Exogenous γ-aminobutyric acid (GABA) application delays physiological damage caused by acute water deficit in Persian lime

Persian lime (Citrus latifolia) is one of Mexico's most important fruit crops and is increasingly exposed to sudden drought events caused by climate change. This study evaluated the effect of foliar γ-aminobutyric acid (GABA) application on the physiological response of Persian lime plants subjected to acute water deficit. Six-month-old plants grafted onto Volkameriana rootstock were treated with 100 mM GABA and subjected to 14 days of irrigation withdrawal, followed by 7 days of rewatering. We assessed chlorophyll fluorescence, gas exchange, and plant water relations. Untreated plants exhibited severe physiological decline, irreversible tissue dehydration, and failed to recover after rewatering. In contrast, GABA-treated plants maintained photosynthetic performance, delayed physiological damage, and showed a clear trend toward physiological recovery after rewatering. Two-way ANOVA showed significant effects of irrigation, GABA, and their interaction. Foliar GABA application enhanced tolerance to acute water deficit by preserving photosynthetic function.