PJB-2019-1019
DETERMINATION OF CRITICAL PERIOD OF WEEDS CONTROL ON YIELD AND YIELD COMPONENTS OF CANOLA (BRASSICA NAPUS CULTIVAR OF HIOLA 50)
RAHMATOLLAH HOSSEINI
Abstract
An experiment was conducted to determine the critical period of weeds control (end of critical period) and weeds interference (beginning of critical period) in Brassica napus (Hiola 50 cultivar). The first group included control of dominance weeds of canola until 15, 25, 35, 45, 60 days after growing which were in 2, 4, 6, 8 leaves and booting stages. Then the control was stopped and weeds were allowed to grow. The second group consists of invasive treatments in which weeds of the field were not controlled from beginning of the emergence of canola until the growth stage. In this study, weeds of each experimental plot according to the growth stages of canola in two treatment groups by genus and species were identified and counted. Then, the average plant density of each weed and its total were reported aspect number per square meter along dry weight. In case of canola, the traits like yield and yield components were measured. Results demonstrated that critical period of weeds control is different depending on species in a way that the weeds had no uniformity in terms of germination time. The present study also showed that dry weight of weeds unlike total number of weeds can be a criterion for determining critical period of weeds control, so dry weight of weeds showed direct relationship with seed yield of canola in a way that delay in weeding in 6-leaf stage onwards caused significant increase of total dry weight of weeds and incurred reduce in seed yield. According to the results, weed control at the early stages of canola development did not have a significant effect on seed yield at least until the 2- leaf stage.
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