The effect of sowing date and cultivars on viral diseases incidence and their interaction with faba bean yield component characters and yield losses was studied. Three cultivars namely Balady (small seeds local cultivar), Giza-3 and Flip-84 were used. Isolation and the identification of viruses showed that faba plants were infected by Alfalfa Mosaic Virus Alfamovirus (AlfMV), Bean Yellow Mosaic Potyvirus (BYMV) Bean Leaf Roll Virus (BLRV), Faba Bean Necrotic Yellow Virus (FBNYV) and Chickpea Chlorotic Dwarf Virus (ChCDV). Disease severity range was 15-53.3%. Viral diseases infection restricted plant growth by almost 50% in all sowivng dates. The least disease reaction was detected the local cultivar, while the highest infection was in Flip- 84 and Giza-3. Number of days for flowering and consequently number of days for maturation were not affected by viral infection, but were highly affected by sowing date. Number of branches per diseased plants was not significant with all cultivars in all sowing dates. While the healthy plant branching pattern differed significantly in all sowing dates. Number of pods and seeds per diseased plant decreased by almost 30-50%. The local cultivar gave the maximum significant pods and seeds under disease stress. Yield was maximum in the first and tenth of Dec. sowing dates. Giza-3 and Flip-84 gave the maximum yield followed bv the local cultivar. The interaction of cultivars and sowing dates with viral diseases and yield showed that Giza-3 reacted almost equally during both seasons. However, Flip-84 reacted more against viral diseases in the second season. While the local cultivar was more adaptable and showed the least diseases reaction in both seasons. Diseased plant height was significantly affected with all cultivars in all sowing dates. Cultivars branching was not affected by the stress of viral infection in all sowing dates. However, healthy plants branching pattern, with the three cultivars was significantly affected by sowing dates tested. Number of pods and consequently number of seeds per diseased plant was sharply decreased in the three cultivars. Yield was maximum (3167 kg/ha) with Giza-3 followed by Flip-84 (2780 kg/ha) and the local cultivar (1634 kg/ha), in the first of Dec. sowing date. Due to viral diseases infection. Yield losses with all cultivars under the tested sowing dates showed a range of 9% to 50.71%. Further yield increase could be achieved if viral diseases-infection are to be avoided through resistant cultivars or sowing dates before the first of December. |
