Investigation of sowing date, nitrogen and herbicide use time on barley weeds

ABSTRACT: In order to evaluate the effect of sowing date, nitrogen and herbicide use time on weeds of barley (Hordeum vulgare L.) a split-split plot experiment as base of randomized complete design with 4 replications was done in Qazvin, Iran. Sowing date in 3 levels included: D1: October 17, October 27 and November 6 as main plot, nitrogen application time in 3 levels included: N1: Beginning of stem elongation, N2: 10 days after the stem elongation and N3: 10 days after the stem elongation as sub plot and herbicide consumption time in 4 levels included: H1: non application, H2: tillering, H3: 7 days after tillering and H4: 14 days after tillering as sub-sub plot were considered. Investigations showed that sowing date of October 17 had least total weeds dry weight in field and sowing date of November 6 had most weed dry weight. So that application of nitrogen at start of stem elongation had the lowest total weeds dry weight and delay in nitrogen application lad to increase total weeds dry weight. The herbicide spraying at tillering stage resulted to low weeds dry weight compare to not spraying and delay in spraying caused to increase weeds dry weight. In general, it could be decrease weeds with nitrogen fertilizing (at start of stem elongation) and herbicide spraying (at tillering stage), if delay in sowing date condition.