Weed Management in Seedling Stage with an Emphasis on Rice Seeds Coating in Direct Seeding System

In order to investigate the effect of different weed control managements on emergence characteristics and morphological growth of rice seedlings in the seedling stage in a direct seeding system, a field experiment has been conducted in the 2020 growing season, Babolsar, Bahnemir, Iran. Being a factorial in a randomized complete block design with three replications, the experiment employs the following treatments: Shiroudi, Khazar, and Hashemi cultivars as well as various weed control management in five levels of seed coating with calcium chloride, seed coating with potassium chloride, weeding, chemical control, and control. The interaction effect of weed management and cultivar shows that coating the seeds with calcium chloride, potassium chloride, and weeding cuts the dry weight of grasses by 55%, 68%, and 85% in Shiroudi cultivar, by 79%, 63%, and 54% in Khazar cultivar, and 30%, 58%, and 35% in Hashemi cultivar, respectively, compared to the control. The maximum percentage of germination with 99%, 97%, and 95% belong to seed coating with potassium chloride, calcium chloride, and weeding in Shiroudi cultivar, respectively. The highest germination rate could be observed in potassium and calcium chloride seed coating treatments and weeding. The lowest density of broadleaf weeds with 0.91 plants m-2 is obtained in Shiroudi cultivar and by managing the seeds coating of this cultivar with calcium chloride. The highest seedling length and weight vigor indices are obtained with 3559 and 137 in Shiroudi cultivar under weeding management, respectively. Results show that seed coating improves the seed yield of rice cultivars.