硅提高红木树种抗寒性的作用机理研究

Precious wood resources is the important strategic resources. Value of Hongmu tree species is the highest in precious timber tree species. More than 98% Hongmu timber of China depends on import, now China pays attention to Hongmu artificial forest plantation，but low temperature stress is the key ecological limiting factor in the introduction and cultivation of Hongmu tree species. In preliminary study, the project group found that improving soil silicon nutrition significantly increased cold resistance of Hongmu tree species, but the mechanism of action is not clear yet。In this research project, we will choose the genus Pterocarpus which is the valuest in Hongmu tree species as study object，use red sandalwood which is of the highest economic value but very sensitive to low temperature stress in Hongmu tree species as test material. Our research technical route of implementing this project is basing on growth responses, taking Si body morphology, location, composition and functions as the main line, putting Si fertilizer to practical application as an important target, and combinating with the simulation of cold shock and long-term ecological location monitoring. Main aspects of this project are as following: explorting Si absorption and distribution characteristics of red sandalwood, the relationship between cold resistance increase and ultrastructure, composition, physico-chemical properties of intracellular Si body; explorting the effects of exogenous Si on membrane lipid composition, phospholipase D activity, major degradation product levels of membrane lipid and the relationship with improving cold resistanc; clarifying the effects of Si and its combined application with N, P, K fertilizers on rhizosphere nutrition, growth characteristics and cold resistance of Hongmu young stand during winter, especially the technical parameters of Si fertilizer application in Hongmu Young stand management of cold resistance and antifreeze. Achievements will be of important significance to introduction and cultivation of Hongmu tree species.

珍贵木材资源是重要战略资源。红木树种在珍贵用材树种中价值最高。我国98%以上红木依赖进口，现重视红木人工林培育，但低温胁迫是限制引种栽培的关键生态因子。项目组前期研究发现，改善土壤硅/Si营养能够大幅提高红木树种抗寒性，但作用机理不清楚。项目以红木树种中最重要的紫檀属树种为对象，选择其中价值最大、对低温胁迫敏感的檀香紫檀为试材，以生长响应为基础，以体内Si体形态、定位、成分与功能为主线，以Si的实际应用为目标，把模拟寒流侵袭同长期定位监测相结合，探究Si吸收分配特性，胞内Si体超微结构、组成成分、理化特性与提高抗寒性的关系，探究Si对膜脂组成、磷脂酶D活性、膜脂重要降解产物水平的影响及其与抗寒性提高的关系，阐明Si及其与N、P、K肥配合施用对根瘤发育和生理功能、根际营养状况、林分生长特性和越冬期间抗寒性的影响，及幼林抗寒防冻中Si肥施用的技术参数。成果对红木引种栽培和用材林培育有重要意义。

调查研究了紫檀属红木树种在中国的引种栽培、生长表现和生态适应性，对其中最珍贵的檀香紫檀研发出一种种子高效催芽育苗方法、一种苗木组培高效快繁方法、一种苗木高效嫁接扩繁方法和一种促进其心材形成的育苗方法。.持续24 h的2.5°C低温即可对檀香紫檀苗木产生伤害，0°C、-2.5°C伤害显著。施Si显著增强檀香紫檀抗寒性，低温胁迫后苗木恢复快，植株健壮，叶片数多，比叶重大，发育好。施Si量1.5、2.25 mmol/kg的差异不显著。.施Si促进低温胁迫下檀香紫檀叶片保持较高叶绿素含量和Chl a/Chl b比值，缓解对两个光合系统和类囊体剁叠的损伤，促进光电子传递，提高光量子效率，降低非调节性能量耗散和光化学淬灭，增强碳同化关键酶Rubisco、Ald、FBPase、RCA及PEPCase活性，提高叶片光合速率、气孔调节能力和光合水分利用效率。.施Si提高檀香紫檀叶片细胞壁提取率，叶片细胞壁中蛋白和低分子量果胶含量、纤维素和半纤维素含量显著增大，而与细胞壁结合较松散、成熟度较低的螯合态果胶、碱溶性果胶含量显著降低；细胞壁PME和PG活性显著升高，Cx活性显著降低，细胞壁水解酶类活性平衡关系改善。.施Si促进低温胁迫下檀香紫檀叶片中有机渗调物质积累，增强POD、APX、SOD和GR活性，抑制H2O2水平升高，有效缓解低温胁迫导致的膜脂过氧化作用。施Si植株叶片表面，特别是上表皮表面的超微形态结构改变，使得主要由线形蜡质晶体构成的稀松的网状结构变得致密、厚实。.施Si提高檀香紫檀叶片细胞含Si量，显著提高所有这些细胞的Ca元素含量，而K元素含量普遍下降，P和Fe元素含量水平显著提高。施Si显著促进檀香紫檀对P和Fe元素特别是对Ca元素的吸收利用，是其提高抗寒性的又一重要机制，这在对其根尖中8种矿质元素含量的检测中得到充分证实。.施Si显著提高檀香紫檀根系和叶片质膜H+-ATP酶和Ca2+-ATP酶活性，增强其跨质膜电化学势和物质运输能力；并显著提高根系和叶片质膜磷脂含量，上调根系质膜糖脂含量，下调叶片质膜糖脂含量，提高叶片质膜磷脂/糖脂比。.与不施Si相比，施Si的檀香紫檀，叶片类囊体膜蛋白含量高，H+-ATPase、Ca2+-ATPase及Mg2+-ATPase活性强，低温胁迫后活性降幅小。施Si苗木叶片类囊体膜上磷脂酶D（PLD）水平较低，低温胁迫后升高幅度小、恢复快。