Effects of exponential fertilization on the biomass and nutrient accumulation and allocation of Pinus armandii container seedlings

The effects of exponential fertilization on the growth and nutrient accumulation of Pinus armandii container seedlings were studied to provide a theoretical basis for the cultivation of strong seedlings.

The Pinus armandii container seedlings were grown under conventional and exponential fertilization regimes, and each container received 100, 200, 300, and 400 mg N, respectively, and the control plants were treated without fertilization. The responses of the growth and nutrient accumulation of the container seedlings to different fertilization were investigated.

The height, root collar diameter and biomass increased first and then decreased with the increase in fertilizer amount under both conventional and exponential fertilization regimes. The maxima of height, root collar diameter and whole-container biomass occurred under the E300 treatment (exponentially fertilized with 300 mg N per seedling), which were 1.39, 1.15 and 1.54 times of the control, respectively. The N concentrations in the roots, stems, and needles of the seedlings increased with the increased fertilizer amount. The N concentration was higher under the exponential fertilization condition than that under the conventional fertilization condition. The P concentration tended to be stable. With the increase in fertilizer amount, the K concentration of the seedlings was increased under the conventional fertilization treatment, which increased first and then decreased under the exponential fertilization condition. Fertilization significantly promoted the accumulation of N, P, and K in the container seedlings. The N accumulation in the roots, stems and needles was the highest under the E300 treatment, which were 2.54, 3.37, and 2.76 times of the control, respectively. Under both fertilization regimes, the allocation proportions of resources to root decreased with the increase in fertilizer amount, and the highest proportion was found under the exponential fertilization treatment. Nutrient harvest efficiency decreased with the increase in fertilizer amount, and N harvest efficiency was higher under the exponential fertilization treatment.

Exponential fertilization treatments significantly enhance the biomass and nutrient accumulation in Pinus armandii container seedlings and allocate more biomass and nutrients into roots. It is suggested to exponentially fertilize Pinus armandii container seedlings with 300 mg N per seedling.