菌根对盐胁迫下胡杨幼苗生长和叶绿素荧光特性的影响

Effects of arbuscular mycorrhizal symbiosis on growth and chlorophyll fluorescence characteristics of Populus euphratica seedlings under salt stress

【目的】研究盐胁迫下丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)对胡杨(Populus euphratica)实生幼苗生长和叶绿素荧光特性的影响,为促进塔里木河下游胡杨繁殖更新提供依据。【方法】以1年生胡杨实生幼苗为材料,设置0.2 g/kg(对照,CK)、3 g/kg(S1)、6 g/kg(S2)和12 g/kg(S3)4个NaCl处理水平,每个NaCl水平下设接种AMF和不接种AMF进行对比,采用盆栽控制试验研究接种AMF对盐胁迫下胡杨幼苗根系菌根侵染率、菌根依存度、幼苗生长、叶绿素荧光参数和叶绿素含量的影响。【结果】1)随着盐胁迫的加剧,胡杨幼苗根系菌根侵染率显著降低,菌根依存度在S2和S3处理下与CK差异显著,表明盐胁迫在一定程度上抑制了AMF对胡杨幼苗根系的侵染。2)盐胁迫的加剧导致胡杨幼苗株高相对增长率、基径相对增长率、总根长、细根长、根表面积和生物量降低,但同水平盐胁迫下接种AMF能提高幼苗的上述指标,其中S1处理下的根系表面积和S2处理下的根冠比在接种AMF与未接种AMF间差异达到显著水平,说明接种AMF对盐胁迫下胡杨幼苗的生长具有促进作用。3)盐胁迫导致最大光化学效率(F_(v)/F_(m))、PSⅡ潜在光化学效率(F_(v)/F_(0))和光化学淬灭系数(qP)较CK下降,但是接种AMF能提高盐胁迫下叶绿素荧光指标,其中F_(v)/F_(m)、F_(v)/F_(0)、qP在S2和S3处理下显著高于不接种AMF组;幼苗叶片叶绿素含量在S3处理下接种AMF组显著高于不接种AMF组,且较CK增加了18.3%,表明接种AMF能减轻盐胁迫对胡杨幼苗光系统的损伤,也可提高叶片叶绿素含量。【结论】接种AMF能提高胡杨幼苗对盐胁迫的抗性,有助于胡杨幼苗快速度过生长脆弱期。

【Objective】The effects of arbuscular mycorrhizal fungi(AMF)on chlorophyll fluorescence characteristics and growth of Populus euphratica seedlings under salt stress were studied to provide basis for promoting reproduction and regeneration of P.euphratica in the lower reaches of the Tarim River.【Method】One-year-old P.euphratica seedlings were tested with four NaCl treatment levels of 0.2 g/kg(control,CK),3 g/kg(S1),6 g/kg(S2),and 12 g/kg(S3).For each NaCI level,the groups with and without AMF inoculation were compared.The effects of AMF inoculation on root mycorrhizal infection rate,mycorrhizal dependence,seedling growth,chlorophyll fluorescence parameters and chlorophyll content were analyzed.【Result】1)With the intensification of salt stress,the root infection rate of Populus euphratica seedlings decreased considerably.The mycorrhizal dependence in S2 and S3 treatments was significantly different from the CK group,suggesting that salt stress inhibited root infection of AMF.2)In seedlings not inoculated,intensification of salt stress led to decreases in relative growth rates of plant height and basal diameter,total root length,fine root length,root surface area,and biomass.AMF inoculation improved these indexes at the same level of salt stress.There were substantial differences in root surface area of S1 treatment and root shoot ratio of S2 treatment in comparison with uninoculated samples.It indicates that AMF promoted the growth of P.euphratica seedlings under salt stress.3)The maximum photochemical efficiency(F_(v)/F_(m)),PSII potential photochemical efficiency(F_(v)/F_(0)),and photochemical quenching coefficient(qP)decreased under salt stress.AMF inoculation improved the chlorophyll fluorescence indexes as the values of F_(v)/F_(m),F_(v)/F_(0) and qP under S2 and S3 treatments were significantly higher than those in the samples without AMF inoculation.The chlorophyll content of seedlings in the S3 treatment was significantly higher than in the uninoculated group and increased by 18.3%compared with the control group.This indicates that AMF inoculation reduced the damage to the photosystem of P.euphratica seedlings under salt stress and increased the chlorophyll content of leaves.【Conclusion】AMF inoculation improved the resistance of Populus euphratica seedlings to salt stress and helped the seedlings pass through the fragile growth period.