Influence of Potassium and Sodium on Metabolism of Peanut Cotyledons During Germination

• Published in: Botanical gazette (Chicago, Ill.) Ill.), 1947-06, Vol.108 (4), p.570-581
• Main Author: Dyer, Hubert J.
• Format: Article
• Language: English
• Subjects: Cotyledons; Lipids; Peanuts; Plant roots; Planting; Plants; Potassium; Seedlings; Sodium; Starches
• ISSN: 0006-8071
• DOI: 10.1086/335444

1. Virginia peanuts were grown in the dark in pots of quartz sand and were watered daily or every second day with either a complete nutrient solution (+K -Na), a solution in which sodium had been substituted for potassium (-K +Na), or one in which neither sodium nor potassium was present(-K -Na). 2. Cotyledons were harvested at the 6th or 7th and again at the 15th day after planting, were counted, weighed, and analyzed for reducing and total sugars, starch and dextrins, acid-hydrolyzable substances, soluble and insoluble nitrogen, and total lipids. 3. At 7 days carbohydrates were more abundant and lipids and crude protein less abundant in the -K +-Na than in the +K -Na cotyledons. At ~15 days the lipid relationship had reversed itself. Plants grown with -K -Na solution had somewhat more lipid material in their cotyledons at each stage than either of the other groups. 4. Determinations of lipolytic activity and histological study of the vascular structure of the cotyledonary petiole revealed no differences between treatments at 7 or 15 days. 5. The total dry weight of plants at both 7 and 15 days was less for -K +-Na than for +K -Na plants; this is interpreted as indicating a higher respiratory rate owing to potassium deficiency. 6. The more rapid utilization of protein under -K +Na conditions is probably a reaction to the low availability of potassium for the catalysis of nitrate reduction. Since the latter condition limits the opportunity for the formation of amino acids in the -K plants, such new protein as is formed in the developing seedling axis must come from resynthesis of the proteins withdrawn from the reserve areas. 7. Histological preparations revealed the presence of several times as much starch in the seedling axis of the -K plants as in the controls. This appears to be confirmatory of the seedling's inability to utilize carbohydrate in protein synthesis. 8. No definite evidence of interference with translocation under -K conditions was found. 9. It is suggested that potassium may have a specific role in protecting the lipid substrate from lipase. 10. Additional evidence was obtained that sodium may to a certain extent alleviate potassium deficiency.