Serengeti ungulates: feeding selectivity influences the effectiveness of plant defense guilds

Association of Themeda triandra, a palatable grass species, with less palatable plants protected it from grazing by two comparatively unselective herbivores, wildebeest and African buffalo. Grazing on T. triandra by two more selective herbivores, Thomson's gazelle and zebra, was not related to the relative abundance of less palatable plants. The differential effectiveness of plant defense guilds against different ungulates may contribute to the high species diversity of the East African grazer fauna.     

虫害诱导的植物挥发物

综述了植物挥发性物质的特性,挥发物与韧皮部取食的昆虫,茉莉酮酸(JA)与挥发物的释放,C6挥发物与植食性昆虫的作用,挥发物的诱导物及挥发物的生态学功能,为以后研究植物挥发物、植物-植食性昆虫-植食性昆虫天敌间的相互关系等方面提供了依据。     

上部叶烘烤过程中叶片与主脉含水率变化对烤烟质量的影响

\t\t\t\t\t目的\t\t\t\t\t探讨烘烤过程中烤烟烟叶表皮微形态特征的结构变化。\t\t\t\t\t\t\t\t\t\t\t\t\t方法\t\t\t\t\t以烤烟品种K326适熟的上部烟叶为材料,采用扫描电镜技术观察烘烤过程中(烘烤前、36 ℃末期、38 ℃末期、42 ℃末期、48 ℃末期、54 ℃末期和68 ℃末期)烟叶下表皮微形态特征。\t\t\t\t\t\t\t\t\t\t\t\t\t结果\t\t\t\t\t随着烘烤温度的升高,烤烟叶片气孔器长度从烘烤前的27.46 μm减小至68 ℃末期的22.47 μm;气孔器密度从烘烤前的103.76个/mm²增加至68 ℃末期167.48个/mm²,气孔器逐渐突出于表皮之上,形状从阔椭圆形逐渐变为椭圆形,气孔外拱盖内缘形状从浅波状到深波状;表皮细胞密度从烘烤前的463.24个/mm²增加至68 ℃末期的895.42个/mm²,垂周壁波纹显著加深,平周壁逐渐凸起;表皮细胞角质层从近于光滑到具条纹甚至具脊状突起;表皮蜡质纹饰从稀疏小颗粒状到大颗粒状甚至为块状。具分泌功能的腺毛顶部细胞形状从完整饱满状到细胞壁明显凹陷,部分从柄细胞处脱落。\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t结论\t\t\t\t\t烤烟烘烤过程中表皮微型态特征变化显著,这些特征变化可为烤烟烘烤特性的研究提供参考。\t\t\t\t