[Objective] This study aimed to shorten the multiplication culture and root- ing culture periods of Rh. chrysanthum Pall. [Method] The Rh. chrysanthum Pall tis- sue culture plantlets collected from Changbai Mountain were used as material, and the effects of different hormone combinations and coconut milk on the proliferation and differentiation of Rh. chrysanthum Pall tissue culture plantlets were investigated. In addition, the rooting medium and transplanting matrix for Rh. chrysanthum Pall tissue culture plantlets were explored. [Result] The medium composed of modified MS, iBA （3 mg/L） and ZT （1.5 mg/L） was the optimum medium for subculture mul- tiplication of Rh. chrysanthum Pall tissue culture plantlets. The multiplication multiple and average plant height were significantly improved by adding coconut milk into the medium （150 mg/L）. [Conclusion] For Rh. chrysanthum Pall tissue culture plantlets, the optimum rooting culture medium was composed of modified MS （1/4） and IBA （5.0 mg/L）, and the tissue culture plantlets began to root 8 d after the inoculation. The root induction treatment was carried out after a 15-d sand culture, and the suitable matrix was composed of tufty soil, humus soil and perlite （2：1：1） with a survival rate of 95.66%.
With apical leaves of Lycium ruthenicum Murr as experimental material, the polyploids of L. ruthenicum were induced with colchicine solution, and total four polyploidy plants were identified by chromosome courts. The results showed that tetraploid plants of L. ruthenicum were successfully induced with 300 mg/L of colchicine solution after 7 and 21 d of induction, with 400 mg/L of colchicine solution after 14 days of induction, and with 500 mg/L of colchicine solution after 7 days of induction, respectively.
With tissue cultured-seedlings of Rhododendron chrysanthum Pall. in Changbai Mountain as test material, the effect of EMS treatment on the heat toler- ance of R. chrysanthum, as well as the possible heat tolerance mechanism, was in- vestigated in this study so as to lay a foundation for the popularization, application and germplasm resource innovation of R. chrysanthum. The results showed that when the leaves of the tissue cultured seedlings were treated with medium with 0.1% of EMS for 2 d, the survival rate of the leaves was 48.92%, thus the con- centration of EMS was close to the semi-lethal dose, and the EMS concentration and treatment time could be used as screening conditions for heat-tolerant mutants. The plantlets regenerated from EMS-treated leaves were treated with different tem- peratures, and related physiological indicators were determined. The results showed that the chlorophyll content, MDA content, Pro content, SOD activity, POD activity and soluble sugar content of regeneration plantlets in the treatment group were sig- nificantly different from those in the control group. At the same temperature, the chlorophyll content, soluble sugar content, Pro content, SOD activity and POD ac- tivity were significantly higher and the MDA content was significantly lower in the treatment group compared with the control. In conclusion, EMS treatment improved the heat tolerance of tissue-cultured R. chrysanthum seedlings.
In order to obtain hazelnut lines with the characteristics of strong cold re- sistance, large fruit and high quality capable of overwintering safely in Yanbian ar- eas, with 173 lines of Corylus heterophylla × C. heterophylla ×C. avellana hazelnut as materials, fruit-related characters were measured and analyzed. Eight excellent individuals were preliminarily selected for further identification of cold resistance and high yield. They selected single plants were 57-1, 57-3 and 55-24 of combination 6- 34-1×S1-5, 56-3, 56-5 and 55-19 of combination 6-34-1×S3-1, 21-12 of combination 6-37-2×S3-1 and 21-12 of combination 6-23-1×S3-1.
