宁夏荒漠草原沙芦草种群生长适应性研究
Study on Growth Adaptability of Agropyron Mongolicum Population in Desert Steppe of Ningxia

本研究以宁夏荒漠草原沙芦草种群为对象,通过室内萌发、盆栽控制及野外种苗建植试验,结合天然草地调查,研究了不同温度和水分条件下沙芦草种子的萌发特性、水分控制条件下不同播种方式沙芦草的根系特征和叶绿素荧光特性、野外不同微生境沙芦草幼苗的定居规律及自然生长状态沙芦草的资源分配特征,以探讨沙芦草种群的生长适应性。主要结果如下:(1)沙芦草种子适宜的萌发温度为25/15℃~30/20℃,在30/20℃正常供水时的发芽率最高,达68%。水势胁迫的增加限制了种子的萌发,沙芦草采取延迟萌发、缩短萌发周期、降低萌发率等策略适应干旱。(2)水分胁迫显著影响沙芦草根系构型,导致根系体积和生物量的降低;播种方式则主要影响沙芦草的总根长。沙芦草与沙生冰草混播时根系在轻度和重度干旱胁迫下表现为偏利共生,中度干旱胁迫下则表现为互利共生的关系。(3)单播沙芦草叶片的相对叶绿素含量随水分胁迫的增加呈上升趋势。混播时沙芦草的最大光化学效率Fv/Fm和光合性能指数PIABs随水分胁迫的加剧呈增加的趋势。(4)野外去除植被和自然覆盖条件下沙芦草种子出苗率均不足40%,存活率为35.93%~51.15%,植株以生物量向地下转移的方式适应自然生境。与沙生冰草混播时,沙芦草幼苗主要通过增加叶面积的方式增强种间竞争能力。(5)自然生境中,沙芦草根、茎部的生物量分配速率显著高于叶片,不同群落其构件生物量均表现为:根生物量>茎生物量>叶生物量>穗生物量。沙芦草根系生物量和养分分配主要受土壤水分制约,地上各构件则主要受土壤养分和颗粒组成的影响。

In this study,the Agropyron mongolicum populations,which distributed in desert steppe in Ningxia were selected as the research objects.Through the in door germination,pot culture control and wild seedling establishment experiments,combining with natural vegetation investigation,the germination characteristics of seeds under different temperature and water conditions,the root system characteristics and chlorophyll fluorescence characteristics under different sowing pattern and water control conditions,the settlement laws of seedlings under different micro-habitats in the field and the resource allocation characteristics of A.mongolicum under natural growth conditions were studied to explore the growth adaptability of A.mongolicum population.The main results are as follow:(1)The suitable germination temperature for A.mongolicum seeds was 25/15℃-30/20℃,and the highest germination rate was 68%under normal water supply at 30/20℃.The seeds germination were restricted with the increasing of water potential.A.mongolicum adapted to drought by delaying germination,shortening germination period and reducing germination rate.(2)Water stress significantly affected the root system configuration of A.mongolicum,resulting in the reduction of root volume and biomass.Sowing patterns mainly influenced the total root length of A.mongolicum.The root systems of A.mongolicum and A.desertorum showed symbiosis of favoritism under mild and severe drought stress and symbiosis of mutualism under moderate stress when they were sown together.(3)The relative chlorophyll contents in the leaves of A.mongolicum increased with the increase of water stress under single planting.The Fv/Fm and PIabs in the leaves of A.mongolicum increased with the increase of water stress under mixed planting.(4)The emergence rates of A.mongolicum under the conditions of vegetation removal and natural coverage in the field were less than 40%,and the survival rates were 35.93%~51.15%.The plants adapted to natural habitats by transferring biomass to underground.When mixed with A.desertorum,the seedlings of A.mongolicum mainly enhanced the interspecies competitiveness by increasing leaf area.(5)In natural habitats,the biomass distribution rates of the root and stem ofA.mongolicum were significantly higher than that of the leaves,and the component biomass of different communities were as follows:root biomass>stem biomass>leaf biomass>spike biomass.The biomass and nutrient distribution were mainly restricted by soil moisture,while the above-ground components were mainly affected by soil nutrients and particle composition.

沙芦草; 荒漠草原; 干旱胁迫; 适应性;

Agropyron mongolicum; Desert steppe; Drought stress; Adaptability;

许冬梅; 彭文栋;

S812

27555462K