Infleunce of Nitrogen Rates and Soil Type on Glucosinolate Production in Brassica Carinata.

Brassica carinata is an oilseed crop that is being bred to produce biojet fuel. In addition to many favorable agronomic traits, B. carinata also produces defensive compounds known as glucosinolates (GLS). The type and quantity of GLS that are being produced can vary with species, environmental stress conditions, and between different plant parts or growth stage. However, certain GLS can also be toxic to animals, interfere with oil production, and recruit specialized pests. For this reason, breeding efforts are underway to reduce the amount of GLS concentrations. In this study, we investigated how various soils types and nitrogen rates affected oil and GLS concentration of seeds and in the roots and shoots at different growth stages. We found a significant increase in root biomass when grown in soil gathered from Bahia grass pastures than sand or soil with an intensive land use history. There is a strong inverse correlation between oil and GLS concentration (r = -0.91, p < 0.01) and with oil and protein (r = -0.96, p < 0.01) in seeds when varying nitrogen fertilization rates. Leaf tissue maintained a high concentration (>70 µmols/g of tissue) of GLS during vegetative stages that greatly decreased during the reproductive stage. Indole GLS were more pronounced in the roots with sinigrin (an allyl-GSL) making up the majority (>90%) of the GLS. These results correspond with the growing evidence that aliphatic GLS are actively transported to the seed and their reduction may improve oil production. However, the diversity of GLS throughout B. carinata may indicate the need to maintain certain non-aliphatic GLS for disease resistance.