Document Type : Research Article
In order to evaluate the effect of planting date of soybean cultivars in weed management, experimental design in the form of strip split plot as a randomized complete block design with three replications was conducted in Dasht-e-Naz Company Sari-Iran, in 2008. Treatments studied included three planting dates with a 20 days intervals (5 / 17, 6/ 6 and 2008/6/ 26) soybean cultivars (BP, JK, 032, 033 and Sahar) and weed control, including: 1 - Sonalan as pre-planting (3lit/ha) 2 - Sonalan as per-planting (3 lit/ha) + Sencore (Sonalan coincident) (700 g/ ha) 3 - Sonalan as per-planting (3 lit/ha) + Sencore (Metribuzin) as per-emergence (700 g/ ha) 4 – Control + Basagran as per-emergence (3 lit/ha) 5 – Treflan (Trifluralin) as per-planting (3 lit/ha) + Basagran as per-emergence (3 lit/ha) 6 – control. The results showed that planting date had a different effect on the density of either weed. The result also showed that Ethal-fluralin (Sonalan) can control narrow leaf weeds by alone. But combination of Ethal-fluralin (Sonalan) with Sencore (Metribuzin) whether pre-planting or pre-emergence can be control broadleaf weeds including wild melon (Cucumis melo), velvetleaf (Abutilon theophrasti), Sow thistle (Sonchus oleraceus) and nightshade (Solanum nigrum). These treatments also gave the highest seed yield. Between experimental cultivars, JK and 033 reduced density of wild melon. 033 also reduced the Barnyard grass (Echinochloa crus-galli) density. BP, Sahar and JK produced the highest yield, but BP had the highest yield in presence of weeds.