Evaluation of Digital Image Acquisition Methods for Determining Soybean Root Characteristics

Advances in root research have occurred with the use of computer digital image analysis. The WinRhizo system has the capability of analyzing images acquired from a flatbed scanner, digital or video camera, and image files. The objectives of this study were to compare the use of a digital camera with that of a flatbed scanner as the method of acquiring root system images, and to determine the usefulness of the WinRhizo software for quantifying root characteristics of soybean [ Glycine max (L.) Merr.]. Digital camera and scanner images of string segments and soybean roots from the field and greenhouse were analyzed using the WinRhizo software. Root surface area, volume and average diameter estimates from digital camera images were up to 3, 17, and 6 times greater, respectively, than those estimated from a scanned image of the same root. Immersing roots in water prior to scanning significantly increased estimated values for root length, surface area and volume by 13, 20, and 33 percent, respectively. Digital image analysis of root systems depends on the quality of the root image, and on the preparation of the root system for photographing or scanning. Computer digital image analysis can be used effectively to analyze root systems if special precautions are taken to avoid certain errors.