Analysis of the fertilization response characteristics of improved variety for high yield and high quality Populus tomentosa

Objective The most suitable cultivation method for forest trees has an important impact on the improvement of forest productivity. Based on hybrid origin, Populus tomentosa individuals are significantly different in fertilization treatment response. In order to ensure the rapid growth and high-yield of plantation forest and reduce the pressure on environmental protection, the most suitable fertilization proportion should be formulated for elite of P. tomentosa.

Method In this study, three improved varieties of P. tomentosa were used for different fertilization treatments. The most suitable fertilization proportion affecting their important growth traits were profiled. And the candidate gene expression patterns related to fertilizer utilization were systematically analyzed.

Result The experimental results showed that the optimum fertilization proportion of ‘Yiyang 1’ is N (3 g) + P₂O₅ (2.25 g) + K₂O (1 g); the optimum fertilization proportion of ‘Yiyang 2’ was N (3 g) + P₂O₅ (2.25 g) + K₂O (0.5 g); ‘Yiyang 3’ was the best fertilization proportion of N (7 g) + P₂O₅ (2.25 g) + K₂O (0.5 g). Among them, nitrogen is the most significant nutrient element affecting the seedling height, ground diameter and biomass of the improved species of P. tomentosa. To analyze the genetic basis of nitrogen utilization in poplar, the expression patterns of 16 candidate genes related to assimilation and metabolism of nitrogen transport in leaves and roots under different nitrogen fertilization levels were analyzed. The candidate genes’ expression pattern analysis indicated that the nitrogen-related candidate genes of P. tomentosa were clustered into different modules in leaves and roots, and the expression patterns of clones were significant different.

Conclusion This study preliminarily clarified that three improved forest varieties of P. tomentosa has significantly different fertilization response characteristics. Systematic analysis of their transcriptional regulation specificity will facilitate the analysis of molecular mechanism of their nitrogen fertilizer response characteristics and help for further molecular design of genetic improvement of nitrogen absorption and utilization efficiency in P. tomentosa.