Chemical Constituents of Amaranthus retroflexus

Abstract

1. There is a large amount of nitrate in the organs of A. retroflexus. The stem and branches are the primary nitrate storage organs. The rate of nitrate absorption increases with the aging of the plant, perhaps partly being due to the development of the root system with numerous branching rootlets, increasing the radius of the feeding area from a few inches to 2 ft. or more. 2. This high capacity for nitrate absorption and storage must be an important factor in making Amaranthus a very successful competitor against cultivated plants, so effectively withdrawing as it does the nutrient element most commonly limiting plant production. It would be interesting to know how generally and to what degree weeds possess this power. 3. The carbohydrates and nitrogen compounds fluctuate throughout the growing period. The fluctuation of the carbohydrates is in the reverse order of the nitrogen compounds. This inverse ratio is not a truly mathematical constant, but in general when the carbohydrates are high the nitrogen compounds are low, and vice versa. As the nitrate nitrogen composes more than 50 per cent in the stems and branches, there is a possibility that nitrates have some modifying effects on this reciprocal relationship. This inverse ratio is due partly to the synthesis of protein, chlorophyll, phospholipin, and other organic nitrogen compounds at the expense of the soluble carbohydrates. 4. Tissue analysis of the seeds shows the distribution of different forms of phosphorus in the various fractions. The organic phosphorus, which consists chiefly of phosphoprotein and nucleoprotein phosphorus, is high, and that of the inorganic form is low. 5. The distribution of nitrogen in seeds is in the same order as that of the phosphorus. The insoluble portion contains 80-83 per cent of the total. The soluble part varies from 17 to 20 per cent, most of which is in the organic form. The inorganic form is represented by the nitrate nitrogen. 6. The predominating sugars in the seeds are the polysaccharides. These compose nearly one-half of the total dry weight of the seeds. In both A. retroflexus and A. blitoides there is absence of lipin sugars in F1 and reducing sugars in F2. Only a small amount of non-reducing sugars was present in the two varieties. 7. The presence of nitrogen and phosphorus in the lipin fraction indicates that the seeds contain phosphatides. Phytosterolwas also present. By comparison, A. retroflexus has 2.8 times as much as A. blitoides.