Effect of Nitrogen and Phosphorus Addition on Growth Rhythm of Pinus yunnanensis Seedlings

PurposeTo explore the effects of different fertilizer amount of nitrogen (N) and phosphorus (P) on the growth of Pinus yunnanensis seedlings, and to select the most suitable N and P fertilization ratio for the growth of P. yunnanensis seedlings.

MethodsThe two-year-old seedlings of P. yunnanensis were taken as the research object, and the root fertilization with different N and P ratios was continuously tracked for 1.5 years. The seedling height and ground diameter growth of P. yunnanensis seedlings in the same year and the following year after fertilization were measured, and their growth rhythm and allometry were analyzed.

ResultsThe seedling height and the ground diameter showed an S-shaped “slow-fast-slow” growth curve. Fertilization changed the growth rhythm of P. yunnanensis seedlings, and extended the time of the rapid growth period. It also changed the growth track of seedlings, reduced the slow growth of P. yunnanensis seedlings, and promoted the height growth of seedlings. The medium level of N and P (N 0.4 g/plant, P 0.8 g/plant) could effectively promote the height growth of seedlings, and the high level of P (P 1.6 g/plant) could effectively promote ground diameter growth of seedlings.

ConclusionThis study reveals the growth rhythm of P. yunnanensis seedlings in the year of fertilization and the following year in response to different fertilizer amount. And it provides theoretical research for N and P fertilization in the cultivation of high-quality P. yunnanensis seedlings.