iqiq] WOO—AMARANTHUS 315 



Of late much significance is being attached to the carbohydrate- 



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nitrogen ratio of plant tissues, or, as Fischer (6) puts it, the :^. 



On the basis of work done by him and others, Fischer makes the 



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following generalizations. If the value of r^ rises by an increase 



in the amount of carbon, or by a decrease in the amount of nitrogen 



furnished the plant, there is an increase in the amount of flowering. 



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 If the value of ^ drops by a decrease in the amount of carbon, or 



by an increase in the amount of nitrogen furnished the plant, there 

 is an increase of vegetative growth and a reduction of flowering. 

 Briefly stated, a great preponderance of carbohydrates in plants 

 favors flowering. Since the carbon of plants is fixed from the 

 carbon dioxide of the air by photosynthesis, conditions that favor 

 photosynthesis will tend to increase the ratio, and according to 

 Fischer the flower production. He found that increased partial 

 pressures of carbon dioxide in the air had this effect. Since nitro- 

 gen is absorbed from the soil in the form of nitrates, conditions 

 that favor nitrate absorption will decrease the ratio, and according 

 to Fischer favor vegetation. 



Kraus and Kraybill (12), on the basis of much more critical 

 work, including numerous cultures, tissue analyses, and micro- 

 chemical and anatomical studies, conclude that a very high 



carbohydrate , . ,. , . , ,. , 



^^T value gives httle vegetation and little or no repro- 



, . ,. carbohydrate , . , 



duction; a medium ^,^^: value gives moderate vegetation 



and good reproduction; and a low ^^^^ value gives vigor- 

 ous vegetation and little reproduction. Through their extreme 

 conditions of culture, withholding nitrates, it is probable that Kraus 

 and Kraybill got much higher carbohydrate plants than Fischer 

 obtained in his cultures, hence their conclusion that very high 



carbohydrate . ,. , . 1 • t 1 

 ^r^^ gives little vegetation or reproduction, in short, 



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Fischer worked only on the portion of the ^^ curve that induced 



fair vegetation and good reproduction or extreme vegetation and 

 little reproduction, but not on the extreme of the curve that greatly 



