Effects Of Nursery Fertilization On Seedling Quality And Summer Afforestation Performance Of Pinus Tabuliformis

Pinus tabuliformis is the main afforestation tree species in northern China,which has strong adaptability and resistance.It is widely used in mountain afforestation,and is of great significance to the rational use of difficult sites.Fertilization is an indispensable management method in the process of seedling cultivation,which palys a positive role on improving seedling quality and afforestation preformance.This experiment studied the effects of conventional fertilization and fall fertilization on one-year-old P.tabuliformis container seedlings and bareroot seedlings.Two conventional fertilization levels(0,80 mg N·plant^-1)and four fall fertilization levels(0,12,24,36 mg N·plant^-1)were set up.By measuring the morphological indexs,nutrient absorption and accumulation status before summer afforestation to analyze the effect between conventional fertilization and fall fertilization on the quality of P.tabuliformis container seedlings and bareroot seedlings.Two seedling types seedlings of 8 fertilization treatment combinations cultivated in the nursery were subjected to summer afforestation experiments to explore the best raising seedling and fertilization methods,and provide theoretical basis and technical support for the cultivation of strong seedlings of P.tabuliformis.The main conclusions are as follows:（1）The interaction of conventional fertilization and fall fertilization had significant effects on height,biomass and nutrient accumulation of P.tabuliformis container seedlings.The height,biomass,nitrogen content,phosphorus content and potassium content of container seedlings in treatment conbination of 80-24(conventional fertilization 80 mg N·plants^-1+fall fertilization 24 mg N·plants^-1)were the highest.Overall,the optimal fertilization combination of P.tabuliformis container seedlings was 80-24.（2）The interaction of conventional fertilization and fall fertilization had significant effect on the phosphorus content of P.tabuliformis bareroot seedlings.0-36,80-0,and 80-24treatment combinations had higher phosphorus content.From the main effect,the conventional fertilization of 80 mg N·plant^-1 significantly increased the biomass,root nitrogen content and root potassium content of bareroot seedlings;the fall fertilization of 24 and 36 mg N·plant^-1significantly increased the stem nitrogen content of bareroot seedling.（3）The distribution of nitrogen content in different organs of container seedlings and bareroot seedlings was different.The distribution of nitrogen content in the organs of container seedlings was root>needle>stem,and that of bareroot seedlings was needle>root>stem;the distribution of phosphorus and potassium content in the organs of container seedlings and bareroot seedlings was needle>root>stem.（4）Conventional fertilization significantly increased the soil available phosphorus and available potassium content in P.tabuliformis container seedlings and bareroot seedlings,and fall fertilization significantly increased the soil available phosphorus in container seedlings.（5）The results of summer afforestation test showed that seedling type and conventional fertilization had great influence on the afforestation performance of P.tabuliformis.The afforestation performance of container seedlings was significantly better than that of bareroot seedlings.Conventional fertilization had a positive effect on the afforestation performance of P.tabuliformis.Compared with no fertilization,80 mg N·plant^-1 conventional fertilization could significantly improve the survival rate and the first year root-collar diameter growth of P.tabuliformis.The survival of summer afforestation of container seedlings of P.tabuliformis are closely related to the initial root-collar diameter,biomass and nutrient content.