. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1074 BIOLOGICAL EFFECTS OF RADIATION Blaauw (5) the curvature of a plant resulting from unilateral illumination is caused by the light-growth responses of the opposite sides which are differently illuminated. The minimum amount of radiation required to produce phototropism is 20 meter-candle-seconds. It also appears that the product of light intensity and time of exposure is a constant.^ 80
. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1074 BIOLOGICAL EFFECTS OF RADIATION Blaauw (5) the curvature of a plant resulting from unilateral illumination is caused by the light-growth responses of the opposite sides which are differently illuminated. The minimum amount of radiation required to produce phototropism is 20 meter-candle-seconds. It also appears that the product of light intensity and time of exposure is a constant.^ 80 2, LIGHT-GROWTH RESPONSE Blaauw pointed out the fact that plant organs which show phototropic curvatures also show typical light- growth responses and where no re- sponse is observed neither is there phototropic curvature. D i 11 e w i j n (17) reasoned that, "If the theory of Blaauw is correct, it must be possible to deduce the phototropical curva- tures from the light-growth response of proximal and distal ; Using Avena saliva, he determined the light- growth response to several different quantities of light and also to one- FiG. 1.—Graphs showing growth of thirtieth of thcse quantities which Avena saliva. The abscissa represents , „ i i i- i • time in hours and the ordinate rate of he figured to be the light mtensity growth in microns per minute. The in- received on the distal sidc in com- tensity of hght is indicated in meter- . • i i • i candles. The light lines represent the parison With that received on the growthresponseforJ.^0 the light intensity proximal side. This value is greater of the response represented by the heavy . <• rr 7 • 7 1 • lines. The arrow indicates the moment lOr Avena than ior Helianthus and IS of illumination with the duration marked y^ry largely due to the light absorbed above. The predicted phototropic re- . 1 /• -\r v 1 sponse is indicated by plus and minus by the primary leaf. More light signs.
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Keywords: ., bookau, bookcentury1900, booksubjectbiology, booksubjectradiation
