To reveal the genetic variation in water-use characteristics of Larix olgensis clones and select superior clones with characteristics of drought-tolerance， 25 superior clones of the 37-year-old L. olgensis were used as the research materials. Nine drought tolerance-related twig and needle traits were measured， and their correlations were analyzed. A comprehensive evaluation of the drought tolerance was conducted using the membership function method and cluster analysis. The results indicated that significant differences（P<0.01） occurred in needle traits among clones. Anatomical and morphological traits exhibited lower coefficients of variation（CV） （11.06%-11.83%）， whereas physiological traits exhibited higher CV（22.15%-39.24%）. In contrast， no significant differences were observed in twig traits among clones. Hydraulic diameter exhibited the smallest CV（6.15%）， while the thickness to span ratio exhibited the largest CV（25.26%）. Strong correlation among traits was found within organ level. In needles， epidermal thickness was significantly positively correlated with cortical thickness（P<0.05）， and both were significantly negatively correlated with water-use efficiency（P<0.01； P<0.05）. Stomatal transpiration was significantly negatively correlated with residual transpiration（P<0.01） and significantly positively correlated with specific leaf area（P<0.05）. In twigs， hydraulic diameter and potential specific hydraulic conductivity were both significantly negatively correlated with thickness to span ratio（P<0.01）. However， there was only a significant negative correlation between needle stomatal transpiration and twig thickness to span ratio across organs（P<0.05）. Principal component analysis of the nine twig and needle traits revealed two relatively independent axes. The first axis reflected a trade-off between hydraulic efficiency and hydraulic safety in twig； the second axis， composed of leaf traits， reflected a trade-off from conservative to efficient water-use strategies. Based on the drought-tolerance evaluation， 25 clones were classified into three categories： comprehensive and strong drought-tolerant， moderate drought-tolerant， and drought-sensitive groups. Clones 338， 774， 128， 125， 214， and 565 demonstrated strong drought tolerance. These findings provided a theoretical basis and practical guidance for selecting suitable afforestation materials adapted to different arid regions.
%U https://bbr.nefu.edu.cn/EN/10.7525/j.issn.1673-5102.2026.01.013