This study was conducted to investigate the effects of crown numbers on growth and yield of ever-bearing strawberry (Fragaria × ananassa Duch.) 'Goha' cultivar. Strawberry seedlings were planted with 55 × 30 cm distance on April 29, and the randomized block experimental was designed by putting the crown numbers by 1, 3, 5 and crown-unremoved as the control. At the early growth stage, as the numbers of crown decreased, the size of leaf became larger and inflorescence diameter became thicker. Plant height became higher as the number of crown increased at the final harvesting time. Fresh weight of crown-unremoved plants was 118 g, showing 77.2 g higher than that of plants with one crown. Numbers of the developed inflorescence of plants with five crowns and crown-unremoved was 20.1, whereas 6.8 of plants with one crown, resulted in 13.3 more crowns. However, crown number did not significantly affect the fruit quality. As the crown number increased, the average fruit weight was lighter and the marketable fruit rate was shown to decrease significantly. The marketable yield of crown-unremoved plants was 17,372 kg･ha -1 , showing 68% higher than plants with one crown. Therefore, crown management without thinning crowns was recommended and inflorescence thickness less than 3 mm should be removed for successful production of ever-bearing strawberry 'Goha' cultivar during summer season.

This study was conducted to improve the acclimatization rate of in vitro strawberry plantlets through bioreactor culture using the growth retardant flurprimidol. Different concentrations [0 (Control), 0.1, 0.5, 1.0, and 2.0 mg･L -1 ] of flurprimidol were added during bioreactor culture. After six weeks of treatments, various growth characteristics were investigated and in vitro plantlets were acclimated in the greenhouse. The growth rate of treated plantlets was much lower than that of control, and as the treatment concentration increased, the growth rate was much decreased. Shoots of plantlets treated with flurprimidol were shorter (2.2-3.7 cm) than those of control (7.9 cm). The number of roots per treated plant was around 11.6-34.2, compared with 51.8 in the control. Root length was also lower (0.88-3.08 cm) than control (4.36 cm). However, the number of new shoots and leaves increased in all treatments except for 2.0 mg･L -1 concentration. The root was partially decayed in 1.0 mg･L -1 concentration and was completely decayed in 2.0 mg･L -1 . The survival rate in 0.1 mg･L -1 and 0.5 mg･L -1 concentrations was 100% and 23.3% respectively. After four weeks of acclimatization, the plantlets restarted growth, and growth characteristics of shoots and roots recovered to the levels of control, except for fresh weight. Based on our results, a concentration of 0.1 mg･L -1 flurprimidol is appropriate for improvement of acclimatization rate of in vitro strawberry plantlets in bioreactor culture.

This study was carried out treatment of polyethylene glycol (PEG) in order to increase of survival rate of acclimated plants of strawberry's in vitro plantlets through bioreactor culture. We used PEG with molecular weight 6000 (PEG 6000) in this study. Concentration of PEG is non-treatment, 5, 10, 15, and 20 g･L -1 each bioreactor. 5 g･L -1 of PEG was treated at 1 st , 2 nd , 3 rd , 4 th , and 5 th week during culture. We investigated growth characteristics of in vitro plantlets after 6 weeks cultivation. Growth amount of all PEG treatment decreased as compared to non-treatment. The more concentration increased, the more plant growth decreased. In 5 g･L -1 of PEG, shoot length was shorter than non-treatment that shoot length was 7.9 cm and especially fresh weight that is 1.6 g was more decrease than non-treatment. Shoot length was ranged 3.0-3.9 cm at 1 st week treatment to 4 th week treatment of 5 g･L -1 PEG. The shoot length was not significant by 5.3 cm at 5 th week treatment. The survival rate was improved 5.4% at the treatment of 4 th week and was improved 8.7% at the 5 th week as compared to non-treatment. In order to improve of survival rate of strawberry' in vitro plantlets through bioreactor culture, the method is suitable that adding 5 g･L -1 of PEG in the medium and 5 th week's treatment is suitable.

This study was conducted to determine the optimal MS medium strength to improve sprouting rate of apical meristem of strawberry 'Seolhyang' in vitro. Strawberry apical meristems at size (0.2 mm to 0.3 mm) with leaf primordials were cultured on the MS media with four strength levels (1/4×, 1/3×, 1/2×, and 1×) and the sprouting rate and growth characteristics were evaluated after eight weeks after cultivation. Shoot rate of 'Daewang' apical meristems was 93.6% whereas 'Seolhyang' apical meristems were sprouted with 31.6% on 1× MS medium strength. Different sprouting rates were observed in 'Seolhyang' apical meristem with 31.6% in 1× medium, 75.0% in 1/2× medium, and 94.4% in 1/3× medium. The sprouting rate was improved with the decrease of medium strength, but the shoot rate in 1/4× medium decreased up to 54.5%. Shoot length was 0.9 cm in 1× medium, 1.2 cm in 1/2× medium, 1.6 cm in 1/3× medium, and 1.9 cm in 1/4× medium. Shoot length was longer as medium strength decreased and numbers of leaves and roots were not significant differences among the medium strengths. As a result, sprouting rate was highest and plant growth was best in 1/3× MS medium compared to the others.