Weed suppression ability of six soybean [Glycine max (L.) Merr.] varieties under natural weed development conditions

Abstract

The weed suppression ability of different soybean varieties was studied in a field experiment in 2010. The experiment was carried out in a randomized complete block design using a split-plot arrangement with 3 replicates. The main plots were either weedfree (hand weeding) or infested with the natural weed population (weedy). Six soybean varieties (Sari, Telar, Sahar, Hill, 032 and 033) were randomized within the main plots. The relative biomass total (RBT), relative crowding coefficient (RCCcw) and competitive balance index (Cb) were recorded and were regressed against crop traits under weedy conditions. The results showed a reduction in the maximum height of the soybean varieties under weedy conditions. No significant relationship was found between weed biomass and the canopy height of the varieties. Competition indices and the weed suppressive ability of soybean showed intergenotypic variation in competitive ability between the varieties tested. Weed pressure reduced the yield and yield components of all the soybean varieties. Under weedy conditions the soybean variety Hill gave a higher economic yield than the others, with high weed biomass suppression ability.