EFFECT OF TILLAGE SYSTEMS AND CROP SEQUENCE ON THE RHIZOSPHERE MICROFLORA OF WINTER-WHEAT

The effect of different soil cultivation intensities on the occurrence of microfungi in the rhizosphere, rhizoplane and roots was studied in a six-course crop rotation using 50% cereals. The experiment was carried out on a chernozem soil at Hrušovany near Brno (Czechoslovakia) in a cereal production area. Winter wheat was grown in conventional-, minimal- (shallow) and zero-tillage systems. The in vitro antagonistic activity of the rhizosphere microflora against Gaeumannomyces graminis v. Arx et Olivier var. tritici Walker was assessed using the biotic effect method. Zero tillage resulted in an increased number of fungal isolates obtained from the rhizosphere and the rhizoplane and a decrease in isolates from the roots, especially at the Feekes growth Stage 10.1 - 10.5. Gaeumannomyces graminis var. tritici was more common under conventional tillage than under the other variants while the reverse was true of Fusarium. The higher antagonistic activity of the rhizosphere microflora under zero tillage conformed with the better visual health of winter wheat plants. © 1990.