Growth and Nitrogen Retranslocation of Nutrient-Loaded Clonal Betulaalnoides Transplanted with or without Fertilization

Lin Chen,Bernard Dell,Yue Ma,Ji Zeng,Hua Li,Zhaoying Li

doi:10.3390/f12111603

Abstract

Nutrient loading can improve the growth and nutrient content of nursery-grown Betula alnoides Buch.-Ham. ex D. Don, but it is unknown whether nutrient loading enhances growth and nutrient uptake after transplanting. Plants were grown with three nutrient loading treatments (N100, N200, and N400; 100, 200, and 400 mg N per plant as 15N-urea) in nursery containers and then transplanted into plastic pots, with or without controlled-release fertilizer (F0 and F10, 0 and 10 g per plant). The N400 plants had a smaller size but higher nitrogen concentration relative to the N100 and N200 plants before transplanting. However, 180 days after transplanting, the N200 and N400 plants had superior root collar diameter, root length, and root area compared to the N100 plants, due to an increase in 15N retranslocation to new stems and new leaves. Moreover, transplant fertilization (F10) enhanced the height, root collar diameter, root length, and plant dry mass, but not nitrogen concentration or retranslocation, relative to F0. We recommend that medium- and high-dose nutrient loading is implemented in B. alnoides nurseries to optimize growth after transplanting. Additional fertilizer at transplanting may be advantageous in supporting growth, owing to the rapid depletion of nutrient reserves after planting out in the field.

Highlights

Until the root system of transplanted tree seedlings is fully developed and essential nutrients can be readily obtained from the soil, the growth of seedlings may depend on the retranslocation of stored nutrients [1,2]
Our previous research established that B. alnoides can be nutrient loaded in the nursery using exponential regimes, and the optimal nitrogen application amount for this species was in the range 100–400 mg N per plant [14]
We further found that a medium- to high-dose nutrient loading (200 and 400 mg N per plant) resulted in superior root collar diameter, root length, root area, and 15 N retranslocated to new stem and leaf organs at 180 days after transplanting compared to low-dose nutrient loading (100 mg N per plant)

Summary

Introduction

Until the root system of transplanted tree seedlings is fully developed and essential nutrients can be readily obtained from the soil, the growth of seedlings may depend on the retranslocation of stored nutrients [1,2]. Michx.) and white spruce (Picea glauca (Moench) Voss) seedlings in the nursery, only aspen seedlings showed increased new leaf, new stem, and old stem biomass and nitrogen retranslocation rates after transplantation [1]. These results indicate that the impact of nutrient loading on field growth performance may be species specific

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Conclusion