Sweet Sorghum Yield Performance Across Florida.

Finite petroleum reserves, high dependence on foreign petroleum and climate concerns associated with fossil fuels have led to renewed interest in bioenergy crops in the U.S. Thus, we have conducted a study looking at the performance of currently available sweet sorghum cultivars across Florida. The effects of planting date (three sowing dates from late March to Middle of June) and cultivar (Dale, Topper 76-6 and M 81E) on biomass, juice and brix were investigated at three sites in North, Central and South Florida for plant and ratoon crops. Averaged across sites, plant crop green yields ranged from 48 to 73 Mg ha^-1, with M 81E yielding better than Topper 76-6 which yielded better than Dale. Plant crop yields were greatest for the May planting date, intermediate for the March/April planting date and lowest for the June sowing date. Ratoon crop green yields were affected by site, cultivar and planting date, ranging from 5 to 67 Mg ha^-1 with greater yields generally correlating to earlier initiation of ratoon. Juice brix values ranged from 7.5 to 19.3% across all treatments, averaging 14.4 and 13.1% in the plant and ratoon crops, respectively. Brix values were about 20% lower on the muck soil location compared to the sand soil locations and about 20% lower in M 81E compared to Dale and Topper 76-6. Combining plant and ratoon harvests, this translates to estimated ETOH yields of 2350 to 6780 L ha^-1 yr^-1. Overall, earlier planting dates performed better than late planting dates. Topper 76-6 performed better compared to the Dale and M 81E, which were similar. Our results indicated that sweet sorghum production in Florida can be competitive with corn ethanol yields in the Midwest, but understanding genotype, environment and management will all be critical to optimizing sugar yields from sweet sorghum in Florida.