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

Abstract 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, the way in which stomatal regulation responds to resprout age remains poorly understood. Methods This study was conducted in the field on 1- to 13-year-old resprouts of C. korshinskii. We focused on measuring three core parameters: leaf water potential (Ψleaf) at predawn and midday; stomatal conductance (gs) in the morning and midday; and stomatal sensitivity to 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 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 declined from 1.68 to 1.48; and water potential corresponding to a 50 % reduction in gs decreasing from −1.95 to −2.59 MPa. These shifts were correlated with more negative Ψo and πtlp and with 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.