生物学毕业论文.doc

落叶松根系分泌物对胡桃楸幼苗生长的影响 摘 要 胡桃楸（Juglans mandshurica Maxim）是东北三大硬阔之一；林业调查研究表明，在落叶松与胡桃楸混交林中胡桃楸的生长状况明显好于胡桃楸纯林，因而推测落叶松和胡桃楸之间可能存在一种相互影响的关系。 用四种浓度的落叶松根系分泌物及其乙酸乙酯、氯仿、甲醇萃取物处理胡桃楸幼苗，通过紫外-可见分光光度法测定胡桃楸幼苗叶片的叶绿素含量、可溶性糖含量，然后测量胡桃楸幼苗的苗高、地茎和生物量。结果显示，各处理胡桃楸幼苗的可溶性糖含量均比对照高；当浓度为1 g﹒L-1和0.1 g﹒L-1时，胡桃楸幼苗的全株生物量、根生物量、总叶绿素含量均比对照略高；而浓度为0.01 g﹒L-1和0.001 g﹒L-1时，胡桃楸幼苗的以上三项生理指标均比对照略有下降，这表明落叶松根系分泌物对胡桃楸幼苗的促进作用与其施加浓度有关，呈现一种高浓度促进、低浓度抑制的趋势。其中，落叶松根系分泌物的甲醇萃取物对胡桃楸幼苗的影响与其他处理相比，对胡桃楸幼苗的影响最显著，表明有效化感物质可能存在于甲醇萃取物中。 关键词：胡桃楸；落叶松；化感作用；可溶性糖含量；叶绿素含量 Affects of the root exudates of Larix gmelini to Manchurian walnut seedlings Abstract Manchurian walnut (Juglans mandshurica) is one of the rare tree species in Northeast China. Silvicultural practice showed that larch (Larix gmelini) could evidently accelerate the growth of Manchurian walnut in mixed plantations of the two species. Then we hypothesize that there may be an effect between the two species. In this study, we treated the Manchurian walnut seedlings using four different concentration of the root exudates of the larch trees as well as its methanol, chloroform and ethyl acetate extraction . Then futher we mensurated the content of the chlorophyll and the dissoluble carbohydrate as well as the sheets and roots of the seedlings using UV-Vis spectrophotometry. The result showed that all treatments had a higher content of the dissoluble carbohydrate compared to the control samples. There are an advantage effect on the quality of the whole plant and the root as well as the total content of chlorophyll of the Manchurian walnut seedlings when the concentration of the root exudates of the larch trees are 1g﹒L-1 and 0.1g﹒L-1, while a disadvantage effect when the concentration are 1g﹒L-1 and 0.1g﹒L-1. That indicated that the effect may be related with the concentration of the root exudates of the larch trees. Especially the the methanol extraction of the larch trees even had a distinct effect to the seedlings. Key words：Juglans mandshurica; Larix gmelini; allelopathy; the