Steinger Thomas, Müller-Schärer Heinz
Botanical Institute, University of Basel, Hebelstrasse 1, CH-4056, Basel, Switzerland.
Zoological Institute, University of Basel, Rheinsprung 9, CH-4051, Basel, Switzerland.
Oecologia. 1992 Aug;91(1):141-149. doi: 10.1007/BF00317253.
Centaurea maculosa seedlings were grown in pots to study the effects of root herbivory by Agapeta zoegana L. (Lep.: Cochylidae) and Cyphocleonus achates Fahr. (Col.: Curculionidae), grass competition and nitrogen shortage (each present or absent), using a full factorial design. The aims of the study were to analyse the impact of root herbivory on plant growth, resource allocation and physiological processes, and to test if these plant responses to herbivory were influenced by plant competition and nitrogen availability. The two root herbivores differed markedly in their impact on plant growth. While feeding by the moth A. zoegana in the root cortex had no effect on shoot and root mass, feeding by the weevil C. achates in the central vascular tissue greatly reduced shoot mass, but not root mass, leading to a reduced shoot/root ratio. The absence of significant effects of the two herbivores on root biomass, despite considerable consumption, indicates that compensatory root growth occurred. Competition with grass affected plant growth more than herbivory and nutrient status, resulting in reduced shoot and root growth, and number of leaves. Nitrogen shortage did not affect plant growth directly but greatly influenced the compensatory capacity of Centaurea maculosa to root herbivory. Under high nitrogen conditions, shoot biomass of plants infested by the weevil was reduced by 30% compared with uninfested plants. However, under poor nitrogen conditions a 63% reduction was observed compared with corresponding controls. Root herbivory was the most important stress factor affecting plant physiology. Besides a relative increase in biomass allocation to the roots, infested plants also showed a significant increase in nitrogen concentration in the roots and a concomitant reduction in leaf nitrogen concentration, reflecting a redirection of the nitrogen to the stronger sink. The level of fructans was greatly reduced in the roots after herbivore feeding. This is thought to be a consequence of their mobilisation to support compensatory root growth. A preliminary model linking the effects of these root herbivores to the physiological processes of C. maculosa is presented.
通过全因子设计，在花盆中培育矢车菊幼苗，以研究黄斑齿爪鳃金龟（鳞翅目：曲胫蛾科）和黄斑长跗萤叶甲（鞘翅目：象甲科）对根部的取食、草类竞争以及氮素短缺（每种情况均分为存在或不存在）的影响。本研究的目的是分析根部取食对植物生长、资源分配和生理过程的影响，并测试这些植物对食草作用的反应是否受植物竞争和氮素有效性的影响。两种根部食草动物对植物生长的影响显著不同。虽然蛾类黄斑齿爪鳃金龟在根皮层取食对地上部和根部生物量没有影响，但象甲黄斑长跗萤叶甲在中央维管组织取食则大大降低了地上部生物量，而根部生物量未受影响，导致地上部/根部比值降低。尽管两种食草动物消耗了大量根部组织，但对根生物量没有显著影响，这表明发生了补偿性根系生长。与草类的竞争对植物生长的影响大于食草作用和养分状况，导致地上部和根部生长以及叶片数量减少。氮素短缺并未直接影响植物生长，但极大地影响了矢车菊对根部食草作用的补偿能力。在高氮条件下，受象甲侵害的植物地上部生物量与未受侵害的植物相比减少了30%。然而，在低氮条件下，与相应对照相比减少了63%。根部食草作用是影响植物生理的最重要胁迫因素。除了根部生物量分配相对增加外，受侵害的植物根部氮浓度也显著增加，同时叶片氮浓度降低，这反映了氮素向更强的库的重新分配。食草动物取食后，根部果聚糖水平大幅降低。这被认为是其被调动以支持补偿性根系生长的结果。本文提出了一个将这些根部食草动物的影响与矢车菊生理过程联系起来的初步模型。
