t ha⁻¹ under deficit irrigation (50% ETc) to 1.21 t ha⁻¹ under the 100% ETc treatment, which achieved the highest production levels. Despite reduced yield under deficit irrigation, the 50% ETc treatment achieved the highest water productivity (0.75 kg m⁻³), indicating more efficient water use for grain production. Moderate and full irrigation treatments (75–125% ETc) promoted increased vegetative growth, suggesting additional forage potential for integrated crop–livestock systems. Overall, the results demonstrate that cowpea can be successfully cultivated under deficit irrigation strategies, with irrigation levels between 75% and 100% ETc representing a suitable balance between grain yield and water use efficiency. These findings support the adoption of cowpea as a resilient crop for sustainable, climate-adaptive agricultural systems in regions affected by water scarcity and soil constraints.