OCCURRENCE OF MANGANESE IN WHEAT 



By William P. Headden, 

 Chemist, Colorado Agricultural Experiment Station 



The presence of manganese in various plants has been observed repeat- 

 edly. It is now stated that it has been shown to be present and has been 

 determined in a great many grains, roots, leaves, and whole plants and 

 that it is probably present in all plants. 



It is generally asserted that this manganese is to be considered as an 

 accidental constituent and that it has no physiological function. An 

 opposite view, however, is held by some who maintain that it performs 

 an important catalytic function in the plant. Bertrand, for instance (i),^ 

 has shown that the enzym laccase can not act as an intermediary between 

 the oxygen of the atmosphere and certain organic compounds in the cells 

 of the plants if it is deprived of its manganous oxid, with which it forms a 

 feeble compound. He has further shown that this enzym, laccase, is very 

 generally diffused throughout the vegetable kingdom and that whenever 

 laccase functions in the nutrition and growth of plants, manganese is a 

 necessity. The amount of manganese contained in this laccase is only 

 O.I2 per cent. 



There are some data on the effects of manganese on wheat, oats, barley, 

 grass, etc. Guthrie and Cohen (3) attribute the death of grass on certain 

 spots to the presence of 0.254 per cent of manganic oxid in the soil. 

 They account for the death of barley in certain soils in the same manner. 

 Voelcker (7), experimenting with different salts of manganese, applied 

 in quantities up to 200 pounds per acre, obtained results which are sum- 

 marized as follows for experiments with wheat : 



The chlorid and nitrate produced a good color in the plants. The iodid distinctly 

 retarded germination and gro\vth. The untreated plots produced as good plants as 

 any of the others except those which had received an application of nitrate or phos- 

 phate. The phosphate, chlorid, sulphate, and red oxid (Mn304) each gave an increase 

 in yield. 



Kelley (6) states that some plants vegetate normally in the presence 

 of manganese salts, others are stunted in growth and die back from the 

 tops of the leaves, which turn yellow or brown and sometimes fall off. 

 Plasmolysis is produced. Chlorophyll may be destroyed as in the pine- 

 apple. The ash shows an increased percentage of manganese. The 

 percentage of lime is increased and that of the magnesia is decreased. 

 This ratio, on the authority of Loew, is considered an important one. 

 The absorption of phosphoric acid is lessened. The formation of man- 

 ganous phosphate is suggested as the possible cause of this. 



• Reference is made by number to " Literature cited," p. 355. 



Journal of Agricultural Research, Vol. V, No. 8 



Dcpt. of Agriculture, Washington, D. C. Nov. 22, 1915 



(349) 



Colo.- 



