Abstract: Haloxylon persicum Bunge ex Boiss. et Buhse, a perennial shrub, is an important species in sand fixation and ecosystem regeneration in desert. In this study, the response of growth and biomass allocation of the species under different salt treatments was evaluated. Three kinds of salt (NaCl, Na₂SO₄ and compound salt mixed by NaCl and Na₂SO₄ with equal mol ratio) and six salt gradients 〔0 (CK), 50, 100, 200, 300 and 500 mmol/L〕 were designed in the study. Morphological characteristics, dynamic change of biomass accumulation and biomass allocation in the seedlings under different salt treatments were determined. It is confirmed that salt kind and salt content could significantly affect the biomass accumulation, biomass allocation and morphological characteristics of H. persicum seedlings. The results are as follows: (1) The morphological structure of assimilating branches under different salt treatments was different. Root length was promoted under moderate salt concentration, but it was restricted under high salt treatment. The height, stem diameter and biomass accumulation of  H. persicum seedlings were positively correlated with treating time and salt concentration. Compared with the contrast, the biomass of H. persicum seedlings under 500mmol/L compound salt (mixed by NaCl and Na₂SO₄) treatment after 70 days was decreased by 77%, 87% and 78%, the aboveground biomass by 78%, 87% and 74%, and the underground biomass by 75%, 81% and 76%, respectively; (3) Rootshoot ratio was increased with the time under all treatments, but it was different from different treatments. There was no significant difference in rootshoot ratio between the contrast and all the NaCl or compound salt treatments after 25 days, but the rootshoot ratio was increased under high salt concentration of Na₂SO₄. Rootshoot ratio was in an increase trend with increasing salt concentration regardless what kinds of salt; (4) There was an obviously allometric relationship between aboveground biomass and underground biomass, and the accumulating rate of underground biomass was higher than that of aboveground biomass. Additionally, saline treatments did not change the allometric parameter (a)significantly. The results demonstrated that the response of H. persicum seedlings varied with salt kinds, content and treatment time. Under salt stress, the response of H. persicum seedlings to Na₂SO₄ was faster than to NaCl and compound salt, such response trended to a similarity with the time.

Key words: salinized soil, Haloxylon persicum, seedling, biomass, accumulation rate, salt kind, salt concentration, Gurbantonggut Desert
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