Investigation of Relationship between Physiological and Yield Traits by Root and Sugar Yield in Sugar Beet Hybrids under Normal and Salinity Stress Conditions

To determine the relationship between some physiological and yield traits under salinity stress conditions and screening quantitative indices of salinity tolerance, 28 sugar beet (Beta vulgaris L.) genotypes derived from the cross between full-sib 8001 with moltigerm male-sterile single cross C2 and male-sterile monogerm 231×261 with two control varieties were tested in a randomized complete block design with three replications under salinity and normal conditions at Miandoab Agricultural and Natural Resources Research Station. Relationships between traits with root and sugar yield were investigated using correlation, regression and path analysis. Under normal conditions, root yield showed positive correlation with pure sugar yield and negative correlation with sugar content and potassium to sodium ratio. Under salinity stress conditions, positive correlation was observed between root yield and sugar yield, pure sugar yield, potassium to sodium ratio and relative water content of leaves and negative correlation with sodium content and molasses sugar. Changes in environmental conditions caused change in the relationship between root yield and some traits. The results of regression and path analysis showed that under normal conditions if root yield was variable, sugar content and white sugar yield traits justified the changes, thus, in path analysis white sugar yield had the most positive and direct effect and sugar content had the most direct and negative effect on root yield. However, when sugar yield was variable, the traits potassium content, the relative amount of water loss, and nitrogen content justified the changes and among these traits, nitrogen content had the most positive direct effect and the other two traits had the most negative direct effect on sugar yield. On the contrary, under saline condition, if root yield was variable, sugar yield, white sugar yield, syrup purity, and sugar content explained the changes and white sugar yield had the most positive direct effect and sugar yield had the most negative direct effect on root yield. But, when sugar yield is variable, pure sugar yield and syrup purity justify the changes and white sugar yield had the most positive direct effect on sugar yield.