Evaluation of sugar beet commercial cultivars resistance against root rot caused by R. solani and F. oxysporum

In the present study, the resistance of 30 common commercial sugar beet cultivars against root rot caused by Rhizoctonia solani and Fusarium oxysporum was evaluated in West Azerbaijan province during 2017 and 2018. Cultivars were inoculated in pots under controlled greenhouse conditions. The experiment was conducted in completely randomized design with 15 replications and 5 controls for each treatment. Ranking based on root rot intensity caused by inoculation of R. solani was done eight weeks after inoculation with a scale of 1-9. Harvest Index was also calculated for each treatment. Ranking based on leaves color yellowing and root rot caused by F. oxyporum were recorded weekly from the second week after inoculation with 0-5 index. The mean of area under disease progress curve (AUDPC) was calculated for the disease development comparison among cultivars. Also, in order to compare the cultivars damping off under normal condition, a field experiment was conducted in a randomized complete block design. Missing or dying plants were counted three time after thinning and weeding. Dying plants were identified and transferred to the laboratory for diagnosis of the disease. The results of AUDPC calculation were obtained under field conditions and resistant cultivars were identified. The white sugar yield of cultivars per unit area was calculated. The results obtained from the cultivars resistance in the field and greenhouse with the genetic characteristics of the cultivars introduced by the sugar beet seeds companies were compared and resistant cultivars with high yield were introduced. The BTS233, Flores, Delta, and Murialle showed relative resistance to both pathogens and showed significant yield per hectare and are recommended in fields with contamination.