Study of Relationships among Qualitative and Quantitative Traits in Sugar Beet Genotypes Infected with Rhizoctonia

In order to study and compare the correlation between the quantitative and qualitative traits of sugar beet genotypes, using multivariate methods under Rhizoctonia disease a trial was carried out at Miandoab Agricultural and Natural Resources Station in 2014.The experimental design was randomized complete block design with four replications. The experimental materials were sixteen sugar beet genotypes. Analysis of variance showed significant differences among the genotypes for all traits, except root sodium content. Based on stepwise regression analysis, gross sugar yield, molasses sugar content and gross sugar content by justifying %89.99 of changes in white sugar yield were considered as the most effective traits in justification of white sugar yield. Factor analysis identified five factors by justifying 81.62% of total data variances. Finally, the three groups were set up in the cluster analysis at similarity distance of 10. The cluster 2 was subjected to groups a (the highest rate) for yellowing score, uniformity score, growth score, healthy plant number, root yield, gross sugar yield, white sugar content, white sugar yield and extract percentage, and was placed in group b (the lowest rate) for root potassium content and alkalinity. Eventually, based on path analysis and regression analysis, the gross sugar yield was determined as the most effective trait on the white sugar yield and the genotypes in cluster 2 were identified suitable for cultivation under the conditions of Rhizoctonia infestation.