Study on Stem Tip Detoxification and Tissue-cultured Rapid Propagation Technology of Three Kinds of Purple Yam

The medium suitable for the stem tip induction, virus-free seedling proliferation and rooting of purple yam and the matrix for the transplantation and domestication of in vitro regenerated seedlings were screened, in order to provide healthy seedlings for the production. Three kinds of purple yam were used as the test materials, and different concentrations of 6-BA, NAA, KT and GA₃ were added to MS medium, thus to study the effects of different concentration ratios of plant-growth regulator on the stem tip induction, subculture proliferation and rooting. Then, the in vitro regenerated seedlings were transplanted into the seedbeds of imported peat soil, perlite and coconut bran with different ratios, and the effects of different matrix ratios on the survival rate of transplanting were observed. The results showed that the shoot tip seedling rates of Wuyishan purple yam, Hutoushan purple yam and Zhenghe sweet potato were the highest in MS medium supplemented with 1.0 mg·L⁻¹ 6-BA + 0.1 mg·L⁻¹ NAA, which were 77.78%, 77.78% and 71.11%, respectively. The proliferation coefficient of Wuyishan purple yam was the highest in MS medium supplemented with 1.0 mg·L⁻¹ 6-BA + 0.5 mg·L⁻¹ KT + 0.3 mg·L⁻¹ NAA + 0.1 mg·L⁻¹ GA₃ + 0.2 g·L⁻¹ AC, which was 4.6. The proliferation coefficients of Hutoushan purple yam and Zhenghe sweet potato were the highest in MS medium supplemented with 0.5 mg·L⁻¹ 6-BA + 0.2 mg·L⁻¹ KT + 0.1 mg·L⁻¹ NAA + 0.1 mg·L⁻¹ GA₃ + 0.2 g·L⁻¹ AC, which were 4.83 and 4.82, respectively. The root growth of Wuyishan purple yam, Hutoushan purple yam and Zhenghe sweet potato was the best in MS medium supplemented with 0.5 mg·L⁻¹ IBA + 0.5 mg·L⁻¹ NAA + 0.5 mg·L⁻¹ CCC + 0.5 g·L⁻¹ AC. The transplanting survival rate of three kinds of purple yam was the highest when transplanted in 100% matrix of imported peat soil, which was 82.7%, 80.0% and 82.0%, respectively.