WHEAT CROPPING SYSTEMS WITH WHITE AND BLA CK OATS FOR GRAIN PRODUCTION

During the period from 1985 to 1989, at the National Wheat Research Ce nter (CNPT-EMBRAPA), Passe Fundo, Rio Grande do Sul, Brazil, the effec ts of crop rotation systems with white (Avena saliva) and black oats ( Avena strigosa) on wheat (Triticum aestivum) yield and root disease se verity were assessed. The cropping systems comprised: 1) monoculture o f wheat; 2) one winter with wheat, and one with black oat; 3) one wint er with wheat, and two with black oats; 4) one winter with wheat, and three with black oats; 5) one winter with wheat, and two with white oa ts; 6) one winter with wheat, and three with white oats. Root disease severity was higher under monoculture than under rotation, even in sea sons with normal precipitation. Grain yield was not influenced by crop ping systems, in the mean of years. Root disease severity and grain yi eld of wheat in rotation systems were influenced by the year.