Mineral composition of winter oilseed rape (Brassica napus L.) seeds as a tool for oil yield prognosis

The key objective of winter oilseed rape cultivation, resulting from its broad spectrum of uses, is to harvest maximum yield of oil. It has been formulated a hypothesis, which assumed that mineral composition of seeds allows a reliable prediction of both crude oil concentration (COC), and yield of oil (YOI). This concept has been validated in three 2007/08, 2008/09, 2009/10 seasons. The field experimental design was composed of six fertilizing treatments: absolute control (AC), NP, NPK, NPKMgS1 (1/3 total MgS rate applied in spring), NPKMgS2, (total MgS rate applied in autumn), NPKMgS3 (2/3 - autumn, 1/3 - spring). The COC depended on both factors, but any interactional effect was found. The YOI was a result of interaction of both factors, reaching the highest value of 2.6 t*ha-1 in 2008 in the plot fertilized with NPKMgS2. The COC was a result of positive impact of calcium and negative by both nitrogen, and magnesium. The YOI was the best predicted by calcium concentration. It has been found that any calcium concentration increase above 3.0 g*kg-1 DM resulted in decrease of the crude oil yield. The prediction of both oil characteristics was more reliable based on nutrient accumulation in seeds. As again magnesium was the key predictor of COC, exerting a negative impact on this characteristic. The optimum set of YOI predictors was depended on the group of treatments. In all considered treatments, the YOI was affected by the interactional effect of phosphorus (negative), and potassium (positive). In the set of treatments, composed of NPK and its variants with MgS rates, the YOI was depended on the amount nitrogen and zinc in seeds. The first nutrient affected positively and the second negatively the yield of crude oil.