Abstract: Differentiation of the key functional traits among the species within the genus Lysimachia can help understand the mechanism of their ecological adaptation. We quantitatively analyzed the variation and co-variation relations regarding the root, stem and leaf functional traits of nine species from Lysimachia cultivated under the environmentally homogeneous potted conditions using the comparative method in plant functional ecology. The results showed that the variation degree of ten plant functional traits represented by the coefficient of variation (CV) was different at the generic level. Leaf size had the highest degree of variation (CV=75.0%), followed by specific root length (CV=60.7%) and specific stem length (CV=46.5%), and lowest for leaf carbon concentration (CV=3.6%), with the maximum value of CV being 21 fold of the minimum. The subgen. Lysimachia and subgen. Palladiawere significantly different in functional traits (P<0.05). Subgen. Lysimachia was characterized by a combination of plant functional traits dominated by specific root length, specific stem length, and specific leaf area. However, subgen. Palladia had greater root specific density and leaf size. The plant functional traits of Lysimachia were speciesspecific, with significant differences in leaf size, specific leaf area, leaf dry matter content, leaf carbon concentration, leaf nitrogen concentration, leaf C∶N ratio, specific root length, root specific density, specific stem length, and stem specific density (P<0.05). The root, stem and leaf functional traits worked in synergy as a whole plant for each of the nine Lysimachia species. Specifically, leaf size was negatively correlated with specific stem length (R²=0.484, P<0.01) and specific root length (R²=0.149, P<0.01), while specific stem length was positively correlated with specific root length (R²=0.348, P<0.01). Both the leaf economics spectrum and the plant economics spectrum were found for the nine Lysimachia species.

Key words: soil water and salt movement, quality, arid area of Southern Xinjiang, cotton yield, irrigation regime, mechanically-harvested cotton