Studies On The Growth Promotion And Insect Resistance Of Arbuscular Mycorrhizal Fungi On Peanut

Peanut is widely planted all over the world.China is the world ’s largest exporter of peanuts,and Shandong Province is known as the hometown of peanuts,peanut planting area ranks among the top in the country.In recent years,due to the adjustment of crop layout,the reform of cultivation techniques,and climate change,the dominant species of pests on the ground in the main peanut producing areas of Shandong have been aggravated year after year,which seriously restricts peanut production.At present,the prevention and control of peanut pests on the ground is still dominated by chemical control methods,and the problems caused by pesticide residues,environmental pollution and pest resistance are increasingly prominent.Arbuscular mycorrhizal fungi(AMF)can form symbionts with host roots to promote plant growth and improve their resistance to abiotic and biotic stresses.Under the background of chemical fertilizer and pesticide reduction,more and more attention has been paid to the use of beneficial rhizosphere microorganisms to improve crop nutrient metabolism and pest resistance.In this paper,the arbuscular mycorrhizal(AM)fungal root endorhizobium rhizopus CD-1 was used as the research object.Under the premise of determining the symbiosis between AMF and peanut,the growth-promoting and yield-increasing effects of AMF colonization on peanut were determined by agronomic traits,photosynthetic characteristics,mineral absorption and yield indicators.The effects of AMF colonization on peanut pest resistance were determined by indoor biological activity determination and field effect determination experiments.The mechanism of AMF on host insect resistance was preliminarily explored by biochemical determination technology.This study provides an important basis for the development of new peanut pest biocontrol microbial agents.The main results are as follows:AMF can efficiently symbiose with peanut,increase seedling emergence rate and promote peanut growth.The results of trypan blue staining showed that the symbiotic rate of AMF and peanut could reach 60%.After AMF colonization,peanut seedling emergence rate was significantly increased,and peanut seedling emergence time was significantly shortened.The main stem diameter,root length,pod number and full fruit rate of peanuts at different growth stages were significantly higher than those of the control group.The field yield of peanut increased by 18.11% after inoculation with AMF.Further,the results of photosynthetic characteristics showed that the net photosynthetic rate,transpiration rate and stomatal conductance of peanut plants colonized by AMF were higher than those of peanut plants not inoculated with AMF at flowering stage,podding stage and harvest stage,especially at podding stage.In addition,the absorption rates of N,P,K,Ga and other mineral elements in peanut plants after AMF colonization were significantly higher than those in peanut plants without AMF inoculation.Therefore,AMF colonization significantly promoted peanut growth.The colonization of AMF could significantly enhance the resistance of peanut to the dominant species of flower thrips and cotton bollworm.The results of indoor bioassay showed that the growth and development of H.armigera were significantly inhibited after feeding on AMF-colonized peanut leaves compared with feeding on non-AMF-colonized peanut leaves.The mortality of H.armigera increased by 2.75,2.77 and 3.10 times on the 5th,10 th and 15 th day,respectively,and the total development duration was prolonged by 1.17 times.Colonization of AMF significantly reduced the selectivity of F.intonsa to peanuts,and the number of feeding insects was twice lower than that of uninoculated peanut leaves.The results of field pest damage investigation showed that AMF colonization could reduce the damage of flower thrips and cotton bollworm,which was consistent with the trend of pot experiment results.AMF colonization can significantly improve the defense response level of peanut in response to pest stress.The results of hormone determination showed that thrips and cotton bollworm feeding on AMF colonized plants could significantly induce JA accumulation,and JA content increased by 68.6 % and 98.7 %,respectively,compared with non-feeding AMF inoculated peanut plants.The results of enzyme activity determination were consistent with the results of hormone determination.The activities of PPO,POD and CAT increased significantly after pests fed on AMF colonized plants than those fed on peanut plants not inoculated with AMF.