6o Diseases of Greenhouse Crops 



veloped a height fifteen times as great as that in the 

 blue house, where practically no growth was made. 

 The red light in this case acted as a fertilizer. 

 Moreover, the sensitiveness of the plants grown in 

 the red house had increased considerably. The 

 slightest movement or breath was sufficient to cause 

 the leaflets to close, or the pedicels to droop. The 

 sensitiveness diminished under the white or green 

 color, while under the blue glass the sensitiveness 

 was almost lost. The plants in the red house were 

 first to bloom. In the white house they increased 

 in stockiness and in vigor, but did not seem to in- 

 crease in height. The plants in the house with the 

 red glass possessed foliage which was lighter than 

 those grown in the white house, while under the 

 blue glass the foliage was much darker. After three 

 months the height of the plants in the different 

 houses was as shown in Table 8. 



Table 8 



Date 



Red 



White 



Green 



Blue 



June 13 



Meter 

 0.030 



Meter 

 0.030 



Meter 

 0.030 



Meter 

 0.030 



July 22 



0.230 



0. 120 



0.080 



0.035 



August 16 



0.380 



0.240 



0. 100 



0.035 



August 30 



0.470 



0.270 



0. 100 



0.035 



October 12 



0.500 



0.380 



0.100 



0.035 



From the preceding table it is seen that the 

 plants in the hothouse with the red glass attained 



