The effect of antifungal drugs and fungicides on the viability and vigour of barnyard millet (Echinochloa crus-galli) seeds

Disinfectants applied in seed viability and vigour testing should effectively inhibit the development of pathogens while exerting a minimal impact on seed physiology. However, many chemical disinfectants are not highly effective, and they alter metabolic processes in seeds. In this study, selected antifungal drugs were tested on barnyard millet seeds and compared with agricultural fungicides. Seedling roots were analysed microscopically to determine the causes of chemical agents' adverse effects.
Incubation of barnyard millet seeds under continuous exposure to fungicides and nystatin inhibited seedling growth and failed to sterilise seeds to the extent required for laboratory analyses. Fungal infections on the seed surface were most effectively eliminated by 0.5% natamycin suspension applied continuously or for one hour. However, when applied at the above concentration, natamycin also inhibited seedling growth and decreased the vigour index. Incubation of seeds with 0.25% natamycin suspension for one hour was less detrimental to seed physiology and matched the most effective disinfection. The apices of seedling roots treated with 0.25% natamycin for one hour were free of necrotic changes. Prolonged exposure to natamycin at a higher concentration led to necrosis of root apex cells, which decreased the growth rate and vigour of barnyard millet seedlings.