Spatio-temporal variations in axial conductance of primary and first-order lateral roots of a maize crop as predicted by a model of the hydraulic architecture of root systems
Spatio-temporal variations in axial conductance of primary and first-order lateral roots of a maize crop as predicted by a model of the hydraulic architecture of root systems
复制标题
DOI：
10.1007/s11104-005-5373-7
复制
发表时间：
2006-04-01
期刊：
影响因子：
4.9
通讯作者：
Pages, L.
中科院分区：
文献类型：
--
作者：
Pierret, A.;Doussan, C.;Pages, L.
水分沿植物根部(轴向路径)运输的速率随时间而变化，部分取决于木质部的成熟。由于实验条件的限制，田间条件下根系功能异质性的动态研究大多仍是未知领域。机械建模的最新进展提供了绕过这种实验限制的机会。本文利用Doussan等人开发的基于结构的模拟方法，研究了玉米作物初级和一级侧根的轴向电导的局部变化动态。(《植物学年鉴》：81,213-223,1998)具体地说，我们假设，长距离调水的主要阻力点可能来自主轴和支根的水力成熟度(或载水能力)之间的差异。为了验证这一假设，在30、60和100天后，在玉米(Zea Mays L.)下测试了10、50和100 cm土层中根电导的空间分布。作物按8株m(-2)密度播种。随着作物的发展，相应的根群包括越来越多的水力成熟的一级侧根(分支根)：经过100天的生长期，绝大多数侧根在所有土壤深度到100厘米处都达到了最大轴向电导。相反，很大一部分主轴(主根)的轴向电导仍然很低，即使在土壤浅层和生长100天后也是如此。初生根和侧根水力成熟度的不平衡在100 cm土层最为明显，仅为前者的10%，而后者为80%，在100d生长期后达到最大轴向导度。
Rates at which water can be transported along plant roots (axial pathway) vary through time, in part depending on xylem maturation. Because of experimental constraints, the dynamics of root functional heterogeneity under field conditions remains mostly uncharted territory. Recent advances in mechanistic modelling offer opportunities to bypass such experimental limitations. This paper examines the dynamics of local variations in axial conductance of primary and first-order lateral roots of a maize crop using the architecture-based modelling approach developed by Doussan et al. (Annals of Botany: 81, 213-223, 1998). Specifically, we hypothesised that points of major resistance to long distance water transfers could arise from discrepancies between the hydraulic maturity (or water carrying capacity) of main axes and branch roots. To test this assumption, spatial distributions of root axial conductance were tested after 30, 60 and 100 days at soil depths of 10, 50 and 100 cm under a maize (Zea mays L.) crop sown at a density of 8 plants m(-2). As the crop developed, the corresponding root populations encompassed ever increasing amounts of hydraulically mature first-order laterals (branch roots): after a 100-day growth period, the vast majority of laterals had reached their maximum axial conductance at all soil depths down to 100 cm. In contrast, the axial conductance of a large proportion of main axes (primary roots) remained low, even at shallow soil depths and after 100 days of growth. The imbalance between the hydraulic maturity of primary and lateral roots was most conspicuous at soil depths of 100 cm, where similar to 10% only of the former compared to similar to 80% of the latter, had reached their maximum axial conductance after a 100-day growth period.