Role of Auxins iti Control of Leaf Senescence 



333 



4 - 



X 



in I 



X 



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 a: 

 li- 



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TOTAL NITROGEN 



• 2:4-D treated areas of leaf 

 3 2:4-0 untreated areas of leaf 

 O Control leaves 



INSOLUBLE NITROGEN 



^'^-^ 



SOLUBLE NITROGEN 



6 8 10 

 DAYS AFTER TREATMENT 



14 



Fig. 2. Nitrogen content of discs cut from 2,4-D-treated Euonymus leaves and 

 from control leaves at various time intervals after treatment. Values which are 

 significantly different (P = 0.65) from the respective control at any one time- 

 point are marked with an asterisk. 



polyethylene bag attached to a flask containing BaCi403. Carbon di- 

 oxide was liberated by injecting an excess of perchloric acid through a 

 vial closure to give an internal concentration of approximately 2 per 

 cent COo and a total of 50 microcuries of C^^ as Ci^Oa- Four hours later 

 the bag was removed, and drops of 2,4-D ester in ethanol, or ethanol 

 only, were applied to the leaves in the manner previously described. 

 At intervals of 2.5, 6.5, and 12 days from the application of 2,4-D, 



