Inhibition of chlamydospore production in Fusarium oxysporum by ammonia and high ion concentrations

NH 4 Cl in a Tris–HCl buffered solution inhibited chlamydospore production in germinated macroconidia of Fusarium oxysporum. KCl, CaCl 2 , and buffer solutions at higher concentrations were also inhibitory but to a lesser extent. At fixed concentrations of NH 4 Cl and KCl mixed at different ratios, chlamydospore production decreased with increasing concentrations of [Formula: see text]. This effect was stronger at pH 8.5 than at pH 7.5, suggesting that NH 3 is the active component. In conclusion, both NH 3 and high ion concentrations can be inhibitory to the production of chlamydospores in salt solutions. No qualitative differences were found between chlamydospores formed at different concentrations of ammonia.