The objective of this study was to evaluate the behavior of wild poinsetia (Euphorbia heterophylla L.), and its control by soil liming and black oat cover crop management in no-till soybeans. One experiment was conducted on Latossolo Roxo dystrophic soil, at Embrapa Soja Experiment Station, at Warta, Londrina, PR, in 1997/98. The experimental design was a randomized complete block design, in a factorial 2x2x2, with four replications. The treatments consisted of: 1. Liming (with and without), 2. Oat cover crop (with and without) and, 3. herbicide control (with and without). Assessment of the weed seedbank evolution in time and of the emerging flora were made at preand post-emergence of soybean sowing. From the time oat was chopped until soybean pod filling stage (R5), there was a mean decrease of the seedbank by 83,2%, under liming or oat cover management, and 91,9% where there was a no liming or oat cover. Emergence rate at pre-sowing soybean were of 4,7%, as a mean, equal for liming or not, but higher for oat absence, as to presence; at post-sowing, mean emergence rate was of 12,6%, with no differences between managements. A major weed infestation in the oat management treatment, without control, reduced s oybean yield. The infestation was supressed by liming, producing significatively more.
Seedbank; Avena strigosa; liming