关键的植物结构和分配性状取决于多年生草本植物虎耳草叶茴芹的相对年龄。

Key plant structural and allocation traits depend on relative age in the perennial herb Pimpinella saxifraga.

作者信息

Niinemets Ulo

机构信息

Department of Plant Physiology, University of Tartu, Riia 23, Tartu EE 51010, Estonia.

出版信息

Ann Bot. 2005 Aug;96(2):323-30. doi: 10.1093/aob/mci180. Epub 2005 Jun 19.

DOI:10.1093/aob/mci180

PMID:15965271

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4246880/

Abstract

BACKGROUND AND AIMS

Perennial plant formations always include a mixture of various-aged individuals of community-creating species, but the physiological and competitive potentials of plants of differing age and the importance on whole community functioning are still not entirely known. The current study tested the hypothesis that ontogenetically old plants have limited biomass investments in leaves and enhanced foliage support costs.

METHODS

Leaf structure, size and biomass allocation were studied in the perennial herb Pimpinella saxifraga during plant ontogeny from seedling to senile phases to determine age-dependent controls on key plant structural traits. The average duration of the full ontogenetic cycle is approx. 5-10 years in this species. Plants were sampled from shaded and open habitats.

KEY RESULTS

Leaflet dry mass per unit area (M(A)) increased, and the fraction of plant biomass in leaflets (F(L)) decreased with increasing age, leading to a 5- to 11-fold decrease in leaf area ratio (LAR = F(L)/M(A)) between seedlings and senescent plants. In contrast, the fraction of below-ground biomass increased with increasing age. Leaflet size and number per leaf increased with increasing age. This was not associated with enhanced support cost in older plants as age-dependent changes in leaf shape and increased foliage packing along the rachis compensated for an overall increase in leaf size. Age-dependent trends were the same in habitats with various irradiance, but the LAR of plants of varying age was approx. 1.5-fold larger in the shade due to lower M(A) and larger F(L).

CONCLUSIONS

As plant light interception per unit total plant mass scales with LAR, these data demonstrate major age-dependent differences in plant light-harvesting efficiency that are further modified by site light availability. These ontogenetic changes reduce the differences among co-existing species in perennial communities, and therefore need consideration in our understanding of how herbaceous communities function.

摘要

背景与目的

多年生植物群落总是包含处于不同年龄阶段的群落构建物种个体的混合体，但不同年龄植物的生理和竞争潜力以及它们对整个群落功能的重要性仍不完全清楚。本研究检验了这样一个假设，即个体发育成熟的老龄植物在叶片上的生物量投资有限，且叶片支撑成本增加。

方法

对多年生草本植物 saxifraga 在从幼苗期到衰老期的个体发育过程中，研究其叶片结构、大小和生物量分配，以确定年龄对关键植物结构性状的控制。该物种整个个体发育周期的平均持续时间约为 5 - 10 年。从遮荫和开阔生境中采集植物样本。

主要结果

单位面积小叶干质量（M(A)）随年龄增加而增加，小叶中植物生物量的比例（F(L)）随年龄增加而降低，导致幼苗和衰老植物之间的叶面积比（LAR = F(L)/M(A)）下降了 5 至 11 倍。相反，地下生物量的比例随年龄增加而增加。小叶大小和每片叶的小叶数量随年龄增加而增加。这与老龄植物中支撑成本的增加无关，因为叶片形状的年龄依赖性变化以及沿着叶轴的叶片紧密排列补偿了叶片大小的总体增加。在不同光照强度的生境中，年龄依赖性趋势是相同的，但由于较低的 M(A) 和较大的 F(L)，不同年龄植物的 LAR 在遮荫条件下大约大 1.5 倍。