3. Filter paper (Whatman No. 3). 
4. Black bags made of two layers of black sateen cloth. 
5. A solution of 3 percent hydrochloric acid (HCl) in absolute propanol 
(propyl alcohol) (3 ml. HCl in 97 ml. of propanol). 
Procedure: 
1. Place three sheets of filter paper in each petri dish and moisten with 
water. 
2. Place 20 seeds on the filter paper, cover the dishes with the lids, and 
place each dish in a black cloth bag, keeping the temperature at about 
SOC F. 
3. Allow 4 days for the seedlings to germinate and then begin treatments. 
4, Place the dishes under the fluorescent lamps for periods of 0, 4, 8, 16, 
or 24 hours, then return the dishes to their black cloth bags. 
5. The amount of anthocyanin formed can be observed from 16 to 24 hours 
after irradiation, 
6. Count out a certain number of seedlings (say 10) from each dish and 
place each lot of 10 seedlings inthe solution of HCl in l1-propanol. Place 
them in a refrigerator (about 40°) for 16 to 24 hours. 
Observations: 
The amount of anthocyanin formed by the various light treatments can be 
estimated by assigning a numerical scale that increases with increasing 
color, or it can be measured by differences in optical density as measured 
with a colorimeter. or spectrophotometer. The amount of anthocyanin can 
then be plotted graphically by plotting the amount of anthocyanin as a 
function of the time (hours of light). 
Supplementary Reading: 
Siegelman, H. W., and Hendricks, S. B. Photocontrol of anthocyanin 
synthesis in turnip and red cabbage seedlings. Plant Physiol. 32: 393- 
39ISLT 1957. 
DEMONSTRATION C-2: Effect of light on tomato skin and fruit color. 
Materials: 
1, Mature green tomato fruits from a normally red-fruited variety when 
ripe, such as the variety Rutgers, Their skin color should be greenish- 
white with no visible red, pink, or yellow color. These are readily ob- 
tainable from home gardens any time prior to frost and from local 
wholesale vegetable distributors in the larger cities where southern- 
grown green-mature fruits can be obtained throughout the winter. 
2. A light facility, using incandescent or fluorescent lamps that provide a 
eee intensity of 20 foot-candles or more. Keep the temperature at 
OE, 
3. A dark facility that provides total darkness, using light-tight black 
bh oe cloth bags made of two layers of cloth. Keep the temperature at 
TO 
19 
