Development of Leaf Spectral Models for Evaluating Large Numbers of Sugarcane Genotypes

Abstract

Leaf reflectance has been used to estimate crop leaf chemical and physiological characteristics. Sugarcane {Saccharum spp.) leaf N, C, and chlorophyll levels are important traits for high yields and perhaps useful for genotype evaluation. The objectives of this study were to identify sugarcane genotypic variation in leaf hyperspectral reflectance, leaf chemical (chlorophyll, N, and C), and yield (juice sucrose content, commercial recoverable sucrose [CRS], cane yield in tonnes of cane per hectare [TCH], and sucrose yield in tonnes of sucrose per hectare [TSH]) traits and to determine relationships between leaf reflectance and these chemical and yield traits. In Stage II of the Canal Point, FL, sugarcane cultivar development program, we measured spectral reflectance and chemical traits on three leaves of the top visible dewlap from each of 87 genotypes in December

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

“…1E-G) with the CV values ranging from 3.8 to 68.3% across years and wavebands (Fig. Zhao et al (2012b) also found that leaf reflectance values had the greatest variation among sugarcane clones at wavelengths of 550 and 710 nm. Similar to the results observed in the CV patterns of canopy reflectance at different wavebands across clones, the two peaks of CV values of reflectance across measurement dates were also found in two wavebands centered at 550 and 800 nm.…”

“…Johnson and Richard (2011) suggested that simple models of sugarcane leaf reflectance before maturity could be developed to describe much of the variability in stalk sucrose levels in Louisiana. Our results indicated that it was difficult to develop a quantitative relation between CRS and sugarcane leaf (Zhao et al, 2012b) or canopy reflectance measured during early and mid-growth stages under the conditions of these studies at Canal Point, FL. In the present study, stalk population, cane yield, and sucrose yield were most significantly and positively correlated with canopy reflectance in wavelengths of 800, 980, and 1200 nm (i.e., near-infrared range) in all 3 yr, although these three yield traits correlated with reflectance in other wavebands in 1 or 2 yr (Table 5).…”

“…Weed control and other field management activities are performed based on the routine management practices at the location. These Stage II clones are evaluated for diseases in June through July of the coming year and for yield and final harvest in October through November on plant cane crop only in the CP program (Zhao et al, 2012b). For the 2010, 2011, and 2012 planted clones at Stage recoverable sucrose, which was calculated as described by Legendre (1992).…”

“…Thus, Zhao et al (2012b) investigated the quantitative relationships between leaf hyperspectral reflectance and leaf N, chlorophyll, and yield traits across large numbers of clones. Thus, Zhao et al (2012b) investigated the quantitative relationships between leaf hyperspectral reflectance and leaf N, chlorophyll, and yield traits across large numbers of clones.…”

“…Most of these reflectance-related studies in sugarcane primarily focused on classification or discrimination but not quantitative equation development with limited numbers of sugarcane cultivars or clones. Thus, Zhao et al (2012b) investigated the quantitative relationships between leaf hyperspectral reflectance and leaf N, chlorophyll, and yield traits across large numbers of clones. They found that leaf reflectance could well estimate leaf N and chlorophyll contents but had poor or no correlation with yield components.…”