350 S. M. Siegel and F. Porto 



Table 3. Interaction of peroxides and antioxidants in seed germination. 



Growth promotion under ordinary atmospheric conditions is com- 

 mon to a number of protectants against oxygen stress. Thus lAA and 

 indole reduce damage by oxygen, ozone, and organic peroxide; mesca- 

 line and isoniazid protect against ozone; C0+2 protects against oxy- 

 gen, hydrogen peroxide, and organic peroxides. 



One example will illustrate the effects of simultaneous treatment 

 with several protectants: lettuce seed in 5 X 10"^ Af p-menthane hydro- 

 peroxide failed to germinate even after 100 hrs. at 25°C. With 

 lO-^M ascorbic acid, 4 seeds germinated in a population of 200; 

 with 10-^M lAA or CoCU, 10 germinated. Addition of ascorbic acid 

 to lAA had no further effect, but mixtures of CoClo either with 

 ascorbic acid or lAA permitted germination of 14 seeds. Finally, all 

 three protectants combined enabled 26 seeds to germinate. 



If the antioxidant properties of hormones are functionally im- 

 portant, hormonal recjuirements should be sensitive to environmental 

 oxidant level. This proposition was tested with elevated levels of 

 oxygen and peroxides. Reduction in oxidant level should lower the 

 hormone requirement. Elimination of the aerobic Co^- requirement 

 for C. tctani by removal of oxygen provides a partial test of the pro- 

 posed relationship. AVhen 2-week-old cucumber seedlings are held 

 under anaerobic condition (argon) for a limited period, the subse- 

 quent growth of hypocotyl sections is enhanced, and scnsiti\ity to 



