| Maize,as a major cereal crop in arid regions,is severely affected by drought.The impact of drought on maize growth is a key research focus.Although hydrogels can improve soil water holding capacity,most existing hydrogels are non-degradable.Therefore,it is necessary to explore natural,non-toxic,and degradable hydrogel materials.Plants rely on rhizosphere microbial communities,such as arbuscular mycorrhizal fungi,to alleviate drought stress.However,the combined application of hydrogels and arbuscular mycorrhizal fungi needs further investigation.In this study,carboxymethyl cellulose/furfural/chenodeoxycholic sodium hydrogel and arbuscular mycorrhizal fungi were selected as the test subjects.A sevenweek pot experiment was conducted in a greenhouse using maize as the test plant.The effects of hydrogel,arbuscular mycorrhizal fungi,and their combined application on maize growth under drought stress were investigated by analyzing physiological and biochemical indicators of maize plants and analyzing their impact on soil microbial communities using highthroughput sequencing methods.The main findings are as follows:(1)The synthesized CMC/FU/CSN hydrogel exhibited a porous structure.Characterization analysis using X-ray diffraction,Fourier-transform infrared spectroscopy,and electron spectroscopy confirmed the crystal structure,chemical bonds,functional groups,and elemental characteristics of the hydrogel.Water absorption capacity,water retention capacity,hydrogel soil degradation,and thermogravimetric analysis further verified the good performance of the synthesized hydrogel.(2)In terms of maize growth and physiology,hydrogel,arbuscular mycorrhizal fungi and combined application could promote the growth of leaves and roots of maize seedlings under different drought stress conditions.For example,under moderate drought stress,the plant height,stem diameter,aboveground fresh weight and root fresh weight of maize seedlings in the combined treatment group increased by 44.12%,75.97%,112.39% and 148.29%respectively.At the same time,leaf water content,root-shoot ratio,total root length,number of root tips,root surface area and root volume were also significantly increased.In addition,the three application methods significantly reduced the contents of hydrogen peroxide,superoxide anion and malondialdehyde in maize leaves and roots,promoted the accumulation of soluble sugar and free proline,and increased the activities of catalase and peroxidase.For example,under moderate drought stress,the catalase activity of leaves in the combined treatment group increased by 45.95% and the peroxidase activity of leaves increased by 57.04%compared with the control group.These results indicated that the three application methods could enhance the osmotic regulation and antioxidant capacity of maize seedlings,and improve their water use efficiency and drought resistance.(3)In terms of microbial community response,all three application methods significantly increased the richness and diversity of rhizosphere bacteria and fungi while decreasing the richness and diversity of root-associated bacterial communities,with no significant impact on root-associated fungi.Rhizosphere and root-associated microorganisms shared similar dominant taxa.At the phylum level,Proteobacteria were the most abundant in the bacterial community composition,while Ascomycota dominated the fungal community composition.PCo A analysis showed that the three application methods had a significant impact on bacterial community beta diversity,with the treatment involving the sole application of arbuscular mycorrhizal fungi having the largest effect.However,there was no significant impact on beta diversity of the root-associated fungal community among the three application methods.Furthermore,LEf Se analysis revealed enrichment of different microbial taxa in different treatment groups.In the rhizosphere bacterial community,the combined application of hydrogel and arbuscular mycorrhizal fungi significantly enriched Deinococcota,Deinococci class,Flavobacteriaceae order,Sphingomonadales order,and Alteromonas genus.In the root-associated bacterial community,the relative abundance of Enterobacteriales order,Enterobacteriaceae family,and Pseudomonas genus was significantly increased in the combined treatment group.Regarding rhizosphere fungi,the combined application of hydrogel and arbuscular mycorrhizal fungi significantly increased the relative abundance of Mortierellales class,Olpidiomycota class,Olpidiales order,Trichosporonales order,and Olpidiaceae family.In the root-associated fungal community,the relative abundance of Sirobasidiaceae family,Sirobasidium genus,and Ceriporia genus also significantly increased in the combined treatment group.In conclusion,the green and degradable CMC/FU/CSN hydrogel is an environmentally friendly material for alleviating drought stress,improving corn growth,enhancing water and nutrient supply,and increasing photosynthetic activity and drought resistance.The combined application of hydrogel and arbuscular mycorrhizal fungi demonstrates significant synergistic effects.On one hand,it promotes the colonization and growth of mycorrhizal fungi,and on the other hand,microbial community analysis suggests that rhizosphere microorganisms are sensitive to different application methods.Therefore,the combination of green hydrogel and arbuscular mycorrhizal fungi provides a theoretical basis for land improvement and sustainable agriculture. |
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