A study in Pantnagar, Uttarakhand, found that in aerobic rice, the critical period for weed competition is between 15 to 45 days after sowing. During this time, yield losses ranged from 4.8% to 76%. Beyond 15 days after sowing, rice yield decreased significantly due to fewer panicles and grains per panicle. To achieve 95% of the maximum yield in aerobic rice, it is crucial to manage weeds effectively during this critical period.