Influence of flood depth and duration on growth of lowland rice weeds, Cote d'Ivoire

The growth of weeds from the soil seedbank and sown Echinochloa colona and E. crus-pavonis was studied in relation to different water depths (0, 2 4 a nd 8 cm) and flood durations (2, 4 and 7 days in 7). Deeper flooding increa sed plant numbers in Ammannia prieriana, Sphenoclea zeylanica and Heteranth era callifolia, but decreased plant numbers in E. colona and E. crus-pavoni s and had no effect on Fimbristylis littoralis. Increased flood duration in creased plant numbers in H. callifolia, had no effect on S. zeylanica or A. prieriana, but decreased plant numbers in S. filicaulis, E. colona and E. crus-pavonis. Weed biomass at 28 days followed a similar pattern, with incr eased depth resulting in higher biomass of H. callifolia and A. prieriana, but lower biomass of S. filicaulis, E. colona and E. crus-pavonis. Deeper b ut intermittent flooding stimulated growth of A. prieriana, and F. littoral is. (C) 2001 Elsevier Science Ltd. All rights reserved.