The density of weeds in different planting dates of agricultural rice species in the conditions of direct cultivation using the dry-bed method.

To investigate the weed response to ecosystems of local and high-yield rice cultivars at different planting dates in direct cultivation by dry-bed seeding, an experiment was conducted in the form of a split-plot in a randomized complete block design with three replications in the research farm of Shavor Research Station. The main plot of planting date in three levels (June 15, June 25, and July 5) and four rice cultivars including two local cultivars Champa and Red-anbori and cultivars High-yielding and improved Danial and Shafagh was grown as a subplot at each planting date. According to the results, the highest and lowest number of weeds in the sampling on the first and second planting dates were obtained with an average of 123 and 61 plants, respectively. Among rice cultivars, the lowest weed density was observed in sample in Danial cultivar. In this experiment, the predominant species in the samples were two weeds barnyard grass and chinese lantern. The rate of weed emergence was around 0.56 to 0.63 number per day. in all three planting dates in the range of 20-40 days after planting. Therefore, weed control and field care during this period is essential to achieve optimal grain production.