【作者】 张华林；

【导师】 谢耀坚；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2013， 博士

【摘要】 桉树（Eucalyptus）与杨树、松树一起被称为世界三大速生树种，它是我国南方发展速生丰产林的战略性树种。尾巨桉DH32-29具有轮伐期短、木材产量高、干形通直圆满、自然修枝好、抗逆性强等优点，目前在我国南方大多数省市种植面积不断扩大，苗木需求量也随之不断增多，供不应求。但目前我国桉树组培容器苗在苗期生长阶段一般采用经验式的施肥量和施肥方法，集中或周期等量地供应，使苗木生长前期养分浓度过高，肥料流失而造成浪费，而后期施肥不足造成苗木体内养分稀释等问题，制约了苗木生长潜力的最大发挥，存在苗木质量差、肥料浪费和污染环境等问题。因此，幼苗生长阶段的营养调控技术已成为快速培育桉树优质壮苗的关键技术之一。但是，桉树人工林面积在盲目扩大的同时，也逐渐出现了一些如土壤退化、林地肥力下降等问题，如何通过施肥保持土壤肥力，并达到优良的林分生长也是桉树产业面临的主要问题。本研究以尾巨桉DH32-29组培苗为材料，从不同施肥方法和施肥量方面对尾巨桉幼苗和出圃苗的生长、生理、光合作用及养分需求等方面的影响研究，得出以下结果：（1）设置每株施N0、50、100、150、200mg的5个氮素水平处理，采用砂培法进行尾巨桉幼苗指数施肥试验，探讨不同氮素供应水平对其幼苗生长、质量及养分含量的影响，旨在揭示尾巨桉幼苗的氮素需求特征，确定其适宜施氮量。结果表明：随着施氮量的增加，尾巨桉幼苗的苗高、地径、整株生物量、叶绿素含量（土壤作物分析仪器开发值，SPAD值）与苗木品质指数也随之增大，当施氮量大于100mg株^-1后苗木地径、整株生物量和苗木质量指数基本趋于稳定，而苗高和叶绿素含量SPAD值则显著减小；尾巨桉幼苗的苗木质量指数与苗高、地径和整株生物量均存在显著正相关；运用临界浓度法确定出尾巨桉幼苗N、P、K含量的临界值分别为26.6，3.8，16.5g kg^-1，最适含量范围分别为26.6³8.5，3.8⁵.3，16.5²1.4g kg^-1；综合各指标得出尾巨桉幼苗的最适施氮量为100mg株^-1；（2）以尾巨桉轻基质组培苗为材料，研究4个施氮量和2种施肥方法对苗木生长及生理特性的影响。结果表明，经氮素处理的尾巨桉幼苗的生长指标和叶绿素含量均显著高于对照（P<0.05）；指数施氮60mg株^-1处理的尾巨桉幼苗的地径、叶面积、叶长、叶宽及各叶绿素含量均为各处理中的最大，且显著大于其它处理；经指数施肥方法处理的尾巨桉轻基质幼苗的根部、茎部和叶片的氮磷含量显著高于经平均施肥方法和对照处理的苗木，平均施肥处理的苗木钾含量则较高；通过主成分分析对9个尾巨桉施肥处理进行综合评价，结果得出指数施肥方法优于平均施肥方法，施氮浓度使苗木生长和生理表现优劣由大到小循序为：60mg株^-1>80mg株^-1>40mg株^-1>20mg株^-1，指数施氮60mg株^-1为该试验中的最优处理组合；（3）以尾巨桉出圃苗为试验材料，采用温室盆栽法，研究不同施肥处理对尾巨桉苗期生长、生物量的分配和光合生理特性的影响。结果显示，不同处理下尾巨桉苗木的生长、不同部位的生物量和光合生理指标差异显著（P<0.05）；根据新老叶SPAD值差异的大小，不同施肥方法的苗木稳定性由强到弱为：指数施肥>直线施肥>平均施肥；指数施肥2000mg株^-1处理的尾巨桉苗木的地径、叶干重、茎干重、地上部分干重、整株生物量、净光合速率和蒸腾速率皆为最大，指数施肥处理的苗木拥有较高的光合速率，因此获得了较多的茎叶生物量；综合各指标得出不同施肥方法对尾巨桉苗期影响的优劣为：指数施肥>直线施肥>平均施肥，经指数施肥方法施氮2000mg株^-1的处理组合为该试验中的最佳施肥组合；（4）以尾巨桉出圃苗为试验材料，研究不同施肥处理对尾巨桉苗期根系形态特征的影响。结果表明，不同施氮处理对尾巨桉苗木苗期根系的生物量、总根长、根系平均直径及比根长影响差异显著（P<0.05）；相同施氮浓度下，不同施肥方法处理的尾巨桉苗木的根系生物量、总根长及根系表面积由大到小的顺序为：指数施肥>直线施肥>平均施肥>CK；3种施肥方法经抛物面模型拟合的方程的拟合度好于经线性模型的拟合，抛物面模型对不同施肥方法下尾巨桉苗木生长指标与根系生物量和比根长进行拟合，获得了较高的R2和较低的残差平方和（RSS）更多还原

【Abstract】 Eucalypts, together with poplars and pines are known worldwide as the three groups ofthe fastest growing forest trees. In southern China, Eucalyptus urophylla×E.grandis cloneDH32-29has mang advantages including short rotations, fast growth and high yields, straighttrunk,good natural pruning and relatively wide adaptability for their timber.Consequently thearea of the eucalypt plantation resource has increased rapidly over the past20years or so,inmost China’s southern provinces.This rapid increase in plantation areas in conjunction withrelative short lengths used for these species has resulted in the eucalypt seedling demands oftenexceedling supply.At present empirical fertilization methodologies are commonly used during thepropagation of eucalypt nursery stock（seedlings and vegetative propagules） in mostnurseries;the fertilizers are supplied intensively,periodically and equivalently.However,thiskind of methodology supplies unnecessarily high nutrient quantities during early growthstages,resulting in wastage of fertilizer,sub-optimal quality seedlings/propagules andenvironmental pollution.So the techologies for nutritional regulation in the growing stage ofseedlings and propagules has already become one of the key techniques of propagating highquality eucalypt propagules.In the study reported here,fertilization technologies were studied at the stages of thenursery propagation and early plantation growth for Eucalyptus urophylla×E.grandis cloneDH32-29vegetative propagules. Growth, physiology, photosynthetic indices and nutrientdemands of propagules were studied with different fertilization methods and fertilizer quantitesduring the propagation period.The results are as follows:（1） An exponential fertilization trial was conducted with five dose levels of nitrogen(applying a total of0,50,100,150,200mg propagule^-1) to assess the effects of nitrogen levelson growth, quality and nutrient status of E. urophylla×E. grandis propagules. The objective of this study was to reveal the nitrogen demand and determine the optimal nitrogen amount for E.urophylla×E. grandis propagules.Height, ground diameter, total plant biomass, soil and plantanalyzer development（SPAD） value and quality index of propagules increased with increasingN supply up to100mg propagules^-1. At rates above this level, ground diameter, total plantbiomass and quality index remain unchanged, but height and SPAD value decreased markable.Quality index showed a significant positive correlation with height（R=0.423）, grounddiameter（R=0.645）,and total plant biomass（R=0.834）. The critical level approach was used foridentifying N, P and K deficiencies of propagules, and the critical values of those nutrientswere26.6,3.8and16.5g kg^-1respectively, while their optimal concentrations ranged from26.6to38.5,3.8to5.3,16.5to21.4g kg^-1, respectively. In conclusion,100mg propagules^-1would be the optimal nitrogen amount for E. urophylla×E. grandis propagules.（2） The effects of nitrogen treatments with the exponential fertilization method, meanfertilization method and non-fertilization on the growth and physiological indices of E.urophylla×E. grandis tissue culture propagules in light media were studied during athree-month period. The results indicated that increasing N supply could significantly increasethe growth and chlorophyll contents of propagules （P<0.05）.The treatment with60mg Nplant^-1provided for significantly higher（P<0.05）ground diameter, root volume, leaf area, leaflength, leaf width and chlorophyll contents than all the other8treatments. N, P contents ofroots, stems and leaves of propagules subject to exponential fertilization treatment were higherthan those given the mean fertilization treatment, but K content of different tissues ofpropagules given the mean fertilization treatment were higher. Principal component analyses ofthe different treatments showed that the exponential fertilization methodology was better thanthe average fertilization methodology with N concentrations in descending sequential orderwas60mg propagule^-1,80mg propagule^-1,40mg propagule^-1and20mg propagule^-1.Thetreatment of exponential fertilization methodology with60mg propagule^-1N was the optimaltreatment in this study. （3） Growth, biomass allocation and photosynthetic characteristics of E. urophylla×E.grandis propagules coming out from nursery was studied by pot culture method in agreenhouse, the results showed that growth, biomass of different tissues and photosyntheticindices of propagules under16treatments（3fertilization methods×5N supply levels,andnon-fertilization） were significantly different （P<0.05）. According to the different SPAD valueof new and old leaves, the propagules stability in different fertilization methods from strong toweak is: exponential fertilization> linear fertilization> mean fertilization; Ground diameter,leaf dry weight, stem dry weight, aboveground dry weight, total biomass and netphotosynthetic ratio（Pn） from the exponential fertilization treatment with2000mg N plant^-1were all the maximums in all treatments. It was concluded that propagules given exponentialfertilization method were superior to the propagules under other fertilization methods; thetreatment combination of exponential fertilization method with2000mg N propagule^-1was theoptimal one in this experiment.（4） In this study, the effects of nitrogen treatments with different fertilization method onthe biomass and morphology parameters in roots of E. urophylla×E. grandis propagulescoming out from nursery were studied during a three-month period. The results suggested thatthe biomass and morphology parameters were significantly differennt among the treatments（P<0.05）. In the same nitrogen application concentration, root biomass, root length and rootsurface-area of propagules from different fertilization methods ranked as exponentialfertilization> linear fertilization> mean fertilization> non-fertilization. Degree of fitting of theParaboloid model equation was superior to that of linear model equation. As a multi-variatenonlinear model, the Paraboloid model when applied to the simulations involving both heightand ground diameter, provided a better fit for both root biomass and specific root length withhigher correlation coefficient（R2）and lower residual sum of squares （RSS）更多还原