Effects of sand burial on growth and biomass allocation of Nitraria tangutorum

Sand burial is an important way to change seedling growth in sand land. Nitraria tangutorum is one of the main constructive plants in desert areas. In order to investigate the impacts of sand burial on seedling growth and biomass allocation, the plant propagation were cut successfully and grown in testing grounds, which were buried by sand with four sand-burial depths(0, 5, 10 and 15 cm) for two months. The growth of the seedlings in different sand-burial and biomass were examined once a month for three months. The results showed that 1) At the mid-period and late-period of the experiment, the basal diameter, mean diameter of root and total root length of N. tangutorum seedlings increased more significantly with light and moderate sand burial than other treaments. 2) At the early-period and mid-period of the experiment, the primary branch of stem and leaf mass increased more significantly in 0 cm sand-burying than other treatments, while the relative growth rate and net assimilation rate were mostly higher than other treatments. 3) Compared to other treaments, light sand burial had a marked influence upon the secondary branch, which could significantly increase the stem and leaf mass, number of leaves and total leaf area of N. tangutorum. 4) The relative growth rate and net assimilation rate of N. tangutorum seedlings were mostly lower in 15cm sand-burying than in other three treatments, suggesting that light sand burial can promote the growth of N. tangutorum seedlings, while heavy and severe sand burial injure the plant growth seriously. N. tangutorum, as a clonal plant of stem-layering, should be buried with sand lightly in order to promote the growth of branches and the ablity of exual reproduction when used for fixing mobile sand.