Belowground herbivory decreases shoot water content and biomass of Lolium perenne seedlings under nutrient-poor conditions
Belowground herbivory decreases shoot water content and biomass of Lolium perenne seedlings under nutrient-poor conditions
复制标题
在营养不良的条件下，地下食草会降低多年生黑麦草幼苗的芽含水量和生物量
作者：
Tsunoda;T.;Kachi;N.;Suzuki;J.-I.
已知在营养贫乏条件下的地下草食会显著降低植物生物量和根冠比。然而，在不同营养条件下发生的地下植物-食草动物相互作用变化背后的机制尚不清楚。我们用多年生植物lolium perenneL进行盆栽试验。和三龄幼虫的日本菊。试验采用三因子随机区组设计；3个因素分别是养分量（丰富/贫乏）、养分异质性（均匀/异质）和地下食草动物（存在/不存在）。营养不良条件下幼苗的相对含水量（RWC）小于营养丰富条件下，单一草食显著降低了营养不良条件下幼苗的相对含水量（RWC）。富营养化条件下植物生物量大于贫营养化条件下。草食动物在营养贫乏的条件下比在营养丰富的条件下更能减少植物生物量。养分异质性对植物生物量没有影响，但草食量和养分量相互作用影响根系向养分斑块的增殖。在营养不良的条件下，植株较小；因此，更大比例的根被地下食草动物移走了。失去较大比例的根系会导致RWC变小，从而限制了补偿性生长。因此，l的增长。多年生植物在营养贫乏的条件下更严重地受到地下食草动物的限制。
Belowground herbivory under nutrient-poor conditions is known to significantly decrease plant biomass and root:shoot ratios. However, the mechanisms behind the changes in belowground plant–herbivore interactions that occur under different nutrient conditions remain unclear. We performed a pot experiment usingLolium perenneL. and the third-instar larva ofPopillia japonicaNewman. The experiment used a three-way factorial randomized-block design; the three factors were nutrient amount (rich/poor), nutrient heterogeneity (homogeneous/heterogeneous), and belowground herbivore (present/absent). Relative water content (RWC) of shoots under nutrient-poor conditions was smaller than that under nutrient-rich conditions, and a single herbivory significantly reduced the RWC under the nutrient-poor conditions. Plant biomass was larger under nutrient-rich conditions than under nutrient-poor conditions. A herbivore decreased plant biomass more under nutrient-poor conditions than under nutrient-rich conditions. Nutrient heterogeneity had no effect on plant biomass, but herbivory and nutrient amount interactively affected root proliferations to nutrient patches. Plants were smaller under nutrient-poor conditions; thus, a larger proportion of the roots was removed by a belowground herbivore. A loss of a larger proportion of roots would cause the small RWC, which restricts compensatory growth. Consequently, growth ofL.perenneis more severely limited by a belowground herbivore under nutrient-poor conditions.