Estimating cotton growth and developmental parameters through remote sensing

K. Raja Reddy; Duli Zhao; Vijaya Gopal Kakani; John J. Read; K. Sailaja

doi:10.1117/12.515226

22 December 2003 Estimating cotton growth and developmental parameters through remote sensing

K. Raja Reddy, Duli Zhao, Vijaya Gopal Kakani, John J. Read, K. Sailaja

Proceedings Volume 5153, Ecosystems' Dynamics, Agricultural Remote Sensing and Modeling, and Site-Specific Agriculture; (2003) https://doi.org/10.1117/12.515226
Event: Optical Science and Technology, SPIE's 48th Annual Meeting, 2003, San Diego, California, United States

Abstract

Three field experiments of nitrogen (N) rates, plant growth regulator (PIX) applications, and irrigation regimes were conducted in 2001 and 2002 to investigate relationships between hyperspectral reflectance (400-2500 nm) and cotton (Gossypium hirsutum L.) growth, physiology, and yield. Leaf and canopy spectral reflectance and leaf N concentration were measured weekly or biweekly during the growing season. Plant height, mainstem nodes, leaf area, and aboveground biomass were also determined by harvesting 1-m row plants in each plot at different growth stages. Cotton seed and lint yields were obtained by mechanical harvest. From canopy hyperspectral reflectance data, several reflectance indices, including simple ratio (SR) and normalized difference vegetation index (NDVI), were calculated. Linear relationships were found between leaf N concentration and a ratio of leaf reflectance at wavelengths 517 and 413 nm (R₅₁₇/R₄₁₃) (r² = 0.70, n = 150). Nitrogen deficiency significantly increased leaf and canopy reflectance in the visible range. Plant height and mainstem nodes were related closely to a SR (R₇₅₀/R₅₅₀) according to either 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 [(R₉₃₅-R₆₆₁)/(R₉₃₅+R₆₆₁)] (r² = 0.67~0.78). Lint yields were highly correlated with the NDVI around the first flower stage (r² = 0.64). Therefore, leaf reflectance ratio of R₅₁₇/R₄₁₃ may be used to estimate leaf N concentration. The NDVI around first flower stage may provide a useful tool to predict lint yield in cotton.

Citation Download Citation

K. Raja Reddy, Duli Zhao, Vijaya Gopal Kakani, John J. Read, and K. Sailaja "Estimating cotton growth and developmental parameters through remote sensing", Proc. SPIE 5153, Ecosystems' Dynamics, Agricultural Remote Sensing and Modeling, and Site-Specific Agriculture, (22 December 2003); https://doi.org/10.1117/12.515226

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