The balanced-growth hypothesis and the allometry of leaf and root biomass allocation
The balanced-growth hypothesis and the allometry of leaf and root biomass allocation
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DOI：
10.1046/j.1365-2435.2002.00626.x
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发表时间：
2002-06-01
影响因子：
5.2
通讯作者：
Meziane, D
中科院分区：
文献类型：
--
作者：
Shipley, B;Meziane, D
1.许多植物生长的生态模型都假设平衡生长：生物量优先分配给叶或根，以增加对有限外部资源的捕获。另一种解释是基于非线性（异速生长）分配作为植物大小的函数。本研究的目的是在这两种替代方案之间进行测试。来自22种不同草本植物的共1150株植物在水培沙培中生长，高（1100 mumol m（-2）s（-1））和低（200 mumol m（-2）s（-1）PAR）辐照度的因子组合与全强度和1/6稀释度的Hoagland水培溶液杂交。在发芽后15、20、25、30和35天收获植物，并测定叶和根组分的干质量。这些数据被用来检验平衡增长和异速生长分配的假设.光照和养分供应均影响根、冠的斜率和截距，与异速生长假说相反，但与平衡生长假说一致;降低养分供应增加了对根的分配;降低光照增加了对叶的分配.随着植物的生长，植物向根分配的生物量相对多于向叶分配的生物量。为了使平衡生长假说是正确的，每单位根质量的养分吸收净速率必须相对于每单位叶质量的碳获得净速率一直在下降。我们提出了两个原因：（i）老根降低了养分吸收效率;（ii）较大的根系更快地降低了水培溶液冲洗之间的有效养分。这些结果支持平衡生长的概念，在许多植物生长的生态模型中发现。
1. Many ecological models of plant growth assume balanced growth: that biomass is allocated preferentially to leaves or roots to increase capture of the limiting external resource. An alternative explanation is based on nonlinear (allometric) allocation as a function of plant size. The objective of this study was to test between these two alternative explanations.2. A total of 1150 plants from 22 different herbaceous species were grown in hydroponic sand culture in factorial combinations of high (1100 mumol m(-2) s(-1)) and low (200 mumol m(-2) s(-1) PAR) irradiance crossed with a full-strength and a 1/6 dilution of Hoagland's hydroponic solution. Plants were harvested at 15, 20, 25, 30 and 35 days postgermination, and dry mass was determined for leaf and root components. These data were used to test the hypotheses of balanced growth and of allometric allocation.3. Both irradiance and nutrient supply affected the slope and intercept of the root : shoot allometry, contrary to the allometric hypothesis but in agreement with the hypothesis of balanced growth; decreased nutrient supply increased allocation to roots; and decreased irradiance increased allocation to leaves.4. Plants allocated relatively more biomass to roots than to leaves as plants grew larger. In order for the balanced-growth hypothesis to be correct, the net rate of nutrient uptake per unit root mass must have been decreasing relative to the net rate of carbon gain per unit leaf mass.5. We suggest two reasons why this might be the case: (i) older roots decreased their efficiency of nutrient uptake; and (ii) larger root systems more rapidly decreased the available nutrients between flushes of hydroponic solution.6. These results support the notion of balanced growth that is found in many ecological models of plant growth.