| Budget Amount *help |
¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Research Abstract |
We irradiated UV-C rays on plant seedlings of vegetable under same intensity (23 muW), changing duration from 0 to 150 minutes, just before transplant. Plants grew much more at about 30 minutes of irradiation, and less under longer irradiation, that is, plant growth were effected in both ways of acceleration and inhibition depending on duration of irradiation of UV-C rays.
We considered this phenomena from point of view of the logistic theory for plant growth, and made clear the mechanism the optimum factor, one of the action form of environment elements. This means that there is the most favorable value of irradiation time for plant growth, which accelerate growth much more than the normal. Such result was appeared in two weeks after UV-C rays irradiation.
As the key point of acceleration of growth, there was the inhibition of growth to leaves in every treatments during about one week after irradiation, and activity in roots was increased in the same time. We confirmed it by the hydroponic cultivation, that is, the comsumption rate of disolved oxygen increased quite large in the same duration of inhibition of leaves.
Though measurements of photosynthetic rate, transpiration rate and stomata conductance, water use efficiency (= photosynthetic rate/transpiration rate) were changed greatly by UV-C rays irradiation from low in the first one week to high in the next 2-3 weeks, comparing to the non-treated vegetable.
By the experiments on the effect of air temperature on growth of irradiated seedlings in summer and wingter, it was made clear that the duration of inhibition was shorter in high temperature than in lower temperature, and the degree accelerated growth in the field was higher in summer, This means that such method using UV-C rays to plant seedlings may be one of favorable methods for taking measurement against comming global warming.
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