Fertilizer-Functional Microbes Screen And The Study Of Growth-Promoting Efficacy On Wheat

Due to the long-term unreasonable application of chemical fertilizers,a series of environmental problems are caused,such as soil structure damage,soil organic matter content reduction and water pollution etc.,which will be detrimental to the safe production of food,sustainable development of agriculture and environmental protection.However,microbial fertilizers can avoid a series of environmental pollution problems and have become preferred choice of fertilizer on the development of green ecological agriculture,compared with the chemical fertilizers.In order to separate and screen nitrogen-fixing,phosphorus solubilizing and potassium-dissolving bacteria with fertilizer effect potential,in this study,the conventional spread plate Ashby nitrogen-free,Mengjinna organic phosphorus,PKO inorganic phosphorus and potassium-dissolving bacteria medium plate method was utilized to isolate bacteria from soil.Quantitative rescreening of high-efficiency strains by means of acetylene reduction,molybdenum anti-colorimetric method and flame spectrophotometry.The plant height,fresh weight,dry weight,tiller number and chlorophyll content of wheat and plant nitrogen,phosphorus and potassium content were statisticed in the pot experiment.Soil fertility indexes such as soil organic matter,alkali nitrogen,available potassium and phosphorus,soil cation exchange capacity,pH,and activities of soil sucrose,alkaline phosphatase and urease were measured by conventional methods.The main results of this study were as follows:(1)A total of 57 strains of bacteria were isolated from the soil,including 20 strains of autotrophic nitrogen-fixing,10 strains of inorganic phosphorus-dissolving bacteria,7 strains of solubilized organophosphorus bacteria,and 20 strains of potassium-dissolving strains.Two strains of highly efficient nitrogen-fixing strains DNX23(Pseudomonas sp.)and DNX24(Azotobacter chroococcum),highly soluble inorganic phosphorus strain RP5(Klebsiella variicola)and organophosphate strain OP3(Klebsiella sp.),two strains high-efficiency of potassium-dissolving strain JX13(Pseudomonas sp.)and JX16(Rhizobium sp.),and a strain of potassium-releasing strain JX27(Bacillus sp.)with both cellulose degradation ability were screened,and these 7 strains have different degrees of IAA production ability.(2)The quantitative experiment indicated that the nitrogenase activities of strains DNX23 and DNX24 were 33.91 nmol/gh and 152.56 nmol/gh,respectively,the phosphate solubilizing capacity of RP5 and OP3 strains was as high as 231.68 mg/L and 29.93 mg/L,separately,the potassium-dissolving activities were 193.33 mg/L and 224.66 mg/L respectively from the high-efficiency potassium-releasing bacteria JX13 and JX16,and the potassium-solubilizing rates of the strains with the strong ability to dissolve inorganic phosphorus were respectively 38.5% and 32.2%;(3)Compared with the treatment of applying single-straw rot cooked matter,treatments of straw rot cooked matter while inoculate separately three different combinations strains of 0176+JX27+OP3+DNX24+JX13,0176+JX27+OP3+DNX24+JX16 and 0176+JX27+OP3+DNX23+RP5 obviously increased the chlorophyll content of wheat and the nitrogen,phosphorus and potassium of plants,fresh weight,dry weight,etc.At the same time,the concentration of organic matter,alkali nitrogen,available phosphorus,soluble potassium and soil cation exchange increased in varying degrees,and activities of soil sucrase,alkaline phosphatase and urease as indicators of soil fertility increased observably;(4)Based on the application of straw rot cooked matter and 75% of chemical fertilizers,the results of inoculation of the above three different mixed strains suggested that the wheat height,fresh weight,tiller number,dry weight and chlorophyll content and plant nitrogen,phosphorus and potassium were no significent difference compared with the treatment of 100% chemical fertilizer,basic physical and chemical properties of soil and the activities of soil alkaline phosphatase sucrase and urease were not remarkably different in comparison with the wheat applying the 100% chemical fertilizer.It is indicated that the application of straw rot cooked matter while inoculation of the above three different combinations strains can promote the growth of wheat by improving the soil physical and chemical properties and increasing soil nutrients,thereby reducing the use of chemical fertilizers.The above results are helpful to provide strain resources for the development of microbial fertilizers in the future and to supply basic theoretical basis for the comprehensive application of different fertilizers.