Microbial Inoculation Is Crucial for Endocarp Opening of Panax ginseng Seeds in Warm Indoor Stratification

Panax ginseng Meyer is one of the most popular traditional medicinal plants in Korea. Since ginseng seeds are morpho-physiologically dormant and have a very short lifespan, the harvested seeds need outdoor warm and cold stratification for 100 days each. The seeds were covered by a fruit coat (endocarp), which opened during warm stratification. Farmers must, therefore, dehisce (open the endocarp) seeds annually. The conditions for embryo growth, dehiscence percentage, and endocarp hardness were temperature, watering, stratification substances, solution scarification, and microbial inoculation of the seed endocarp. Watering, temperature (17.5 °C), and aeration are crucial for embryo growth as a germination condition. Moreover, microbial-mediated endocarp decomposition is necessary for dehiscence and embryonic development. This study suggests that a combination of embryo growth and microbial-mediated decomposition of the endocarp during warm stratification is a prerequisite for the dehiscence of ginseng seeds, implying physical and morpho-physiological dormancy. Any microbes (fungi, actinomycetes, and bacteria) tested with high or low cellulose-decomposing ability increased the dehiscence percentage by 66% compared to the untreated control. Seeds of three varieties of P. ginseng and one variety of P. quinquefolius were successfully dehisced by fungal inoculation of seeds. This approach opens the door for year-round indoor dehiscence of ginseng seeds without substrates, such as sand.