镉胁迫下深色有隔内生真菌对玉米生长和根际土壤养分的影响

Effects of Dark Septate Endophytic Fungi on Maize Growth and Soil Nutrient under Cadmium Stress

为探究重金属胁迫下深色有隔内生真菌(Dark septate endophytes,DSE)对植物和土壤微环境的影响,设置3个水平土壤Cd质量浓度(0,5,10 mg/kg),选择6种DSE菌种(链格孢菌Alternaria terricola、尖镰孢菌Fusarium acuminatum、穗状弯孢菌Curvularia spicifera、高粱细基格孢菌Ulocladium sorghi、丛赤壳菌Neonectria radicicola和根异茎点霉菌Phoma radicina)进行玉米回接试验,以阐明Cd胁迫下DSE真菌对玉米生长、光合作用、抗氧化性,以及土壤pH、养分及酶活性的重要意义。结果表明:Cd胁迫下,6种DSE菌种均能定殖玉米根系。双因素方差分析结果表明,DSE与Cd胁迫及其交互作用显著影响玉米地径、叶绿素含量、丙二醛(MDA)、过氧化物酶(POD)、土壤pH和养分及酶活性(P<0.05)。当植物未受到Cd污染时,菌株U.sorghi(US)显著增加地下干质量和土壤有机质含量,降低MDA的积累和土壤速效磷含量。在5,10 mg/kg Cd质量浓度下,A.terricola(AT)显著增加玉米叶片数和地径;菌株P.radicina(PR)和N.radicicola(NR)显著提高植物地上干质量;AT、C.spicifera(CS)、F.acuminatum(FA)和US显著提高叶片中叶绿素含量和降低MDA在植物中的积累;AT降低了土壤速效磷含量;US显著提高土壤有机质含量并对土壤酸性磷酸酶和脲酶活性具有抑制作用(P<0.05)。Pearson相关性分析表明:土壤pH与地径和叶绿素含量显著正相关,有机质与植物谷胱甘肽显著负相关,速效磷与叶片数显著负相关(P<0.05)。方差分解表明:DSE菌种、Cd浓度和土壤因子共解释玉米生长和生理指标的42.1%和14.5%,其中DSE单独解释了27.4%和8.4%。随着Cd浓度升高,DSE显著促进植物生长,增加植物抵抗重金属能力,提高土壤养分可利用性,证明了在土壤Cd胁迫下DSE对植物生长和抗逆性有重要影响。

The effects of dark septate endophytic(DSE)on plant and soil microenvironmental functions were investigated under heavy metal stress,six DSE strains(Alternaria terricola,Fusarium acuminatum,Curvularia spicifera,Ulocladium sorghi,Neonectria radicicola and Phoma radicina)were selected for maize reconnection experiment to clarify the significance of DSE fungi on maize growth,photosynthesis,oxidation resistance,soil pH environment,nutrients and enzyme activities under Cd stress.We found that maize roots can be successfully colonized by all six DSE fungal species under Cd stress.Two-factor ANOVA indicated that the interaction between DSE and Cd stress significantly affected corn diameter,chlorophyll content,MDA,POD,soil pH environment,nutrients and enzyme activities(P<0.05).When plants were not polluted by Cd,US significantly increased the underground dry mass and soil organic matter content,and decreased the accumulation of MDA and soil available phosphorus content.AT 5 and 10 mg/kg Cd concentrations,A.terricola(AT)significantly increased the number of leaves and ground diameter of maize.PR and NR significantly improved the aboveground dry quality of plants.AT,CS,FA and US significantly increased chlorophyll content in leaves and decreased MDA accumulation in plants.AT reduced the content of available phosphorus in soil.US significantly increased the content of soil organic matter and inhibited the activities of soil acid phosphatase and urease(P<0.05).Pearson correlation analysis showed that soil pH was positively correlated with ground diameter and chlorophyll content,organic matter was negatively correlated with plant glutathione,and available phosphorus was negatively correlated with leaf number(P<0.05).Variance decomposition showed that DSE strain,Cd concentration and soil factors accounted for 42.1%and 14.5%of the growth and physiological indexes of maize,and DSE alone accounted for 27.4%and 8.4%.With the increase of Cd concentration,DSE significantly promoted plant growth,increased plant resistance to heavy metals and improved soil nutrient availability,which confirmed that DSE had an important impact on plant growth and stress resistance under soil Cd stress.