Hoagland 



— 80 



Plant Nutrition 



period of illumination, with relatively large absorption 

 of water. In summer the total salt absorption for 24 

 hours was approximately double that for 12 hours, 

 but in winter, with its deficit of light energy restrict- 

 ing growth and metabolism, the total absorption for 



gao 



z60 

 w 

 o 

 a 



z 

 te20 



z 

 < 



Z80 



a 



H60 



§40 



a 



WINTER 



SUMMER 



Ca 



PQ. 



ORGANIC DRY 



MATTER WEIGHT 



100 



eo 



60 

 \M> 



20 



O 



rlOO 



60 



60 

 -40 



20 







Textfigure 22. — Distribution of various nutrients in 

 barley plants between root and shoot under various meth- 

 ods of supplying salt to the plants, i.e. during day or 

 night or for full 24 hours. (Each set of 3 blocks repre- 

 sents the 3 conditions). Experiments are shown for sum- 

 mer and winter seasons. In all cases most of the nutrients 

 were found in the shoots. (Shown by vertical distribu- 

 tion). (From Broyer and Hoagland). 



24 hours was considerably less than twice that for a 

 12 hour period. 



Evidently the plants were at work absorbing salt 

 the full twenty-four hours, when salt was made avail- 

 able to them for this period. It was not the movement 

 of water that chiefly determined the amount of salt 

 absorbed, but rather the metabolic activities of the 



