This study was conducted to examine effects of plant growth regulators and light resources on the formation of multiple shoot and plant regeneration of Hovenia dulcis var. koreana Nakai. Stem and shoot tip were cultured on MS medium or WPM supplemented with various plant growth regulators. At the single treatment, the highest shoot formation was obtained when stem explants were cultured on WPM supplemented with kinetin 1.0mg·L-1. MS medium containing NAA 0.1 and TDZ 0.1mg·L-1 gave the best results for shoot induction rate and shoot growth in combination treatments. Of the BAP and kinetin tested, BAP 0.5mg·L-1 on WPM was found to be more effective for shoot growth from shoot tip. Under white fluorescent light treatment, shoot growth was much higher than blue, red LED treatments. Root induction from in vitro growth of plantlet was the best on WPM supplemented with 1.0mg·L-1 IBA. The results suggest that selection of plant growth regulators and light resources could be important factor to achieve an efficient in vitro growth.

For the purpose 　of breeding a high-yield superior variety of Korean raisin tree (Hovenia dulcis var. koreana Nakai), whose value as an edible and medicinal resource is increasing, tree candidates for superior individuals were selected from its 11 habitats in Korea from 1996 to 1998. A clone bank preserve was created in 1998 with 70 clones proliferated by grafting; the fruition traits (e.g., the number of fructified laterals, the average number of bunches per fructified lateral, the average number of bunches per fruiting lateral, the fruitpetiole weight per individual, and the yield per individual) of 47 clones that had bloomed and borne fruit were investigated and analyzed in 2002; five upper-ranking clones whose yield per individual exhibited a 261% improvement against the total average were picked in 2005; and three clones, including ‘oong-Sung 1’ that showed a difference in their fruit petiole ripening stage, were finally selected in 2007 as high-yield new cultivars of Korean raisin tree.

Hovenia dulcis var. koreana Nakai is recently known to be a useful tree because of their medicinal function. In 1996, candidate trees were selected from 10 regions in Korea, and a clone bank was established in 1998 by grafted 70 candidate clones of candidate trees in order to breed high-yield superior trees. From 2003 to 2005, five clones were selected and screened by analyzing flowering and fruiting characteristics of 47 clones in the clone bank. “Poong-Sung 1”, a new high-yield superior H. dulcis var. koreana Nakai cultivar was finally selected from the 5 clones. The final selection focused on fruiting characteristics such as the number of fructify lateral (NFL), the number of average bunch per one fructify lateral (NABFL), the number of average bunch per fruiting lateral (NABPFL), the weight of fruit petiole per individual (WFPI) and the yield of individual (YI). Fruit petiole of “Poong-Sung 1” has dark brown skin color and fruit flesh color. Fruiting characteristics of “Poong-Sung 1” showed large better results and selection effects with an average of 19.3Ea (NFL), 4.75Ea (NABFL), 91.68Ea (NABPFL), 4.7 kg (WFPI) and 11.26 kg (YI) which are 158.8%, 147.1%, 233.9%, 401.7% and 412.5% superior compared to the mean of 47 clones, respectively.

우량품종 육성을 위해 선발된 헛개나무 차대묘 20가계의 생장특성과 엽특성을 조사한 결과, 전체 평균 묘고는 61.6cm, 평균 근원직경은 6.98mm였으며, 가계별로는 KW 2-5 가계가 평균 묘고 79.3cm로 가장 우수한 생장을 보인 반면 근원직경에서는 JN 2-2 가계가 평균 9.16mm로 가장 우수한 생장을 나타내었다. 묘고와 근원직경에서 가장 우수한 생장을 보인 KW 2-5와 JN 2-2 가계는 가장 낮은 생장을 보인 가계들과 비교하여 각각 57%와 53%의 우수한 생장을 보였다. 묘고와 근원직경의 초기생장 상위 10% 가계를 선발했을 때 KW 2-5와 JN 2-2 가계가 전체 가계 평균에 비해 125%의 선발 효과를 보였으며, 상위 20% 가계를 선발했을 때 KW 2-5, JN 2-2, KW 1-1, KW 1-15 가계에서 115%의 선발효과를 나타냈다. 한편, 엽장과 엽폭, 엽병길이와 엽병직경 및 엽형지수와 측맥수 등 6항목에 대하여 엽특성을 조사한 결과, 평균 변이계수는 9.4~42.4%로 나타나 변이 폭이 큰것을 알 수 있었으며 특히, 엽병길이와 엽병직경 특성의 변이계수가 각각 42.4%와 28.7%로 다른 특성들에 비해 큰 값을 나타냈다. 조사된 엽특성들은 모두 가계간 유의적 차이가 인정되었으며, 엽장과 엽형지수간 상관을 제외한 모든 특성들간의 상관에서는 정의상관 관계가 인정되었고 특히, 엽장과 엽폭특성간의 상관계수가 0.8049로 나타나 두 특성간에 매우 유의적인 관계가 있는 것으로 나타났다.

This study used RAPD markers to assume genetic diversity and variation in selected populations of Hovenia dulcis var. koreana. Ratio of polymorphic RAPD markers were 93.4% in selected populations of Hovenia dulcis Thunb., difference of genetic structure among populations and within populations showed 16.45%, 83.55%, respectively in amount of total genetic variation of 4 populations. Total gene diversity(HT) that show genetic diversity appeared 0.313 and coefficient of gene differentiation(GST) that compare genetic differentiation of populations appeared 0.1645, analysis of AMOVA for variation among populations and within populations was significantly different (P〈0.001). Genetic diversity of whole populations showed that 12.44% difference among population and 87.56% difference within populations. As a result, difference within populations was larger than difference among populations in genetic diversity. Nei's genetic distance and cluster analysis appeared that mean genetic distance among populations was 0.076, thus dividing two main groups and geographic relationship did not show in populations.