Hoa gland — 76 — Plant Nutrition 



greatly, under the influence of these factors of root 

 environment, even when the same nutrient solution 

 and the same aerial environment are provided for the 

 plants. Further, at any given period the amount of 

 salt absorbed by the plant per unit of water absorbed 



ABSORFTIOH AKD TRANSLOCATION OF SALT IH A CnCURBIT 



In another experiment, a lerge plant rapidly trans- 

 piring, but with roota In a non-aerated aolutlon, 

 absorbed In the roots very little Br and none was 

 translocated to upper parte of the plant. Large 

 amounts of Br were absorbed end translocated in plant* 

 with aerated roots* 



Table 3. — Absorption a»nd translocation of salt in a cu- 

 curbit as affected by conditions influencing transpiration 

 and by aeration of culture solution. (From Broyer). 



will depend on the amount of salt already absorbed 

 and on available sugar and probably other organic 

 substances stored in the roots.* 



Another simple experiment will illustrate the view 

 that salt does not normally move into a plant merely 

 in relation to the water absorbed. A large and actively 

 transpiring squash plant had its roots placed in a 

 solution containing bromide, with insuflficient aeration 

 of the roots. A little bromide entered the roots, but 

 none at all, within experimental error, was found in 

 the stems or leaves. A similar plant which had its 

 roots well aerated not only absorbed much more 

 bromide but also translocated significant amounts to 

 all parts of the shoot. I may add that squash roots 

 have a high requirement for aeration under ordinary 

 water culture conditions. 



* Early experiments of this laboratory (Hoagland, 1923) 

 gave definite evidence on the differential absorption of water 

 and solutes but the full implications of the experiments were 

 not appreciated at the time. 



