Mehdi Esmaeiltabar; Faezeh Zaefarian; Shahram Nazari; Rahmat Abbasi
Abstract
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 ...
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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.
mojtaba khazaie; mohammad hassan hadizadeh; ehsan zaidali
Abstract
In order to determine the critical period of weed control (CPWC) in Corn (Zea mays L.), an experiment was carried out in a randomized complete blocks design with 14 treatments and three replications during 2013 growing season in the Nahavand climatic conditions. Two series of the treatments including ...
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In order to determine the critical period of weed control (CPWC) in Corn (Zea mays L.), an experiment was carried out in a randomized complete blocks design with 14 treatments and three replications during 2013 growing season in the Nahavand climatic conditions. Two series of the treatments including weed-free and weed-infested were applied in the regular time distances of 10, 20, 30, 40, 50 and 60 days after Corn emergence. Two check treatments including full and no control of weed during the whole season were also included. The nonlinear models kind of Logistic and Gompertz were applied to determine the start and end of critical period of weed control respectively. Major weed species were field bindweed (Convolvulus arvensis L.), red root pigweed(Amaranthus retroflexus L.), pigweed(Amaranthus blitoides L.) and lambsquarters(Chenopodium album L.) with greater biomass and size. The results showed that periods of weed- free and weed- infested differently affected the dry weight and number of weeds in all treatments. The critical periods of weed control in Corn by accepting a 5% acceptable yield loss, it is necessary to control weeds in a period between 14-47 days after planting or 117- 566 growth degree day(4-12 leaf stage) and by accepting a 10% acceptable yield loss it is necessary to control weeds in a period between 23-36 days after planting or 220- 419 growth degree day(6-10 leaf stage).