藏东南高寒草甸两种嵩草根系导管解剖结构对生境干旱化的响应  

Responses of root vessel anatomical structures to drought exposure for two Kobresia species in an alpine meadow habitat in Southeast Tibet

作　　者：杨春娇 韩雨圳 李忠馗 张大才[1] 王洪斌 栗宏林[1] YANG Chun-jiao;HAN Yu-zhen;LI Zhong-kui;ZHANG Da-cai;WANG Hong-bin;LI Hong-lin(Key Laboratory of National Forestry and Grassland Administration on Biodiversity Conservation in Southwest China,Southwest Forestry University,Kunming 650224,China)

机构地区：[1]西南林业大学西南地区生物多样性保育国家林业和草原局重点实验室,云南昆明650224

出　　处：《草业学报》2022年第2期76-87,共12页Acta Prataculturae Sinica

基　　金：国家自然科学基金项目(31960340,31660054)资助。

摘　　要：导管是植物输导水分的通道,其结构的可塑性是植物适应生境的重要机制,也将决定水分输导的效率和安全性。矮生嵩草和大花嵩草是对水分依赖程度不同的生态类型,两者输导水分的效率和安全性是否存在差异?在藏东南高寒草甸沿土壤水分梯度设置6个样方,采集矮生嵩草和大花嵩草根系若干,采用石蜡切片和显微照相测量法,测量两种嵩草导管直径、管腔面积、管壁厚度等指标,利用相关性分析、单因素方差分析、主成分分析等方法,分析两种嵩草根系导管结构的动态变化及其对土壤水分的响应。结果表明:矮生嵩草管壁厚度与土壤含水率呈显著负相关,导管密度与土壤含水率呈显著正相关(P<0.01);大花嵩草管壁厚度和加固系数与土壤含水率呈显著负相关,管腔面积和导管平均直径与土壤含水率呈显著正相关(P<0.01)。矮生嵩草导管密度和加固系数显著高于大花嵩草,水分输导安全性得到很好的保护;大花嵩草管腔面积、导管平均直径、水力直径显著高于矮生嵩草(P<0.01),水分输导效率优势明显。矮生嵩草窄导管和中型导管比例相当,对水分输导效率和输导安全性的调节能力强;大花嵩草始终以中型导管占比最高,对水分输导效率和输导安全性的调节能力弱。不同生态类型植物对生境干旱化的适应策略不同,矮生嵩草属于耐旱型植物,对水分输导效率和输导安全性的调节能力强,对干旱生境适应能力强;大花嵩草属于湿润型植物,水分输导效率高,但输导安全性低,对干旱生境的适应能力弱。Xylem vessels in the vascular tissue of roots are the channels by which plants transport water,and the plasticity of their structure is an important mechanism for plants to adapt to the habitat,which will also impact the efficiency and safety of water transport.Kobresia humilis and Kobresia macrantha are two Cyperaceae species that differ in their soil moisture preferences,K.humilis being more tolerant of drier environments.This research investigated whether there is any difference in water transport efficiency and safety between these two Kobresia species.To answer this question,K.humilis and K.macrantha root samples were collected at six sample plots along a soil water gradient in an alpine meadow of Southeast Tibet.Collected root samples were embedded in paraffin,sectioned by microtome.The vessel diameter,lumen area and wall thickness of the two species of Kobresia were measured by microscopy and image analysis and a cell wall coefficient of reinforcement(cwr)for the vessels was derived.From these data an overall vessel density and hydraulic diameter were calculated,and histograms of diameter class distributions for the sampled roots were prepared.Correlation analysis,one-way ANOVA and principal component analysis were used to analyze and interpret the data.In K.humilis vessel wall thickness was significantly negatively and vessel density significantly positively(P<0.01)correlated with soil water content;In K.macrantha vessel wall thickness and cwr were significantly negatively and vessel lumen area and average diameter significantly positively(P<0.01)correlated with soil water content.Vessel wall thickness of both species was increased in dry soil conditions and decreased in wet soil conditions.Comparing K.humilis and K.macrantha,vessel lumen area and average diameter,stele hydraulic diameter were all very significantly less,while cwr and vessel density were very significantly greater in K.humilis than in K.macrantha(P<0.01).K.macrantha is a species adapted to continuously wet environments,while K.humilis is

关 键 词：导管结构 径级结构 耐旱性 输导效率 输导安全性 

分 类 号：S812[农业科学—草业科学]