Evaluation of sugar beet germplasm for resistance to Rhizoctonia root rot
2007
Mahmoudi, S.B. | Ebrahimi Koulaie, H. | Soltani, J. | Vahedi, S. | Arjmandian, A. | Keshavarz, K. | Chaharmhali, M. | Mesbah, M.
Different sugar beet genotypes were evaluated against a highly virulent isolate of Rhizoctonia solani AG2-2, in greenhouse, micro plot and invitro condition as well as natural infested field. In order to evaluation of resistance of genotypes in greenhouse and micro plot conditions, the 12-14 old plants inoculated with 6-8 corn kernels as inoculum. Evaluation of genotypes in the natural infested fields carried out in the randomized complete block design with four replications in the infested field in Khorassan province. The number of healthy plants was compared among genotypes. In screening at invitro condition, germinated seeds were placed around actively colony of the pathogen on WA and the amount of diseased seedlings was measured using 1-4 scale 7 days after inoculation. Different evaluation methods had correlation with each other. Evaluation in micro plots was simple, reliable and appropriate method in comparison with the others. In the first year, 12 genotypes were evaluated. The genotypes were classified in 3 groups based on the evaluation in micro plots and greenhouse conditions. FC709-2 and 9597 were the most resistance and susceptible genotypes respectively. The results of evaluation under the natural infested field as well as invitro condition were the same as micro plots and greenhouse conditions. The genotypes FC703 and FC718 had appropriate level of resistance to Rhizoctonia. In the second and third years, diploid and tetraploid pollinators were evaluated. None of them were resistant to the disease. FC709-2 was the most resistance genotype in the 3 years of evaluation. In the population named BP2and diploid pollinator 7233p.12-81many resistant individual plants were found. Selection of them can result in more resistant populations.
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