| Finus sylvestris var.mongolica shoot blight is serious in the Dongfanghonglin site,a desert of Tailai County,Qiqihar City,Heilongjiang Province.To analyze the factors affecting the pathogenies of Pinus sylvestris var.Mongolia shoot blight.Temporary standard sites were established,and the incidence and susceptibility index of the diseases were investigated according to the grading standards.In the investigation of different stand densities,with the decrease of planting density,the soil moisture content was significantly(P<0.05)lower and the incidence of disease was significantly higher.However,when the planting density is greater than 6 m×6 m,there is no significant differences between the afforestation density and the disease index.The afforestation density is larger than a certain area,the effect of competitive pressure between the 33-year-old Pinus sylvestris var.Mongolia is little.Water is an important factor affecting Pinus sylvestris var.mongolica shoot blight.In the western part of Heilongjiang province,water has restricted Pinus sylvestris var.mongolica shoot blight.,There are 12,14 genera of soil fungi and mycorrhizal fungi in Pinus sylvestris var.mongolica forest,totaling 19 genera.The most widely distributed are Penicillium spp.Trichoderma spp.,Paecilomyces spp.,Aspergillus sp.,Mucor spp.,Fusarium spp.and Acremonium sp.Under the same site conditions,there were significant differences in species composition,dominant populations between rhizosphere soil fungi and non-rhizosphere soil fungi.The incidence of Pinus sylvestris var.mongolica is closely related to site conditions and planting density.To explore the optimum growth conditions and the cycle of Suillus granulatus,the sample was firstly isolated and identified(registration number MG027689.1).Then Medium single carbon,single nitrogen,combination test,temperature screening test was carried out to obtain a medium suitable for the growth of Suillus granulatus.The dry weight of the fermentation broth was determined every 5 d.The results showed that the maximum daily growth of Suillus granulatus was 28?32 d.Sucrose and glucose were the best carbon sources.For carbon source utilization,disaccharide>monosaccharide>polysaccharide>no sugar,differences were significant(P<0.05).Yeast extract is the best nitrogen source.In the combined test,the mycelium of the combination of glucose and yeast extract powder grew better,and the maximuum radius was 58.75 mm.Glucose and yeast medium were the best medium,and the optimum temperature was 25?.The Logistic curve equation Y=1108.9/[1+4.32559283×EXP(-0.136617433t)].Fitness R2 was 0.975 and inflection point age(1nB)/K=10.7 days.Therefore,the turning point appears around 10d,and the mycelial growth enters the rapid growth period,which is an important period of fermentation culture.To study the mechanism of ectomycorrhizal enhancing the resistance of hosts,with 3-year-old seedlings of Pinus sylvestris var.mongolia inoculated with Suillus granulatus(SG group),Sphaeropsis sapinea and Suillus granulatus(SG x pathogen group),and Sphaeropsis sapinea(pathogen group),we studied the effects of changes of disease index,chlorophyll concentration and activities on disease resistance related enzymes(CAT,PPO,SOD).The results showed that under the pathogen stress,Suillus granulatus could effectively increase the content of chlorophyll,the activity of PPO and SOD,and decrease the disease index and the activity of CAT.Most of the indicators reached significant differences(P<0.05).Under the action of the pathogen,Suillus granulatus could positively regulate the physiological and biochemical indexes of Pinus sylvestris var.mongolica and improve the resistance against Pinus sylvestris var.mongolica shoot blight. |
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