Using Carbon Stable Isotope to Evaluate Water Efficiency Following Seasonal Variation of Coffee Leaf in Lamdong Province, Vietnam

This study examines the water use efficiency (WUE) of coffee plants across different seasons by using carbon isotope (δ13C). In Lamdong province, Vietnam, we set up a 300 m2 coffee farm to measure water use efficiency using carbon stable isotope ratios. We designed a sampling area, collected leaf samples during different irrigation seasons, measured local climate conditions and optimized the δ13C analysis procedure. Using ANOVA analyzing 54 leaf samples between two groups of seasons, we found that WUE of coffee plant was 14% higher in the rainy season (0.22) compared to the dry season (0.19), with a p-value of 0.017. The WUE of coffee plants is higher in the rainy season because the increased water availability reduces water stress, allowing the plants to maintain better hydration and more efficient carbon absorption.