Background : Unlike Dioscorea japonica or Dioscore opposita, Dioscore alata is a high-temperature crop mainly cultivated in Africa and subtropical regions. Due to recent climate change, its cultivation area is expanding in Korea. In 2016, the Institute for Bioresource Research clarified optimal harvesting stage to increase its tuber yield and ensure safe storability. Methods and Results : As the seed-tubers for this study, Dioscorea alata tubers were cut into a size of 50 g, disinfected with lime powder, dentated on the seed bed with electrothermal wire installed on March 20th, and then planted on the main field on April 15th. The planting distance was 120 ㎝ in width, where the furrows of 90 ㎝ were cladded with black vinyl, in two rows with a column spacing of 25 ㎝. The amounts of applied fertilizers were 2,000 ㎏ compost, 34 ㎏ N2, 28 ㎏ P2O6, and 28 ㎏ K2O. The compost and P2O5 were used in full, where as N2 and K2O were used as original fertilizer 14 (10 ㎏) and additional fertilizer 20 (18 ㎏), respectively. The crop was harvested in six times from September 20th to November 9th, in an interval of 10 days. While harvesting, the ground fresh weight yield and underground tuber yield were investigated. The underground tuber yield was 836, 1,744 and 2,975 ㎏ low at the early harvests on September 20th, 30th, and October 10th, respectively, while it was 3,622, 3,828, 3,818 ㎏ high on October 20th, 30th, and November 9th, respectively. The ground fresh weight yield remained the same. To clarify tuber storability by harvest time, they were stored at 15℃after harvest, and then healthy and corrupt tubers were studied on March 23th. The corruption ratio by harvest time was highest at 39.1% and 29.3% on October 30th and November 9th, respectively, when frost and low temperature damaged harvest. It was 59.0% and 42.8% at the early harvests on September 20th and 30th, respectively. The corruption ratio was lowest on October 20th and October 10th at 29.3% and 39.1%, respectively. Conclusion : Ford. Dioscore alata cultivation, Korea presents a premature and disadvantageous environment with lower temperature and pre-harvest frost at the time of planting. After raising seeding on an electrically heated hot bed, the optimal harvesting stage should be from planting in the middle of April where temperature rises above 1 5℃ to harvesting in the period October 10th - 20th so as to achieve the maximum tuber yield and high storability.

Background : study of long yam and short yam (Dioscorea. opposita) are cultivated in temperate regions but tropical yam (Dioscorea alata) are mainly grown in Africa and sub-tropical regions cultivated crops. Recent tropical yam cultivation area of Korea increased but lack the proper cultivation techniques to climate warming. This study was conducted to elucidate the effect of the timely harvest on Tropical yam at 2015 in Institute of Bioresources Research, GBARES. Methods and Results : Tuber of tropical yam were cut as 40 g, and dust-coating sterilized with lime. Seedlings were grown in heating wire installed seed bed from 11. March to 16. May. Experimental field were fertilized 2,000 kg compost, 34 kg N2, 28 kg P2O5, and 28 kg K2O. All amount of compost and P2O5 treated as basal fertilizer. N2 and K2O treated 14 and 10 kg of basal fertilizer, and 20 and 18 kg of additional fertilizer, respectively. Tillage, covering black PE film with 60×25 cm spacing holes on 120 cm row were conducted. Emergence days from 6. April to 18 May until 28 days to 36 days but 15. June and 9. June were each 19 and 7 days. Dry weigh in early stage due to seedling date, while seedling date according from 6. April to 18. May had no difference. seedling date was not effective on total number of tuber but number of marketable tuber (over 200 g). Marketable tuber number of seedling date according to 20. April was increased 35~132% as 4,028 number per 10 a. And tuber with 20. April was 13~73 g heavier. Tuber yield and marketable tuber yield of seedling date as affected by 20. April were respectively 2,518 and 1,273 kg per 10 a compared to 6. April and from 4. May to 15. June as 1,743~2,457 kg and 484~1,027 kg. Conclusion : Tropical yam is low temperature in the cultivation of Korea but also adverse environmental conditions. Frost is not mature enough off before harvesting. Yam had significant increased marketable tuber (over 200 g) yield due to seedling in mid-April Requires cultivation technology.