Barry Glaz, USDA-ARS, Sugarcane Field Station, Canal Point, FL
Research has shown that rapidly growing sugarcane (Saccharum spp.) tolerates short-duration flooding well during the summer in Florida. However, little is known about the flood response of recently planted or recently ratooned sugarcane. The purpose of this study was to test the yields of two sugarcane genotypes exposed repeatedly to different flood durations and drainage depths soon after planting and ratooning. Genotypes CP 06-2400 and CP 06-2897 were transplanted into lysimeters in March 2011. Water-table depths were maintained at 42 cm until flood treatments were initiated on 30 Mar. 2011 and 27 Mar. 2012 in the plant-cane and first-ratoon crop, respectively. Treatments were 0, 2, 4, and 6 d flood durations combined with drainage depths of 15 and 42 cm. Flood treatments were repeated twice in plant cane and three times in first ratoon with 1 wk drainage between flood events. After the final flood drainage, all water-table depths were 42 cm until harvest in October. As flood duration increased from 0 to 6 d, commercial recoverable sucrose (CRS) decreased linearly at the rate of 0.95 g sucrose kg-1 cane d-1 of flood (R2 = 0.97**). The CRS of CP 06-2897 was not affected by drainage depth, but the CRS of CP 06-2400 was significantly less at the 15 than at the 42 cm depth. Tonnes of cane (TCH) and tonnes of sucrose ha-1 (TSH) were not affected by flooding when drainage depth was 15 cm. However, when drainage depth was 42 cm, TCH and TSH decreased at the rates of 0.95 (R2 = 0.94*) and 1.07 (R2 = 0.91*) t ha-1 with each additional day of flood, respectively. Also, TSH of CP 06-2400 was more negatively affected by increasing flood duration than that of CP 06-2897. Compared with previous research, the present results indicate that young sugarcane is more susceptible to periodic flooding than well established sugarcane and that this susceptibility varies substantially among genotypes and is influenced by depth of drainage before and after flooding.