Effects Of Nitrogen And Phosphorus On Growth In Cotton Colonized With AM Fungi Under GR24

Arbuscular mycorrhizal fungi?AMF?,which belongs to Glomeromycota,are a kind of endomycorrhizal fungi and wildly distributed in the earth.The root system of host plants secretes signaling hormones to induce mycelium branching,which promotes the establishment of symbiotic system between AM fungi and host plant.In the symbiotic system of AM fungi,the host plants provide carbohydrate for AM fungi through photosynthesis,while AM fungi absorb mineral elements?such as N and P?and transfer them to the host plants through the transportation of mycelium.The two communicate in a complex and orderly way.In this study,seedling stage cotton was used as host plant,AM fungi were inoculated,hormones were applied to promote mycelial differentiation to form AM fungal symbiosis system.The effects of different hormones,hormones and differnet nitrogen sources,hormones and different phosphorus levels on the growth and development of host plants and nitrogen and phosphorus nutrition were investigated,as well as the optimal ratio of different concentrations of hormones,nitrogen and phosphorus combinations AM Fungi infection of host plants.The conclusions were as follows:?1?By adding two signal substances at different concentrations?Apigenin and GR24?,the optimal concentration of signal substances at the seedling stage of cotton plants was investigated.The conclusions were as follows:150 nmol L^-1 apigenin and100 nmol L^-1 GR24 treated cotton plants had the best yield increase effect;Different concentrations of apigenin had no significant difference in AM fungal infection rate and100 nmol L^-1 GR24 could shorten the time for AM fungi to infect cotton plant roots;Apigenin at different concentrations had no significant difference in cotton plant leaf chlorophyll and 100 nmol L^-1 GR24 cotton plant leaf chlorophyll was significantly higher than the blank group.?2?Under the condition of GR24,4 mmol L^-1 different nitrogen sources?arginine,glutamine,potassium nitrate,ammonium sulfate,urea?were added to investigate the effect of hormones and different nitrogen sources in AM fungal symbiosis system on seedling cotton stage.The conclusions are as follows:Under the condition that GR24was a hormone substance,the application of different nitrogen significantly increased the biomass of cotton plants,and urea was the best nitrogen source;The application of different nitrogen all increased the AM fungi infection rate and accumulation of chlorophyll in cotton plants;Application of urea under the condition that GR24 was a hormone substance significantly increased the nitrogen content of cotton plants above and below the ground;The application of urea significantly increased the phosphorus content of cotton plants above ground;The application of ammonium sulfate significantly increased the phosphorus content of cotton plants below ground;This shows that in the AM symbiotic system,GR24 and different nitrogen sources have beneficial effects on host plants growth and development,nitrogen and phosphorus content absorption and transport.?3?Under the condition of GR24,different concentrations of phosphorus source?KH₂PO₄?were added to investigate the effect of hormones and different concentrations of phosphorus source in AM fungal symbiosis system on seedling cotton stage.The conclusions were as follows:Under the condition that GR24 was a hormone substance,KH₂PO₄ of different concentrations had no significant effect on cotton biomass;0.25mmol L^-1 was the best phosphorus concentration for AM fungi to infect cotton plants,and when the phosphorus concentration was too high,AM fungi would be inhibited to infect cotton plants.However,together with exogenous phosphorus,GR24 can promote AM fungi to infect cotton plants,and GR24 can significantly improve the ability of root accumulation of nitrogen and phosphorus under the condition of suitable phosphorus concentration,and there is no significant difference in phosphorus content in the subsurface part of cotton plants under different phosphorus concentrations.?4?To investigate the effect of different concentrations of GR24,N and P on the nutrition of seedling stage mycorrhizal cotton plants.The conclusions showed:When the concentration of GR24 is 100 nmol L^-1,the concentration of urea is 10 mmol L^-1,the concentration of KH₂PO₄ is 0.05 mmol L^-1,the treatment is the biomass of cotton plant was the best,the absorption of nitrogen and phosphorus was the best,and it was most helpful for AM fungi to infect the host plant.