Effect of Varying Irrigation Levels on Growth and Yield of Serengeti and Theresa French Bean Cultivars: A Case Study in Huye District, Rwanda

Effective irrigation management is essential for maximizing crop yield and quality while conserving water resources. This study evaluated the impact of varying irrigation levels on the growth and yield of two French bean cultivars, Serengeti and Theresa, conducted in 2024 at the Agricultural Research Center of Rwanda Polytechnic–Huye College. Key objectives included determining crop water requirements, establishing irrigation schedules based on daily soil water balance, and examining the effects of three irrigation regimes (Full irrigation (100% ETc), Deficit irrigation( 50% ETc), and Rainfed as Control on yield parameters across both cultivars. The experiment followed a split-plot design in a Randomized Complete Block Design with three replications. Soil moisture levels were monitored using PR2- Moisture Sensors. The results of conducted field experiments revealed that the seasonal irrigation water requirements for full irrigation, deficit irrigation, and rainfed treatments were 111.38 mm, 99.5 mm, and 24.5 mm, respectively. Seasonal evapotranspiration rates were measured at 160.4 mm for full irrigation, 143.9 mm for deficit, and 80.84 mm for rainfed. The fresh pod yield ranged between 5.9 – 11.7 tons ha⁻¹ for Serengeti and 5.3 – 20.3 tons ha⁻¹ for Theressa, while dry matter yields varied from 1.0 – 1.66 tons ha⁻¹ for Serengeti and 0.8 – 2.88 tons ha⁻¹ for Theressa. Plant height ranged from 22 cm to 40.1 cm, and pod lengths for Serengeti and Theressa were between 9.3 – 17.64 cm and 8.8 – 15.8 cm, respectively. The mean number of grains per pod was 7. Yield response factors (ky) for Serengeti and Theressa were 1.029 and 1.20, respectively. The highest crop evapotranspiration productivity (WPET) and water productivity (WP-irrigation) were recorded for Theressa at 127.2 kg ha⁻¹ mm⁻¹ and 135.6 kg ha⁻¹ mm⁻¹, respectively. Monitoring soil moisture balance highlights the economic advantages of efficient irrigation techniques tailored to local conditions.