基于叶片水势的内蒙古典型草原植物水分适应特征研究

The adaptability of plants to water based on leaf water potential in typical steppe in Inner Mongolia

水分是限制草原生态系统植物生存、繁殖和扩散最重要的生态因子,植物通过多样的水分适应策略适应干旱环境。为了解典型草原植物水势特征及其影响因素,在2017年和2018年的生长季对内蒙古典型草原71种植物的叶片黎明水势、午后水势、叶片和根系功能性状进行了测定与分析。结果表明:测定的71种植物叶片的黎明水势分布于-2.67--0.63 MPa,午后水势分布于-4.67--1.01 MPa;一年生植物的叶片具有最高的黎明水势、午后水势和最小的水势日差值(叶片的黎明水势与午后水势的差值),多年生禾草的叶片具有最低的黎明水势、午后水势和最大的水势日差值;71种植物对水分的适应策略可分为高水势保持型、低水势忍耐型和变水势波动型;叶片午后水势与叶片干物质含量和根系深度呈极显著的负相关关系(P<0.01),但与比叶面积呈极显著的正相关关系(P<0.01)。本研究有助于从植物生理学的角度上准确认识典型草原植物的水分适应性及水分生态特征。

Water is the most important eco-factor which strongly constrains the survival,reproduction,and dispersal of plants in typical steppes.Plants can adapt to arid environments through various water strategies.To elucidate the characteristics of leaf water potential and its relationships with the functional traits of leaves and roots in the typical steppes in Inner Mongolia,we measured the predawn water potential,midday water potential,and functional traits of leaves and roots in 71 plant species during the growing seasons in 2017 and 2018.We had the following key results.The predawn and midday water potential of all the 71 species ranged from-2.67 to 0.63 MPa and from-4.67 to-1.01 MPa,respectively.Among five plant functional groups,the annual plants had the highest predawn and midday water potential,and the smallest diurnal range of water potential(i.e.the difference between predawn water potential and midday water potential);the perennial grasses followed the opposite patterns.The water-adaptive strategies of 71 plant species were quantitatively classified into three types:high water potential type,low water potential type,and fluctuant water potential type.Across 71 plant species,their midday water potentials exhibited significantly negative correlations with their leaf dry matter content and root depths(P<0.01),and significantly positive correlations with their specific leaf area(P<0.01).Our findings might help us to understand the water adaptability and water ecological characteristics of plant species in the typical steppes in Inner Mongolia from the perspective of plant physiology.