| Wheat is the secend most important cereal crop after corn in China.However,In recent years,the occurrence of wheat sharp eyespot was becoming more and more serious,which had seriously threatens the yield and quality of wheat.Traditional agrochemicals play critical roles in disease control but compromise the environment and induce pesticide resistance.Previous studies showed that fungal polysaccharides can activate plant defense responses,regulate plant growth,and induce plant resistance to plant fungal and viral diseases.The propose of this study is to investigate the effect on wheat growth and explore the physiological and molecular mechanisms of of inducing wheat resistance to sheath blight after Ganoderma lucidum polysaccharides(GLP)seed dressing.Then GLP and chemicals were used together to screen effective formulations for controlling wheat sharp eyespot and evaluate their effects on soil microorganisms,to provide theoretical basis for wheat disease control.The results were as follows:(1)Greenhouse experiment results indicated that,the seed dressing of GLP can enhance the germination potential of wheat and promote the growth and development of wheat seedling stage,and with the increase of treatment concentration,the effect is more obvious.The combination of GLP and chemical agent can improve the effect of chemical agents on the prevention and control of wheat sharp eyespot,and alleviate the effects of hexaconazole on wheat seedling stage.8 g a.i./100 kg seed dose of GLP of Jimai 22 Shannong 23 and Luyuan 502 seed germinating potential were 55.00%?53.75% and 55.00%,significantly higher than that of the control.After 7 days of wheat emergence,The plant height of Jimai 22 Shannong 23 and Luyuan 502 which treated by 8 g a.i./100 kg seed dose of GLP were 8.57 cm?8.94 cm and 10.98 cm,significantly higher than that which treated by 4 g a.i./100 kg seed dose of GLP and control.Jimai 22 Shannong 23 and Luyuan 502 seed germinating treated by combination of hexaconazole with dosage of 0.5 g a.i/100 kg seed and GLP with dosage of 4 g a.i/100 kg seed were 50.00%?48.25% and 51.25%,significantly higher than that which treated by 0.5 g a.i./100 kg seed dose of hexaconazole.(2)Field control experiment results indicated that,the combination of hexaconazole with dosage of 0.5 g a.i/100 kg seed and GLP with dosage of 4 g a.i/100 kg seed is the best scheme of insecticide control of wheat sharp eyespot.The control effect of wheat sharp eyespot was more than 78% in the early winter of winter wheat,the control effect reached 67% in the wheat jointing stage,and the control effect of wheat grain filling period was 60%.It not only reduces the amount of pesticides used,but also improves the control effect and prolongs the effective time.(3)Laboratory test of enzyme activity showed that seed treated GLP could somewhat increase PAL,POD and SOD activity,reduce MDA content,increase chlorophyll a and b and root vigor of wheat.(4)QRT-PCR results showed that the relative expression of salicylic acid signal pathway related genes NbPR1 a,broad-spectrum resistance gene WMS533 and anti sheath blight related gene RS33 were significantly increased after seed treated by GLP,indicating that these genes were closely related to the mechanism of GLP induced wheat disease resistance.(5)The results of macrogenome analysis showed that GLP,hexaconazole,and the combination of hexaconazole and GLP seed dressing can reduce the diversity of Fungi Community in the brown soil and saline soil.Moreover,the reduction of fungal community diversity in saline alkali soil is higher than that in brown soil.The combination of 4 g a.i./100 kg seed dose of GLP and 0.5 g a.i./100 kg seed dose of hexaconazole can effectively reduce the relative abundance of Fusarium,Rhizoctonia,Gibberella and Bipolaris in soil,and effectively control wheat soil borne diseases. |
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