DETERMINATION OF THE NITROGENOUS FRACTIONS IN VEGETATIVE TISSUE OF THE PEACH

All vegetative parts of the peach contain a glucoside which may be hydrolyzed to form hydrocyanic acid, benzaldehyde, and glucose by the action of any enzyme, or enzymes, also present in the various tissues. The cyanogenetic glucoside or glucosides are not present in the same concentration in all parts of the plant. Thus in the fruit flesh it is found only in very minute amounts, although some investigators (12) have reported it to be absent from this part. Cyanogen compounds are known to occur in many plants, however, but they are supposed to be present only as glucosides. Nevertheless, Willaman (26) and others have found in some plants what was regarded as either free hydrocyanic acid or hydrocyanic acid from a very unstable glucoside. Although no free hydrocyanic acid is known to exist in the peach, the cyanogenetic glucoside, or glucosides, are either more stable in dormant or slowly growing plants than in rapidly growing ones, or else their specific enzymes are relatively inactive in the slowly growing plants. Because of the presence of a nitrogenous glucoside, or glucosides, peach tissue cannot be macerated in the preparation of an extract of soluble nitrogen without a consequent loss of nitrogen. Certain modifications in the procedure commonly employed for plant analyses are necessary, therefore, and the nitrogen contained in this glucoside must be determined and removed completely from an aqueous extract of peach tissues before the remaining nitrogenous fractions can be determined accurately. In the present study an attempt has been made to modify the methods commonly employed for the determination of the nitrogenous fractions in plants in general, so that they may be used for investigations of these fractions in the tissues of the peach (Primus persica Stokes). The methods described are suitable for use with samples comprising 50 gm. or more of fresh plant material. Samples of this size have been found adequate to give representative results. Only aqueous extracts prepared from fresh plant material were regarded as suitable for use in this connection, since Chibnall (4) has shown that such extracts are more applicable than any others in a study of the nitrogen distribution in plants. The investigation is admittedly incomplete in that it does not include a study of the composition of all parts of the peach plant sampled at various 1 Journal Series paper of the New Jersey Agricultural Experiment Station, Department of Plant Physiology.