Study On Phyllostachys Heterocycla And Castanopsis Fargesii Seedlings To Nitrogen Nutrition

Phyllostachys heterocycla and Castanopsis fargesii are important greening and economic tree species in south China,have the important status in the ecological environment.In recent years,because bamboo expand to the surrounding areas heavily,it restricts the p eripheral evergreen broad leaved tree survival and growth.Prophase research showed that bamboo interface's expansion to the evergreen broad-leaved forest soil total N mineralization and nitrification,significantly lower than the broadleaved forest and soil ammonium enhanced,concluded that the soil N supply change is one of the important factors to expand driven bamboo success.Therefore this study chose bamboo and dominant species and broadleaved forest C.fargesii seedlings as experimental objects,and studied influence of exogenous nitrogen supply changes on two species of tree growth when under the controlled environment,the results showed that:(1)P.heterocycla is partial or ammonium tree species.When at low concentrations,P.heterocycla seedling's height,leaf number,leaf area,chlorophyll(SPAD value)and the index and biomass of the root system configuration,there was no significant difference between the different forms of nitrogen.However,with increasing of the concentration of the nitrogen,P.heterocycla seedling growth gradually increase and increase significantly in the differences between the different forms of nitrogen.Among all of these,P.heterocycla grew best under the condition of high concentration of ammonium nitrogen.C.fargesii is facultative partial or ammonium tree species.With the increase of nitrogen concentration C.fargesii seedling growth showed a trend of slow increase.The index of C.fargesii seedling's height,leaf number,leaf area,chlorophyll(SPA D value)and biomass are in relatively high concentrations of ammonium nitrogen i n mixed or ammonium nitrate nitrogen source is better.In terms of different cultivation ways,when in individual cultivation and mixed cultivation conditions,P.heterocycla and C.fargesii have the similar fea tures reacting to different nitrogen and nitrogen form,had no significant effect on seedling each growth index((P >0.05).In addition,the research results showed that the P.heterocycla and C.fargesii partial or ammonium,but under the corresponding condition,P.heterocycla's growth rate is far greater than C.fargesii.(2)High P.heterocycla seedling growth dynamic research results showed that with the extension of processing time(56 d later),different concentrations of ammonium(2,8,16,24,32,40 mmol/L)have effects on P.heterocycla growing,and the differences of effects is gradually obvious.,the high concentration of ammonium(>16 mmol/L)has obvious promoting effect on the seedling height growth,and high concentration ofammonium is more advantageous to blade number,chlorophyll content,root biomass and the increasing of the dry weight of each part,but with the increasing of concentration of ammonium nitrogen,the index growth of the root system configuration was restricted.P.heterocycla also had a certain degree of growth in the process of different c oncentration of NO3-,but different concentration of NO3-on the influence of the P.h eterocycla shoot height growth difference did not reach significant level in the whol e process.In addition,P.heterocycla seedling leaf number,leaf area and chlorophyll(SPAD value)and the root system configuration indexes basically decreased as the concentration of ammonium increasing.However,nitrate concentrations of different t reatment had no significant effect on P.heterocycla biomass.Showed that nitrate nitr ogen without promoting effect to bamboo seedling height growth and high concentr ation of nitrate on bamboo growth also has a certain inhibitory effect.C.fargesii seedlings height also slowly increased with the extension of the processing time,with high concentration of ammonium(>16 mmol/L)treatment of seedlings is higher,and higher ammonium concentration is more advantageous to leaf number,each part of the chlorophyll content,leaf biomass aboveground growth,and the indexes of root growth is show some suppression.However,higher nitrate concentration(>16 mmol/L)to deal with all the seedlings died after 8 weeks,so C.fargesii able to tolerate the highest nitrate concentration of 8 mmol/L.(3)Measured NH4+ and NO3-ion flow of C.fargesii and P.heterocycla root by noninvasive micro measurement technology,the results showed that NO3-are characterized by outside when the P.heterocycla and C.fargesii roots are in range of 30 mm,as for the NH4+ they have both absorbing area and outside area,but the performance of 2 species are different.Among them,only after 10 mm off the root hair zone,the P.heterocycla is on the absorption of NH4+ concentration and within 10 to 30 mm NH4+ internal flow showed increasing trend.On the absorption of NH4+ C.fargesii focused before 1.8 mm from the apex of the root tip meristematic zones,and within the scope of 0.3 to 1.8 mm NH4+ in rhe gradually reduced.Above all,P.heterocycla and C.fargesii growth showed a certain degree of prejudic ammonium and ammonium resistance,but the P.heterocycla growth rate and the ability to reproduce is far greater than C.fargesii.So that P.heterocycla characteristics of soil nitrogen expansion to the evergreen broadleaved forest of change may be one of Phyllostachys heterocycla successful expansion strategy.