Optimum Culture Conditions of Sweetpotato Stem Cut for Shoot-transplant Production during Winter

고구마 줄기묘의 원동육묘 적정조건

This study was conducted to know the optimum conditions for overwinter culture of sweetpotato stems in PE film house. The stems will be used as transplant shoots in the next year instead of sprouts produced from storage roots. Sweetpotato stems were cut at field on harvest season and planted in PE film house under three different conditions of PE film mulching, tunnel, or mulching plus tunnel in comparison with the non-treatment of PE film on October 10 and November 10. The survival rate of sweetpotato stems, which was evaluated on April 10 after overwinter, was higher in the treatment planted on October 10 than that on November 10, and with PE film treatments, it was higher in tunnel or mulching plus tunnel than that of the non-treatment of PE film. The survival rate of sweetpotato stems to planting densities was 95-96% in 10$\times$2cm (333 stems/$m^2$) or in 10$\times$4cm (250 stems/$m^2$) when compared with 10$\times$2cm (500 stems/$m^2$). The survival rate under low temperature showed 95% until 20 days at 5$\pm$1$^{\circ}C$, and 0% within 5 days at 2$\pm$1$^{\circ}C$. From these results, it was concluded that there were optimum conditions that cutting time is middle October, planting density is 10$\times$3cm, and minimum maintenance temperature is 5$^{\circ}C$ in growing conditions of sweetpotato stems. Root yield produced by trans-planting shoots using the stems was similar to yield by shoots produced from roots, and the survival rate was not different among varieties.

본 연구는 고구마 수확시기에 줄기를 예취하여 월동 재배할 수 있는 조건을 구명하여 이듬해에 본포 삽식묘로 활용함으로서 씨고구마의 저장, 파종 및 묘 생산에 소요되는 노력과 비용을 절감하고자 시험을 수행하였던 바 다음과 같은 결과를 얻었다. 1. 줄기묘의 월동재배를 위해서는 터널피복처리에 의해 생존이 가능하였으며 적정 재식시기는 10월 중순이었다. 2. 줄기묘의 재식밀도는 10$\times$3cm(333주/$m^2$)가 적정하였다 3.줄기묘의 겨울철 생육을 위해서는 최저 5$^{\circ}C$이상이 필요하였다. 4. 줄기묘의 묘수는 씨고구마에 의해 생산된 묘수에 비해 적었으나 줄기묘의 조기 증식에 의해 묘수를 증가시킬 수 있었다. 5. 줄기묘의 본포 수량성은 씨고구마묘와 차이를 보이지 않았다. 6. 품종간에는 줄기묘의 월동 후 생존율에 큰 차이를 보이지 않았다.