path analysis under normal and salt stress conditions in sugar beet germplasm

understanding the relationship between root yield and other traits in sugar beet may be a crucial step towards successful breeding of this important crop. path analysis provides a useful method in analyzing the genetic and phenotypic coefficients of correlations. this method is able to effectively unveil direct and indirect effects among traits of interest. in this research, root yield, yield components, some morphological traits and their relationships were investigated. the study included 20 different sugar beet genotypes that were planted in field under normal (ec= 1.1) and salt stress (ec= 12 ds/m) conditions. genotypes were also screened in greenhouse under similar conditions. data analysis was done by calculating the coefficients of correlations between root yield and other evaluated traits. then, using regression analysis a model including significant traits was developed. finally, path analysis was used to dissect root yield with traits remained in the model into determine direct and indirect effects. our findings indicated that under normal condition, traits including canopy cover and number of plants per m2 together accounted for 56 percen of the variation in root yield. however, under salt stress condition, four variables including canopy cover, number of plants per m2, na and k content together accounted for up to 87 percentage of the variation in root yield. using path analysis it was found that under normal condition, canopy cover had a considerable positive effect (p = 0.5534) on root yield while under salt stress, in addition to canopy cover (p =  0.5919) the k+ content (p = 0.6591) also indicated a considerable positive effect on root yield. we concluded that traits including canopy cover and k+ content may be used to accelerate the selection process in breeding programs wherever a huge number of germplasm has to be evaluated.