Water Deficit During Pod Development Affects Eco-Physiological Traits, Growth, and Yield in Pea Varieties Under Greenhouse Conditions in Tropical Highlands

Water deficit during reproductive development is one of the main constraints on pea (Pisum sativum L.) productivity in tropical highlands. In this study, five varieties with contrasting leaf architectures were evaluated under controlled greenhouse conditions, with and without water deficit applied from the time of pod formation. Key ecophysiological variables, including leaf area index (LAI), radiation extinction coefficient (k), interception efficiency (RIE), radiation use efficiency (RUE), and water use efficiency (WUE), along with yield components, were measured. Deficit significantly reduced biomass, RUE, and yield, although the harvest index (HI) remained relatively stable. Varieties with the afila gene showed greater stability in LAI and WUE, but lower biomass accumulation. Correlation analyses revealed that, under optimal conditions, yield was closely associated with structural and functional traits, a relationship that weakened under stress. These results demonstrate the importance of integrating morphophysiological characteristics into breeding and agronomic management programs to develop more efficient and resilient varieties under water deficit conditions in the high tropics.