| The red soil hilly area in southeast China covers an area of 1.13 million square kilometers,accounting for 11.8% of the total land area of the country,and is the main battlefield of agricultural production.Due to the subtropical climate conditions and the characteristics of soil parent material,phosphorus in red soil is a nutrient element that is easily deficient and an important limiting factor of subtropical soil productivity.The use of arbuscular mycorrhizal fungi(AMF)to obtain nutrients from agricultural ecosystems is an effective way for red soil crops to absorb soil phosphorus(P).Given the problems of biological function degradation,low phosphorus bioavailability,and low crop yield in red soil in Southern China,regulating the AMF community in the rhizosphere of crops and optimising the mutualistic symbiotic relationship with the host is key to breaking the bottleneck of crop phosphorus uptake in red soil regions.In this study,four diversified fertilization measures were combined with ecological intercropping in red soil dryland with organic(straw,pig manure,bio-fertilizer)and inorganic fertilizers,and the optimal fertilization mode was screened based on crop yield and phosphorus activation level in red soil.Further,we used amplicon highthroughput sequencing,fluorescence quantitative PCR and microscopic observation techniques to analyze the effect of optimal fertilization measures in red soil dryland on the composition of the AMF community.Also,a deduction of the mechanism through which the optimized AMF community stimulates the host maize phosphorus uptake was performed.The results showed that the organic-inorganic application of peanut/corn intercropping combined with straw/biofertilizer(In+NPKSB)increased total phosphorus(TP)and available phosphorus(AP)by 29.07% and 1.35 times in red soil dryland compared with other fertilization methods.Moreover,the relationship between AMF family levels in maize roots was enhanced.The AMF colonization rate of this measure was 2.24 times higher than that of the traditional fertilization measures,the activities of acid/alkaline phosphatase(ACP/ALP)in the maize rhizosphere were increased by 32.18% and 41.66%,the phosphorus transport genes in maize roots were up-regulated by 25.13%-81.86%,and maize biomass and yield was increased by 34.98%and 67.27%,respectively.The study confirmed that the fertilization measures of peanut/maize ecological intercropping in red soil dryland combined with the organic and inorganic application of straw/bio-fertilizer can optimize the AMF community composition in maize roots,promote soil phosphorus activation,and improve the phosphorus transport efficiency of host roots,which is beneficial for red soil.This study,therefore,provides a theoretical basis for promoting the integrated application of sustainable agricultural development in red soil dryland according to local conditions. |
