Báo cáo khoa học: Analysis and simulation of the architecture of a growing root system: application to a comparative study of several tree seedlings

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Báo cáo khoa học: "Analysis and simulation of the architecture of a growing root system: application to a comparative study of several tree seedlings"Analysis and simulation of the architectureof a growing root system: application to a comparativestudy of several tree seedlingsM. L. E. 1 Dreyer H.Joannes 1 Colin-Belgrand 2 Pages1 INRA, Centre de Recherches Foreshores, BP 35, 54280 Seichamps, and2 INRA, Station d’Agronomie, Domaine-de-St-Paul, 84140 Montfavet, France.Introduction root architecture ModelingIt has been that the The basis of root architecture modeling is frequently suggested extension of root an adequate definition of branching termi- and theshape spatialsystems markedly influence the rate and nology. In this respect, two mainpatterns of nutrient uptake from the soil. approaches may be outlined. The first one is based on a topological or morphometric Many nutrient and water uptake models description of ramifications. Fitter (1987)have been proposed, based on root distri- applied this approach to describe andbution patterns; for instance, spatial simulate root systems of various herba-(mostly vertical) distribution of roots may ceous species. Basic structural units arebe related to physical and chemical prop- the links, straight segments between suc-erties of successive soil layers as in the cessive nodes (branching points). Theempirical model of Gerwitz and Pages order of these links is counted from the(1973). Parameters describing extension, periphery of the branching structuresuch as total root length, explored soil towards the primary axis (hypocotyl). Mainvolume and rooting density, are frequently parameters are either topological (likeused. magnitude) or geometric (like link lengths, On the other hand, a root system may branch spacing, branching angles). Thealso be described as a network of resis- main limitation of this approach is that it istances to nutrient and water transfers. It purely descriptive and cannot be used toappears therefore important not only to describe growth.quantify root distribution, but also to ana- The second approach is based on de-lyze the spatial ramified architecture, in velopmental analysis beginning from theother words, the connecting links between root origin and evolving with growth andthe different parts of the root system.increasing complexity. First-order roots ori- growing root system with all its dynamic aginate from the hypocotyl and bear aspects (Belgrand et al., 1987). It is also asecond-order laterals and so on (Hackett a root is defined developmental approach:and Rose, 1972). In this way, each root the non-branched structure formed asmember has a distinctive identity and through the activity of a single apicaleach order of roots has specific dimen- meristem. The growth and architecture ofsions, properties and branching patterns growing root systems of young tree seed-(Rose, 1983). In a developmental model, lings are studied by direct and non-de-the simulation of root growth and ramifica- structive observations in ’minirhizotrons’,tion is based for each root-order on time of where root growth occurs at the interfaceemergence of the successive axis, elon- between the lower wall of rhizotrons andgation rate and rate of lateral branching the soil.(Lungley, 1973; Rose, 1983). The ...