Effects Of Glycine On The Growth Of Malus Hupehensis Seedlings

For exploring the effect of glycine on growth of apple,the model material Malus hupehensis was used.Firstly,in order to explore the effect of glycine on the growth and development of M.hupehensis seedlings,a 12-day concentration gradient experiment was designed that seedings were treated with different concentrations of glycine treatment,with no treatment as a control.Root scanning was used to detect the root growth level of M.hupehensis seedlings.The total nitrogen content was determined by kjeldahl method.The total phosphorus content was determined by vanadium-molybdenum-yellow photometric method.The total potassium content was determined by atomic absorption spectrophotometer.Afterwards,an experiment in soil was designed with high concentration glycine treatment.The root growth level,plant mineral element content and rhizosphere soil element content of M.hupehensis seedlings were determined by the above methods.The microbial biomass of rhizosphere soil was measured by standard plate count method(SPC).High-throughput sequencing techniques were used to detect microbial diversity in rhizosphere soil.The main research results are as follows:1.Under the same culture days,when the glycine concentration was lower than 6 mM,the root-shoot ratio increased with the increase of glycine concentration and reached the maximum value at 6 mM.And when the glycine concentration was higher than 6 mM,the root-shoot ratio decreased with the increase of the glycine concentration,and reached the minimum at 24 mM.Under the same glycine concentration,the root-shoot ratio increased with the increase of culture days and reached the maximum on the 12 th day.This indicated that glycine had a concentration-dependent effect on root growth.At the optimum concentration(6 mM),glycine had the largest effect on root growth.The promoting effect gradually increased with the increase of concentration at 0~6 mM,which had a positive effect on the growth of M.hupehensis seedlings.At 6~24 mM,the promoting effect decreased gradually with the increase of concentration,and the inhibiting effect increased continuously.At 24 mM,there was almost no promoting effect,which had a significant adverse effect on root growth of M.hupehensis seedlings.2.Under the same culture days,the total nitrogen content in plants increased with the increase of glycine concentration,and reached the maximum at 24 mM.Under the same glycine concentration,the total nitrogen content in plants increased with the increase of culture days and reached the maximum value on the 12 th day.However,after the glycine concentration exceeded 6 mM,the total nitrogen content decreased with the increase of concentration.This indicated that when the glycine concentration was 0~6 mM,with the increase of the glycine concentration,the nitrogen absorption of M.hupehensis seedlings gradually increased,and the nitrogen absorption efficiency gradually increased.At 6~24 mM,with the increase of the glycine concentration,the nitrogen absorption of M.hupehensis seedlings also increased gradually,but the nitrogen absorption efficiency decreased gradually.3.Under the same culture days,when the glycine was lower than 6 mM,with the increase of the glycine concentration,the total phosphorus content and total potassium content in the seedings increased continuously and reached the maximum at 6 mM.And when the glycine concentration was higher than 6 mM,with the increase of the glycine concentration,the total phosphorus content and total potassium content in the seedings decreased continuously and reached the minimum at 24 mM.Under the same glycine concentration,the total phosphorus content and total potassium content in plants increased with the increase of culture days,and reached the maximum on the 12 th day.This indicated that glycine regulated the concentration dependence of phosphorus and potassium absorption in M.hupehensis seedings.At the optimal concentration of 6 mM,glycine had the largest promoting effect on phosphorus and potassium in the seedings.The promoting effect gradually increased with the increase of the concentration when the glycine concentration was 0~6 mM,which had a positive effect on the seedling plants of M.hupehensis.At 6~24 mM,the promoting effect gradually decreased with the increasing of the concentration,and the inhibiting effect increased continuously.When the glycine concentration was 24 mM,there was almost no promoting effect,which had a significant adverse effect on M.hupehensis seedlings.4.Under the condition of high concentration of glycine,there was no significant difference in root diameter,length,volume and root-shoot ratio of M.hupehensis seedlings compared with the control.The total nitrogen content in the plants increased under the condition of high glycine concentration,but the total phosphorus content and total potassiumcontent in the seedings decreased.This indicated that the promoting effect of glycine on root growth almost disappeared at a higher glycine concentration,but it still had a certain promoting effect on the absorption of nitrogen,and under such conditions,the absorption of phosphorus and potassium was significantly inhibited,which had a significant adverse effect on the growth of M.hupehensis seedlings.5.Under the condition of high glycine concentration,there was no significant change in the microbial biomass of fungi,but the microbial biomass of bacteria and actinomycetes in rhizosphere increased significantly compared with the control.However,the microbial diversity decreased significantly,which showed that the microbial community structure changed significantly and the rhizosphere soil microenvironment changed significantly.The decrease in microbial diversity and the simplification of microbial community structure is probably caused by the microbial competition induced by glycine.This microbia may be one of the most important factors that affect the absorption of mineral elements in plants.In summary,an appropriate amount of glycine at low concentration can significantly promote the growth of plants,especially the growth of roots,and promote the absorption of mineral elements by plants,which is conducive to the healthy growth of plants.The promotion effect of excessive high concentration glycine to plant growth and nutrient absorption is greatly reduced,which is converted into inhibition effect,which is not conducive to plant growth.This inhibition is probably induced by excessive glycine,which makes a small number of microorganisms that can utilize glycine in rhizosphere rapidly increase,and suppress the growth space of other microorganisms.Thus,it greatly changes the microbial community structure of the rhizosphere and makes it simple.Finally,it is shown that glycine can affect plant growth directly by its own characteristics of organic nitrogen and indirectly by affecting rhizosphere microorganisms.This experiment lays a theoretical foundation for the future research on the application of glycine in agricultural production.