Exponential nutrient loading shortens the cultural period of Larix olgensis seedlings

Abstract

Traditional nursery culture of Changbai larch (Larix olgensis Henry) in Northeast China requires up to a 2-year nursery production period. The high cost of seedling culture for this duration has been identified as a constraint. As a potential means to help to shorten the cultural period, we evaluated growth, biomass accumulation, and nitrogen (N) uptake dynamics of 1-year-old seedlings subjected to nutrient-loading treatments at intensive rates of 500 mg N seedling⁻¹ supplied exponentially (E500) and 135 mg N seedling⁻¹ supplied exponentially (E135) or conventionally (constant). Also included were an unfertilized control and the standard fertilizer regime for 2-year-old seedling production (77 mg N seedling⁻¹ supplied conventionally over 2 years). At the end of nursery culture, though seedlings in the constant treatment had more biomass and N accumulation at the whole-seedling level, much of this was allocated to needles. While seedlings in the E500 treatment exhibited signs of toxicity, those in the E135 treatment had equivalent end-of-nursery N concentration in woody tissues to those produced over 2 years; root collar increment and survival 69 d after outplanting were also similar. Our results suggest that exponential nutrient loading at an optimal rate could increase available nutrient reserves in woody tissues of deciduous tree seedlings, therefore having the potential to improve seedling performance after outplanting.

Keywords:

• Larix olgensis
• nutrient loading
• nitrogen
• nutrient reserves
• outplanting performance

Acknowledgments

Funding for this study was provided by Special Funds for Scientific Research Public Welfare Project of Forestry (201004021), “11th Five-Year Plan” of National Key Technology, Research and Development Program (2006BAD24B01) and National Forestry Technology Achievements Development Project of 2011 (2011-44) from State Forestry Administration, P.R. China, and Sub-project from 3rd Phase of “Project 211” Plan for Culture of Innovative Graduates in Beijing Forestry University (000-0811000). We thank Changji Jiang and Fusen Liu from Jiangmifeng nursery, Forestry Division of Jilin, China, for supplying the materials and facilities for the experiment; Chunsheng Bai and Jinwen Liu for helping with harvests and seedling quality test; Yuwei Liu, Jianfeng Dong, Tianyu Bai, and Yuan Chai for their help in plant sample determination. Finally, we appreciate constructive comments and insightful suggestions of two anonymous reviewers and the editor.