THe Errect oF MANGANESE CoMPOUNDS ON SOILS AND PLANTS 387 
Other investigators have stated that the effect of manganese on yield 
is not marked. While Bertrand (1909) notes that the favorable results 
of manganese are not apparent until harvest time, Miss Brenchley 
(1914) states that there is a retarding effect on the ripening of the grain 
but not on the yield. Takeuchi (1909-13) reports that the control plants 
of flax were behind the manganese plants in growth and flowering. Aso 
_ (1904-05) found that rice treated with manganese flowered four days earlier 
than did the checks. Salomone (1907) states that the stimulation of the 
vegetative portion of plants is greater than that of the grain. Comparison 
of the data in tables 7 and 8 shows that greater differences in the yields 
were obtained when the plants were harvested before they matured. 
Manganese content of yellow leaves 
Several investigators have reported that the yellow leaves of manganese 
plants contain more manganese than do the green leaves. The leaves of 
the plants grown on soil treated with manganese sulfate (page 385) were 
analyzed for their manganese content by the colorimetric method described 
in Bulletin 31 of the United States Bureau of Soils. The results are given 
in table 10: 
TABLE 10. Anatyses or LEAVES OF WHEAT GROWN ON Sort TREATED WITH MANGANESE 
SULFATE 
Manganese (in parts per million grams 
of dry matter) in 
Parts per million of manganese added 
} E 
Green | Yellow ee 
leaves leaves is ites 
Oe oo od a6 woe aaNet ee aenes et ie en Trace Trace Trace 
JQ). 2» 2.0, cue, Saline shee A ere nd ee Ea i ORE oe Sa ea Trace Trace Trace 
BO). ooo ne 6a oe Lee ee eee Seen Gen eee Trace 3.8 1.22 
ICD. oo oo s se eee ee ee sehr ae LS) U P95 Srot 
OOO Raper eet tyke Mh ee See 1.95 E25 Sel2 
If Aso (1902-03) is correct in stating that the colorimetric tests for the 
oxidizing enzymes showed that ‘ the yellowish leaves of the manganese 
plants gave reactions of higher intensity than the green leaves of the control 
plants,” it seems that the intensity of these enzymes is proportional to 
