Effect of Row Spacing and Herbicide Application on Weed Control, Photosynthetic Pigments and Rapeseed Grain and Oil Yield

Rapessed is one of the most important oilseed crops. Weeds, also are most important factors that limit the production of the oil crops and greatly affect the quantity and quality of their extracted oils. To investigate the effect of row spacing and herbicide application on photosynthetic pigments and rapeseed yield, a factorial experiment based on a randomized complete block design with three replications was conducted during 2017-18 at Bayekola Research Station, Neka, Mazandaran. Factors were planting arrangement in two levels )one and two-row plantings( and weed control in 7 levels of  application of herbicides consisting of Trifluralin (Treflan) 2.5 l.ha-1 before planting and mixed with soil, Quinmerac + Metazachlor (Butisan Star) 2.5 l.ha-1 pre-emergence, Trifluralin 2.5 l/ha before planting + Quinmerac + Metazachlor 2.5 l.ha-1 pre-emergence, Chlopyralid (lontrel) 1 l.ha-1 + Haloxyfop-R-Methyl (Super Gallant) 0.8 l.ha-1 at 2 to 4 weeds leaf stage, Paraquat (Gramaxon) 2 l.ha-1 at 4 to 6 weeds leaf stages, weed control and without weed control. The results showed that by changing the planting arrangement and using combination of Trifluralin with Quinmerac + Metazachlor and/or application of Paraquat (as a guided herbicide) in two-row culture, the rapeseed chlorophyll content increased by 38.06% and 34.11% as compared to without weed control. Also, weed dry weight decreased by 87.16% and 94.97%, and rapeseed grain yield increased by 73.4% and 76.79%, respectively, which resulted in increasing crops,s extracted oil. It can be concluded that by modifying the canola planting pattern we can increase canola,s oil yield, and application of guided herbicide or combination of Trifluralin with Quinmerac + Metazachlor, to control weeds.