Quality of Rapeseed (Brassica napus L.) Following Application of Chemical Agents at Different Stages of Plant Ripeness

Rapeseed (Brassica napus L.) encounters a number of difficulties during mechanized harvest as a result of rapid changes in the ripeness of its canopy. Chemical agents such as diquat, glyphosate and glufosinate ammonium accelerate the ripening of rapeseed plants and improve their uniformity. Their application affects the qualitative composition of rapeseed and, as a result, determines the applicability of the material produced for food or energy. This study determined certain quality parameters of rapeseed cv. Californium following the application of diquat, glyphosate and glufosinate ammonium at different stages of canopy ripeness. The preparations, especially when applied at the optimum stage of ripeness, resulted in an increase in the content of basic components such as protein and fat in the seeds. Changes in the fatty acid composition of seeds treated with chemicals at different stages of plant ripeness were not uniform. However, the sum of unsaturated fatty acids increased compared with the control samples after application of these preparations (especially diquat and glufosinate ammonium). The acid and peroxide values obtained for the seed samples were significantly higher, but most of the chemicals used decreased the values of those parameters. The strongest negative effect on seed quality was that of glyphosate, resulting in high values in acid number, especially at optimum time of application (at seed moisture of 12-16% and pod moisture of about 25%, or 29 d from the onset of flowering).