Figure 14.— Carbon-14 labeled corn plants at silking and 

 tasseling. growing in the biosynthesis chamber. 



added, and symptoms that resembled copper de- 

 ficiency developed. A new medium replaced the 

 old, and the chelate w T as left out. The plants then 

 recovered and grew fairly well. They were har- 

 vested at early heading when the plants were about 

 98 days old. Another crop of wheat will be grown 

 without chelate. 



Temperature was maintained at 67° F. ±1.5° 

 for 18 days, then was increased to 70° ±1.5°. 

 Daylength was 14 hours. Figure 15 shows young 

 wheat plants growing in the chamber. 



Growth of Tobacco 



Tobacco seed was germinated in the greenhouse, 

 and the seedlings grown in nutrient solution until 

 they were about 12 inches tall. Four seedlings 

 were then placed in the growth chamber in nutri- 

 ent solution Ci described by McMurtrey (J), ex- 

 cept that Perma Green Fel35 was added at 10 

 p. p.m. to supply iron. Two crops of radioactive 

 tobacco were grown. The first was labeled with 

 carbon-14, tritium, and nitrogen-15. The second 

 crop was labeled with only carbon-14. Three 

 weeks after placing the plants in the chamber, 

 the door was opened and the suckers removed and 

 the plants sprayed with maleic hydrazide, to re- 

 duce sucker growth and increase alkaloid 

 production. 



SUMMARY 



A biosynthesis chamber was designed, and 

 plants were grown in it from seedling stage to 

 maturity in an atmosphere containing carbon-14 

 dioxide. Carbon dioxide content of the chamber 

 was monitored and recorded constantly and C0 2 

 was introduced into the chamber automatically. 

 Light intensity, daylength, temperature, aeration, 



and partial control of humidity were achieved 

 with relatively simple equipment. Crops of corn, 

 soybeans, wheat, and tobacco were grown in solu- 

 tion culture in the chamber, and the incidental 

 problems associated with their growth were 

 largely solved. 



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