INFLUENCE OF WHEAT SEEDLINGS UPON THE 
HYDROGEN ION CONCENTRATION OF 
NUTRIENT SOLUTIONS" 
Linus H. JONES AND JOHN W. SHIVE 
Introduction 
That the reaction of nutrient culture media bears a very impor- 
tant relation to their biological properties is a fact that is well 
recognized. Consideration of H ion concentration is of vital im- 
portance in connection with plant culture studies, not only 
because of the profound influence which this factor exerts upon 
the manner in which plants respond toward certain nutrient ele- 
ments in the media, but also because of its intimate relation to 
plant growth in general. 
The H ion concentrations of some nutrient solutions commonly 
used for plant physiological studies undergo rapid and pronounced 
changes in contact with the roots of growing plants, while the 
reaction of other nutrient solutions changes only slightly or not at 
all under similar conditions, owing to the fact that they possess 
Strong buffer properties. The rate, direction, and degree of 
reaction change are dependent, of course, upon a number of differ- 
ent factors, some of the more important of which are the composi- 
tion and concentration of the nutrient solutions, and the species, 
age, and activity of the plants. It is not the purpose of this paper, 
however, to consider the various factors involved in the relation 
of the plants to the reaction changes which they may be capable 
of bringing about in nutrient solutions in which they are grown, 
but to report briefly an experiment carried out for the purpose 
of comparing the various nutrient solutions, commonly used for 
plant cultures, with respect to the initial H ion concentrations 
of the solutions, and to study the reaction changes induced in them 
by contact with the roots of young wheat plants. 
* Paper no. 68 of the Journal Series, New Jersey Agricultural Experiment Station, 
Department of Plant Physiology. 
391 
