| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
With 7 Rhizoctonia isolates obtained from 4 orchid species out of 10, symbiotic capability to Spiranthes sinensis seeds was tested on oat medium. A binucleate Rhizoctonia isolate obtained from Gymnadenia camtschatica was the most effective symbiont to this orchid. Two binucleate Rhizoctonia isolates, possibly Rhizoctonia repens, obtained from Spiranthes sinensis itself were symbiotic to the orchid but far less effective. And there was a considerable difference between the two in their effectiveness.
The effect of culture media on the symbiosis was considerably large but it could not change the essential nature of the symbiosis. For this orchid the medium containing mineral・salts, 1% cellulose, 0.1% sucrose and 0.02-0.05% yeast extract was better than the oat medium for symbiotic culture.
The addition of mycelial powder or culture filtrate of the compatible fungus to non-symbiotic culture did not stimulate the germination or protocorm growth. Although this orchid was found to germinate non-symbiotically on a wide range of media irrespective of light conditions, the protocorm growth was very slow and it required more than 16 months from seeding to attain sufficient growth for transplanting. However, symbiotic seedlings attained to this state in less than 3 months.
The effect of population density on the growth of symbiotic seedlings was outstanding. This effect did not seem to have any relation to the competition among the aerial part of seedlings, but depended mainly upon the quantity of medium per individual seedling; there was a distinct linear relation between the growth of seedling and the amount of medium per individual. The enhancing effect of the quantity of medium on growth continued beyond 60ml of oat medium per individual seedling.
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