Qiu LlU，Minggao CHEN，Jiyou WU*，Chunying DONG，Xiaofei HUANG，Shoucheng HUANG，Aimin TANG，Mingjun HUANG

1.Hunan Academy of Forestry，Changsha 410004，China

2.Jindong Woodland in Yongzhou City，Hunan Province，Yongzhou 426191，China

Nutritional Properties and Fertilizer Demand Rules of Young Phoebe bournei Forest

Qiu LlU1，Minggao CHEN1，Jiyou WU1*，Chunying DONG1，Xiaofei HUANG1，Shoucheng HUANG2，Aimin TANG2，Mingjun HUANG1

1.Hunan Academy of Forestry，Changsha 410004，China

2.Jindong Woodland in Yongzhou City，Hunan Province，Yongzhou 426191，China

This study aimed to investigate the absorption characteristics of nitrogen，phosphorus，potassium，calcium and magnesium and rules in fertilizer demand by young Phoebe bournei forest.The results showed that the nitrogen，phosphorus，potassium and magnesium contents in young Phoebe bournei leaves were increased with the proceeding of growth，but the calcium content was increased.During the growth period，the nitrogen，phosphorus，potassium and magnesium contents were relatively high in June，July and August.This study will help to understand the nutritional characteristics and fertilizer demand rules of young Phoebe bournei forest，thereby providing scientific theoretical guidance for application of fertilizer in Phoebe bournei.

Phoebe bournei；Fertilization；Nutritional characteristics；Fertilizer demand rule

P hoebe bournei（Lauraceae: Phoebe）is an evergreen big tree.It is a valuable timber species unique to China，and is China’s second-class protected plant species［1-2］.So far，the exploitation activity of Phoebe bournei，one precious species，is very rare.Most studies focus on population structure，spatial layout，seed dormancy and germination， introduction and cultivation，breeding and photosynthetic and physiological characteristics of Phoebe bournei［3-14］.Phoebe bournei is widely distributed in the subtropical evergreen broadleaf forest.It favors warm and humid conditions.In China，Phoebe bournei is one of the most widely distributed Phoebe species in China.

In this study，the absorption and utilization characteristics of nitrogen，phosphorus，potassium，calcium and magnesium and fertilizer demand rules of Phoebe bournei were studied. In addition，the effect of fertilization on growth of Phoebe bournei was investigated.This study will provide certain reference for scientific fertilization in Phoebe bournei.

Materials and Methods

Test material

The test material was 3-year-old Phoebe bournei forest.

Overview on test site

The test site was located in the Jindong Woodland in Yongzhou City，Hunan Province.In the test site，the landscape is composed of sandstone，shale and carbonaceous slate.The test site has deep and fertile soil with high organic matter content.The test site has a subtropical southeast monsoon climate with annualaverage temperature of 17.5℃，absolute maximum temperature of 39.3℃，absolute minimum temperature of-13.6℃，average temperature in January of 6.5℃，average temperature in July of 28.9℃，average annual sunshine time of 159.9 h，average annual rainfall of 1 600-1 900 mm and average relative humidity of 81%.The nursery has analtitude of 200 m and soil pH of 5.0-6.5，which are all suitable for the growth of Phoebe bournei.

Test design

Total five fertilization treatments were arranged （Table 1）.The randomized block design was adopted. There were five plots for each treatment，and there were five plants （in a row）in each plot.There was one isolation strip between two adjacent treatments.

Monthly changes in contents of nutritional elements in Phoebe bournei

During May to December，2014，the leaves of young Phoebe bournei forest were sampled in the last third of every month.In the collected leaves，the contents of nitrogen，phosphorus，potassium，calcium and magnesium were determined.

Results and Analysis

Monthly changes in nitrogen content in young Phoebe bournei forest under different fertilization treatment

As shown in Table 2，the nitrogen contentin Phoebe bourneileaves showed certain variation rule in different treatment.In all the treatments，the nitrogen content reached the peak in August.And then，with the increase of leaf age，the nitrogen content was reduced.Among the months，the nitrogen contentwas relatively high in June，July，August，September and October.Among the treatments，the nitrogen content was higher in treatment 3 during May to October.

Monthly changes in phosphorus content in young Phoebe bournei forest under different fertilization treatment

Table 3 showed that the change in phosphoruscontentin Phoebe bournei leaves showed certain rule in different treatment.The phosphorus content reached the peak in August and September.Among the months，the phosphorus content was relatively high in June，July，August，September，October and November.Among the treatments，the phosphorus content in Phoebe bournei leaves was higher in treatment 3 during May to November.

Table 1 Fertilization treatments for young Phoebe bournei forest

Table 2 Monthly changes in nitrogen content in young Phoebe bournei forest under different fertilization treatment mg/kg

Table 3 Monthly changes in phosphorus content in young Phoebe bournei forest under different fertilization treatment mg/kg

Table 4 Monthly changes in potassium content in young Phoebe bournei forest under different fertilization treatment mg/kg

Monthly changes in potassium content in young Phoebe bournei forest under different fertilization treatment

As shown in Table 4，the change in potassium contentin Phoebe bournei leaves showed certain rule in different treatment.After the peak，the potassium content was decreased with the increase of leaf age.Among the months，the potassium content was relatively high in June，July，August and September.

Monthly changes in calcium content in young Phoebe bournei forest under different fertilization treatment

As shown in Table 5，there were great significant differences in calcium content in Phoebe bourneileaves among different treatments.From a comprehensive point of view，in different treatment，the calcium content in Phoebe bournei leaves was all in-creased with the increase of leaf age. Monthlychangesinmagnesium content in young Phoebe bournei forest under different fertilization treatment

Table 6 showed that there were great significant differences in magnesium content in Phoebe bournei leaves among different treatments.In overall，the magnesium content in Phoebe bournei leaves was all increased with the increase of leaf age in different treatment.In June，July and August，the magnesium content was relatively high in all the treatments.

Table 5 Monthly changes in calcium content in young Phoebe bournei forest under different fertilization treatment mg/kg

Table 6 Monthly changes in magnesium content in young Phoebe bournei forest under different fertilization treatment mg/kg

Conclusions and Discussion

With the increase of leaf age，the contents of nitrogen，phosphorus，potassium and magnesium in Phoebe bournei leaves were all decreased，but the content of calcium was increased. Generally，content of movable element in plant tissue and organ will gradually decline with the growth of plant，but content of fixed element will be increased with the aging of tissue and organ of plant.Nitrogen，phosphorus，potassium and magnesium are all movable elements，so their contents were decreased with the growth of Phoebe bournei.However，calcium is difficult to be re-transformed or re-utilized，so the content of calcium in Phoebe bournei leaves was increased.

The contents of nitrogen，phosphorus，potassium and magnesium in Phoebe bournei leaves were higher in June，July and August，which was consistent with the higher growth rate of Phoebe bournei during that time.It suggests that the fertilization in Phoebe bournei should be conducted in June.

During the fertilization in Phoebe bournei，more nitrogen element should be applied，and magnesium should be added appropriately.Taking the absorption capacity of young Phoebe bournei forest into account，fertilizer should not be applied too much so as to avoid loss and waste.The specific recipe forapplication ofnitrogen，phosphorus，potassium and magnesium still needs further study.

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Responsible editor：Tingting XU

Responsible proofreader：Xiaoyan WU

閩楠幼林營養(yǎng)特性及需肥規(guī)律研究

劉球1，陳明皋1，吳際友1*，董春英1，黃小飛1，黃守成2，唐愛民2，黃明軍1（1.湖南省林業(yè)科學院，湖南長沙410004；2.湖南省永州市金洞林場，湖南永州426191）

為探討閩楠幼林的氮、磷、鉀、鈣、鎂等營養(yǎng)特性及需肥規(guī)律，開展了閩楠幼林施肥研究，結(jié)果表明：N、P、K、Mg含量隨閩楠生長而下降，而Ca的含量隨葉齡增長而上升；6月、7月和8月N、P、K、Mg含量相對較高。該文旨在了解閩楠幼林的營養(yǎng)特性以及所需肥料的規(guī)律，為閩楠科學施肥提供理論指導。

閩楠；施肥；營養(yǎng)特性；需肥規(guī)律

湖南省林業(yè)科技計劃項目“閩楠、紅椿家具材良種選育與應用”（XLK201406）；“閩楠測土配方定量施肥技術(shù)研究”。

劉球（1985-），女，湖南安化人，在讀博士，助理研究員，從事森林培育方面的研究。*通訊作者，博士，研究員，從事森林培育方面的研究，E-mail：hnforestry@sina.com。

2015-09-19

Supported by Forestry Science and Technology Plan Projects of Hunan Province（XLK201406）.

*Corresponding author.E-mail:hnforestry@sina.com

Received:September 19，2015 Accepted:November 5，2015

修回日期 2015-11-05