Growth and Yield Variations among Generations in Field Cultivation of Virus-free Sweet Potato Plants

This work was conducted to investigate the variation of growth and yield among three generations ($TC_0$, $TC_1$, and $TC_2$) in the field cultivation of virus-free sweetpotato (Ipomoea batatas) plants. Virus-free generations of three cultivars ('Matnami', 'Shinhwangmi', and 'Yeonhwangmi') were cultivated with $75{\times}25cm$ planting density on May 20th, covered with black vinyl film. At 30 days after planting, vine growth in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, and vine length in $TC_0$ showed the highest growth among treatments. At harvesting time after 120 days, vine diameter, number of node, and number of branch in $TC_0$, $TC_1$, and $TC_2$ were more increased than farmer's plant, but were not statistically significant. Fresh weight of shoot in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, but was not statistically significant among generations or cultivars. Number of tuber per plant and mean weight of tuber in $TC_0$ and $TC_1$ showed significant increasement, but that in $TC_2$ did not show significant difference as compared to the farmer's plant. Weight of tuber per plant in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. Marketable yield, percentage of marketable tuber, and percentage of small tuber (40 to 200g) in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. The large tuber over 300g showed the lowest percentage in $TC_0$. Marketable yield in $TC_2$ was significantly decreased as compared to $TC_0$, and was not significantly different as compared to the farmer's plant. Marketable yield in 'Matnami' was highest among cultivars. From this results, Farmers are required to renew every three years to maintain the yield and quality of virus-free plants. However, the exchange period of virus-free plants is desirable to renew every 2 or 3 years according to the degree of virus reinfection.

고구마 바이러스 무병묘의 세대간 생육 및 수량 변이

고구마 바이러스 무병묘 재배에 따른 세대 간 수량변이를 구명하기 위하여, '안노베니', '연황미', '맛나미' 등 3품종의 무병묘 세대($TC_0$, $TC_2$, $TC_3$) 삽수를 $75{\times}25cm$로 정식하여 흑색비닐로 멀칭재배하였다. 정식 30일째 줄기신장은 대조구인 농가묘보다 무병묘 세대에서 유의한 증가를 보였으며, $TC_0$에서 가장 왕성하였다. 120일째 수확기 생육은 줄기길이, 원줄기 마디수와 곁가지수는 농가묘보다 무병묘 세대에서 높았으나, 통계적 유의성은 없었다. 무병묘 세대의 지상부 생체중이 농가묘보다 유의하게 증가하였으나, 무병묘 세대간 그리고 품종간에는 유의한 차이가 없었다. 주당괴근수와 평균괴근중은 농가묘보다 $TC_0$와 $TC_1$ 세대에서 유의한 증가를 보였으나, $TC_2$ 세대에서는 농가묘와 차이가 없었다. 무병묘 세대의 주당괴근중은 농가묘보다 유의하게 증가하였고, 무병묘 세대간에는 $TC_0$에서 가장 높았다. 무병묘 세대의 평균상저수량, 상저비율과 소형 고구마(40-200g) 비율도 농가묘보다 유의한 증가를 보였다. 300g 이상 괴근비율은 $TC_0$ 세대에서 가장 낮았다. $TC_2$ 세대의 상저수량은 $TC_0$ 세대보다 유의하게 낮았고, 농가묘와도 유의한 차이가 없었다. 품종간 상저수량은 '맛나미'에서 가장 높았으며, '안노베니', '연황미' 순이었다. 따라서 무병주의 수량과 품질 유지를 위해서 농가는 3년 주기로 교체하는 것이 필요하다. 다만 교체주기는 바이러스 재감염 정도에 따라 2-3년 주기로 실시하는 것이 바람직할 것이다.