This study aimed to determine the optimal concentration of F. graminearum conidia for artificial inoculation in wheat spikelets and to verify the type of head blight resistance (Type I and / or II) in wheat cultivars. The study consisted of two experiments, and in the first one, the optimal concentration of conidia mL-1 was determined for artificial inoculation in four cultivars. Thus, the tested concentrations were 5x103, 15x103, 25x103, 35x103and 40x103 conidia mL-1. Twenty-one days after inoculation, the incidence of F. graminearum in spikelets was quantified, and regression analysis was used to determine the optimal concentration of conidia ml-1 for each cultivar. In the second experiment, the resistance of wheat cultivars to artificially inoculated head blight was evaluated, using the same methodology adopted in the previous experiment and the concentration of 31x103 conidia mL-1. The evaluated variables were severity, affected grains and incidence in affected spikelets. The best concentration for artificial inoculation of head blight in wheat spikelets is 31x103 conidia mL-1. The greatest severity of the disease was observed for wheat cultivars BRS 208 and Pampeano, and the highest percentage of affected grains was noted for BRS 208. The cultivars Pampeano and BRS 177 did not show Type I resistance to head blight but had Type II resistance, while the cultivars Mirante and BRS 208 had neither of the resistance types.
Gibberella zeae; inoculum concentration; Type II resistance.
