不同土壤pH下AM真菌对苜蓿苗期生长的影响

Effect of arbuscular mycorrhizal fungi on alfalfa seedling growth at different soil pH

在温室盆栽条件下,以紫花苜蓿(Medicago sativa)为试验材料,分别单独接种幼套球囊霉(Claroideoglomus etunicatum)、根内球囊霉(Rhizophagus intraradices)和这两种丛枝菌根(arbuscular mycorrhizal,AM)真菌的混合菌剂,并设定pH分别为6.48、5.0和3.0共3个梯度,探究不同pH条件下AM真菌对苗期苜蓿生长的影响。结果表明,随着pH的降低,苜蓿株高、叶片数、叶绿素含量、净光和速率,以及磷(P)吸收和生物量等显著降低,而MDA浓度显著增加。AM真菌的存在可以缓解酸胁迫对植物造成的伤害,与未接种AM真菌处理相比,接种AM真菌的处理均可在一定程度上促进植物生长、P吸收以及光合作用的进行,并提高超氧化物歧化酶(SOD)活性,降低丙二醛(MDA)浓度,增加植物生物量的积累。其中,以混合接种效果最好,苜蓿株高、叶片数,叶绿素含量、净光和速率、总P含量和生物量分别提高195.53%、332.57%、89.65%、167.42%、915.01%和97.70%(P<0.05)。此外,SOD酶活性提高137.11%(P<0.05),MDA浓度降低47.15%(P<0.05)。

The present study was performed in a greenhouse to test the effects of arbuscular mycorrhizal fungi(AMF)on the growth of Medicago sativa(alfalfa)in the seedling stage under different soil pH.The plants were inoculated with Claroideoglomus etunicatum,Rhizophagus intraradices along with the mixture of two AMF fungi at three different soil pH values(6.48,5.0,and 3.0).The results showed that with the reduction of soil pH,the plant height,leaf number,chlorophyll content,net photosynthetic rate,phosphorus absorption,and biomass of alfalfa were significantly reduced,whereas malondialdehyde(MDA)concentration was significantly increased.The presence of AMF alleviated the damage caused by acid stress on the plants.Compared to NM treatment,inoculation with AMF promoted plant growth,phosphorus absorption,and photosynthesis.Moreover,alfalfa colonized by AMF had a higher value of superoxide dismutase(SOD)enzyme activity and biomass,and a lower MDA concentration.The mixture of C.etunicatum and R.intraradices had the most significant positive effects on plant growth.The plant height,leaf number,chlorophyll content,net photosynthetic rate,total phosphorus content,and biomass of alfalfa were increased by 195.53%,332.57%,89.65%,167.42%,915.01%,and 97.7%(P<0.05),respectively.In addition,the activity of SOD increased by 137.11%(P<0.05)and the concentration of malondialdehyde(MDA)decreased by 47.15%(P<0.05).