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FACTORS INDUCING MINERAL‐DEFICIENCY SYMPTOMS ON THE POTATO PLANT

1942; Wiley; Volume: 29; Issue: 4 Linguagem: Inglês

10.1111/j.1744-7348.1942.tb06136.x

1744-7348

G. A. Cowie,

Potato Plant Research

Summary The data are based upon observations derived chiefly from twenty‐four replicated manurial trials made on the potato crop in 1937 and from twenty‐five further trials of a different design in 1938. They deal with the manurial and other factors that induce deficiency symptoms relating to potash, phosphates and calcium respectively on the potato plant. Leaf scorch, and the other potash‐deficiency symptoms on the aerial part of the plant are normally induced by NP and not by nitrogen treatment. The presence of leaf scorch on the nitrogen plots in a number of trials has been satisfactorily correlated with a high level of available phosphates in the soil, as indicated both by a chemical test for phosphate solubility and the degrees of response to phosphate applications. An increase in the level of nitrogen in the NP treatment results in the intensification of potash‐deficiency symptoms. A certain interaction between nitrogen and phosphates is shown to be the primary factor in inducing potash‐deficiency symptoms on the part of the plant above ground. The blackening of cooked tubers which has hitherto been assumed to indicate potash deficiency has been found to result from a combination of high nitrogen with low potash in the soil. Phosphate deficiency is induced by nitrogen and NK treatments, but more strongly by the latter. Phosphate‐deficiency symptoms and not potash‐deficiency ones become evident on the nitrogen plants under conditions of low phosphates and low potash in the soil. Calciumdeficiency symptoms appeared at three centres on poor sandy soils with pH values ranging between 45 and 5. Observations failed to detect signs of magnesia deficiency on the plants at any centre and in either season. The results of this observation were borne out by the absence of significant yield responses to magnesia with one exception in each season.