Carinata Yield and Physiological Response to Nitrogen Levels.

Carinata (Brassica carinata), a non-food oil seed feedstock for biofuel is a potential winter crop for southeastern US. However, there are agronomic constraints for Brassica carinata in the southeast US, including fertility optimization for production. The objective of this study was to evaluate carinata growth, yield and physiological response over different N rates on sandy loam soils. A study was conducted during 2018 and in 2019 in Jay, FL with N rates of 0, 45, 90, 134, 179 kg/ha arranged as a RCBD with four replications and in 2019 in Midville, Tifton and Shellman, GA with N rates of 0, 45, 90 and 134 kg/ha arranged as a RCBD with four replications. A positive linear yield response till 134 kg/ha was found with increasing N rates in Shellman and Tifton in 2019 while the response was limited till 90 kg/ha in Shellman, GA in the same year. Similarly, linear response till 134 kg/ha was observed in 2019 in Jay, FL while there was an increased response till 179 kg/ha in 2018. The biomass growth response curve increased significantly during pod development initiation stage (162 DAP) and fully ripe stage (188 DAP) after a top dress application of N at bolting (92 DAP) in 2018. Similar biomass growth response were observed in 2019. When the data across site years were pooled with location as a random effect to increase the scope of inference across southeast US, the data indicate a linear yield response up to 134 kg/ha. These rates are higher than the current 90 kg/ha recommendation for B. carinata previously published. These data suggest that N fertility recommendations may need to be altered for optimal carinata yield.