Abstract: In order to explore the relationships between the planting density and the branching pattern and biomass of Moringa oleifera in dry and hot valley basin, and to search for a more reasonable planting density of this plant, a field survey was conducted on the branching pattern and biomass of M. oleifera plantations under different planting densities. There existed significant negative correlations between the plant height, basal diameter, crown breadth, and branch number and the planting density, and significant differences in the biomass of root, stem, and foliage, the pod number, length, and diameter, and the grains per pod under different planting densities. Planting density had significant effects on the branching pattern of M. oleifera, mainly manifesting in the significant differences in the ratios of first order branch to second order branch and of second order branch to third order branch, and the third order branch length. In different directions, the branching pattern had significant differences in the length of main and lateral branches and the angle of first order branch. For the purposes of using foliage and pod, the more reasonable spacing of M.oleiferacould be 0.9 m ×0.9 m and 1.5 m × 1.5 m, respectively. In sum, the significant differences in the branching pattern and biomass of M.oleiferaplantations under different planting densities suggested that M. oleifera had high morphological plasticity and ecological adaptability to the changing environment.

Key words: stoichiometry, soil nutrient, nutrient limitation, desert herb, life form.