Spectral indices for yellow canola flowers

Reproductive growth, such as by flowers, may contribute to a canopy-level signal yet there are no current indices that measure variation in flowering. This study was conducted to determine how flowers influence the overall canopy signal and what bands of light may be useful for estimating variation in flower density and leaf area index (LAI). The effects of the number of yellow flowers per unit area and LAI on canopy spectral reflectance of spring canola (Brassica napus L.) were investigated in a field study consisting of three water regimes and three fertilizer nitrogen levels near Pendleton, Oregon, USA. A band ratio of green and blue light was strongly (r2 = 0.87) related to the number of yellow flowers per unit area, whereas a ratio of near-infrared and blue light was most suitable for estimating LAI during flowering. Spectral information during flowering may improve how remote sensing is used to describe plant development and reproductive capacity during the growing season.

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