COMPUTER-VISION-BASED SYSTEM FOR PLANT-GROWTH ANALYSIS

A computer vision system with a CCD camera and an infrared lighting ap paratus was developed to conduct noncontact, three-dimensional plant g rowth analyses. The infrared lighting apparatus was designed to obtain plant images in the dark by exposing plants to wavelengths of 800 nm and greater. Processing algorithms were developed to extract plant out lines, detect node positions, and produce thinned lines from images. T he system was capable of resolving interimage differences of 5% of a p ixel, or 0.025 mm. The system was tested by conducting growth analysis of Verbena bonariensis L. stem elongation. Using a mirror, front and side plant images were simultaneously captured every 12 min for three days and were stored on a magneto-optical disk. Three-dimensional stem length and growth rates were computed from the images. A comparison o f stem elongation during the light showed that growth rate was dramati cally different from that during the dark. Growth rate significantly i ncreased after the transition from night to day. The average growth ra te during the light and dark was 1.70 and 0.56 . mm h(-1), respectivel y.