Sugar beet hybrids response to rhizomania disease in the infected fields

Rhizomania is one of the most important diseases of sugar beet causing dramatic reduction in yield and quality. Because of the rapid spread of rhizomania in sugar beet fields, successful production of the crop is not possible without the use of highly tolerant cultivars. The aim of this study was to compare some of the agronomic characteristics of rhizomania-resistant hybrids with domestic and foreign commercial varieties. The study was carried out in randomized complete block design with four replications in four regions including Karaj, Mashhad, Miandoab and Zarghan in 2013-14. Seven promising hybrids together with three domestic (one susceptible and two tolerant) and two foreign cultivars as checks were evaluated. Different characteristics such as infection rate, growth score, root length and diameter, and also single root weight were measured. Infection rate was measured based on Luterbacher’s 1-9 scale. At harvest, roots were weighed and sugar content was determined. Infection rate results showed that roots produced in Karaj in 2014 and Miandoab in 2015 were free from the symptoms and therefore, these two regions were considered as non-contaminated environments. The highest rate of infection was observed in Zarghan in both years. Overall, (7112×SB36)×SB27 was selected as the superior hybrid in terms of root yield, sugar content, growth and root uniformity.