The Effects of Seeding Time on Growth, Contents of β-carotene and Sugars of Carrots in Jeju Island

파종기가 제주산 당근의 생육과 β-carotene 및 당함량에 미치는 영향

An optimum seeding date for carrots growing in Jeju was determined. In early growth stage, the number of leaves was more in Hyang-yang #2 cultivar (HY2) than that in the others, meanwhile that of Hukjun 5 chon (H5) and Shinhukjun 5 chon (S5) was higher in the latter half of the growing season. The weight of leaves was greater in HY2 until 2 months after seeding, but thereafter drastically increased and resulted significant difference at harvest in S5. The length of roots was greater in H5 and S5 than in HY2 when seeded on July 17 and measured after September 13, but it was similar in all cultivars when seeded on August 1 and later. The diameter of the roots was greatest in HY2, regardless of seeding dates, meanwhile no difference was found among other cultivars. The weight of roots was greatest in HY2 when seeded on July 17, August 1 or later, meanwhile it was greater in H5 after November, when seeded on August 15. The percentage of roots cracked was 20, 15, and 10% respectively for HY2, S5 and H5. The percentage of roots branched was 0.3% in HY2. The percentage of roots cracked or branched was much higher when seeded on August 1 than on July 17, and was high (40%) in HY2 and S5, compared to H5 when seeded on August 15. The content of sucrose, glucose and fructose increased until 110 days after seeding in all cultivars, but fructose and glucose contents decreased in about 135 days after seeding, but sucrose contents increased continuously even after 135 days. Sucrose content increased and fructose and glucose contents decreased in S5, but this trend was reversed after late November. Sugar contents was different among the cultivars seeded on August 15, while sucrose content decreased and glucose and fructose contents increased with time. The content of ${\beta}$-carotene was more than 12,000 IU in all cultivars, but decreased in 170 days after seeded on July 17. The content was highest in HY2 and followed by S5 and H5 in order. It was not different among the cultivars in 170 days after seeding on August 1, but was higher in S5 than the other cultivars in 170 days after seeded on late and decreased with seeding date.

제주에서 당근의 적정 파종기를 파악하기 위한 실험을 하였다. 엽수는 생육초기에는 '향양 2호(HY2)'가 다소 많았으나 후반기로 갈수록 오히려 '흑전 5촌(H5)'과 '신흑전5촌(S5)'에서 많아지는 편이었다. 엽중은 파종후 2개월까지는 'HY2'가 무거웠지만 후반기로 갈수록 'S5'의 증가율이 현저히 커서 후기에는 유의차를 보였다. 근장은 1차파종에서는 9월 13일부터 'H5'과 'S5'가 'HY2'에 비하여 길었으며 2,3차 파종기에서는 3품종이 거의 비슷한 경향을 보였다. 근경은 파종기 모두에서 품종간에는 큰 차이가 없었다. 근중도 1차, 2차파종기때는 역시 'HY2'가 무거웠고 3차파종기에서도 11월 이후부터는 'H5'이 더 무거운 편이었다. 1차파종인 경우 'HY2'가 20% 'S5'는 15%, 'H5'는 10%의 열근율을 나타내었으나 기근율은 'HY2'가 0.3%에 불과 하였다. 2차파종인 경우는 1차파종때보다 열근율과 기근율이 훨씬 높았고 특히 3차 파종인 경우는 'HY2', 'S5'는 40%의 높은 발생율을 보였다. 당함량은 3품종 모두 파종후 110여일경 까지는 sucrose, glucose 및 fructose가 증가하다가 135일을 전후하여 fructose, glucose는 감소하였으나 sucrose는 계속 증가하는 경향을 보였다. 품종별로 보면 'S5'인 경우 sucrose가 크게 증가하고 fructose, glucose는 감소하였으나 하순부터는 sucrose가 감소하고 fructose, glucose는 서서히 증가하였다. 그러나 3차파종기부터는 3품종 모두에서 당함량에는 차이는 있었으나 오히려 sucrose가 감소하고 glucose와 frucose가 증가함을 보였다. ${\beta}$-carotene 함량은 파종후 110일경에는 1차파종인 경우 'HY2', 'S5', 'H5', 순으로 거의 12,000IU를 웃돌았고 170일경에는 감소되는 경향을 보였다. 2차파종은 170일경에는 품종간에 큰 차이가 없었고 3차 파종기에서도 170일이 지난 후 'S5'는 다소 증가하는 편이었지만 파종기가 늦을수록 ${\beta}$-carotene 함량이 적어지는 경향을 보였다.