Evaluation Method and Cultivar Selection of Submergence-tolerant Sweet Potato Seedlings

Objective A simple, efficient method to predict the submergence tolerance of sweet potato cultivars was developed.

Method In a pot experiment, changes in color, morphology, and other phenotypic traits of the stems and leaves of sweet potato seedlings being submerged in water for varied durations were monitored. Specific scoring criteria, calculation method, and evaluation scheme were applied to compare the submergence resistance of 72 sweet potato germplasms at seedling stage for tolerance classification.

Results Two flooding durations, 72h and 144h, were selected for the evaluation. A scoring system on the stem and leaf phenotypes to quantitatively differentiate the reactions of seedlings to the treatment into 6 classifications was established. Tolerance of the 72 germplasms to submergence varied significantly. More than half of the varieties were relatively tolerant, but 17 substantially. For instance, Zhanshu 118 and Fushu 404 were found to be highly submergence-resistant, whereas Quanshu 830 and Kanghanzhong intolerant to the treatment.

Conclusion The quantitative evaluation method distinctively separated 72 sweet potato germplasms based on the flooding tolerance of their seedlings. Further observation to confirm with field performances of the cultivars is in order before the method could be used as a tool for studying the physiological trait and/or breeding of submergence-tolerant varieties.