Abstract

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Mixed information on the appropriate temperature required by P. teres f. teres pathotypes for successful infection of barley is one of the bottlenecks especially on sensitive studies on virulence and pathogenicity that require specific conditions. The study aimed at determining how morphologically diverse species of P. teres respond to different temperature regimes at different time interval. Infected leaf tissues were collected from major barley growing zones representing high, medium and low altitudes. Isolation was done from these tissues in pathology laboratory and three morphologically distinct pathotypes from high and low altitudes selected for virulence and pathogenicity assessment. Susceptible barley variety (Sabini) was then planted in split-split plot experimental arrangement in randomized complete block design with three replicates. Severity data was scored on a 1-5 scale, transformed as log10 (x +1) then subjected to analysis of variance on Genstat statistical software release 14.1 at 5% level of significance. A significant difference between the means for isolates and temperature ranges was separated using contrast, comparison. Isolates, temperature regimes and all the interactions had significant effect on severity (p < 0.05). This indicates that each of the factors had additive effect on the disease level. However, time interval alone was not significant (p > 0.05). The ‘Chep 3’ isolate from medium altitude was most virulent at 30 – 40 °C while the ‘Mau 6’ from high altitude was the most sensitive to temperature and time variation, indicating that these pathotypes are could be adapted to specific zones. Therefore, temperature plays vital role in virulence and pathogenicity but this also depends on time of exposure and strain of the pathogen.

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