2.2. Phenotype assessment
A total of 26 phenotypic trait data (Table 1) were evaluated during the vegetative growth of the plants and when tubers were harvested, including 20 qualitative traits and six quantitative traits. The observed values of 20 qualitative traits were repeated six times, and the measured values of six quantitative traits were observed six times (Table 1). All traits were investigated in accordance with the description specification and data standard of Chinese yam germplasm resources (Huang and Huang, 2013; Wang and Shen, 2014).