草原植物根茎及匍匐茎对逆境及干扰的生态响应机制

This study tries to clarify the response mechanism of stolon and rhizome to both the ecological stresses and disturbances at the levels of population and physiology on the grassland. Cage burial and computer mapping, as well as age analysis and tagging technique will be used in order to identify the nature of physiological response and the stem spreading under the stress of alkalization, water and soil compaction, as well as the disturbance of mowing, reclamation and herding. The growth rate, age structure, growth plasticity, tri-dimensional architecture of the stem and energy allocation under the stress and disturbance as well as the changes of content of proline, MDA, organic acids, soluble sugars, and soluble protein will be studied. The differences and similarities of the responses of stolon and rhizome to the stress and disturbance, pattern of stem renewal and growth along with the general mechanism of responses to the stress and disturbance will also be discussed in the study, which will be expected to be beneficial for the improvement of degenerated grassland through stolon and rhizome colonization.

以草原植物匍匐茎及根茎为研究对象，旨在探明在不同生态胁迫及人为干扰下植物游走茎在种群生态及生理生态两个层次上的响应机制。通过天然草地实验观测、人工实验小区移栽，采用网笼埋入、游走茎上环跟踪及电脑绘图技术以及龄级分析，研究游走茎在盐碱、干旱和土壤紧实的生态胁迫下以及割草、草地开垦和放牧的生态干扰下游走茎的生理生化响应特征以及生长扩散机理。研究在生态胁迫及干扰下游走茎向外扩散及向内填充占居草地裸斑速率及特征、游走茎的龄级组成、游走茎及牙数量的消长规律、克隆生长的可塑性、能量分配规律、游走茎再生特点、三维空间构型特征，同时探明相应的脯氨酸、丙二醛、有机酸、可溶性糖类、可溶性蛋白含量等生理变化特点。比较匍匐茎和根茎对胁迫和干扰响应的异同；分析在不同生态胁迫及干扰下游走茎更新及生长扩散的模式以及对生态胁迫及干扰响应的一般机理，为利用游走茎无性繁殖改良退化盐碱化草地提供理论依据。

本项目以草原植物匍匐茎及根茎为研究对象，研究了根茎及匍匐茎植物对盐碱胁迫、冻融胁迫及酸雨胁迫下的生理响应机制。通过天然草地实验观测、人工实验小区移栽以及室内培养，研究了根茎及匍匐茎植物的生理生化响应特征以及生长扩散机理。羊草根茎生物量、根茎长度密度、分枝角度及根密度、根生物量均在重度盐碱土壤A5条件下最小；节间距和比根长，随着盐碱胁迫的增加而增加，A5条件下最大；盐碱胁迫条件下，根冠比和单位长度根茎重量无显著差异。根茎Na+含量、K+含量和K+/ Na+在不同盐碱梯度土壤条件下差异显著；根茎丙二醛含量与土壤盐碱胁迫显著正相关，羊草根茎各有机酸在不同盐碱梯度土壤条件下差异显著，最大值均出现在A3。酸沉降胁迫下，叶片MDA、POD、SOD值升高，而可溶性蛋白含量降低，CAT活力变化趋势不明显；在冻融胁迫下，叶片抗氧化酶、可溶性蛋白随温度下降先增高后降低，最大值出现在-5 ℃，MDA呈上升趋势，最大值出现在-15 ℃。POD随温度升高而上升,SOD和可溶性蛋白先升高后下降，CAT活力先下降后趋于平稳，MDA含量持续下降。白三叶可通过快速激活抗氧化酶活力和积累丙二醛以抑制膜脂过氧化从而适应酸沉降和冻融的双重胁迫。. 本项目通过研究在不同生态胁迫及干扰下植物生长扩散的模式以及对生态胁迫及干扰响应的一般机理，有望为利用根茎及匍匐茎植物无性繁殖改良退化盐碱化草地提供理论依据。