| Water is one of the most important factors that affect agriculturre.Drought stress reduced the photosynthetic gas exchange capacity of plants,initiated a series of physiological mechanisms to resist the effects of drought on plants,and regulated the concentration of vegetative elements in plant organs and their ecological and chemical metrological characteristics.Arbuscular mycorrhizal fungi(AMF)are the most widespread microbes in the soil and can form symbiosis with host plants.The results showed that AMF could increase the content of nitrogen and phosphorus in host plants,promote the growth of host plants and improve their drought resistance.Therefore,elucidating the mechanism of water and AMF on the photosynthetic physiology of host plants is beneficial to the better utilization of AMF to promote the utilization of symbiotic plants and improve the utilization efficiency of agricultural resources.In this study,alfalfa(alfalfa)was used as the research object.Rhizobium(R),AMF(M)and double-inoculation(MR)were treated by alfalfa under different water treatments by means of greenhouse pot experiment.The control mechanism of water and AMF on the photosynthetic physiology and ecological chemistry of Alfalfa was studied by using aseptic treatment(CK)as control.The conclusions of this study are as follows:(1)Compared with CK,M and MR treatments increased the dry weight of alfalfa by about 4.0 times and 4.5 times(P <0.05)under 75% FWC water treatment.Under 25% water condition,compared with CK,M(P <0.05),and the effect of AMF and R double inoculation on the biomass of alfalfa was significantly higher than that of single inoculation(P <0.05),and the difference was significant synergies.(2)Pn,Tr and Gs of alfalfa were significantly decreased(P <0.05)under CK treatment.M,R and MR significantly increased the Pn of alfalfa(P <0.05),and the effect of MR on Pn was significantly higher than that of M and R(P <0.05),compared with the aseptic control.,Which also indicated that AMF and R double inoculation had significant effect on the promotion of Pn in alfalfa than in single inoculation,and MR had synergistic effect.In addition,M,R and MR treatments could significantly improve the water use efficiency(WUE)of alfalfa under drought stress(P <0.05).(3)The content of Proline was significantly increased(P <0.05),and the content of malondialdehyde(MDA)in alfalfa was significantly increased(P <0.05)Plants start their own defense mechanisms to improve their drought resistance.Further studies showed that M,R and MR treatments could significantly increase the activity of SOD under drought stress(P <0.05).MR could increase the POD activity under drought stress,and significantly reduce the MDA content of alfalfa leaves under drought stress(P < 0.05).However,under drought stress,microbial inoculation did not improve the alfalfa osmotic adjustment mechanism.(4)Water is one of the important factors limiting the absorption of alfalfa photosynthetic C,mineral nutrient absorption.The symbiosis of AMF and R with host plants improved the ability of host plants to obtain resources under drought stress,thus improving their drought resistance.However,due to the alfalfa on the ground and the underground part of the ecological environment have obvious differences,so the roots and leaves on the water and microbial response are more inconsistent.In addition,M and R only play a synergistic effect in C,N,P,K metabolism of alfalfa leaves under drought stress,which also indicates that the synergistic mechanism between AMF and R is affected by multiple environmental factors Influence,its deep-seated mechanism to be further clarified. |
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