Intraspecific variation, trait coordination and resource-use strategies of leaf functional traits in Suzhou tea...

Understanding intraspecific variation in leaf functional traits is essential for revealing plant resource-use strategies and adaptive mechanisms. Suzhou tea landraces (Camellia sinensis (L.) Kuntze), an important local germplasm resource in eastern China, exhibit substantial variation in leaf functional traits, yet patterns of trait variation and coordination remain poorly understood.

A total of 65 tea landrace strains collected from Suzhou, China, were evaluated for nine quantitative leaf functional traits, including morphological traits (leaf dry matter content, LDMC; specific leaf area, SLA), photosynthetic traits (net photosynthetic rate, Pn; transpiration rate, Tr; stomatal conductance, Gs), and chemical traits (leaf carbon, nitrogen, phosphorus, and potassium contents per unit mass; C_mass, N_mass, P_mass, and K_mass), together with four categorical leaf traits. Trait variation, coordination, and functional differentiation were analysed using descriptive statistics, correlation analysis, principal component analysis (PCA), and K-means clustering.

Substantial intraspecific variation was observed among the tea landraces. SLA exhibited the highest coefficient of variation, indicating strong plasticity, whereas C_mass was comparatively conserved among strains. Among categorical traits, tooth-related characteristics displayed considerable diversity, while leaf margin type showed no variation. Significant coordination and trade-offs were detected among leaf traits. SLA was negatively correlated with LDMC, whereas photosynthetic traits (Pn, Tr, and Gs) were strongly and positively correlated with one another. Leaf size exhibited a strong association with SLA (η = 0.87). PCA identified a major axis of trait variation associated with differences in functional trait combinations. K-means clustering separated the strains into two clusters that differed primarily in SLA, N_mass, K_mass, LDMC, C_mass, and photosynthetic traits.

Suzhou tea landraces exhibit considerable intraspecific variation and coordinated trait relationships, indicating substantial functional differentiation among strains despite their common geographic origin. These findings improve our understanding of functional trait variation in tea plants and provide a theoretical basis for germplasm evaluation, conservation, and cultivar selection.