Evaluation of Beta G~rrnpla.sr.1 fer R~sist::J.!!ce to 8e~t Curly cop Virus :n Field ant C~:-=n house Conditions

- One of the important virus disease of sugar beet in Iran is the Curly- top, which is particularly found in Fars, Isfahan and Kerman provinces. The importance of this disease in sugar beet farms and the damage resulting from its infection was so high that the Sugar beet Research Institute was forced to buy the foreign parent of the tolerant cultivar H~505 for tbe infected areas. Based on the availability of rich genetic resQurces in the SRI and those imported form International Gene Bank, and the need to release a tolerant cultivar, an experiment was conducted in the field for three conse~utive years (1379-138]). The experimerital design consisted a simple lattice (Square Lattice) with 25 germ plasms (as treatments) replicated three times in each year. Each plot included a cultivar which was planted in 3 with 8 meters length. Their _plantation time was in accordance with the occurrance of the second offspring of vector hopper. To prevent the hopper population from declining, no insecticides were applied during the growing season. The evaluation of each line was based on the morphologicaJ characteristic and the number of infected and safe plants in each ro'v\\'. and finalJy were expressed on a percent basis. At the and of growing season, the harvesting practice was accomplished and the technological characters of each germ plasm were determined on \{heir provided pulps. The results of the first year showed that the cuJti val's: F- 20489DILLON and F-20488 HM-2980 had the lowest degree of infection and their root yield were 70.13 and 79.44 Ton.ha-( respectively. In the second year, the cultivars: F-2031 1-9825 and F-20511 Chinook had the lo\\vest degree of infection and their root yield were 59.11 and 49.75 Ton.ba"1 respectively. In the third year. the results showed that the culti val's and lines under study: F- 20512 Ranger, 20513-9825 and F-20511 Chinook had the lowest degree of infection due to Curly-top. The maximum root yield in this year is obtained from the cultivar: F- 20510 Bronco about 84.93 Ton-ha"'. Since in field evaluation no one of the new lines didn't show any tolerance to this deseas (except the control and the pre\\-ious tolerant cultivars ) therefore, the green house experiment was not cQnducted.