Water Stress Effects on Physiological Responses, Water Use Efficiency and Yield of Cayenne Pepper (Capsicum annuum L) Under Screen-House Conditions

Abstract

Water stress is a major abiotic constraint limiting pepper productivity in tropical and sub-tropical environments, particularly under protected cultivation where irrigation scheduling determines plant water status. This study assessed Water Stress Effect on Growth, Yield and Water Storage Dynamics in Cayenne Pepper under screen house conditions. The experiment consisted of three watering regimes: No Stress (NS, 100% field capacity), Mild Stress (MS, 60% FC), and Severe Stress (SS, 40% FC), arranged in a Completely Randomized Design with three replications. Results showed that CWS decreased significantly from 215.6 m/Lplant under (NS) to 162.7 m/Lplant under (SS), indicating reduced plant water status under stress while relative water content declined from 86.4% (NS) to 61.3% (SS), indicating reduced plant water status under stress Water use efficiency (WUE) was highest under mild stress (4.85kg/m3) compared to NS (3.12kg/m3) and SS (2.01kg/m3). Proline accumulation (which is an amino acid that accumulates in plant tissues under stress conditions) increased significantly with stress, from 1.6(µmol/g FW (NS) to 7.8(µmol/g FW (SS), reflecting osmotic adjustment. Malondialdehyde (MDA) (which is a marker of cellular damage) also increased from 2.1 nmol/g (NS) to 6.9 nmol/g (SS), indicating enhanced lipid peroxidation under stress. Antioxidant activity (which is enzyme activities that protect plants from oxidative damage) increased progressively from 18.5(%) (NS) to 36.8(%) (SS). Leaf area declined under severe stress (318.4 cm²), while chlorophyll index remained stable under mild stress (59.8 Mg/g). Fruit yield was highest under NS (1.31 t/ha) and lowest under SS (0.81 t/ha). The study concluded that mild water stress improved physiological efficiency and WUE, while severe stress reduced productivity. Moderate irrigation is therefore recommended for optimal pepper production in derived savanna environments.