Assessment of density effects of the common scab-inducing pathogen on the seed and peripheral organs of potato during growth using computed tomography scanning data.

摘要

A new approach to investigating the density effects of a disease on the below-ground organs of a crop plant during growth was developed. The method was evaluated in potato cv. Shepody infected with common scab caused by Streptomyces scabies [S. scabiei]. Two groups of plants were grown in plastic pots in a greenhouse. One group was composed of diseased plants whose seed potato was planted in sand inoculated with S. scabies EF-35, a common scab-inducing strain, and the other was composed of healthy plants (controls). The content of the pots was subjected to computed tomography (CT) scanning every 2 weeks over a period of 10 weeks following planting using a zoom factor of 2 and the helical scan option of a CT scanner formerly used in medical applications. Histogram analysis of CT numbers previously transformed to account for differences in soil moisture content provided the basis for curve fitting. The mean parameter estimates of fitted models and their increments (first differences calculated every 2 weeks) were subjected to repeated-measures ANOVA. On average, the densities of the seed and peripheral organs at 2 weeks after planting were significantly higher in diseased plants than in healthy plants, and changes in density from week 0 to week 2 and from week 2 to week 4 were also significantly different between the 2 groups, reflecting a significant treatment-by-time interaction. These findings demonstrate the development of common scab disease in potato and the potential of the plant CT scan approach in phytopathological studies.