The Time of Application of Maturing Herbicides Affects the Physiological Quality of Canola Seeds

Canola (Brassica napus L. var. oleifera) is a winter growing option for producers, however, harvesting is the phase that requires the most care and decision making to avoid losses in productivity. One of the alternatives that can be used to solve this problem is the application of maturing herbicides. Thus, the objective of this study was to evaluate the physiological quality of canola seeds with the use of herbicides, applied in two seasons, for pre-harvest maturation of the crop. The experimental design was a randomized block design, arranged in a factorial scheme 7x2 + 2 (herbicide x season + control) with four replications. Hybrid 50 canola plants received ammonium glufosinate, paraquat, glyphosate, diquat, saflufenacil, 2,4 - D and paraquat + diuron at two times in the crop cycle (G3 - when the first ten the main stem silica has a width greater than 4 cm, and G4 - when the first ten silicas of the main stem begin to mature), in addition to two unselected controls, for each season, the first being harvested on the day of application of the products, and the second kept in the field until the final cycle of the culture. First germination, germination, seedling length, dry mass, cold test and accelerated aging tests were performed. Herbicides applied in the first season (G3) cause the greatest damage to the seeds, and the plants that remained in the field until the end of the crop cycle and did not receive herbicide application (additional control), result in seeds with better physiological quality. The treatments with diquat, paraquat + diuron and glufosinate of ammonium presented higher efficiency with respect to seed quality, being the best period to carry out the maturation practice in the canola crop in the G4 season.