CAUSES OF SOIL SICKNESS IN REPLANTED PEACHES : 1. THE ROLE OF CYANOGENESIS IN PEACH SOIL SICKNESS

The addition of peach roots to soil prior to planting young peach plants resulted in retarded growth, compared to plants grown in the same soil without root addition, provided that the roots were oven dried or to a lesser extent - air dried. Fresh roots, root and soil extracts and amygdalin did not affect growth. The addition of peach roots and root extracts to the soil resulted in the production of hydrocyanic acid (HCN), the amount produced being largest if oven dried roots were added to soil obtained from a peach orchard, and was somewhat smaller if such roots were added to soil, which has not been planted with peaches before (‘virgin soil’). The addition of dry peach roots to virgin soil, which had been recently planted with peaches, resulted in an increase in the HCN evolution compared to identical not planted soil. The HCN evolution from peach soil which has been replanted with peaches, and to which amygdalin has been added, was larger if the replanted trees were in a reasonable condition, compared to severely declining replants. Thus the rhizosphere of actively growing young peach trees appears to be rich in microorganisms promoting the hydrolysis of cyanogenic glycoside. Hence the prunasin content of replanted peach soil, 30 months after replanting, was more depleted than the content of non-replanted soil from the same plot.

Heat resistant bacilli which were able to hydrolyze amygdalin were isolated from the surface of oven dried peach roots.

Download Adobe Acrobat Reader (free software to read PDF files)