Chapter 1. Evaluation of Cold Resistance of Camellia sinensis (L.) Kuntze by Low Temperature Treatment

This study was conducted to select cold-resistant C. sinensis that can be cultivated in the Bonghwa area through reliable evaluation using a number of cold-resistance indicators for C. sinensis varieties cultivated in the southern region. As a result of investigation in low-temperature damage, the damage with small of amounts green and bright was investigated at ?10℃ in Chamnok and Bohyang. However, Sangnok and Myeongnok cultivars were investigated that the damage with red and dark at ?10℃. According to these results, it is judged that the C. sinensis cv. Chamnok and Bohyang have stronger resistance to low temperatures than Sangnok and Myeongnok. As a result of the chlorophyll content survey, the chlorophyll content decreased as the temperature decreased in all of the cultivars of Chamnok, Bohyang, Sangnok, and Myeongnok. These results were consistent with the characteristics of temperate evergreen broad leaf trees for low temperature treatment. The change in electrolyte elution amount was high at the time of changing from -10°C to -15°C in C. sinensis cv. Chamnok and Bohyang, and this result is judged to have a higher low-temperature tolerance limit compared to green and bright green. The proline content of the C. sinensis Bohyang was higher than that of the C. sinensis Chamnok, Sangnok and Myeongnok. As a result of the reducing sugar content investigation, it was found that the reducing sugar content of C. sinensis Bohyang and Chamnok was higher than that of Sangnok and Myeongnok. The antioxidant activity showed a clear change in antioxidant activity at the time of changing from -10°C to -15°C for Chamnok and Bohyang. In other words, it is judged that the antioxidant system defense mechanism against reactive oxygen species caused by low-temperature stress is more active than that of the Sangnok and Myeongnok varieties. In terms of lipid peroxidation activity, the lipid accumulation content was higher than that of Sangnok and Myeongnok at the -10℃ to -15℃ treatment temperature in the cultivar of Chamnok and Bohyang. These results indicate that the damage to cell membrane lipids is rapidly increased by the reactive oxygen species generated by the low temperature. Therefore, in this study, the C. sinensis cv. Chamnok and Bohyang, which are judged to have high low-temperature tolerance, were selected as cold-resistant varieties.


Chapter 2. The Growth Characteristics of Cold-Resistant Selected Cultivars in the Bonghwa Area

This study was conducted to examine the possibility of growing C. sinensis in the Bonghwa region by planting the domestic C. sinensis cultivars selected in Chapter 1 in Bonghwa, where the average annual temperature is low (9.2℃). As a result of soil investigation in Bonghwa test site, the soil for each test site was irradiated with appropriate levels of pH, EC, substitutional cations, and effective phosphoric acid. The organic matter content was generally low, and the components of heavy metals (cadmium, copper, mercury, lead, chromium, zinc, nickel) were all investigated at levels suitable for soil contamination concerns. As a result of the temperature survey at the Bonghwa test site, Socheon had the lowest temperature at -14.1℃, followed by Chunyang ?12.6℃, Myeongho ?12.6℃, Greenhouse ?10.2℃. As a result of the growth evaluation of C. sinensis, the Myeongho test site had the best growth, followed by Socheon, Greenhouse, Chunyang. In particular, in case of Myeongho and Socheon, it blocks the northwest wind in winter and fog occurs frequently around rivers. It is judged that these environmental factors helped the growth. In addition, it was confirmed that the fertility of the cultivated cultivars Bohyang and Bonghwa had higher growth and photosynthesis compared to the other species. The contents of catechin and caffeine, which are the main biologically active compounds of C. sinensis planted in Bonghwa and Hadong, were investigated. EGC, EC, and EGCG contents of catechin were significantly higher in Hadong than in Bonghwa area compared to Chamnok in Hadong area. The total catechin content was similar, 5.23% in Bonghwa and 5.22% in Hadong. Caffeine content was 0.05% for Bonghwa and 0.38% for Hadong. In general, it is known that the content of secondary metabolites increases when plants are subjected to abiotic stress such as low temperature. Therefore, further research on this is required. In this study, as a result of the growth evaluation of C. sinensis in Bonghwa, Myeongho and Socheon, which block the influence of the northwest wind in winter, are advantageous for cultivation of C. sinensis.


Chapter 3. The Investigation of Efficient Propagation Methods for High Quality C. sinensis

This study was conducted to determine the medium conditions for the uniform propagation of cuttings of cold-resistant C. sinensis selection varieties, and to establish the tissue culture conditions for the mass growth of high-quality tissue cultured seedlings. As a result of cutting C. sinensis according to the type of soil, the survival rate and rooting rate of cuttings were high in the peat moss (PM) + perlite (P) mixed treatment. Based on these results, it is judged that proper drainage and moisturization are important for rooting of the cuttings when cutting C. sinensis. As a result of C. sinensis cuttings treated with growth regulators, the survival rate and rooting rate of the cuttings were high in immersion treatment with growth regulators NAA 5,000 ㎎/L and IAA 5,000 ㎎/L. In particular, it was investigated that 2,4-D treatment was not suitable for treatment with growth regulators as it damaged C. sinensis cuttings. As a result of culturing C. sinensis according to the light quality of LEDs, it was investigated that red light was effective for plant growth of tissue cultured seedlings during C. sinensis tissue culture, and complex light (red, blue, white) was effective for chlorophyll formation in roots and leaves of tissue cultured seedlings. Therefore, it is judged that complex light conditions are effective for the growth of high-quality tissue culture seedlings. As a result of C. sinensis tissue culture according to sugar type and concentration, it was investigated that treatment glucose and fructose at 0% carbon source (sucrose), and treatment sucrose and glucose at 3% carbon source (sucrose) was effective for growth of tissue culture seedlings. Therefore, it is judged that it is necessary to properly supply a carbon source for the growth of high-quality tissue cultured seedlings. In this study, peat moss (PM) + perlite (P) mixed treatment was advantageous when propagating C. sinensis cuttings, and NAA 5,000 ㎎/L and IAA 5,000 ㎎/L instant immersion treatment were effective as growth regulators. When culturing C. sinensis tissue, complex light (red, blue, white) treatment is effective, and it is judged that sucrose and glucose are effective for supplying the medium carbon sources.
The above results are judged to be basic data for cultivating C. sinensis in areas above the northern limit of C. sinensis, such as Bonghwa area, to produce high-quality tea, and at the same time to establish strategies for climate change of several promising forest species.