Genetic contribution to yield gains in the Florida sugarcane industry across 33 years

Sugarcane (Saccharum spp.) is a successful Crop in the Florida Everglades Agricultural Area (EAA) that is characterized by high-N organic and low-fertility sandy soils, periodic freeze, and flood events. After 50 yr of breeding, the possibility of a yield plateau was investigated in the cooperative Florida sugarcane breeding program via an assessment of yield gains in the industry and an evaluation of the contribution attributed to breeding efforts. Long-term commercial and selection trial data, covering a 33-yr period (1968-2000), were used in single-degree-of-freedom regression analyses to determine rates of improvement in sucrose content (SC; kg Mg-1), cane yield (CY; Mg ha(-1)), and sugar yield (SY; Mg ha(-1)). Analyses of commercial data reflected yearly increases of 0.80 +/- 0.08 kg Mg-1 of cane for SC, 0.31 +/- 0.10 Mg ha(-1) for CY, and 0.10 +/- 0.01 Mg ha(-1) for SY. Corresponding gains from selection trial data were 0.74 +/- 0.15 kg Mg-1, 1.06 +/- 0.40 Mg ha(-1), and 0.16 +/- 0.05 Mg ha(-1), respectively. Improvements were significant for all three traits across plant-cane, and first- and second-ratoon crops grown on organic soils but not on sandy soils. About 69% of the total gain in SY was attributed to the cooperative Canal Point public breeding program, via a greater allocation of assimilates toward sucrose accumulation, resulting in a contribution of $99 to 203 million as additional profits to the Florida economy across the 33 yr. The genetic potential of the working germplasm has not been exhausted (no evidence of a yield plateau for SC) in this sugarcane breeding program. These gains and future advances are possible because of the use of a diverse gene pool and a breeding strategy that integrates growers' participation into the program.