MANGANESE AND IRON IN GROWTH OF WHEAT 



367 



Data of the yields of Series 2 are presented in table 2. 



As shown by the data of table 2 manganous chloride on the 

 low plane was toxic to both roots and tops of the plants. This 

 differs from the effect in Series 1, where it stimulated the growth 

 of tops. As in the previous series, but to a less degree, it an- 

 tagonized the effect of ferric chloride at this plane. However, 

 in harmony with the delayed chlorotic effects, the slight stimu- 

 lation by low ferric chloride and the less complete antagonism 

 by manganous chloride toward this salt suggest a varietal resist- 

 ance to the effects of manganese dependent upon a liberal reserve 

 of iron in the seed. On the other hand, the toxic effect of 

 manganous chloride alone is opposed to this point of view. 



TABLE 2 



Yield of six wheat plants grown three weeks in nutrient solutions containing sodium 

 bi-carbonate and manganous and ferric chlorides 



-~ " n 



Si 



n "3 » 

 a 



Dry tops 



Weight in milligrams 



Relative to control = 100. 

 Dry roots 



Weight in milligrams 



Relative to control = 100. 

 Fresh roots 



Maximum length in milli- 

 meters 



Relative to control = 100 



725 

 117 



195 



88 



298 

 108 



The very serious toxicity of the high plane of sodium bi-car- 

 bonate may have depended either upon the disturbed balance 

 of ions attending the precipitation which occurred in all solu- 

 tions on this plane of the series or upon the specific effects of 

 this salt upon the plant. It is remarkable that the degree of 

 toxicity was but slightly influenced by the added presence of 

 manganous chloride. Contrary to the results of Series 1, high 

 ferric chloride stimulated the growth of tops here. In partial 



