Nondestructive discrimination of cabbage plants infected with verticillium wilt using contrast media and an X-ray apparatus

Discrimination between plants diseased by Verticillium wilt of cabbage and healthy plants was tried by using the super soft X-ray apparatus and computed tomography (CT) system. The X-ray photograph of clear contrast were obtained by dipping roots in the undiluted solution of Gastrografin 76% and Urografin 60% (medical X-ray contrast media) for 15 to 20 hr, without any detrimental influences on cabbage tissues. Nondestructive fluoroscopy using the super soft X-ray apparatus did not discriminate discolored vascular bundles from diseased plants, whereas a nondestructive CT system coupled with the X-ray contrast media yielded a clear photograph in the transverse section of vascular bundles. On the early and middle stages of growth, the vascular bundle parts absorbing the contrast media and not absorbing were appeared on the CT photograph of the diseased plants. These not absorbing parts and vascular browning parts coincided on some but not on others. The parts that did not coincide were the early diseased vascular bundle before the browning. Therefore, it was expected that early diseased plants cannot be discriminated by the naked eye. On diseased plants at harvest, the vascular bundle parts that did not absorb the contrast media coincided with vascular browning parts by the naked eye. Therefore, when the sample was made to absorb the medical X-ray contrast media, the use of nondestructive photograph analysis using CT system may discriminate Verticillium infected plants from healthy ones. Furthermore, the method may be usable for breeding disease resistant cabbage cultivars.