Yield and quality of winter oilseed rape (Brassica napus L.) seeds in response to foliar application of boron

This paper presents the results of a 3-year field experiment conducted on soil with moderate levels of boron (B) in north-eastern Poland to determine the influence of foliar application of B (0, 150 and 300 g ha-1) on the yield components, yield, mineral composition, nutritional value and feed value of winter oilseed rape seeds. Foliar application of B at the beginning of bud formation in winter oilseed rape increased seed yield by 0.19 (3%) at the lower B fertilization level to 0.26 Mg ha-1 (4%) at the higher B fertilization level. The observed increase in the yield of winter oilseed rape seeds in response to foliar application of B can be attributed to this micronutrient’s positive influence on seed production in siliques. Foliar fertilization with B increased B content and decreased Zn and Fe levels in the seeds of winter oilseed rape. When B fertilizer was applied at the rate of 150–300 g ha-1, the N and Ca content of the evaluated seeds increased. The fertilizer improved the nutritional value (crude fat content, fatty acid concentrations) of seeds, but deteriorated their feed value (total protein content, acid detergent fiber concentrations, neutral detergent fiber concentrations, quantitative and qualitative composition of glucosinolates)