Influence Of Tillage System On Wheat Root Diseases And Rhizosphere Fungal Diversity

Crop residue is the important nutrient source in both natural and agricultural ecosystem and residue retention has essential effects on soil fertility and crop diseases. Community changing of soil microorganisms especially soilborne pathogens caused by residue retention showed crucial effect on the occurrence of plant diseases. In this study, the occurrence of wheat root diseases was investigated and the fungal diversity was detected using traditional and molecular techniques in residue retention field.⒈Wheat root diseases were investigated at wheat seedling, booting and heading stages. Results indicated that different tillage patterns had significant influence on the occurrence of wheat root diseases. The disease incidence and disease index was higher in the half and zero tillage farming fields than that in the deep tillage fields with straw clearing and straw returning.⒉Soilborne pathogens were isolated from diseased wheat roots collected from different tillage farming fields. Fusarium graminearum and Bipolaris sorokinianum were the most important pathogens associated with wheat root rot diseases. The pathogenicity test was conducted using pathogens isolated from different tillage farming fields. Results showed that the pathogens from half and zero tillage fields were more pathogenic on wheat than that from deep tillage fields. The quantity of Fusarium was also calculated using soil dilution method, and the number of Fusarium in half tillage soil was much higher than that in other tillage pattern soils.⒊PCR-DGGE detection system was built up using nested PCR for detecting Fusarium diversity in the different tillage farming soils. In the first round, 2-5 ng of DNA template was suitable for the PCR amplification. In the second round, the first round PCR product was used as template with annealing temperature at 67℃. In DGGE detecting, the polyacrylamide gel with 45% -60% denaturing gradient was used, the voltage of 90 V and electrophoretic time of 7-8 h showed better effect on PCR product separation.⒋The fungal diversity in wheat rhizosphere soil collected from the three wheat growing stages was detected using DGGE finger printing technique. Result showed that soil microorganism diversity was significantly influenced by different tillage patterns. Fungal and Fusarium diversities were significantly influenced by both different tillage patterns and growing stages, while Pythium diversity was influenced significantly only by the growing stages .