Eight vermiculite-based root media prepared with addition of complete fertilizer (2 g/L; N-P2 O5 -K2 O, 10-10-14) for potatoes (Solanum tuberosum L.) and a commercial root medium were evaluated in 2000 to develop the root media suitable for potato plug seedling production. The eight media consisted of various ratios of vermiculite, perlite, peatmoss, and compost. In addition, four rates (0, 1, 2, or 4 g/L) of the complex fertilizer for potato were added to a root medium (70% vermiculite, 10% perlite, 10% peat moss, and 10% compost by volume) to determine the optimum addition rate of the complex fertilizer for plug seedlings. Compost addition to the media increased plant height, the number of leaves per plant, and top and root fresh weight of 15-day old plug seedlings. The seedlings raised in root media containing compost produced significantly higher total tuber yield. Addition of the complex fertilizer to root media enhanced seedling growth and increased the number of tubers per plant and tuber yields. The results suggest that root media containing 50% vermiculite, 0 to 20% peat moss, 10% perlite, 20 to 40% compost, and 2 g/L complex fertilizer for potato appear suitable for potato plug seedling production.

For the mass production of plug seedlings in cultivar ‘Dejima’ potato (Solanum tuberosum L.) the optimal apical cutting diameter for rooting and rapid multiplication of stem cuttings in hydroponics were determined. In addition, the best planting date was predicted to increase tuber yield of plug seedlings at fall cropping in Cheju-Do, Korea. Days to initial rooting decreased as the cutting diameter was reduced. Plant height, leaf number, root length and root weight per plant were favorable as the cutting diameter was small. The ideal cutting diameter was 1-2 mm in this experiment. In the hydroponic cultures, the Japanese standard (JS) nutrient solution was the most effective for multiplication of stem cuttings. It was able to propagate more than 20 times a month from a single mother plant. Viability of plants, which were derived from plug seedlings using stem cuttings, was excellent when transplanted to the field. The number of tubers and tuber yield in both of the plug seedlings and seed potato planting plots were high when planted on 25 August. The number and yield were reduced when planted on 15 August, 5 September and 15 September. The degree of decrease of tuber yield in the plug seedling planting plot however, was lower than that of seed potatoes when the planting date was late. In the case of small tubers (under 30 g), the number of tubers and tuber yield were evidently increased in the seed potato tuber planting plot; the yield of large tuber (over 80g) in the plug seedling planting plot was higher than that of the seed potato. The total tuber yield per plant in the plug seedling planting plot was less than that of the seed potato; therefore, in order to increase tuber yield it was necessary to increase field plant density.

제주도 화산회토 신개간지에 있어서 숙전화를 촉진시키는 한가지 방법으로서 적응력이 강하고 잡초의 재생을 억제하는 능력이 강한 두과작물을 선택하고자 알팔파, 화이트클로버, 채두, 완두, 대두 및 차풀 등의 6개 두과작물을 공시하여 이들의 근류착생 정도를 조사하고 이중 근류착생이 가장 양호하였던 차풀의 잡초와의 경합관계를 조사한 결과는 다음과 같다. 1. 착생된 근류의 무게는 차풀에서 가장 무거웠고 다음은 완두, 대두, 화이트클로버, 채두 및 알팔파의 순이었다. (알팔파는 관찰 불가) 2. 자연초지에 차풀을 파종할 경우 그 건물중은 4년차까지 거의 직선적으로 증가하였으나 띠는 3년차 부터 감소하는 경향이었다. 3. 제주도 지방의 신개간지에서는 지력증진을 위해서 차풀을 재식하는 것이 유리할 것으로 추론되었다.