混合盐碱对紫花苜蓿苗期根系特征的影响  

Alfalfa seeding root characteristics under complex saline-alkali stress

作　　者：张晓磊[1,2] 刘晓静[1,2] 齐敏兴[1,2] 刘艳楠[1,2] 蒯佳林[1,2] 

机构地区：[1]甘肃农业大学草业学院,兰州730070 [2]草业生态系统教育部重点实验室/中美草地畜牧业可持续发展研究中心,兰州730070

出　　处：《中国生态农业学报》2013年第3期340-346,共7页Chinese Journal of Eco-Agriculture

基　　金：甘肃省自然基金项目(1010RJZA157);草业生态系统教育部重点实验室(甘肃农业大学)项目(CYZS-2011012)资助

摘　　要：为研究紫花苜蓿根系对混合盐碱胁迫的响应,探索紫花苜蓿对混合盐碱的适应特点,为紫花苜蓿在盐碱地的栽培实践提供理论依据。本试验以"甘农三号"紫花苜蓿为试验材料,采用两种中性盐NaCl和Na2SO4及两种碱性盐NaHCO3和Na2CO3,按不同比例混合成为A(NaCl∶Na2SO4=1∶1)、B(NaCl∶NaHCO3=1∶1)、C(NaCl∶Na2SO4∶NaHCO3∶Na2CO3=1∶1∶1∶1)、D(Na2SO4∶Na2CO3=1∶1)、E(NaHCO3∶Na2CO3=1∶1)5种混合盐,分别以25 mmol.L 1、50 mmol.L 1、100 mmol.L 1、150 mmol.L 14种盐浓度,模拟出20种盐度和碱度各不相同的混合盐碱条件对紫花苜蓿幼苗进行处理,测定了根系总长度、根系平均直径、根表面积、根尖数等指标,以了解紫花苜蓿根系在混合盐碱胁迫下的生长特性。结果表明,盐浓度为影响紫花苜蓿根系生长的主要因素。混合盐碱对根尖数的影响表现出明显的负效应,对根系平均直径的影响并不明显。随着混合盐浓度的升高,根系总长度、根表面积呈现先增大后减小的趋势。A、B处理的根长分别在盐浓度为25 mmol.L 1和50 mmol.L 1时达到最大值,分别比对照(0 mmol.L 1)增加50.7%和37.9%,而且差异均达到显著水平(P<0.05);在盐浓度达到150 mmol.L 1时,A、B、C、D、E的根系总长度分别比对照减少26.6%、37.7%、51.6%、37.0%和55.7%,差异显著。A、C、D组处理下仅在25 mmol.L 1时,根表面积显著增加,分别比对照增加21.1%、43.4%和12.7%;在浓度为150 mmol.L 1时,E处理下根表面积显著减小,比对照减少49.6%。表明低浓度混合盐碱对紫花苜蓿根系的生长影响不显著或具有一定的促进作用,高浓度胁迫下抑制根系的生长;在高盐浓度下随着碱性盐比例的增加,对紫花苜蓿根系生长的抑制作用越明显。Ecological environment and agricultural sustainability in present days China have been threatened by soil salinity. Plant roots have been the first to feel adverse soil stress conditions through different physiological processes. Study of alfalfa response to salt stress has mainly focused on the above-ground system or on the growth and physiological response to single salt stress. Alfalfa root response to complex saline-alkali stress has been rarely reported. The primary aim of this study was to determine the response of alfalfa root to saline-alkali conditions. The study also explored alfalfa growth and adaptation characteristics under complex saline-alkali stress conditions and provided theoretical bases for alfalfa cultivation in saline-alkali field. The Medicago sativa L. cv. ＂Gannong No.3＂ was investigated under complex saline-alkali stress conditions at seeding growth stage. 20 different alkali-saline stress conditions simulated saline-alkali soil conditions obtained by mixing two neutral （NaCI and Na2SO4） and alkaline （NaHCO3 and Na2CO3） salts in different proportions [A （NaC1 ： Na2SO4 in 1 ： 1 ratio）, B （NaC1 ： NaHCO3 in 1 ： 1 ratio）, C （NaC1 ： Na2SO4 ： NaHCO3 ： Na2CO3 in 1 ： 1 ： 1 ： 1 ratio）, D （Na2SO4 ： Na2CO3 in 1 ： 1 ratio） and E （NaHCO3 ： Na2CO3 in 1 ： 1 ratio）] and concentrations （25 mmol L-1, 50 mmol L-1, 100 mmol L-1 and 150 mmol-L-1）. To understand alfalfa root growth characteristics in mixed salt stress conditions, total root length, root surface area, average root diameter, root volume and root tip number were analyzed. The results showed that salt concentration was the main driving factor of alfalfa root growth. There was obvious negative effect of the saline-alkali conditions on root tip number and insignificant effect on average root diameter. As treatment concentration increased, total root length and root surface area initially increased followed by a decrease. At low concentration of ~〈50 mmol＇L-1, total root length under

关 键 词：紫花苜蓿 混合盐碱胁迫 根系长度 根表面积 根尖数 

分 类 号：S541.9[农业科学—作物学] S3