Effect of Pre harvest Paraquat Application on Canola (Brassica napus) Yield and Seed Quality

In order to study the effect of pre-harvest application of paraquat on yield and seed quality of canola, an experiment was conducted in Lorestan and Mazandaran during 2006-2007. The experimental design was factorial randomized complete blocks with 3 replications and 10 treatments. Treatments included three doses of paraquat (1.5, 2 and 2.5 L/ha) and three dates of paraqat application (early, on time and late physiological maturity stages of canola), and check (no paraquat application). Results indicated that there was no difference among doses or dates of paraquat application in yield, extracted oil and rapeseed seed germination. There was no difference between the results of two locations of the experiment. Because the population of cruciferous weeds in Lorestan was low, no significant difference of erucic acid content of the extracted oil was observed among treatments. On the other hand, due to the high population of Sinapis arvensis in Mazandaran, the erucic acid content of the extracted oil in paraquat treated plots was lower than in the check plots.