Abstract
The effect of light on maturation of apothecia of Sclerotinia trifoliorum Eriks. was tested by means of planting the sclerotia in moistened sand under the different light conditions in the glass house (15∼20°C). The maturity of apothecia was observed by dividing into the following three grades: i. e., the mature apothecia of which discs expand normaly, and discharge numerous ascospores; the intermediate apothecia having fleshy and long stipes, and bearing relatively less amount of ascospores; and the immature apothecia which have slender, longer and peaked apical ends and bear no ascospore.
The treatment of sclerotia under continuos darkening for 10 days did not affect the maturation of apothecia if they were transplaced under the natural light condition, but the dark treatment for more than 15 days disturbed their maturation in proportion to the length of treatment. Namely, by the continuous 25-days-darkness, 70 per cent of the immature apothecia was resulted despite the keeping of natural light for 15 days after the same darkness mentioned above, but in the continuous darkness for 40 days all the apothecia lasted immature.
The apothecia matured also under the contiunous fluorescent light (White 1, 800lux), and 3-days-alternation of darkness and light, but 15-days-alternation of darkness and light affected slightly to maturation. On the contrary, most of apothecia were immature by 15-days-alternation of light and darkness. And by the other different treatments of change from darkness to light or from light to darkness, mature, intermediate and immature apothecia appeared at the different percentages (v. fig. 2).
Under the light conditions filtered through the cellophanes of different colours, i. e., colourless, yellow, blue, green, and violet, apothecia matured generally, except red cellophane under which many of them lasted immature and failed to produce spores.
As regard to the intensities of illumination, apothecia lasted immature under the illumination less than 100lux, but 50per cent of them were intermediate under 200lux, and 78per cent matured under 600lux, in comparison to full maturation under the conditions of 1, 000∼1, 400lux.
