Characteristics of an Inliibitor From Woody Shoots 



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Fig. 1. Growth of wheat coleoptile sections in mixtures of NalAA and inhibitor. 

 Concentration of lAA in p.p.m. shown on the right hand edge increasing from 

 front to back; concentration of inhibitor in ints/ml shown on the left hand edge 

 increasing from back to front. Growth shown on the vertical scale as per cent 

 increase over original length. 



ment, though supra-optimal, resulted in section growth only just 

 below the controls). The left front edge shows the response to in- 

 hibitor (also on a logarithmic scale) with concentration increasing 

 from back to front. 



While the general effect of increasing concentrations of inhibitor 

 is clearly to reduce growth in each auxin concentration, the detailed 

 interactions of the two substances are somewhat obscured by variabil- 

 ity in response; up to the optimum NalAA (5 p.p.m.) a given concen- 

 tration of inhibitor has a fairly similar effect at all auxin levels. 



