Tubers of cv. R. and cv. W. were independently collected
from Xiuyan of Liaoning Province and Yulin of Shanxi
Province, China. Tubers of the two genotypes were cut into
small square pieces with a single bud, and about 1 g
weight, sterilized with 75% ethanol (v/v) for 30 min, and
washed thoroughly with distilled water. Subsequently,
tuber slices were immersed into 2.9 9 10-5 M Gibberellic
acid (GA3) for 5 min in order to uniformly maintain the
future seedlings. Thereafter, they were rinsed drastically
with distilled water, and germinated on moist sand in an
incubator at 25C. The relative uniformly germinated slices
with buds were picked out and cultured with half-strength
Hoagland’s nutrient solution in the tissue culture house.
The nutrient solution was renewed once in every 2 days