38 NATURE OF ALKALI INJURY TO THE PLANT 



mination. Under similar conditions, a plant would not 

 only be hindered from growing, but would actually be 

 killed. 



A salt solution not sufficiently strong to prevent entirely 

 the germination of seeds may greatly delay it. The author 

 has shown (3) that seeds which normally germinate in six 

 days may be delayed as long as twenty-one days under 

 conditions in eyery way similar except in the salt content of 

 the soil. This delayed germination may be very serious 

 in regions where the normal length of the growing season 

 is greater than that required for maturity of the crop even 

 if growth after germination were satisfactory. 



Effect on Structure of the Plant. Vegetation growing 

 on alkali soil has a characteristic appearance similar to 

 that found growing under desert conditions. It generally 

 lacks that bright green appearance of vigorous and healthy 

 growth. This condition is observed even in water-logged 

 land where there is an ample supply of moisture. A 

 similar moisture supply without alkali would result in a 

 succulent growth. 



Harter (4) examined the structure of plants to determine 

 the effect of soluble salts in the soil. He found that culture 

 in a soil containing considerable quantities of sodium 

 chloride together with other salts produced measurable 

 changes in the leaf structure of wheat, oats, and barley. 

 The most notable modification produced was the conspicu- 

 ous bloom or waxy deposit that formed on the surface of 

 the leaves. This development of bloom was accompanied 

 by an easily measured increase in the thickness of the cuticle 

 and outer walls of the epidermal cells and by a marked 

 decrease in their size. 



In regard to transpiration of the plants, it was found 

 that when the alkali salts are present in sufficient con- 



