CONTROLLED ENVIRONMENTAL CONDITIONS 



303 



Figure 123. (31) Premier and Hoosier Beauty roses grown in gantry crane house 

 with additional light and CO2 showing the effect in forcing clusters of three sturdy 

 roses at one time. New canes with flowers were produced from the root-stock in about 

 the same time required to produce a single flower bud from existing canes in the control 

 plants. (32) Nasturtium plants 70 days old from seed. The one in the center receiving 

 both additional hght and gas is flowering profusely. The plants from Greenhouse 1 

 receiving additional light only are little better than the controls (at right) on the normal 

 length of day. (33) Geranium showing the flowering with supplementary light in Green- 

 houses 1 and 2 and the injury of continuous illumination (24-hour day). The control 

 plant is at the right. (34) Variegated coleus, showing the increased growth with both 

 additional light and gas (Greenhouse 2) as compared with additional light only (Green- 

 house I) at left and control greenhouse at right. The 24-hour day plant shows considerable 

 light injury. (35) Eggplant showing the additional growth and fruiting with additional 

 light only (left) and with both light and gas (center). The control at right did not fruit 

 during the experiments. 



It is seen in Fig. 123 that a ten-fold increase in CO2 in the air wdth 6 hours' 

 extra illumination gives a marked increase in the growi;h and flowering of 

 rose, geranium, nasturtium, and eggplant, and also in the gro^\-th of varie- 



