Effects Of Two Fertilization Methods On Stock Quality Of Pinus Tabulaeformis Container Seedlings

The aim of this study was to find the effects of exponential fertilizer and fall fertilizer regimes on the quality of seedlings under steady nutrition state. Exponential fertilization regime with seven different fertilizer gradients of10.20,40,60,80,100,120mg· N·plant-1were applied on Pinus tabulaeformis container seedlings during growth period. Fall fertilization of0(control),12,24and48mg· N· plants-1were applied on seedlings processed in exponential fertilization level of10,40,80, and120mg· N·plants-1during the growth period. After a growing season in the greenhouse, the seedlings with exponential fertilization regime were outplanted in the field and seedlings with fall fertilization regime were potted in the greenhouse and outplanted in the field for further study.The results showed that:(1) The steady nutrition model demonstrated that optimum amount of fertilization for Pinus tahulaeformis container seedlings was100mg· N· plant-1. With this fertilization amount, seedling biomass, N content and the number of needle primordial all achieved the maximum of967.3mg·plant-1,19.23mg·plant-1,100· plant-1respectively; Shoot height and root collar diameter (RCD) were8.48cm and0.29cm, which were21.1%and43.0%larger than the national seedling standard, respectively:The rate of seedling qualification was96.9%, it was11.9%higher than national seedling standard. The experiment also discovered that exponential fertilization had no obvious impact on the length of terminal bud, but it significantly increased the coarseness of terminal bud (p<0.001). The coarseness of terminal bud was0.33cm, which was larger than RCD under100mg· N· plant-1.(2) Fall fertilization could improve the seedling nutrient content, cold tolerance and field performance. The best combination of fall fertilization and exponential fertilization was fall fertilization of24mg· N· plants-1and exponential fertilization of40E-24.With this combination, seedling N content was increased by15.9%compared to the control, cold resistance at-20℃had increased by95.2%, field performance was the best. On the contrary, excessive fall fertilization (48mg· N· plants-1) did not promote seedling growth but showed some seedling damages.(3)The effects of fall fertilization were influenced by prior period exponential fertilizer, so fall fertilization must be considered the fertilization regime during seedling growing period.