Sugarcane Genotype Variation in Leaf Photosynthesis Properties and Yield as Affected by Mill Mud Application

Abstract

Variability in yield among sugarcane (a complex hybrid of Saccharum spp.) genotypes grown with and without mill mud application on sand soils in Florida has been documented, but little is known about what causes yield differences and if there are any relationships between yield components and physiological parameters. This study determined responses of leaf relative chlorophyll level (SPAD readings), photochemical efficiency of photosystem II in dark‐adapted leaves (Fv/Fm), leaf stomatal conductance (gs), net photosynthetic rate (Pn), transpiration rate (E), difference between leaf and air temperatures (Tl–Ta), and spectral reflectance in one Erianthus [Erianthus arundinaceus (Rez.) Jeswiet] and seven sugarcane genotypes and their relationships to yield components across genotypes. Reflectance, Fv/Fm, SPAD, gs, Pn, E, and Tl–Ta were measured on leaves at the top visible dewlap during the first‐ and second‐ratoon crops on a Margate sand soil (siliceous, hyperthermic Mollic Psammaquent) with or without mill mud added before planting. Mill mud application reduced leaf reflectance at wavelengths of 560 and 710 nm and significantly increased leaf SPAD, gs, Pn, and E in the first‐ratoon crop only. Genotypic differences were detected in most physiological traits and yield components. Most physiological traits correlated with cane and sucrose yields when no mill mud was added. Genotypic variation in physiological and yield responses to mill mud application and genotype × mill mud interactions in yields indicated that augmenting yield selection of genotypes with leaf physiological traits will improve sugarcane breeding programs for sand soils.