Performance of Sugar Beet Hybrids in Different Levels of Rhizomania Disease Severity

In Iran, about half of the sugar beet fields are infected by Rhizomania disease and the severity of infection in various regions is different. Then the selection of appropriate varieties which could have high yields in different infected conditions is important.
Material and To compare promised resistant hybrids to rhizomania in different conditions of infection to the disease levels, an experiment was conducted in four regions including disease free and infected areas with different infection levels. In the this study, 19 monogerm diploid hybrids resistant to rhizomania were compared with foreign and domestic resistant varieties in randomized complete block design with four replications. In the disease free location, the percentage of seedlings emergence in domestic genotypes relative to the average of foreign resistance varieties, leaf number, leaf arrangement, green intensity and uniformity of crops were determined in the early growing season. At the harvest time in infected areas, the disease severity index was determined. In all areas, number, yield and quality of roots in each treatment were measured.
Results confirmed that disease intensity of experimental regions was different. There was a significant variation among promising hybrids in the investigated properties.
Generally, with increasing disease severity, root number, root yield, sugar yield, sugar content and nitrogen of roots were significantly reduced. In contrast, the gross amount of sodium and potassium increased in roots. Hybrid SB26 because of high root numbers, root yield, sugar content and sugar yield and low sodium content of root as well as low disease severity was chosen as a superior hybrid. The results of this study confirmed that also in condition of disease free, a resistant variety has better quantitative and qualitative characteristics in comparison to a susceptible variety.