| 摘要: |
| 【目的】对不同氮磷钾施肥条件下闽楠幼苗根系形态和苗木质量进行研究，为闽楠壮苗培育提供科学依据。【方法】以1年生闽楠盆栽实生苗为材料，采用“3414”施肥试验方法，设氮、磷、钾3个因素，每个因素设不施肥和低、中、高施肥4个水平，其中中水平为常用施肥量（当地N、P2O5和K2O的常用施肥量分别为0.532，0.133和 0.356 g/株），低水平为中水平的0.5倍，高水平为中水平的1.5倍，共计14个处理。采用田间随机区组试验和常规田间管理，分析不同施肥处理对闽楠幼苗根系形态指标（总根表面积、总根体积、根平均直径、根尖数、根系总根长、小细根长、粗细根长、粗根长、比表面积、组织密度和比根长）的影响；通过相关分析，揭示各根系形态指标与植株形态（苗高、地径和苗木质量指数）、植株营养元素（N、P、K和C）积累量、叶片生理生化指标（叶绿素总量、净光合速率(Pn)、水分利用效率(W)、淀粉含量、酸性磷酸酶和硝酸还原酶活性）的相互关系；通过极差分析，筛选最佳氮磷钾施肥方式；通过逐步回归分析和通径分析，构建苗木质量的施肥调控途径，筛选影响苗木质量的关键指标。【结果】施肥可以显著提高闽楠幼苗的总根表面积、总根体积、根尖数、小细根长和根总长度，其中以中水平NPK配施（N 0.532 g/株,P2O5 0.133 g/株,K2O 0.356 g/株）时的根系养分吸收量最大，低水平P肥与中低水平NK肥配施（N 0.532 g/株,P2O5 0.067 g/株,K2O 0.178 g/株）时的养分输运能力最强，低水平N肥与中水平的PK肥配施（N 0.266 g/株,P2O5 0.133 g/株,K2O 0.356 g/株）时的养分利用效率最高。粗细根长随P肥施用量增加相应增加，比表面积随P肥施用量增加先降后升，组织密度随N和K肥施用量增加先降后升，而施磷肥对其无显著作用；其余指标大部分均随N、P和K肥施用量增加先增后降。在施肥方式中，氮磷钾3因素配施时闽楠根系生长最好；在双因素配施中，粗根生长以磷钾肥配施最好，其余指标均以氮磷肥配施最好；在单因素施肥中，以氮肥对闽楠根系生长最好，磷肥最差。总根表面积、比根长、粗根长、根尖数、比表面积、硝酸还原酶活性和植株N积累量是培育闽楠壮苗的主导因素，其中以提高植株N积累量最为关键。【结论】氮磷钾配施条件下，闽楠主要通过提高根尖数、延长小细根和粗细根长度，提高根系总长度和总表面积，调节根平均直径，改变比表面积和比根长，保持总根表面积和比表面积在一定水平上的平衡，促进营养元素特别是N元素的吸收，调控地上部分和地下部分各器官的平衡生长，提高苗木质量指数。 |
| 关键词: 闽楠 施肥方案 氮磷钾肥 根系形态 苗木质量 植株元素积累量 |
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| 基金项目:福建省林木种苗科技攻关项目“闽楠气培扦插及组培新技术研究”（KLh16H04A）；福建省林业科技项目“基于水土保持的锥栗林生态栽培技术研究”（K1520033A）；福建省水土保持试验站项目“长汀县红壤侵蚀区人工群落演变特征及改造提升技术研究”（KH180280A） |
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| Effects of fertilization on root morphology and seedling quality of Phoebe bournei |
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WANG Yan,FENG Jinling,WU Xiaohui,et al
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| Abstract: |
| 【Objective】This study investigated root morphology and seedling quality of Phoebe bournei seedlings under different nitrogen (N),phosphorus (P) and potassium (K) fertilization treatments to provide basis for the cultivation of strong seedlings.【Method】In this experiment,1-year-old potted seedlings of P. bournei were selected in the “3414” fertilization experiments,which included a total of 14 experimental treatments with three factors of N,P and K and four levels for each factor (zero,low,medium and high fertilization level).The medium level was the usual amount of fertilization,with N,P2O5 and K2O rates of 0.532,0.133 and 0.356 g/plant,respectively.The low level was 0.5 times of the medium level and the high level was 1.5 times.The random block field experiment and conventional field managements were adopted.The effects of different fertilization treatments on root morphological indexes (total root surface area,root volume,mean root diameter,root-tip number,total length of root,small fine root length,thick fine root length,coarse root length,specific root surface area,root tissue density and specific root length) of P. bournei seedlings were analyzed.The correlation analysis method was used to reveal the relationship between each root morphological index and plant morphology (seedling quality index,height and ground diameter),plant element (N,P,K and C) accumulation,and leaf physiology and biochemistry (chlorophyll content,Pn,W,starch content,acid phosphatase activity and nitrate reductase activity).The range analysis method was used to screen the best NPK fertilization mode.The stepwise regression analysis and path analysis methods were applied to determine key indexes and to construct a fertilization mode to regulating seedling quality.【Result】Fertilization significantly increased total root surface area,root volume,root tip number,total length of root and small fine root length of P. bournei seedlings,with the largest nutrient absorption under medium level of N,P and K application (N:0.532 g/plant,P2O5：0.133 g/plant,and K2O：0.356 g/plant),the maximum nutrient transport capacity under low level of P fertilizer combined with low and medium levels of N and K fertilizers (N:0.532 g/plant,P2O5:0.067 g/plant,and K2O:0.178 g/plant),and the highest nutrient use efficiency under low level of N fertilizer combined with medium level of P and K fertilizers (N:0.266 g/plant,P2O5:0.133 g/plant,K2O:0.356 g/plant) for root system.The thick fine root length increased,and specific root surface area decreased firstly and then increased with the increase of P fertilizer application.The root tissue density had no significant changes by P fertilizer,which decreased firstly and then increased with the increase of N and K fertilizers.Other root indexes increased first and then decreased with the increase of N,P and K fertilizers.NPK fertilization was the best for root growth of P. bournei seedlings.With the application of two fertilizers,PK fertilization was the best for coarse root growth,while NP fertilization was the best for other indexes.N fertilizer was the best for root growth,and P fertilizer was the worst for P. bournei seedlings under single fertilization.Total root surface area,specific root length,coarse root length,root tip number,specific root surface area,nitrate reductase activity and plant N accumulation were the leading factors for cultivating strong seedlings of P. bournei,in which plant N accumulation was dominating.【Conclusion 】After NPK fertilization,P. bournei seedling increased number of root tip,extended small fine root and thick fine root length,improved total root length and surface area,adjusted root average diameter,changed specific surface area and root length for keeping the balance of total root surface area and specific surface area,promoted absorption of elements,and regulated balanced growth of organs in aboveground and underground parts to improve seedlings quality. |
| Key words: Phoebe bournei fertilizer scheme N,P and K fertilization root morphology seedling quality plant element accumulation |
