16 EFFECTS OF ARTIFICIAL SHADING ON PLANT GROWTH. 



n/2 light, but under n/5 illumination the strong taste had almost 

 entirely disappeared. When the light was reduced to n/7 the flavor 

 was even better, but the plants were by no means as desirable in 

 habit of growth as in brighter light. 



RADISH. 



In n/93 light the radish continued for 30 days in bed B. In bed A 

 all plants subjected to this reduction of light had died before this date. 

 At the end of 50 days plants were still growing in n/15 light, although 

 the growth was very slight. The shade tolerance of radishes is about 

 the same as that of lettuce. 



Growth was quite consistently better in n/2 and n/5 than in full 

 light, the plants having been not only heavier (Table VIII) but taller 

 (Table IX) and showing more nodes (Table XI). The plants in bed 

 A seem to have been better than those in bed B according to measure- 

 ments of height and weight, but observations at the end of the exper- 

 iment failed to show any consistent difference. 



General observations showed that the best growth of radishes took 

 place in sections 4 and 5, and a decided reduction in section 3 and in 

 full light. There was practically no production of roots below section 

 3. The effect of shade could not be noted in the flavor. 



POTATO. 



Because of the large amount of stored food material, potato plants 

 were able to continue growth in the deepest shade for a period of 50 

 days. At the end of 30 days there was a noticeable difference in the 

 height of the plants in the different shades (Table V), and by the end 

 of 50 days the plants under shades which gave a light intensity vary- 

 ing from n/7 to n/2 became much taller than normal, especially those 

 in bed A (Table IX). In diameter of stem there was little difference 

 either after 30 days or after 50 days. (Tables VI and X.) In weight 

 there was considerable variation after 30 days (Table IV), and even 

 more after 50 days (Table VIII). The plants gained greatly in weight 

 during this period in light n/2 to n/7, but in light n/15 the plants 

 weighed less at the end of 50 days than at the end of 30 days. This 

 loss is also indicated by the shrinkage of the diameter of the stem. 

 The number of nodes developed was greater in light n/2 to n/7, and it 

 is evident that the increased height was due to an increase in the num- 

 ber of nodes and not to greater length of the individual segments. The 

 number of nodes developed did not differ greatly in full light and in 

 light intensities of 1/15 normal or less. (Table XL) The height of the 

 plants was about the same in normal light as in a light intensity of 

 n/15. (Tables V and IX.) 



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