SULPHATE CONTENT OF THE LEAF-TISSUE FLUIDS OF 
EGYPTIAN AND UPLAND COTTON 1 
By J. Arthur Harris, headj Department of Botany, University of Minnesota, and 
collaborator, Bureau of Plant Industry, U. S. Department of Agriculture; Clara 
T. Hoffman, field assistant, Office of Alkali and Drought-Resistant Plant Inves¬ 
tigations, Bureau of Plant Industry, U . S . Department of Agriculture (1928-24) 
and Walter F. Hoffman, assistant agricultural biochemist, Division of Agri¬ 
cultural Biochemistry, Minnesota Agricultural Experiment Station 
INTRODUCTION 
Previous investigations by the Office of Alkali and Drought- 
Resistant Plant Investigations and the Office of Biophysical Investi¬ 
gations of the Bureau of Plant Industry, United States Department 
of Agriculture, have shown that the Egyptian and Upland types of 
cotton are differentiated not merely by well-marked external botan¬ 
ical characters ( 6 ) 2 but by the physicochemical properties of their 
leaf-tissue fluids. 
Since these physicochemical properties may be of significance as 
factors underlying differences in the drought and salt tolerance of 
the two forms as grown under the saline conditions of the Southwest,, 
it has seemed desirable to investigate them in detail. In a first, 
study (4) based on cultures made in 1920 and 1921 it was shown that 
Pima Egyptian and Meade and Acala Upland cottons are differen¬ 
tiated with respect to the osmotic concentration, specific electrical 
conductivity, and hydrogen-ion concentration of their leaf-tissue 
fluids. These results have been confirmed by unpublished studies, 
on these and on other varieties of Egyptian and Upland cotton 
grown in 1922, 1923, and 1924, and the investigations have been 
extended to the tissue fluids of the Fi and F ? hybrids. The results 
of these investigations are only partially published. 
In their first discussion of the differentiation of the two types of 
cotton with respect to osmotic concentration as measured in terms 
of freezing-point depression, A, and specific electrical conductivity, k , 
the writers pointed out that the higher value of the specific electrical 
conductivity and the possibly higher value of the ratio of specific 
electrical conductivity to freezing-point depression, k/A, in the 
Egyptian type evidence a greater capacity of this type for the 
absorption and retention in solution of salts derived from the soil. 
It has since been shown (5) that the chloride content of the leaf- 
tissue fluids of Pima Egyptian cotton is significantly higher than that 
of Meade, Acala, and Lone Star Upland cotton grown in immediate 
association. The present investigation has to do with the sulphate 
content of the Egyptian and Upland types of cotton. 
1 Received for publication Dec. 24, 1924; issued December, 1925. 
2 Reference is made by number (italic) to “Literature cited,” p. 661* 
Journal of Agricultural Research, 
Washington, D. C. 
( 653 ) 
Vol. XXXI, No. 7 
Oct. 1, 1925 
Key No. G-509 
