Background : Recently, there have been dynamic researches conducted on stevia as natural sweetener subtitute for sugar, However, Researches related to harvest period and parts of plant in stevia are few. Therefore, this study was conducted to select optimum harvest time and parts by measuring the natural sweeteners contents and analyzing antioxidant materials and activity according to harvest times, parts of plant. Methods and Results : Stevia was cultivated in plastic house, The leaves were harvested from April to October and the stem were only harvest in July and September. Stevia leaves and stems were extracted using high temperature and pressure extraction: Dried stevia leaves of 5g were added by 100ml of distilled water equivalent to 20 times of dry weight, and the mixture were extracted by autoclave at 121℃ for 15min. The contents of Rebaudioside A and Stevioside of stevia leaves harvested from April to October showed a tendency to increase gradually from July to October as the temperature increased, but the contents of rebaudioside A and stevioside decreased slightly in August due to excessively high temperature. The extraction yield of stevia leaves were highest in October and September, and there was no significant difference in the other period. In the stevia stems, the extraction yield was lower than that of stevia leaves in general regardless of harvest time. Total phenolic contents and flavonoid contents according to harvest time showed little difference among treatment. Conclution : stevia leaves were better than stevia stems regarding the use of rebaudioside A and stevioside as natural sweeteners. Also, it was confirmed that the stevia leaves of July, September and October, except for the high temperature period of August, had superior in quality and quantity.

Background : Codonopsis lanceolata is currently used as vegetable, as well as materials for traditional medicines. However, consumers have nagative views on using pesticides and chemical fertilizer in C. lanceolata cultivation. Therefore, this research was conducted to select the appropriate organic fertilizer to improve the growth and saponin components of C. lanceolata by some organic fertilizers application. Methods and Results : Organic fertilizers were applied as 4 types: mixed organic matter, fermentation cake, bacterial culture and rice husks, excluding conventional chemical fertilizer and non-treatment used as control. The result analyzed in soil after fertilizer application showed that soil pH was acidified in fermentation cake and chemical fertilizer treatment, especially, chemical fertilizer treatment showed very high phosphoric-acid content than other treatments, and total N content was higher in fermentation cake, mixed organic matter and chemical fertilizer. Growth of C. lanceolata showed superior tendency in the treatment of mixed organic matter and fermentation cake. Lancemacides could be identified as foetidissimoside A, lancemaside A, lancemaside B, and lancemaside D. However, among them, quantitative analysis could not be conducted on foetidissimoside A due to its very low content, and lancemaside A was the most abundant saponin in the root from all the treatments. The content of lancemaisde A according to organic fertilizer application showed the highest value in the treatment of mixed organic matter, followed by the fermentation cake, bacterial culture, non-treatment, rice husks and chemical fertilizer, in that order. The content of lancemaside B and D was very low compared to lancemaside A, and there was no difference among treatments. Conclusion : The growth of C. lanceolata was superior in application of mixed organic matter and fermentation cake, and the major saponin, lancemaside A, was also increased.