title: Critical period of weed control in winter canola (Brassica napus L.) in a semi-arid region.
abstract: In order to determine the critical period of weed control in winter canola (Brassica napus L. cv. Okapi) an experiment was carried out at research field of Tarbiat Modarres University, Tehran, Iran on 2004-2005 growing season. Fourteen experimental treatments which divided into two sets were arranged in Randomized complete blocks design with four replications. In the first set, the crop was kept weed-free from emergence time to two-leaf stage (V2), four-leaf stage (V4), six-leaf stage (V6), eight-leaf stage (V8), early flowering (IF), 50% of silique set (50% SS) and final harvest (H). In the second set, weeds where permitted to grow with the crop until above mentioned stages. In this study critical period of weed control was determined according to evaluate seed bank emerged weed biomass effect on canola grain yield loss using Gompertz and logistic equations. Result showed a critical time of weed control about 25 days after emergence (between four to six-leaf stages) with 5% accepted yield loss. Therefore, weed control in this time could provide the best result and avoid yield loss and damage to agroecosystem.
authors.affiliation: Department of Agronomy, Faculty of Agriculture, Tarbiat Modarres University, P.O. Box 14115-336, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Aghaalikhani
authors.forename: S R
authors.initials: SR
authors.lastname: Yaghoobi
mesh_terms: D000383:Agriculture / Q000379:methods*; D029688:Brassica napus / Q000378:metabolism*; D018556:Crops, Agricultural; D003889:Desert Climate; D017753:Ecosystem; D007492:Iran; D018515:Plant Leaves / Q000378:metabolism*; D012044:Regression Analysis; D012621:Seasons; D012987:Soil; D013045:Species Specificity; D013997:Time Factors
chemical_list: D012987:Soil