2020 Volume 19 Issue 1 Pages 21-27
We applied the rhizosphere soil assay method used for asparagus, and conducted the following tests to establish a soil sickness risk evaluation method for the Japanese pear. First, when we measured the pear soil gradually diluted with non-pear soil with the rhizosphere soil assay, the inhibition rate of soil decreased from 75.6 to 18.3% according to the level of dilution (y = 12.9ln(x) + 11.5, r = 0.97, x: proportion of pear soil, y: percentage of soil inhibition). In addition to this, in the same way as the above-mentioned test, we gradually diluted the pear soil with non-pear soil, and we planted an annual nursery of pear. As the results, the growth of shoots increased accordingly. Therefore, it was clear that the rhizosphere soil assay method was effective as a technique to evaluate the risk of soil sickness for the pear. On the other hand, when we measured the soil around a pear tree planted in the field with the rhizosphere soil assay method, it was revealed that there is a difference in distance and depth.