Root structure and drought tolerance of rapeseed under PEG imposed drought

A new method based on sand culture and 14%(m/V) polyethylene glycol-6000(PEG-6000) was developed to evaluate root traits of 39 rapeseed genotypes at seedling stage and the connections between root traits and drought tolerance.Results showed that root weight and lateral-root number were significantly inhibited by drought,while root length and root-to-shoot ratio were modestly affected.Significant correlations were found between vigor index and both lateral roots number and root length,implying that these two traits can be used as selecting criteria for drought tolerance.Inbred lines and hybrid varieties had no significant difference on root traits for drought tolerance.By clustering analysis,the 39 genotypes were divided into 5 groups at Euclidean distance of 60.Among them,group A was considered as the most tolerant to drought,and group E was the most sensitive.Three drought tolerant genotypes(OR918,OR805 and OR2025) showed potentials for further breeding program.