PRESENT QUALITY OF WINTER RAPESEED

The quality of winter rapeseed as a material for oil, used in animal f eed and chemical industry has a growing importance for producers. The quality of the final production of winter rapeseed is the result of th ree factors: chemical composition based on genetics, changes in chemic al composition as affected by the cultivation technology, production y ear, and locality of cultivation, the quality of harvested rapeseed, p hysical properties of rapeseed, which strongly influenced the quality of rapeseed during the postharvest handling and storing. The basic qua litative characters of winter rapeseed were studied, not only as stati c values but during ripening of rapeseed. The systematic observations of the quality rapeseed have been accomplished since 1982. In the cour se of ripening the first stabilization of oil and fatty acid content ( Figs 1, 2) appeared and as to 1000-seed weight (TSW) and dry matter co ntent, the stabilization was evident later. The stabilization of oil a nd fatty acid content was observed 17 to 23 days before the harvest (F igs 1, 2). For these reasons the desiccation using the Reglone prepara tion as optimum four to five days before the harvest does not affect d istinctly the main qualitative and quantitative parameters (Tab. I) as well. Only 1000-seed weight with the latest stabilization showed the lower value in desiccated stand. Glucosinolates increased significantl y between the 40th to 60th days after flowering in erucic-free cultiva rs and this time 0 and 00 rapeseed varieties differentiate too (Fig. 2 ). The oil content was influenced by the variety (1 to 4%), the produc tion year and locality of cultivation (1 to 3%), postharvest condition s (0.5 to 1%), compacted soil (0.5%), the complex of agrotechnical con ditions. At this time the oil content again increased due to new varie ties on the oil content by about 46.0 to 47.0 (Fig. 3, Tabs II, III). Now, the production of rapeseed which represented almost 100% for the 00 variety contained 66.7% of glucosinolates at 20.0 mumol per 1 g of seed, being deep below the limit value 35 mumol per 1 g of seed (Figs 4, 5). The genetics of the cultivated varieties and the year, as uninf luenced factor, participated the most in this quality. By selection of varieties and complex of agrotechnical conditions together with the y ear of cultivation, we created the ground for achievement of the desir ed quality production of rapeseed. The harvest, postharvest, handling and storing are important factors. In case the rapeseed is harvested m ature, undamaged, high-quality, then its quality does not change marke dly during handling and storing. Antioxidant-tocopherol content decrea sed (Fig. 6) during the storage.