This study was conducted to elucidate the effect of organic fertilizer on growth characteristics, saponin contents and antioxident activity of Platycodin grandiflorum Ridix roots for organic farming. As basal fertilizers, chemical fertilizer, mixed organic fertilizer, bacterial cultures and fermented oil cake and decomposed manure were treated based on 3 ㎏/10a level before transplanting Platycodin grandiflorum Ridix. In root length, when chemical fertilizer plot and mixed organic fertilizer plot were treated, root length was recorded the highest scores (25.3 and 24.0 ㎝) Root width was recorded the highest score (26.6 ㎝) in chemical fertilizer plot. The number of fine-roots was the highest in mixed organic fertilizer plot and chemical fertilizer plot (20.0 and 17.0), respectively. Fresh weight, which affects directly yield, was the highest in organic fertilizer plot (55.7 g/plant). The content of Platycodin D was shown to 327.4~373.8 ㎎/100 g, the highest values were observed in organic fertilizer plot. The total polyphenol and flavonoid contents were recorded the highest scores (15.5 and 15.3 mg/g, respectively) in organic fertilizer plot. In this study we confirmed that application of organic fertilizer was effective to increase yield and pharmacological effect through increase of the number of fine-roots with high saponin contents.

A field experiment was conducted to investigate the performance of three legume species in a zero-tillage, non-fertilized rice field in a temperate zone. Before the experiment for 5 years, from 1995 to 1999, plant growth patterns of three legume species grown as over-wintering (October-May) cover crops on a paddy field were maintained to study N balance and ~textrmN2 fixation. Decrease in plant density accelerated from after winter to flowering from 1,090, 320, and 5 to 732, 232, and 6 plants ~textrmm-2 in Chinese milk vetch (CMV), white clover (WC), and hairy vetch (HV), respectively. Total dry weights of plants above-ground level were 0.05, 0.11, and 2.43 g ~textrmplant-1 . in WC, CMV and HV respectively but steeply increased at ripening up to 0.77, 2.33, and 26 g ~textrmplant-1 . The root dry weight of HV and CMV rapidly increased while in WC, root dry weight increased slightly towards flowering. The highest nodule numbers were recorded in CMV to April thereafter WC produced the highest. Nodule size was distributed within 7mm in CMV but it was larger in HV varying from 1 to 10mm. Shoot N (g ~textrmm-2 ) greatly increased from over-wintering to flowering in CMV, HV and WC and it ranged from 1.66, 0.5 and 1.92 to 12.6, 3.1 and 13.02 g ~textrmm-2 , respectively. After wintering, the initial shoot N content (%) was more in CMV. Root N content (%) was constant or slightly decreased in HV and WC. Soil total N in the control plot (clean fallow) was the highest on Mar. 2 then decreased rapidly to flowering. Soil N content was constant in HV plots whereas it was low in WC plots for the entire growth period except just after winter. Maximum nitrogenase activities were 9, 37.8, and 131 mol ~textrmC2~textrmH4 ~textrmplant-1 ~textrmhour-1 . in CMV, HV, and WC, respectively. Nitrogenase activity showed a direct correlation with nodule number, size and fresh weight. As a cover crop preceding a rice crop, CMV is more suited to colder regions due to its earlier ripening characteristics. Hairy vetch and WC are recommended for regions with a mild winter and a long summer owing to their late ripening and great N fixation activity.