Yam may germinate for a long time, and the substances in yam may be lost, and the taste will be poor. Although there is no toxin, it may not taste particularly good when eaten. After yam germination, it can be eaten normally without poison.

Yam originated in Pingyao and Jiexiu, Shanxi, China, and is now distributed in North China, Northwest China and the Yangtze River Basin in China, as well as in Korea and Japan. Yam is a deep-rooted plant with strong adaptability, warmth and cold tolerance. It requires sandy loam with deep soil layer, loose soil and good drainage to grow better in sunny and warm plain and hilly environment. The propagation modes of yam are bulbous propagation and tuberous root propagation.

Growth environment of yam

Dioscorea zingiberensis has strong adaptability, and it is a short-day and warm crop. Dioscorea zingiberensis mainly grows in hillsides, valleys and forests at an altitude of150-1500m, in thickets or weeds beside streams and roadsides. Optimum temperature for seedling growth 15-20℃. The optimum growth temperature is 25-28℃, and the growth is slow below 20℃.

Dioscorea is a deep-rooted plant, which requires sandy loam with deep soil layer, loose soil and good drainage, but flat species and block species can also grow in shallow and sticky soil. It is better to grow in the sunny and warm plain and hilly environment. Dioscorea opposita is cold-tolerant, drought-tolerant, but not waterlogging-tolerant, so it is not suitable for planting in soil with too shallow groundwater level or too humid. The water content of sandy soil and loam soil is about 18%.