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Sugarcane (Saccharum spp.) in south Florida is often subjected to flooding due to interacting effects of soil subsidence, pumping restrictions, and tropical storms. While there has been considerable research on the response of sugarcane cultivars to high water tables and periodic flooding, there is a lack of information on commercial cultivar yield response to long-term flooding. An experiment was established in Belle Glade, FL to examine the effect of a 3-month summer flood (July�September) on the growth and yield of cultivars CP 80-1743 and CP 72-2086 during the plant cane (2003) and second ratoon (2005) crop. Harvest samples were taken early-, mid-, and late-season. Flooding sugarcane in the summer caused sequentially greater yield reductions throughout the harvest season in plant cane. Sucrose yields for flooded cane, compared with the non-flooded control, were 9.6 t sucrose ha-1 versus 11.7 t sucrose ha-1 early, 9.2 t sucrose ha-1 versus 12.8 t sucrose ha-1 mid-season and 7.8 t sucrose ha-1 versus 12.3 t sucrose ha-1 at late harvest. In the second ratoon crop, flooding reduced sugarcane tonnage and sucrose yield by 54�64% across sampling dates, and preliminary results indicated that flooding reduced leaf nutrient content by 10�78%. Yield reductions due to flooding in both crops were attributed more to reduced tonnage rather than sucrose content. CP 72-2086 yielded 18�28% greater sucrose than CP 80-1743 when harvested late. However the flood × cultivar interaction was not significant as both cultivars recorded similar yield reductions under flooded conditions. Our results identified severe yield losses caused by a 3-month summer flood in these cultivars, particularly in ratoon crops. Strategies to increase summer on-farm water storage in Florida should focus on short-duration periodic flooding rather than long-term flooding
