| At present,studies on AM fungi and plant growth and insect resistance mainly focus on single inoculation,and most of the research objects are annual herbaceous plants.There are few studies on the growth and resistance to defoliators of forest trees by the combined inoculation of two or more kinds of AM fungi.In order to study the synergistic effect and functional complementarity between different AM fungi and broaden the application range of AM bacteria,the annual Populus pseudo-cathayana × P.deltoides seedlings as the research objects was inoculated with Rhizophagus intraradices(RI)and Funneliformis mosseae(FM)inoculated by single and compound inoculation(M),and uninoculation was designated as control(CK).The effects of single and combined inoculation of RI and FM on the growth and resistance to defoliators of P.pseudo-cathayana×P.deltoides were compared.And the larvae of Hyphantria cunea were used as bioassays to verify their anti-insect performance,in order to provide a theoretical basis for the use of AM fungi to control leaf pests of forest.The main research results are as follows:(1)Both single and combined inoculations of RI and FM could be successfully colonized.The mycorrhizal infection rate,arbuscular growth rate and the number of vesicles in the root were showed "M>RI>FM" in 0～120 days.The mycorrhizal infection rate and the number of vesicles in the root of the three treatment groups increased with the increase of infection days,while the arbuscular growth rate of RI and FM groups decreased by 7.66%～15.03%during 105～120 days.(2)The combination of RI and FM inoculation was more beneficial to the growth and development of P.pseudo-cathayana × P.deltoides than its single inoculation.Plant height,ground diameter,leaf width,leaf area,root activity,the content of chlorophyll a and carotenoid,the activities of ribulose bisphosphate carboxylase,soluble protein content,leaf biomass,and seedling quality index in the M group were significantly higher than those of FM group,RI group and CK group.The chlorophyll b content was significantly lower than that of the FM,RI and CK groups.Leaf length,leaf number,root length,root mean diameter,root volume,root surface area,soluble sugar content,root biomass,and stem biomass were significantly higher than those of the RI and CK groups,but not significantly different from those of the FM group.Glycolate oxidase activity and starch content were not significantly different from the RI group.(3)The combination of RI and FM inoculation was more beneficial to enhance resistance to defoliators of P.pseudo-cathayana × P.deltoides than its single inoculation.Both physical and chemical defenses were higher in the M group than in the FM,RI and CK groups.In terms of physical defense properties,the upper epidermal cuticle thickness,palisade tissue thickness,lower epidermal thickness,leaf thickness,leaf vein closure,and leaf tissue compactness were significantly higher in group M than in FM,RI and CK groups.While spongy tissue thickness and leaf tissue laxity were significantly lower than in FM,RI,and CK groups.Leaf vein spacing was not significantly different from group FM.The upper epidermal thickness was not significantly different from the RI group,and the diameter of leaf veins was not significantly different from both the FM and RI groups.In terms of chemical defense properties,total alkaloid content,cellulose content,peroxidase(POD)activity,catalase(CAT)activity,lipoxygenase(LOX)activity,polyphenol oxidase(PPO)activity,trypsin inhibitor(TI)activity,and pancreatic rennet inhibitor(CI)activity were significantly higher in the M group than in the FM,RI,and CK groups.The total flavonoid content was not significantly different from the RI group,and the tannin content and phenylalanine ammonia lyase(PAL)activity were not significantly different from the FM group.(4)The combination of RI and FM inoculation of P.pseudo-cathayana × P.deltoides had a significant inhibitory effect on H.cunea larva compared to its single inoculation.The luring rate and feeding rate of the 4th instar H.cunea larvae on the leaves of P.pseudo-cathayana × P.deltoides in the M group were lower than those in the FM,RI and CK groups,but not significantly different from those in the RI group.In addition,the feeding quantity,fecal discharge,cellulase activity,acetylcholinesterase(AchE)activity and mixed function oxidase(MFO)activity of 3rd instar larvae in the M group were significantly lower than those in the FM,RI and CK groups.Body length,food utilization,trypsin activity,carboxylesterase(CarE)activity and glutathione S-transferase(GSTs)activity of 3rd instar larvae were significantly higher than those of the RI and FM groups.Food consumption rate and α-amylase activity of 3rd instar larvae were not significantly different from the RI group,and 3rd instar body weight was not significantly different from the FM group.Body weight,feed intake,food consumption rate,cellulase activity,GSTs activity,CarE activity,AchE activity and MFO activity of 4th instar larvae were significantly lower than those of FM,RI and CK groups,and fecal output of 4th instar larvae was significantly lower than those of RI and CK groups.Trypsin activity of 4th instar larvae was significantly higher than the other three groups,body length and food utilization of 4th instar larvae were not significantly different from those of the RI group,andα-amylase activity of 4th instar larvae was not significantly different from those of both the FM and RI groups.Body length,body weight,food intake,fecal output,food utilization,α-amylase activity,cellulose activity,GSTs activity,CarE activity and MFO activity of 5th instar larvae were significantly lower than those of FM,RI and CK groups.Food consumption rate of 5th instar larvae was significantly lower than those of FM and RI groups,AchE activity of 5th instar larvae was significantly lower than that of FM group,and trypsin activity of 5th instar larvae was significantly higher than those of the other three groups.In summary,the combined inoculation of RI and FM performed better than RI and FM single inoculation and no AM fungus inoculation for growth and resistance to defoliators of P.pseudo-cathayana × P.deltoides.Therefore,from the view of comprehensive inoculation effect,RI and FM combined inoculation is a good inoculation method for cultivating P.pseudocathayana × P.deltoides,and the treatment of "RI and FM combined inoculation" can be given priority in practical application. |
PDF Full Text Request