Comparison of Sugarcane and Energy Cane in Growth and Biomass Production.

Sugarcane is one of major crops on sand soils in south Florida, but yields and profits are low compared to sugarcane grown on organic soils in the region. Energy cane may be an alternative crop on sand soils in the future to improve profits because of the growing interest of high biomass for energy. A field study was conducted on a sand soil in Clewiston, Florida to determine growth and biomass production and composition of sugarcane and energy cane. A commercial sugarcane cultivar CP78-1628 and an energy cane (cv. US84-1066) were planted in late October 2010. Data were collected on plant-cane, first-ratoon, and second-ratoon crops in 2011 to 2013. Canopy reflectance, leaf chlorophyll (SPAD) and leaf photosynthetic rate (Pn) were measured during crop growth. Normalized difference vegetation index (NDVI) was calculated based on canopy reflectance data. Stalk population, diameter and length, and about ground fresh biomass (FBM) and dry biomass (DBM) were determined when plants reached mature in December. There were significant differences sugarcane and energy cane in most biomass-yield components. Averaged across measurement dates and three crops, leaf SPAD and Pn did not differ between sugarcane and energy cane, but energy cane had 26% higher NDVI value than sugarcane. Above ground FBM and DBM were 125.9 and 38.6 Mg h^-1, respectively for sugarcane and 140.4 and 50.7 Mg h^-1, respectively for energy cane. Increased biomass production of energy cane was mainly associated with high stalk population rather than mean stalk weight. Compared to sugarcane, energy cane had 163% more stalks, but 48% less mean stalk dry weight due to smaller stalk diameter. The DBM composition was also determined.