Sprouting of Pinus yunnanensis Seedlings in Response to N/P Application

  Objective  Effect of N and P fertilization on the sprouting of Pinus yunnanensis seedlings was studied.

  Methods   One-year-old P. yunnanensis seedlings after coppicing were used in a two-factors-three-levels 3×3 regression experimentation to optimize the fertilization.

  Results  The number of sprouts emerged from the seedlings after coppicing followed the logistic growth pattern independent of N/P application. However, the fertilization promoted the sprouting, altered the time and peak of second sprouting, and increased the sprout count more than when N or P was applied alone. The tillers responded to the N/P application in a binary quadratic regression function to reach the highest count with the input of 0.29 g of N and 1.02 g of P per plant. The combined N/P application enhanced the growth of both potential and effective sprouts on the seedlings, especially, on the effective sprouts, the best result was to use N at 0.4 g and P at 0.8 g·plant⁻¹. On the other hand, application of N or P alone exerted a greater effect than the combined one on the potential sprouts.

  Conclusion  Combined N/P fertilization was more conducive to the increase of the number of sprouts on the seedlings than N or P fertilizer was applied alone. Although high P fertilization benefitted the growth of potential sprouts, when combined with N the application at a medium concentration encouraged the growth of effective sprouts.