The influence of phosphorus on the growth and physiology of the potato plant

Summary

In any study on the importance of phosphorus in potato production it is essential to recognize the fundamental significance of the phosphate esters in plant growth, particularly their role in the conversion of carbohydrates and in the metabolism of starch. In a recent article on the influence of phosphoric acid on the metabolism of plants published by Behrens and translated by Sauchelli (2), the statement was made that “Carbohydrates can enter into the metabolism of plants only by way of the carbohydratephosphoric acid esters. If as a result of phosphorus deficiency, the carbohydrates cannot be made use of. the plants stop building up secondary substances and may also lack energy for chemical synthesis and growth.”

The results of the present investigation have amply confirmed the need for phosphorus in the growth of the potato plant and in tuber development. Moreover, this need has been shown to be highly critical during the early stage of growth when normal meristem development and rapid vine growth are essential for a good crop. Evidence that relatively large amounts of plant phosphorus were needed for subsequent starch phosphorylation is supplied by the finding that tubers from 50-day-old plants contained only 23 per cent of the total plant phosphorus, whereas tubers from control plants, 112 days old, contained 83 per cent. Viewed from the standpoint of its importance in starch metabolism, the phosphorus contained in potato fertilizers has significance far beyond that heretofore fully recognized.

From the results obtained, which show clearly the fundamental need for phosphorus early in growth of the potato plant, it is understandable why potato yields can be expected to increase when a readily available form of phosphorus is applied to soils well supplied with residual phosphorus.