Laboratory of Forest Ecology and Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.
Ann Bot. 2011 May;107(6):1029-37. doi: 10.1093/aob/mcr043. Epub 2011 Mar 7.
It is important to consider the modular level when verifying sexual dimorphism in dioecious plants. Nevertheless, between-sex differences in resource translocation among modules (i.e. physiological integration) have not been tested at the whole-plant level. In this study, sexual differences in physiological integration were examined among ramets, within a genet in the dioecious sprouting shrub Lindera triloba, by a field experiment with girdling manipulation.
Female and male genets were randomly assigned to girdled or intact groups. Girdling of the main ramets was conducted in May 2009 by removing a ring of bark and cambium approx. 1 cm wide at a height of 80-100 cm. The effects of treatment and sex on ramet dynamics (mortality, recruitment and diameter growth) and inflorescence production during 1 year after girdling were examined.
The diameter growth rate of main ramets of both sexes was lower at ground level (D(0)) but higher at breast height (dbh) in girdled than in intact groups. In sprouted ramets with a dbh of 0-2 cm, males in girdled groups had lower growth rates at D(0) than those of intact groups, whereas no girdling effect was found for females. The main ramets in girdled groups produced more inflorescences than intact groups, irrespective of sex, but male ramets showed a greater response to the treatment than females.
In L. triloba, physiological integration exists at the whole-plant level, and sprouted ramets are dependent on assimilates translocated from main ramets, but this dependence weakens as sprouted ramets get larger. Female sprouted ramets can grow in a physiologically independent manner from the main ramet earlier than those of males. This study highlights the importance of considering modular structures and physiological integration when evaluating sexual differences in demographic patterns of clonal plants.
在验证雌雄异株植物的性别二态性时，考虑模块水平很重要。然而，在整个植株水平上，尚未对模块间的资源转移（即生理整合）进行雌雄间差异测试。在这项研究中，通过对雌雄异株萌生灌丛山胡椒（Lindera triloba）一个单株内主枝的环割处理，在田间实验中检验了生理整合的雌雄间差异。
将雌性和雄性单株随机分配到环割或完整组。在 2009 年 5 月，通过在离地面 80-100 厘米的高度处去除约 1 厘米宽的树皮和形成层，对主枝进行环割。检查处理和性别对环割后 1 年内主枝动态（死亡率、繁殖和直径生长）和花序产生的影响。
雌雄两性主枝的直径生长速率在地面水平（D(0)）较低，但在胸高处（dbh）在环割组中高于完整组。在 dbh 为 0-2 厘米的萌生枝中，环割组的雄性生长速率在 D(0)处低于完整组，而对雌性没有发现环割效应。与性别无关，环割组的主枝产生的花序比完整组多，但雄性主枝对处理的反应大于雌性。
在山胡椒中，存在整个植株水平的生理整合，萌生枝依赖于从主枝转移来的同化产物，但随着萌生枝的增大，这种依赖性会减弱。与雄性相比，雌性萌生枝可以更早地以生理上独立的方式从主枝生长。这项研究强调了在评估克隆植物的种群格局的性别差异时，考虑模块结构和生理整合的重要性。
