| Emitted energy was measured from photographs of the spectra of the following lamps: white fluorescent, daylight fluorescent, standard cool fluorescent, white fluorescent-incandescent mixture, and standard cool fluorescent-incandescent mixture. The energy values obtained for each type or mixture of lamps were relative to the energy of a standard lamp spectrum and were, therefore, relative to each other allowing a comparison of their influence on plant growth.;The bean plants grown under the fluorescent lamps alone were of smaller stature, leaf area, and dry weight than those grown under the fluorescent-incandescent lamp mixtures. There was a drop in net assimilation rate in the latter part of the vegetative phase of bean plants grown under the fluorescent lamps. The drop in rate was replaced by a rise upon the addition of incandescent lamps to the fluorescent light panel. The addition of incandescent light and the resultant increase in energy was responsible for the rise in plant leaf area, dry weight, and increased photosynthetic rate. The energy of the types of fluorescent lamps tested was insufficient to support optimum growth of bean plants.;Beans were grown from seed and sampled at 160, 208, 256, and 304 hours of light from the straightening of the hypocotyl hook. From the average leaf area and dry weight, net assimilation rates were calculated from the formula W2-W1 A2-A1 xlogeA2-log eA1T2-T 1 where W2, W1, A2, and A1 are the average plant dry weight and leaf area at times T2 and T1 respectively. |
