Branch Growth, Leaf Canopies and Photosynthetic Responses of Zizyphus jujube cv. “Huizao” to Nutrient Addition in the Arid Areas of Northwest China

Abstract

Jujube is one of the main tree species found in the arid areas of Xinjiang, China. However, the nutritional requirements of central leader jujube trees are not understood. Our aim was to explore the effects of different fertilization gradients on the growth, development, and canopy formation of jujube trees to provide a basis for efficient cultivation. We measured and compared various suitable indices of jujube trees under 16 different fertilization treatments, and we confirmed the treatments suitable for cultivation by correlation and principal component analyses. The jujube tree growth indices under different fertilization treatments significantly differed (p < 0.05). The application of nitrogen fertilizer promoted the growth of branches and leaves. The soil and plant analyzer development value, light, and other traits significantly differed (p < 0.05). The leaf area index and direct transmittance coefficient significantly differed (p < 0.05). Compared with single-fertilizer application, mixed-fertilizer application significantly increased the leaf area index. Correlation analysis showed that the net photosynthetic rate of jujube leaves significantly correlated with the stomatal conductance, transpiration rate, and leaf SPAD content (p < 0.01). We obtained three principal components with a cumulative variance contribution rate of 82.192%. The final ranking showed that the mixed treatment (N 460.77 g/tree, P2O5 460.77 g/tree, and K2O 588.23 g/tree) performed better. To ensure branch and leaf growth, this treatment promoted photosynthesis, enabling the growth and development of fruit trees.