Determination of white clover saponins and agronomic factors affecting accumulation of saponins in white clover.

（1）对白色三叶草皂苷的薄层色谱分析条件进行了研究。确定了白色三叶草中所含的皂甙与大豆中的皂甙不同。（2）不同生态类型白色三叶草中皂苷类化合物的色谱图和含量存在差异，且含量呈季节性变化，5月下旬至7月含量较高，秋季含量较低。（3）以白色三叶草品种为材料，设置3个氮素水平（N：0、0.13、0.39g/盆）和3个遮光水平（RLI：100、60、40%）进行盆栽试验。随着遮荫强度的增加，顶芽再生长度增加，但顶芽和根重均下降。氮素水平对白色三叶草的生长没有影响。施氮量为0 g + RLI为100%时，植株体内的固氮酶活性最高，施氮量和遮光处理降低了固氮酶活性。用薄层色谱和高效液相色谱法从白色三叶草中鉴定出8条皂苷类化合物带（1）~（8）。在N：0中，条带（3）和（4）的浓度较高，而在RLI：100%中，条带（1）、（4）和（6）的浓度较高。（4）绵羊采食试验结果表明，白色三叶草在采食初期适口性极显著，但随着时间的推移，适口性逐渐下降。推测白色三叶草可能含有抑制进食的物质。饲喂白色三叶草的绵羊瘤胃内容物明显起泡。（5）施氮对固氮酶活性抑制较小的白色三叶草生态型对氮肥的利用率较高。

(1).Analytical conditions of white clover saponins by TLC were investigated. It was determined that saponins contained in White clover were different from those in soybean.(2).Chromatogram and concentrations of the glycosides like saponin varied among white clover ecotypes, and the concentration showed seasonal variation, high from late May to July and low in autumn.(3).White clover cultivar was potted and cultivated with treatments of three nitrogen levels, N : 0,0.13,0.39g/ pot, and three shading levels, RLI : 100,60,40%.*As shading was taken at higher intensity, the regrowth length of top increased but both top and root weight decreased. On the growth of white clover, nitrogen level did not showed any effect.*Nitrogenase activity was the highest in the plant under N : 0g + RLI : 100% and decreased by nitrogen application and shading.*Eight bands of glycosides like saponins, (1) - (8), were identified by TLC and HPLC in white clover. The concentrations of band (3) and (4) were higher in N : 0 and those of band (1), (4) and (6) in RLI : 100%.(4).As the result of feeding experiment by sheep, a palatability of white clover was significantly high at the early stage of feeding, but it decreased with the progress of the time. It was supposed that white clover might contain inhibitory substances to eating. Ruminal contents bubbled markedly in sheep feeded white clover.(5).Utilization of fertilizer nitrogen was high in white clover ecotypes which the inhibition of nitrogenase activity by nitrogen application was small.