Study On Influence Of Straw Mulching And Saving On Water On Soil Microorganism Numbers, Microbiota And Root Diseases Of Spring Wheat

The influence of straw mulching and saving on water on the numbers of soil fungi, bacteria, actinomycetes, physiological flora of microorganisms , soil nematodes and root diseases of spring wheat was studied in this paper. The results are as follows: (1) The influence of tillage treatments and irrigation on the numbers of soil fungi, bacteria and actinomycetes of spring wheat The numbers of three microorganisms were straw returned to field>no-tillage>conventional tillage, the numbers in straw returned to field were double to treble in conventional tillage, and the numbers in no-tillage were below double in conventional tillage. With increasing of irrigation quantity, the numbers of fungi reduced, the numbers of bacteria and actinomycetes increased in the beganing and reduced then, and the numbers were the most when irrigation quantity was 1350~1725m3/hm2, but irrigation quantity did hardly influence numbers of bacteria. The numbers of these three microorganisms were a peak at dynamics of season, the numbers of fungi and actinomycetes were the most on heading stages and the least after harvest, but the numbers of bacteria were the most on jointing stages. Dominant genus of fungi was Fusarium in almost all statements and dominant species and genus of bacteria were WJ1 and WJ2, but their secondary species and genus were different. (2) The influence of tillage treatments and irrigation on the numbers of physiological flora of soil microorganisms of spring wheat The numbers of bacillus, nitrifying bacteria, aerobe azotobacter and aerobe cellullolytie were straw returned to field>no-tillage>conventional tillage, the numbers in straw returned to field were double to treble in conventional tillage and the numbers in no-tillage were below double in conventional tillage. The mumbers of denitrify bacteria, oligotrophic azotobacter and oligotrophic cellulolytie were no-tillage> straw returned to field> conventional tillage, the numbers of denitrify bacteria in straw returned to field and no-tillage were double to treble in conventional tillage and the numbers of oligotrophic cellulolytie and oligotrophic azotobacter were below double. With increasing of irrigation quantity, the numbers of nitrifying bacteria reduced and denitrify bacteria increased, the numbers of bacillus, aerobe and oligotrophic azotobacter were the most when irrigation quantity was 975~1350m3/hm2, the numbers of aerobe and oligotrophic cellulolytic were the most when irrigation quantity was 1350~1725 m3/hm2. Physiological flora of soil microorganisms were different at dynamics of season. (3) The influence of tillage treatments and irrigation on the numbers of soil nematodes of spring wheat Patterns of tillage did hardly influence the numbers of nematodes. With increasing of irrigation quantity, the numbers of nematodes increased and change was quick in straw returned to field. The numbers of soil nematodes were a peak during wheat growing in almost all treatments and the numbers were the most on heading stages. The numbers of plant parasitic nematodes were more than non-parasitic nematodes in all treatments. The numbers of parasitic nematodes were conventional tillage>no-tillage>straw returned to field, but the numbers of non-parasitic nematodes were straw returned to field>no-tillage>conventional tillage. The numbers of parasitic nematodes and non-parasitic nematodes were reverse during wheat growing. Soil parasitic nematodes were different in different treatments at same season, but its dominant species and genus were same or secondary species and genus became dominant species and genus at dynamics of season. (4) The influence of tillage treatments and irrigation on wheat root diseases Incidence rates of wheat root diseases were conventional tillage>no-tillage>straw returned to field. With increasing of irrigation quantity, incidence rates were "V"and incidence rates were the least when irrigation quantity was 1350m3/hm2. Incidence rates on heading stages were about double on jointing stages. There were 1500 numbers and 1099 isolates and incidence was 73.27 percent on jointing stage. There were 1500 numbers and 1113 isolates and incidence was 74.20 percent on heading stage. pathogens had Bipolaris sorokiniana , Fusarium graminearum Schw , Fusarium oxysporum Schlecht and Fusarium culmorum in all treatments. Percents of these pathogens were different on jointing stages, however, percent of Bipolaris sorokiniana was the most in all treatments on heading stages. In all, considering fertilizing the soil and preventing disease and nematodes, the best treatment is straw returned to field and irrigation quantity is 1350 m3/hm2.