Submitted to: Biannual Workshop in Color Photography and Videography in Resource
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2005
Publication Date: 3/15/2006
Citation: Yang, C., Tong-Xian, L., Everitt, J.H. 2006. Evaluation of remote sensing technology for estimating cabbage physical parameters. In: Proceedings of the 20th Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment, Bethesda, Maryland. 2006 CDROM. Interpretive Summary: Ground surveys and hand sampling are commonly used to evaluate the effectiveness of different cultural practices and chemical control methods for cabbage production. This study examined aerial photography and ground reflectance data for estimating cabbage physical parameters such as plant diameter and head weight. Statistical analysis showed that cabbage physical parameters were significantly related to the photo-derived plant area and ground reflectance data. These results indicate that remote sensing could be used for evaluating cabbage growth and yield variations and for determining the efficacies of different insecticides for controlling cabbage insects.
Technical Abstract: Remote sensing has long been used as a tool to extract plant growth and yield information for many crops, but little research has been conducted on cabbage (Brassica oleracea) with this technology. The objective of this study was to evaluate aerial photography and field reflectance spectra for estimating cabbage physical parameters. A field experiment was conducted on a cabbage field with 81 experimental plots in south Texas in 2004; different insecticide treatments were applied to the plots. Aerial color-infrared (CIR) photographs were taken from the field shortly before harvest. Meanwhile, field reflectance spectra and plant physical parameters, including plant diameter, head diameter, plant weight and head weight, were measured from a total of 243 plants (three plants per plot). Plant area and digital values for the near-infrared, red, and green bands for each of the 243 plants were extracted from a digitized aerial CIR photo and four different vegetation indices, including the normalized difference vegetation index (NDVI), which was calculated. Correlation analysis showed that the cabbage physical parameters were significantly related to the photo-derived plant area and the spectral variables. Regression analysis showed that head weight was linearly related to plant area with an r2 value of 0.91, while head weight was related with NDVI with a quadratic equation and an r2 value of 0.66. Stepwise regression performed on cabbage head weight and the 651-band field reflectance spectra revealed that 71% of the variability in head weight could be explained by eight significant bands in the spectra. These results indicate that remote sensing can be a useful tool for evaluating cabbage growth and yield variations.