Sugarcane Genotype Response to Nitrogen on a Sand Soil In Florida.

Approximately 20% of sugarcane (Saccharum spp.) grows on sand soils in Florida. Nitrogen deficiency may limit sugarcane yields on these sand soils. The objective of this study was to determine the effects of N fertilizer rate on growth and physiological characteristics of three sugarcane genotypes.  Treatments included N rates of 0, 75, 150, and 225 kg N ha^-1 and sugarcane genotypes ‘CP 80-1743’, CP 01-2390, and ‘TCP 87-3388’. The experiment was planted as a RCB design with five replications. Single-bud stalk sections of sugarcane were planted in pots (0.043 m³ each) filled with Margate sand soil and fertilized with P, K, and micro nutrients prior to planting based on soil analyses. Nitrogen fertilizer applications were equally split at 43 and 121 days after planting (DAP). Starting at 45 DAP, plant growth and leaf photosynthesis components were measured biweekly. All plants were harvested at 184 DAP to measure green leaf area (GLA) and shoot biomass components. Significant differences were detected in leaf photosynthesis, GLA, plant growth, and biomass accumulation among genotypes. Nitrogen rate affected GLA and biomass accumulation, but had little effect on leaf photosynthesis.  There were no genotype × N interactions for most growth and physiological variables. Genotype CP 80-1743 had the least GLA and shoot biomass. Green leaf area and biomass increased quadratically with increasing N rates. These results indicated that sugarcane yield can be improved by cultivar selection and proper N management for Florida sand soils.