Abdolaziz Haghighi

Rice is the most important crop after wheat in Iran. Since direct seeded rice cultivation has recently started in Golestan province and complete information about the effect of weed management, plant density and humic acid on rice grain yield and yield components as well as water use efficiency is not available, these issues have been investigated in this study. Therefore a study was carried out on direct-seeded rice cultivation (cv. Tarom Hashemi) in the cropping years 2018 and 2019 in Gonbad Agricultural Research Station as a split-factorial experiment based on randomized complete block design with three replications. Plant density (plant distance on row) was considered as the main factor (5, 10, 15 and 20 cm), and combination of humic acid consumption (consumption of humic acid, non-consumption of humic acid) and weeds management (control, chemical management and weeding) were considered as sub plots. The results showed that the effect of year on panicle length, number of seeds per panicle, paddy protein and water use efficiency was significant. Also, the effect of humic acid, plant distance on row and type of weeds management on all studied traits including plant height, panicle length, number of fertile tillers per hill, number of grains per panicle, paddy yield, biological yield, harvest index, paddy protein and water use efficiency were significant. Also, the highest paddy yield, biological yield, harvest index and water use efficiency were obtained from plant distance on row 5 cm under humic acid consumption or chemical management and weeding, but the amount of paddy protein was higher in the plant distance on row 10 cm.