Digital acquisition and measurement of peanut root minirhizotron images

Video, photo, or in situ image capture and analysis from minirhizotrons is time-consuming. Computerized root image analysis is expensive and subject to large background error, This paper describes a fast, simple, and accurate method for (i) capturing minirhizotron images through low-cost hardware upgrade of existing minirhizotron equipment, and (ii) processing digital images using low-cost software. This system was developed to monitor root distribution in peanut (Arachis hypogaea L.). Digital images were recorded from a minirhizotron camera directly to a laptop computer hard drive instead of using videotape. This reduced image acquisition time by 36% and eliminated problems associated with manipulating video players. The image analysis system uses a mouse pointer to trade root length and diameter on a computer screen and calculates the distance traversed by the mouse pointer. A paired t-test on accuracy using wires of known length showed no significant difference (P = 0.10) between actual and measured lengths.