Effect of crop rotation on wheat in no-tillage system, in Guarapuava, PR

From 1984 up to 1993, at the Cooperativa Agraria Mista Entre Rios Ltda., Guarapuava, PR, Brazil, the effects of some crop rotation systems on yield, control of root diseases, and other agronomic characteristics of wheat were assessed. Four rotation systems for wheat were studied: 1) monoculture; 2) one winter without wheat; 3) two winters without wheat; and 4) three winters without wheat. The crops grown in summer were soybean or corn. Both winter and summer crops were grown under no-tillage, except in the winter of 1989, when limestone was applied before planting winter crops. A randomized complete block design, with four replications and plots with 60 m(2), was used. The crop rotation was efficient in controlling root diseases of wheat. Crop rotation of wheat under no-tillage controlled root diseases. Wheat grain yields decreased linearly as the severity of root diseases increased.