18 



EFFECTS OF ARTIFICIAL SHADING ON PLANT GROWTH, 



were noticed. After 50 clays, however, the greatest growth was 

 recorded in n/2 light. In the full light great reduction was noticed 

 in the weight of the plant in each case. It is especially interesting 

 that cotton, which is supposed to be a sun-loving plant, was the only 

 plant able to remain alive and in a healthy condition in light as weak 

 as n/93 for as long a period as 50 days. The plants continued in 

 n/15 light in both beds until the end of the experiment, although no 

 appreciable increase in weight resulted. 



In height the best growths recorded were in light of an intensity 

 equal ton/7 or stronger. (Tables V and IX.) In n/93 and n/15 the 

 plants were not noticeably taller at the end of 50 days than at the end 



Fig. 9.— Relative sizes of potato plants 50 days after the beginning of growth. The numbers correspond 

 to those of the shades and the letters indicate the two beds in the experiment. (Traced from photo- 

 graph.) 



of 30 days. In each case the height in normal light at the end of 50 

 days was less than in n/7 to n/5 light. 



The relative diameter of stem is shown in Tables VI and X, and 

 was usually greater in the weaker shades than in full light. A notice- 

 able difference also occurred in the number of nodes developed at the 

 end of 50 days, an increase in number having been observed in the 

 weaker shades. (Table XL) 



A good idea of the appearance of the plants at the end of 30 days in 

 the bed with the fan is given in Plate II, figure 1, and in the bed with- 

 out the fan in Plate II, figure 2. No appreciable reduction in growth 

 took place until the light was reduced below n/7. The relative size of 

 the plants at the end of the experiment (after 50 days) is shown in 

 figure 10. 



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