Relations between mosaic disease infections and total cyanide levels in cassava leaves
1985
Ayanru, D.K.G. (Benin Univ., Benin City (Nigeria). Dept. of Microbiology)
Lamina samples of four cassava (Manihot esculenta Crantz) clones - TMS/GP/B 4107, RP/B 5028, U 42046 and W 4488 - infected by the African cassava mosaic disease (ACMD) were assessed for total cyanide, 3-5 months after field propagation, using an enzymatic assay method. Cyanide content of leaves of varying ages from paired plants (with and without ACMD symptoms) and plants grouped into classes of symptom severity were compared. Contents varied considerably (500-3500 mg/kg fresh wt), and differences between means were significant (P 0.01). Depending on the level of infection, leaf age and cultivar susceptibility, HCN values increased, reduced or remained unchanged, thus it would be unwise to use leaf analysis to screen cultivars for low cyanide. The variations are explained on the basis of known effects of plant viruses on the biogenesis of cyanohydrins
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