Seed Chemical Composition Responses to Nitrogen and Sulfur Nutrition in Oilseed Brassicas.

Nitrogen (N) and sulfur (S) are both vital structural elements needed for synthesis of proteins and oils. A greenhouse study was conducted at the North Florida Research and Education Center during the 2015/2016 season to quantify the effects of N and S nutrition on Brassica carinata cv. AAC A110 and B. napus cv. Canterra 1918 growth, yield and yield components. Four nutrient treatments (100N, 100S; 100N, 0S; 0N, 100S; and 0N, 0S of N and S in full strength Hoagland solution) were imposed 38 days after planting. Oil concentration increased with nutrient stress in both species. Regardless of S availability, oil content increased by 28 (carinata) and 18% (napus) when N was limiting. Inversely, carinata and napus protein content decreased by 40 and 42% when N was limiting. Carinata very long chain fatty acids (carbon length >20) increased when S was limiting, regardless of N availability while there was no response to treatment in napus. Erucic acid (C22:1) did not vary with N and S nutrition in both species. Oil yield did not change with S availability when N was optimum. When N was limiting, mean oil yield decreased by 72% regardless of S availability in both species. Nitrogen and S nutrition need to be balanced for optimum growth and oil yield and quality.