Assessment of Sugarcane Yield Potential across Large Numbers of Genotypes using Canopy Reflectance Measurements

Canopy reflectance indices have been used to monitor plant growth and estimate yields in many field crops. Little is known if canopy reflectance of sugarcane (a complex hybrid of Saccharum spp.) can be used to estimate growth and yield potential across large numbers of genotypes (clones) in the early stages of a breeding program. The objectives of this study were to identify clonal variation in sugarcane canopy reflectance and yield components and to determine if there were any putative relationships between canopy reflectance or reflectance indices and yield variables. In Stage II of the Canal Point sugarcane breeding and cultivar development program (CP program), canopy reflectance data were collected five to six times from each of 156 to 164 randomly selected clones during the growing seasons in 2011 through 2013 using a multispectral radiometer. Normalized difference vegetation index (NDVI) and other reflectance indices were calculated using the reflectance values. Yield traits, including stalk population, mean stalk weight, cane yield, commercial recoverable sucrose (CRS), and sucrose yield, were determined on mature plants in late October. Stalk population and cane yield were most highly correlated with reflectance at the wavebands centered at 800 and 980 nm and NDVI (r = 0.50-0.68; P < 0.0001), while CRS was not related to canopy reflectance. The best time to measure canopy reflectance for yield estimation across clones was from March to April (tillering stage). Canopy reflectance measurements at the early growth stage can be used as a screening tool to estimate yield potential for large numbers of clones in sugarcane breeding programs.