Study on Relationship Between Cucumber Germplasm and Propamocarb Residue Using Subjective Rating Technique

Propamocarb (PM) residue in cucumber (Cucumis sativus L.) receives little attention. As is well known to all, high PM residue of cucumber could lead to increase in the violation rates of maximum residue limits and ultimately cause harm to human health. Knowledge of PM residue could help cucumber breeders in developing cultivars with low PM residue and improving cucumber quality. In this study, 32 representative cucumber accessions (26 breeding lines and six cultivars) from different regions of China were evaluated for their PM residue in fruit and leaf to provide meaning to the subjective rating, which was highly correlated with PM residual content of fruit (r=0.97) and leaf (r=0.94). In addition, PM residual content of North China ecotype was the highest and Pickling ecotype was the lowest in fruit and leaf of cucumber. The leaf had significantly higher (P<0.01) PM residual content than the fruit, and poor correlation between leaf and fruit was represented. This study verified PM residual relationship between fruit and leaf, and laid the foundation for further identification of germplasm resources and breeding of new varieties for low PM residue of cucumber.