STUDIES ON THE OXIDIZING POWER OF ROOTS 1 



Oswald Schreiner and Howard S. Reed 



The present paper embodies a series of studies upon the oxidizing 

 powers of plant roots grown in aqueous extracts of soils and in 

 solutions of various compounds. The results, it is believed, throw 

 light on the action of plants upon the soil and indicate how 



some 



soil conditions affect certain functions of the plant. 



The experiments which are presented show that plant roots are 

 able to carry on active extra-cellular oxidation, chiefly by means of 

 the enzymes which they secrete. From the standpoint of root excre- 

 tions the study is of interest because it has often been supposed that 

 the roots of growing plants excrete organic and inorganic acids which 

 art in the solution of soil minerals. The idea undoubtedly owes its 

 prevalence largely to the experiments of Liebig 2 and of Sachs 3 

 uhich demonstrated the corrosion of polished marble plates by grow- 

 ing plants. The more recent investigations upon the subject made 

 by Czapev Kossowitch,* and Kunze 6 have shown, however, that 

 ve rv little acid is excreted by the roots of the higher plants, and that 

 th e results of the earlier workers were mainly due to the action of 

 c arbon dioxid. 



This oxidizing power of plants gives them an important action 

 u Pon the soil. Whether they have the power to oxidize the inorganic 

 constituents of the soil remains to be determined; but it has been 

 shown that they are able to oxidize organic substances, such as the 

 Jhromogcns employed in these experiments, at a fairly rapid rate. 

 Ift hese substances are oxidized, it is only logical to conclude that the 

 or ganic substances occurring in the soils are also oxidized by the 

 actl °n of plant roots. 



This oxidation of organic compounds is of additional interest in 

 the light of recent investigations, which show that the cause of unpro- 



' Published by permission of the Secretary of Agriculture. 

 2 Annalen Chem. Pharm. 105:139. 1858. 

 3B ot.Zeit. i8:n 7 . l8 6c. < 



4 TaU.l. t,v _ . 



5 Ann.Sci.Agron.il- 8:220. io°3- 



*Jahrb. Wi ss . Bot. 29:321. 1896. ' * Jahrb. Wiss. Bot. 42:357- "**■ 



355] ° y [ Botanical Gazette, vol. 47 



