Die voorkoms, verspreiding en vorming van sianogenetiese glukosiede by 'n aantal sorghum-soorte

Abstract

The occurrence of cyanogenetic glucosides is of considerable economical importance because they render plants poisonous, and animals consuming this material may _be poisoned. Methods for the utilization of these plants to avoid poisoning have been proposed by several workers, namely Boyd (1938); Rose (1941) and Visser (1956). These methods are based on the principle that plants, as they mature, contain progressively less cyanogenetic glucosides. Certain individual plants and selections contain a higher concentration of cyanogenetic glucosides than other plants of the same species, grown under the same conditions. Leeman (1935) and Visser (1958, unpublished) give an extensive account of plants containing these substanies. In the present investigation six species of Sorghum and 24 selections of S. almum and S. verti­ cilliflorum x S. sudanense were investigated. The age and the part of the plant had a marked effect on the cyanogenetic glucoside content. As the plant matures, the glucosidal content decreases per unit of dry weight. The same applies to the different parts of the plant, namely the younger the part; the higher the concentration of cyanogenetic glucosides. Fertilization with nitrogenous fertilizers caused an increase in the content of cyanogenetic glucosides while phosphatic fertilizers counteracted this effect. From the results it is evident that the application of urea in all instances resulted in,a lower glucosidal content as. was the case with the application of sulphate of ammonia and calciumnitrate. The application of urea however, resulted in a quicker increase of glucoside content. A lack of moisture resulted in the plants containing more cyanogenetic glucosides than where moisture was available in adequate quantities. The possible ex­planation for this may be sought in the fact that plants growing under conditions of moisture deficiency remain for a longer period in a relatively young physiological stage. ( Boyd et alia, 1938). Immediately after frosting, an increase in glucosidal content occurs, but as the plants thaw and wilt, a decrese in glucosides is observed. A condition that frequently occurs is that after a frost, a spell of hot weather prevails. This causes the plants to sprout again and the young sprouts have a high glucosidal content.