Ontogenetic shift in stomatal regulation of <i>Caragana korshinskii</i> resprouts in response to drought following shoot removal

BACKGROUND AND AIMS: Resprouting plants are distributed across diverse global vegetation communities. In Caragana korshinkii, both the leaves and stems of resprouts exhibit reduced hydraulic conductivity and enhanced drought tolerance with increasing age following shoot removal. However, how stomatal regulation responds to resprout age remains poorly understood. METHODS: This study was conducted in the field on 1-13-year-old resprouts of C. korshinskii. We focused on measuring three core parameters: Ψleaf at predawn and midday, stomatal conductance in the morning and midday, and stomatal sensitivity to leaf water potential (Ψleaf). Additional measurements included leaf osmotic potential (Ψo), leaf turgor loss point (πtlp), and leaf dry mass per unit area (LMA). KEY RESULTS: We found that as resprouts aged from 1 to 13 years, the predawn-to-midday Ψleaf difference (Ψpd-Ψmd) increased from 1.1 MPa to 2.1 MPa; the morning-to-midday decline in stomatal conductance (Δgs morning-midday) decreased from 0.19 to 0.04 mol m-2 s-1; stomatal sensitivity to Ψleaf (mψ) declined from 1.68 to 1.48; and gsP50 decreasing from -1.95 to -2.59 MPa. These shifts were correlated with more negative Ψo, πtlp, and increasing LMA. CONCLUSIONS: This study reveals a transition from prioritizing drought avoidance to drought tolerance with resprout age in C. korshinskii following shoot removal. The adaptation highlights stomatal regulation as a key mechanism enhancing resprout drought resistance in arid shrub plantations.