| Field reactions of forty-nine Italian durum
wheat cultivars to soilborne wheat mosaic V.VALLEGA and C.RUBIES-AUTONELL Istituto Sperimentale per la Cerealicoltura, Via Cassia 176, 00191 Rome, Italy and Istituto di Patologia Vegetale, Facolta di Scienze Agrarie, 40100 Bologna, Italy In Italy, soilborne wheat mosaic is widespread in the traditional common wheat growing areas of the North, as well as in several Central provinces, where both common and durum wheats are cultivated (RUBIES-AUTONELL & VALLEGA 1985). The disease often decreases the yield of susceptible cultivars by more than 50%, also affecting test weight, plant height and weediness (TODERI 1969, VALLEGA & RUBIES-AUTONELL 1985). Losses due to soil infestation by the SBWM-virus can be greatly reduced by growing cultivars exhibiting genetical resistance (WIESE 1977). Worldwide, however, only the reactions of common wheats have been studied extensively, whereas little is known about the behaviour of durums. Investigations on SBWM-resistance amongst Italian durums were therefore initiated in 1981-82, and a first report on the reactions of 25 cultivars has been recently published (VALLEGA & RUBIES-AUTONELL 1985). Highly significant correlations between symptom-severity evaluations made in March, at growth stage 3 on the Feekes-Large scale (LARGE 1954), and yield losses were found in these preliminary studies. Further experiments were carried out in 1983/84 and 1985/86 to include newly released materials. The present communication summarizes the data so far collected on the reactions of 49 Italian durums to soilborne wheat mosaic. Materials and Methods During 1981/82, 1983/84 and 1985/86 three different experiments were carried out in a uniformely SBWMV-infested field near Rome, Italy. The trails, each consisting of 25 durum wheat cultivars grown in 10m2 plots with three replicates, were planted -respectively- on 12.11.81, 26.11.83, and 4.12.85. Disease ratings were in all cases made in March, at growth stage 3 on the Feekes-Large scale (LARGE 1954), using the following scale: Resistant (R) = slight or no symptoms; Moderately Resistant (MR) = mild mottling and stunting; Moderately Susceptible (MS) = mottling and stunting; Susceptible (S) = severe mottling and stunting, with virus-killed plants. Different sets of wheats were tested each year, and SBWM resistance evaluations thus regarded a total of 49 entries. Because the reactions recorded on a few cultivars were somewhat variable, the results obtained in different experirments are presented separately. |
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