Varietal Variation of the Scab Disease Resistance in Wheat Evaluated by the 'Cut-spike' Inoculation Method.

Abstract

Resistance to scab in wheat was evaluated by the 'Cut-spike' inoculation method which had been developed earlier (TAKEDA and HETA 1989) to test for scab disease resistance in barley. Spikes at anthesis were removed from the wheat plants at the second internode, arranged in pans with overflowing water and then inoculated with the spore suspension. Spikes were maintained at 25'C and 100% humidity for two days, and then transfered to a growth camber controlled at 185'C (with a sine curve) and about 95% relative humidity. Illumination was about 10, 000 Iux during the 14 hour day. Eight days after inoculation, the percentage of infected spikelets was recorded. Three isolates of Fusarium graminearum Schwabe (No. 44, No. 78 and H 64) were inoculated onto 168 wheat cultivars, and for cornparison 282 barley cultivars were inoculated with isolate No. 78. Three spikes each of the cultivars were tested and the experiment was replicated twice. Because of the morphological differences between wheat and barley spikes, infected spikelet percentage was measured in wheat and infected floret percentage in barley. The data were subjected to statistical analysis after transforming the percentage of infected florets (spikelets) into the degree of angle.