Reaction of Wheat Varieties to Infection by Pythium arrhenomanes or its Toxic Metabolite (s)

Eight wheat varieties some of which were earlier reported to be resistant to Pythium arrhennmanes, were inoculated with P. arrhenomanes. Inoculation was performed by placing ۲-day-old seedlings on the edge of a P. arrhenomanes culture on corn meal agar for ۳ h at ۲۵°C. Infected seedlings were then transferred to test tubes (۹ mm dia.) containing glass beads and ۱ ml of sterile water, and incubated for ۴ days at ۲۵°O Non-inoculated seedlings were exposed to the toxic metabolite(s) from P. arrhenomanes by placing them in test tubes containing ۱ ml of a ۲۵-day-old culture filtrate of P. arrhenomanes. Non-inoculated seedlings grown in test tubes containing sterile water served as controls. Measurements were taken on root and shoot length, as well as fresh and dry root and shoot weights. There was an indication that it may be possible to use the toxic metabolite(s) in screening for resistance to P. arrhenomanes. Although all of the varieties appeared to be susceptible, there were some differences among them in their reaction to fungal infection or exposure to the toxic metabolite(s).