VALUE OF CERTAIN NUTRITIVE ELEMENTS 
In general, magnesium- or calcium-deficiency affects least the 
vegetative development of the plants; in some cases a deficiency in 
either of these elements causes even an increased growth. In potas- 
sium-deficient solutions the growth 
of the plants is less than that of 
the plants grown in normal solu- 
tions, although the effects are not 
marked in any particular instance. 
A deficiency in phosphorus or in 
nitrogen, however, produces a 
markedly unfavorable effect upon 
growth. The relation of the vari- 
ous elements to the general vegeta- 
tive development of the plants is 
shown in figure 2. 
The Relation between Nutrients 
AND Total Dry Weight 
The final vegetative growth and 
the total dry weight of the plants 
in the respective cultures at matu- 
rity correspond quite closely with 
the growth of the plants after stoo- 
ing (at the end of twenty days of 
growth) . Certain specific differences, 
however, such as the amount of grain 
produced, the ratio of grain to 
straw, and the weight of the in- 
dividual kernels under varying nu- 
tritive conditions, are brought out 
only by carrying the plants to ma- 
turity. The plants grown in solu- 
tions deficient in magnesium produce a greater total vegetative 
growth than those grown in normal solutions. The plants grown in 
solutions deficient in calcium show a total vegetative growth equal to 
that of plants grown in normal solutions. It is evident, therefore, 
that if a very small amount of magnesium and calcium is present in 
the culture solution (one tenth of that i|n the normal solution), the 
vegetative development of the plant will not be greatly affected, unless 
Figure 2. Photograph showing the 
growth of oats in the normal solution 
and in solutions with one essential ele- 
ment in each case reduced to one tenth 
normal. 
