甜菊之栽培與Stevioside季節變化之研究

Studies on the Cultivation of Stevia and Seasonal Variation of Stevioside

自民國65年10月至民國66年12月，甜菊在臺北試驗栽培，調查其生長速率、採收期及Stevioside之季節變化等，初步結果如下：1.甜菊之生長受氣溫及日照的影響很大；秋、冬氣溫低，日照短，極易開花，生長速率慢，採收量低；春、夏氣溫高，日照長，生長速率快，採收量高。在每次開花時採收，臺北地區一年可收六次，每次採收後即迅速產生分枝，此為其形態之特徵。2.由本實驗估算甜菊全年之採收量為每年每公頌48,491.05公斤（鮮重），12,024.17公斤（乾重）；其各部位之比例，平均為莖佔41.2%，葉佔43.4%，花佔15.4%。3.Stevioside之含量受植株年齡、氣溫及日照等影響。葉中成分之季節變化，以春末夏初達最高（含13%），盛夏及秋冬則漸減少。在秋季有花時期，其花中含Stevioside 10~18%，而綠莖4%，葉中含10%，此為值得注意之點。上述甜菊之生長型與季節變化情形與日本、巴西等地栽培者不同，今後我們宜努力研究栽培技術、管理、收穫等技術並育成晚生、高產量、Stevioside含量高及搞病之品種。

Cultivation of Stevia was carried out in Taipei during Oct. 1976 to Dec. 1977 to investigate its growth rate, harvesting period, yield, as well as seasonal variation of stevioside content. The preliminary results were summarized as follows: 1. The growth rate was pronouncedly affected by temperature and day-length. In autumn and winter, with prevalent condition of low temperature and short day-length, it bloomed easily and grew slowly with low yield. While in spring and summer, the growth rate was hastened by high temperature and long day-length, and as a result the yield of harvest was quite high. If harvesting was done in the blooming period, it can be collected six times per year around Taipei area. The plant branched off immediately after each harvesting, is a morphological characteristic of Stevia. 2. The yield estimated from this study was 48, 491.05Kg/ha/yr (fresh wt.) or 12,024.17Kg/ha/yr (dry wt.); the weigh fraction of each part was: stem, 41.2%; leaf, 43.4%; and flower, 15.4% respectively. 3. The stevioside content was affected by the age of plant, temperature, and day-length. The seasonal variation in leaves reached maximum content (13%) in late spring and early summer, and started to decrease in late summer, autumn, and winter. It is worthy of noting that, in Autumn, flowers contain 10-18% stevioside, as compared with 10% in leaves, and 4% in stems. The growing type and seasonal variation of stevioside content of this plant grown in Taipei area were quite different from those grown in Japan and Brazil. Further study is necessary to investigate the techniques of cultivation, management, harvesting as well as the breeding experiments that give late-flowering, high yield, high stevioside content, and disease-resistant variety.