Abstract:

【Objective】 We aimed to optimize rooting and transplanting techniques to improve the transplant survival rates of tissue-cultured shoots of Camellia chrysanthoides ‘Huangzun’. 【Method】 Tissue-cultured shoots were aged for 60 days. We optimized the content of basic media including 1/2 B5, 3/4 B5 and B5, and plant growth regulators (PGRs) including ABT and IBA. Differences in rooting rates were determined among five combinations of rooting substrates and additives, including agar 6.0 g/L+sugar 0 g/L, agar 6.0 g/L+sugar 15 g/L, agar 6.0 g/L+sugar 15 g/L+charcoal (AC) 3.0 g/L, substrate with 1V_sand+1V_vermiculite (sand-vermiculite substrate) +sugar 0 g/L, and sand-vermiculite substrate+sugar 15 g/L, and differences in shoot diameter, rooting, transplant survival, and yellowing rates were compared among media comprising sugar 15.0 g/L, K₂HPO₄ 15.0 mg/L, sugar 15.0 g/L + K₂HPO₄ 15.0 mg/L, and without sugar and K₂HPO₄, after the rooting-culture for 35 days, in sand-vermiculite substrate+ 1/2 B5 + ABT 0.5 mg/L + IBA 0.5 mg/L as rooting medium, and after 65 days, with 3V_sand + 1V_vermiculite as the transplant substrate. 【Result】 Rooting rates were 41.1%-42.2% on the optimized medium 1/2 B5 + ABT 0.5-1.0 mg/L + IBA 0.5-1.0 mg/L + sugar 15 g/L + agar 6.0 g/L. The difference in rooting rates was significant among the five combinations of rooting substrates and additives; the rooting rates on sand-vermiculite substrate without sugar and sand-vermiculite substrate + sugar 15 g/L were 84.4% and 68.9%, respectively, which were higher than those on traditional combinations of agar and sugar. Rooting rates on agar 6.0 g/L + sugar 0 g/L, agar 6.0 g/L + sugar 15 g/L, agar 6.0 g/L + sugar 15 g/L + charcoal (AC) 3.0 g/L, were 57.8%, 40.0% and 33.3%, respectively. Rooting rates did not significantly differ among the four conditions, but transplant survival rates significantly differed. The yellowing and quality of seedlings were respectively overcome and improved, the rooting rate reached 91.1%, and the transplant survival rate reached 93.3%, when sugar 15 g/L + K₂HPO₄ 15.0 mg/L was added to the medium at the late stage of the rooting culture. 【Conclusion】 The effects of rooting and transplanting seedlings of C. chrysanthoides ‘Huangzun’ by using traditional culture on agar and sugar were not ideal. This method improved the rooting and transplant survival rates of C. chrysanthoides ‘Huangzun’, and provides a useful means for culturing other plants with rooting difficulties such as Camellia Sect. nitidissima Chi. We applied the sugar-free medium with sand-vermiculite substrate+ 1/2 B5 + 0.5-1.0 mg/L + IBA 0.5-1.0 mg/L at the early stage and added sugar 15 g/L + K₂HPO₄ 15.0 mg/L to the medium at the late stage of rooting culture.

Key words: Camellia chrysanthoides ‘Huangzun’, tissue cultur and rapid propagation, rooting rate, transplantation survival rate, technical optimization, ABT, IBA