Effects of Nitrogen Supply on B. Carinata and B. napus Growth, Seed and Oil Yields and Fatty Acid Composition.

Nitrogen availability is one of the most important abiotic factors that limits crop growth and productivity. A greenhouse study was conducted at NFREC, Quincy, Florida during 2014/2015 to determine the effects of N limitation on B. carinata var. A110 and B. napus var Canterra 1918 growth, seed and oil yields and fatty acid composition. Four N treatments (0, 33, 66 and 100% of N in full strength Hoagland Solution) were imposed 30 days after planting. At 110 days after planting, B. napus accumulated greater biomass than B. carinata across all N rates, however, B. carinata had greater number of reproductive branches, racemes and siliques. As a result, B. carinata produced greater seed yield across all N rates than B. napus. Seed yield per plant linearly decreased with N limitation while oil content increased linearly with decreasing N supply across species. Fatty acid composition differed across the species but did not differ with N availability. This study demonstrates the plasticity of oilseed brassicas and the relationship of reduced growth to seed productivity as a function of N supply.