The aim of this experiment was to explore the effects of root sprouting rejuvenation on the growth of Robinia pseudoacacia cutting seedlings, and provide a theoretical basis for the establishment of Robinia pseudoacacia rejuvenation system in the future production practice.

The cuttings of Robinia pseudoacacia root sprouts and semi-lignified branches of the mother tree were used as propagation materials, and the 1-year-old seedlings of Robinia pseudoacacia were set as the control. The differences in leaf morphology and anatomical structure, dry and fresh weight, gas exchange parameters, chlorophyll fluorescence parameters, photosynthetic enzyme activity and nutrient physiology of seedlings cultivated with different propagation materials were determined.

The results showed that, compared with the seedlings and mother tree branch cuttings, the root sprouting and rejuvenation treatment significantly increased the leaf length, leaf width, leaf perimeter, leaf area, dry and fresh weight, and leaf axis length of Robinia pseudoacacia cuttings, and significantly reduced the thickness of the upper epidermis, palisade tissue, and leaf thickness. Compared with seeded seedlings, the thickness of spongy tissue, leaf compactness, leaf porosity and the P/S ratio had no significant changes. The content of photosynthetic pigment, net photosynthetic rate, transpiration rate, F_v/F_m, F_v/F_o, NPQ and other gas exchange parameters, chlorophyll fluorescence parameters of Robinia pseudoacacia seedlings were significantly increased by root sprouting and rejuvenation treatment, and the rooting sprouts in one year were the highest. The activities of fructose 1,6-bisphosphate aldolase (FBA) and ribulose-1,5-diphosphate carboxylase/oxygenase (Rubisco) in the seedlings after root sprouting and rejuvenation were significantly higher than those in the mother branch cuttings, but there were still significant differences between the seedlings and the seedlings; However, the C/N, N/P, NSC and starch contents as well as the dry and fresh weight of leaves increased. The seedlings after root sprouting and rejuvenation had higher nutrient utilization efficiency and dry matter accumulation, and the one-year-old rooting shoots was the highest.

The cuttings of Robinia pseudoacacia, which have been rejuvenated by root sprouting, have stronger growth potential and juvenility, which provides theoretical support for the breeding of improved varieties and strong seedlings of Robinia pseudoacacia.

Fertile soil is an important guarantee for the efficient growth of Robinia pseudoacacia plantations. Nowadays, cultivating second-generation sprouting forests is an important way to build high-quality Robinia pseudoacacia plantations. However, there is currently little research on the fertilization effect of young Robinia pseudoacacia sprouting forests and a lack of relevant application technology research. Therefore, a study was conducted on the fertilization effect of second-generation Robinia pseudoacacia sprouting forests to explore the optimal phosphorus application rate and fertilization method for promoting the growth of second-generation Robinia pseudoacacia sprouting forests, providing feasible technical solutions for precise fertilization of young Robinia pseudoacacia sprouting forests.

Using 8-year-old second-generation Robinia pseudoacacia sprouts as experimental materials, a two factor randomized block design was adopted for different fertilization methods and amounts. The growth indicators and nitrogen (N), phosphorus (P), and potassium (K) element contents of the tested Robinia pseudoacacia leaves were continuously monitored.

The results showed that the application of phosphorus fertilizer had a significant promoting effect on the growth of second-generation Robinia pseudoacacia sprouting forests; For different cultivation goals of Robinia pseudoacacia, precise cultivation and management can be achieved by adopting different fertilization amounts and methods. For example, for cultivating energy forests, 75 g/plant P₂O₅ can be applied, while for cultivating high-quality building timber forests, 50 g/plant P₂O₅ can be applied; For the juvenile Robinia pseudoacacia sprouting forest, the application of 75 g/plant P₂O₅ treatment resulted in the maximum values of diameter at breast height, volume, biomass, and nitrogen, phosphorus, and potassium nutrient content in the upper leaves of Robinia pseudoacacia, which were significantly higher than other treatments; Under the treatment of applying 100 g/plant P₂O₅, the tree height reached its maximum value; The content of P and K nutrients in the lower leaves reached its maximum value under the treatment of 50 g/plant P₂O₅ application.

Based on the comprehensive evaluation of the measured indicators, this study concludes that broadcasting 75 g of P₂O₅ per tree is the most effective fertilization treatment for promoting the growth of young Robinia pseudoacacia coppice stands.