SALT RELATIONS OF VASCULAR PLANTS 



129 



significantly alter root growth or influence the rate at which 

 potassium was transported into them from the cotyledons. 



F. Foliar Absorption 



Aquatic vascular plants, for example Elodea, Lemna and 

 VaUisneria species, absorb the bulk of their nutrient supply through 



lOOr 



I 2 3 4 5 6 7 



Days since the start of germination 



Fig. 44 (a). Movement of salts in germinating seedlings 

 Iron content of cotyledons (O — O) and axis (x — x) of kidney bean 

 seedlings during the first week of germination (redrawn from Biddulph, 1951); 



the surface of the leaves, and the same is probably true of certain 

 aerial epiphytes of tropical and subtropical regions which grow 

 attached to inanimate objects. Even terrestrial plants which do not 

 normally absorb much salt in this way will readily do so when salt 

 solutions are applied to the leaf surface. This has led to the important 

 agricultural and horticultural technique of foliar feeding (Blatt- 



