16 



MINERAL SALTS ABSORPTION IN PLANTS 



Details of a successful method of preparing excised roots for 

 salt absorption studies were given by Hoagland and Broyer (1936), 

 and this technique with variations has been employed in a number 

 of more recent investigations. 



3. Slices of Storage Tissues 



De Vries (1871) used thin sections of red beet (Beta vulgaris) in 

 an investigation of the permeability of plasmolysed protoplasts, 

 but Nathanson (1904) and Meurer (1909) were perhaps the earliest 

 investigators to employ storage tissue parenchyma on a large scale 

 in absorption studies, and to point out its advantages. The material 



100 



o 

 u> 



O 



a> 

 a> 

 o 



c 



2 

 to 

 a. 



150 



hr 



Fig. 4. Absorption of manganese ( — ) and chloride (— ) from a solutiorn 

 of manganese chloride (0-001 M) by parsnip tissue washed for either 24 hr 

 (o) or 168 hr (x) in aerated distilled water (redrawn from Rees, 1949) 



is readily available in bulk, is easily prepared, and under suitable 

 conditions takes up salts readily. Storage organs which have been 

 widely used include potato {Solanum tuberosum) and artichoke 

 (Helianthus tuberosus) tubers; turnip and swede (Brassica rapa) 

 hypocotyls; red beet and carrot (Daucus carota) roots. 



Freshly-cut slices of these tissues absorb salts slowly, but the 

 cells become more active after washing for a time in aerated distilled 

 water or dilute salt solution (Fig. 4). The fact that some tissues, e.g. 

 the pulp of mature apple fruits, cannot be successfully reactivated in 

 this way, merits further investigation. Steward (1937) emphasized 



