Study on non-structural carbohydrate allocation strategies of psammophytes induced by drought stress in southeastern Xizang

The content of non-structural carbohydrates (NSC) in different plant tissues reflects the energy allocation strategies within plant individuals. Understanding the dynamic changes in NSC under drought stress can provide insights into how plants manage resource distribution in drought conditions. In this study, two psammophyte species from southeastern Xizang (Artemisia gmelinii Weber and Hippophae rhamnoides subsp. Yunnanensis Rousi) were selected to explore the distribution dynamics of NSC in different organs (leaves, branches, coarse roots, and fine roots) under varying drought intensities. Results showed that: (1) Intensified drought stress significantly increased the root-to-shoot ratio and the accumulation of soluble sugars and NSC in branches, coarse roots, and fine roots; (2) Under drought stress, there was a preferential allocation of NSC to underground parts, with leaves and fine roots primarily accumulating NSC in the form of soluble sugars; (3) In the fine roots of A. gmelinii, the proportion of soluble sugars, starch, and NSC decreased with intensifying drought, whereas in H. yunnanensis, the proportion of soluble sugars, starch, and NSC increased with intensifying drought. This study suggests that plants mitigate drought stress by storing more soluble sugars and enhance their drought resilience by allocating more NSC to the roots.