Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2003
Publication Date: October 1, 2003
Citation: Reddy, K.R., Zhao, D., Kakani, V.G., Read, J.J., Sailaja, K. 2003. Linking cotton growth and yield to remote sensing [abstract]. Agronomy Abstracts. CD-ROM.
Three experiments were conducted in 2001 and 2002 growing seasons by varying nitrogen (N) fertilizer, plant growth regulator (PIX), and irrigation in order to investigate relationships between cotton hyperspectral reflectance (400-2500 nm) and growth and yield. Canopy spectral reflectance and leaf N concentration were measured weekly or biweekly during the growing season. Plant height, mainstem nodes, leaf area, and above ground biomass were also determined at different growth stages by harvesting plants in a 1-m row. Seed and lint yields were obtained by mechanical harvest. Linear relationships were found between leaf N and a simple ratio (SR) of leaf reflectance at wavelengths 517 and 413 nm (r2 = 0.70). Nitrogen deficiency significantly increased leaf and canopy reflectance in the visible range. Plant height and mainstem nodes were related closely to a SR of reflectance, R750/ R550, either by a logarithmic or linear function (r2 = 0.63~0.68). The relationships between LAI or biomass and canopy reflectance could be expressed in an exponential fashion with the SR or NDVI (r2 = 0.67~0.78). Leaf reflectance ratio of R517/R413 may be used to estimate leaf N concentration. Lint yields were highly correlated with the NDVI around the first flower stage (r2 = 0.64). Therefore, remote sensing information has the potential for in-season crop growth estimation, leaf N concentrations and crop yield.