Effects of Covering and Uncovering Date on Seedling Emergence of Overwintering Ginseng and American Ginseng

Ginseng and American ginseng need to be covered and protected against cold in winter to survive, and covering and uncovering date has great influences on safe overwintering and seedling emergence. To determine the optimal time, field experiments are conducted at Fusong of Jilin Province from November 2021 to June 2022. Effects of different covering dates on the soil temperature in the overwintering layer and seedling emergence rate of ginseng and American ginseng are studied through different experiment themes. For some cases they are covered in stages in early winter and simultaneously uncovered in spring, and there are also other cases when the ginseng and American ginseng are covered simultaneously in early winter and uncovered step by step in spring. Results show that the emergence rate of ginseng and American ginseng decreases with the delay of coverage date. When 5 cm soil temperature is 0℃, the coverage date for cold prevention is the best, with the highest emergence rate of ginseng and American ginseng. Below -12℃, most or all of American ginseng is frozen to death. When the instantaneous 5 cm soil temperature drops to -14℃, the emergence rate of ginseng still reaches 75%. The emergence rate of ginseng seedlings in other treatments above this temperature coverage is mostly over 86%. When the soil temperature is -7℃ or above, the emergence rate of ginseng seedlings is above 97%. The emergence rate of ginseng seedlings covered by snow is 91%. The soil temperature fluctuates between -14℃ and -8℃, and all uncovered ginseng with an extreme minimum of -16℃ is frozen to death. When ginseng seedlings emerge, the soil temperature of 5-20 cm is around 8-9℃, slightly higher than that of American ginseng. Covering with high insulation fibers to prevent cold, the later the cover is removed, the lower the soil temperature becomes, and the later the seedlings emerge. The date of uncovering affects the progress of seedling emergence, but has little correlation with the emergence rate. The optimal date of uncovering needs to be analyzed further. On frost prone areas in early spring, combined with climate prediction, the emergence progress can be adjusted by uncovering date to avoid spring freezing damage.