PLANT Coors IN MAIze 23 
From these observations it is apparent that variations in soil fertility 
may effectively obscure genetic differences. A knowledge of the influence 
of soil fertility on color development is therefore essential to careful genetic 
work with the plant colors of maize. Moreover, since soil fertility is 
subject to control thru cultural methods, different degrees of fertility 
can be used as an aid to the sharp differentiation of certain genetic types. 
If, for instance, it is desired to separate, in the seedling stage, greens 
and browns on the one hand from the red-purple series on the other, 
this can be accomplished most readily in poor soil. In fact, the writer’s 
practice, in studies requiring this separation, is to grow the seedlings in 
pure sand. In this medium seedlings of the purple-red series of color types 
become highly colored at a very early age, while seedlings of the green 
and brown types show absolutely no red color. If, however, it is desired 
to distinguish sharply between purple and dilute purple or between sun 
red and dilute sun red, fairly fertile soil is essential, and, usually, the 
more fertile it is, the more easily can the separation be made. The stronger 
colors develop almost as well in rich as in poor soil, while the weaker 
colors develop much less intensely in rich soils than in poor ones. On 
very poor soils, it is difficult to separate sun reds from dilute sun reds, 
and almost if not quite impossible to distinguish with -certainty between 
sun reds and weak sun reds or between weak sun reds and dilute sun reds. 
Lack of particular nutrient elements 
It having been established that differences in soil fertility result in marked 
differences in the development of red color in maize plants, 1t seemed 
important to determine whether particular nutrient salts are more con- 
cerned than others. Accordingly, plants of all the color types included 
in the tests previously reported were grown in glazed earthen jars in 
clean quartz sand and watered with nutrient solutions. The quartz 
sand was obtained from the Department of Agronomy of the University 
of Nebraska, and was known to be practically free from nutrient elements 
except iron. The nutrient salts and distilled water were obtained from 
the Department of Agricultural Chemistry of the same institution. The 
nutrient solution employed was one that had given good results with maize 
in certain experiments conducted previously by the Department of 
Agronomy. The complete nutrient solution, 0.2 per cent strength, 
contained per liter of water the following salts: 1 gram Ca (NOs)2, 0.25 
