“MAGNESIA INJURY” OF PLANTS GROWN IN 
NUTRIENT SOLUTIONS 
W. F. GERICKE 
Among the first signs of injury to the tops of wheat seedlings and 
other cereals grown in nutrient solutions of relatively high (as com- 
pared with other salts in solution) concentration of MgSO,, one of 
the three or more salts commonly used in culture solution experi- 
mentation, is that resulting in abscission of the leaf tips of the 
plants. The progression of this injury consists of wilting, wither- 
ing, desiccation, and finally abscission. This injury has been 
found to be most pronounced on young shoots. It also occurs in 
a much greater degree under conditions conducive for high tran- 
spiration of the plants than forlow. The term ‘magnesia injury’’ 
has been applied to this peculiar phenomenon of abscission of leaf tips, 
being so named because usually found associated with comparatively 
high concentrations of magnesium ion (from MgSO,) in nutrient 
solutions. Additions of soluble calcium salts to nutrient solutions 
giving injury were often found to be beneficial. This lent support 
to the concept that a certain calcium-magnesium ratio, or a range 
thereof, plays an important part in the physiological balance of 
nutrient solutions. 
Recent experiments by the writer appear to bear on this mag- 
nesium question. When wheat seedlings were grown in single 
salt solutions it was found that some cultures gave the typical 
symptoms and others did not. Briefly, the tests were as follows. 
Seedlings 6-8 cm. high, with roots 8-10 cm. long, were fitted 
into and supported on paraffined corks. These were fitted into 
one quart containers (Mason jars) filled with the single salt solu- 
tions to be tested. The solutions were prepared from Baker’s 
C.P. analyzed salts and distilled water. The salts were tested to 
see whether they conformed to specifications, but no further 
purification was made. A small amount of FeSO, (5 drops of 0.01 
mol solution) was added to the cultures at weekly intervals. The 
Botanical Gazette, vol. 74] : [x10 
