No-tillage system of flooded rice genotypes in succession to winter cover crops

The intensive use of the paddy soils in the production of flooded rice beco mes more and more necessary. In this sense, the adoption of the no-till sys tem of rice in succession to winter cover crops is an important alternative to facilitate the cultivation in the same area every year. A trial was con ducted with the purpose to identify more appropriate cover crops for cold s eason to participate of a succession system with no-till system of flooded rice genotypes at the Estacao Experimental do Arroz of Instituto Rio Grande nse do Arroz, in Cachoeirinha, RS, Brazil, in the 1996/97, 1997/98 and 1998 /99 growing seasons. The treatments consisted of four flooded rice genotype s (BRS6, BR-IRGA 409, IRGA 416 and IRGA 417) installed in no-till system on plots with the grasses black oat (Avena strigosa Scheib), white oat (Avena saliva L.) and rye grass (Lolium multiflorum Lam.); with the legumen "serr adela nativa" [Ornithopus micranthus (Benth.) Arechavaleta]; with spontaneo us vegetation and with nude soil (check). For grain yield there was interac tion between cover crops and growing seasons. In the three growing seasons, only the rice cultivated in succession to the legumen "serradela nativa" p resented similar grain yield to that one obtained in the control. On the ot her hand, the rice cultivated in succession to the rye grass was the only o ne presenting inferior grain yield in relation to the check in the three gr owing seasons.