6. Place two boxes on short days and the remaining two boxes on long 
days immediately after planting the seeds. 
7. Additional varieties and intermediate daylengths can be used to broaden 
the experiment. 
Observations: 
Note any differences in the top growth or plant habit at regular intervals 
during the course of the demonstration, Differences should become apparent 
in about 60 days. Carefully remove a few plants at random from a box on 
each daylength and note any differences in bulbing. Do this at regular 
intervals to determine the time of bulbing and the treatment on which it 
occurred. When bulbing is definitely apparent, the experiment may be 
terminated, The plants in the remaining box on each daylength may be 
harvested and the extent of bulbing on eachdaylength noted and recorded, 
Supplementary Reading: 
Boswell, V, R., and Jones, H. A. Climate and vegetable crops: Onions. 
In CLIMATE AND MAN, pp. 388-389. U.S. Dept. Agr., Yearbook of 
Agriculture, 1941. Government Printing Office, Washington, D. C. 
Jones, H. A, Onion improvement: Varietal adaptation. In BETTER 
PLANTS AND ANIMALS, II. Pp. 235-236. U.S. Dept. Agr., Yearbook of 
Agriculture, 1937. Government Printing Office, Washington, D. C. 
Magruder, R., and Allard, H. A. Bulb formation in some American ana 
European varieties of onions as affected by length of day. Jour. Agr. 
Res SA g-toe, LIST. 
Growth Through Agricultural Progress 
26 
* U.S. GOVERNMENT PRINTING OFFICE: 1961 O - 603311 
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