THE PHILIPPINE 
JOURNAL OF SCIENCE 
VOL. 17 DECEMBER, 1920 No. 6 
THE RELATION OF SALT PROPORTIONS AND CONCEN- 
TRATIONS TO THE GROWTH OF YOUNG WHEAT 
PLANTS IN NUTRIENT SOLUTIONS CONTAINING A 
CHLORIDE 
By Sam F. TRELEASE 
Of the College of Agriculture, Los Bafos, P. I. 
TWELVE TEXT FIGURES 
INTRODUCTION 
For the development of higher plants the chemical elements 
carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, cal- 
cium, magnesium, potassium, and iron are unquestionably neces- 
sary. Carbon mainly derived from the carbon dioxide of the 
air, together with hydrogen and oxygen, which enter through 
the roots in the form of water, make up by far the greater por- 
tion of the plant substance. But the other necessary elements 
must be supplied and they also enter through the roots from 
aqueous solution. With the exception of iron, of which but 
little is needed, these essential elements must be furnished in 
relatively large amounts. 
That higher plants require nitfogen, sulphur, phosphorus, cal- 
cium, magnesium, potassium, and iron in an aqueous solution 
about their roots was pointed out very early by Birner and 
Lucanus.? These writers supplied the necessary elements in 
* Botanical contribution from the Johns Hopkins University, No. 58. 
* Birner, H., and Lucanus, B., Wasserculturversuche mit Hafer. (In 
der agr.-chem. Versuchs-station zu Regenwalde i. J. 1864 durchgefiihrt.) 
Landw. Versuchsst. 8 (1866) 128-177. 
175542 527 
