Effects Of Soil Nutrient Conditions On The Growth And Flowering Of Pinus Koraiensis Saplings

Pinus koraiensis Sapling is a valuable timber tree in northern China,which has high economic value.In recent years,with the rising price of pine seeds and the increasing demand for pine seeds,the demand for forest cultivation of P.koraiensis cones has been increasing.It is particularly important to adjust the cultivation techniques to promote the early growth of P.koraiensis,especially to promote its early flowering and fruiting.This study studied the growth and flowering performance of P.koraiensis Sapling transplanted from the same provenance and the same batch of seedlings under different cultivation conditions,and analyzed the effects of different cultivation conditions（mainly soil nutrient conditions）on the growth and flowering of P.koraiensis Sapling,so as to provide reference for determining the reasonable cultivation measures of P.koraiensis Sapling at different stages.The main results are as follows:（1）There are differences in the growth of P.koraiensis Sapling under different soil conditions.The soil nutrients of nursery site are good,and the nutrient contents of total nitrogen,total phosphorus and total potassium were high,which was especially beneficial to the development of various organs of seedling roots,stems and leaves of Pinus koraiensis.The DBH and GROUND diameter of P.koraiensis Sapling in nursery site are 207.1%and 64.2%higher than those of container and built forest.77.9%,63.9%;Seedling nursery P.koraiensis Sapling root thick,root surface area,nutrient absorption,promote the growth and development of aboveground part.The biomass of all parts of P.koraiensis Sapling in nursery site was significantly higher than that in container and built forest.（2）There are differences in the morphology and photosynthetic capacity of P.koraiensis Sapling seedlings under different soil conditions.Seedling nursery culture condition could make P.koraiensis Sapling to grow broad needles,during the growth season,nursery culture condition could significantly improve the needle nitrogen content,chlorophyll a content also increased.Under the same light environment,P.koraiensis Sapling nursery had high light utilization efficiency and strong photosynthetic capacity.While in the container and the constructed forest,P.koraiensis Sapling tended to grow short needles with small surface area.The needles are thin,which is beneficial to light resources and low efficiency,and the photosynthetic capacity is weaker than nursery land.（3）There are differences in flowering ability of P.koraiensis Sapling under different soil conditions.During the flowering period of P.koraiensis,the nursery site and the afforestation are male flowers,and the P.koraiensis Sapling trees with vigorous growth and thick stems are easier to bloom.These hormones,ABA and GA₃,GA₄and GA₇,increased significantly at flowering stage,and GA₄content of nursery site and forest increased by 70.6%and 55.6%,respectively,which had certain induction effect on male flower formation of P.koraiensis.The flowering ability of P.koraiensis is related to its DBH,ground diameter and soil nutrients.（4）There is a strong correlation between soil nutrient conditions and the growth and development of P.koraiensis in different cultivation environments.Soil nutrients total nitrogen,total potassium,total phosphorus and alkali-hydrolyzable nitrogen were significantly positively correlated with DBH and ground diameter of P.koraiensis Sapling.There is a significant positive correlation with the nitrogen nutrient content in P.koraiensis Sapling.ABA,GA₃,GA₄and GA₇were positively correlated.In summary,P.koraiensis Sapling seedlings are sensitive to soil nutrient content in the early growth stage,and the good water and fertilizer conditions of nursery site could significantly improve the growth of P.koraiensis Sapling,enhance the photosynthesis of P.koraiensis Sapling,and contribute to the accumulation of a large number of photosynthetic substances,promoting the growth of P.koraiensis Sapling.Good soil nutrient condition in nursery can increase ABA and GA₃,GA₄and GA₇contents in P.koraiensis Sapling,which is conducive to the flowering of P.koraiensis.There is a certain correlation between the growth and flowering of P.koraiensis Sapling and soil nutrients.Soil nutrient conditions play a decisive role in the growth and flowering of P.koraiensis Sapling,so it is necessary to take measures to ensure the nutrient supply of saplings.