Abstract: Soil moisture is an important factor affecting the morphogenesis of branches and leaves and leaf structure. The purpose of this study was to explore the adaptability of Nitraria tangutorum to water conditions and provide theoretical basis for artificial induction of different morphologies of N. tangutorum. An experiment with potted water control method was conducted using one-year-old stem cuttings of N. tangutorum under six levels of water supply. Water supply calculated based on the average precipitation of the cuttings collection site from March to August in recent ten years was used as control (W4). The other five treatments were then designed as reducing water supply by 15%, 30%, and 45% (designated as W3, W2, W1) and increasing water supply by 15%, 30% (W5, W6). After 10, 30, 50, 70, and 90 days of treatment, branch length, number of nodes, internode length, basal diameter, branching angle, branching ratio, leaf length, width, thickness, length to width ratio and leaf anatomical structure were measured. The results showed that the branch growth of N. tangutorum was significantly inhibited while the node formation and branching ratio were promoted under W3 and W2 treatments. Double layers of epidermis and mucous cells appeared in leaves of N. tangutorum under W2 treatment. With the increases of water supply, leaf length, width, thickness, and length to width ratio of N. tangutorum showed an increasing trend. The branch growth of N. tangutorum was promoted under W5 treatment, especially for primary branch angle. The primary branch angle was 43.5° in the later stage of the experiment. Plant clump shape of N. tangutorum transited from “upright” to “semi-upright”. Under W6 treatment, leaf size reached to the maximum, with length of 21.46 mm, width of 4.69 mm, thickness of 0.47 mm, the length to width ratio of 4.62, and the branch showed excessive growth.

Key words: drought stress, rainfall increasing condition, branch and leaf traits, compound epidermis, mucous cell.