Relationship between Leaf Area Index and Actual Evapotranspiration in Psidium guajava Orchards Using Lysimetric Data

Abstract

Accurate estimation of crop water use is essential for improving irrigation efficiency and sustaining orchard productivity under variable climatic conditions. This study models the relationship between leaf area index (LAI) and actual evapotranspiration (ETa) in Psidium guajava orchards using lysimetric data. Field experiments were conducted with precision lysimeters to measure ETa across different growth stages, while LAI was periodically assessed to capture canopy development dynamics. The results revealed a strong positive relationship between LAI and ETa, indicating that increased canopy density significantly enhances transpiration and overall water use. ETa rates were lowest during early growth stages with limited leaf area, increased progressively with canopy expansion, and stabilized at higher LAI values due to saturation of transpiration capacity. The modeling approach effectively captured temporal variations in water use, enabling improved prediction of crop water requirements under varying environmental conditions. Additionally, the study highlighted that optimal LAI levels contribute to efficient water utilization without excessive loss, supporting balanced crop growth and productivity. While data-driven modeling techniques were employed to establish LAI–ETa relationships, the primary focus remained on orchard water management and agronomic optimization. The findings demonstrate that integrating canopy measurements with evapotranspiration data provides a practical framework for precision irrigation scheduling in Psidium guajava systems. This research contributes to sustainable horticulture by enhancing water-use efficiency, reducing resource wastage, and supporting climate-resilient orchard management practices.