SOME EFFECTS OF POTASSIUM UPON THE AMOUNTS OF PROTEIN AND AMINO FORMS OF NITROGEN, SUGARS, AND ENZYME ACTIVITY OF SUGAR CANE

Abstract

Using same plants as in the preceding abstract, determinations were made of invertase, amylase, ereptase, total and amino N, reducing sugars, total sugars, pH, titratable acidity, and buffer systems. After 2 months the K-deficient plants had higher percentages of amino N and lower percentages of protein N in blades and stems than the control plants. After 7 months the K-deficient blades had higher percentages of amino and total N than the controls, but the reverse in stems. The K-deficient blades and stems of partially deficient plants, contained higher percentages of reducing sugars, lower percentages of sucrose, and less active invertase than the controls, suggesting that sucrose is synthesized by invertase in sugar cane. There was a positive correlation between amount of K supplied and total sugar stored in stems. Amylase activity was greater in K-deficient plants than in controls, in both blades and stems. Several possible causes of the increased amylase activity in K-deficient plants were examined and the conclusion suggested that K deficiency removes a protective action of K from amylase, thus allowing the enzyme to be activated more readily by P, which is present in higher amts. in K-deficient plants than in controls. Sugar cane deficient in K developed these characteristics: low moisture %; high total ash content when young, followed later by low ash %; high % of Ca, Mg, P, and Fe at certain ages; derangements in synthesis and translocation of proteins and sugars; phloem necrosis; Fe accumulations at nodes: weak invertase activity; strong amylase activity.