Research On The Tillering Laws And The Plasticity Of Growth Forms Of Caespitose Clonal Plant Tall Fescue Grass (Festuca Arundinacea)

The more abundant phenotypic plasticity of caespitose clonal plant compared with stoloniferous and rhizomatous clonal plant is thought to be resulted from its unique clonal modularity and physiological integration based on the characteristics of clonal growth, which plays an active role in the course of adaption to its environment, maintenance of the stability and expansion of its distribution.Tall fescue grass(Festuca arundinacea Schreb.) was used as material in this paper. The modes of tillering formation, clonal growth habits of tillers and the quantitative characteristics of tall fescue grass in the course of development from seed to single bunch under suitable conditions and conditions of combination of ecological factors. The plasticity of tillering laws and growth forms of tall fescue grass was revealed.In the suitable conditions, the characteristics of tillering growth tended to be phalanx. The process of tillering is from the center to the outside. Two types of tillers were formed, the root-based tiller and the leaf-based tiller. The root-based tiller usually takes the strategy of occupation of the horizotal space, whereas the leaf-based tiller usually takes the strategy of utilization of the space being occupied. The diameters of tillers in the bunch basically accord with normal distribution. The bunch of tall fescue grass might formed gradually in the form of consolidation at every steps. Within the bunch structure, the so-called complex tillers usually located in the outside of the bunch and the simple tillers, in the inside, which implys the functional specialization of tillers of different types.Under the impacts of some limiting ecological factors, the bunch tended to become simple in term of tiller structure and become homogeneous in term of quantitative characteristics. The treatments of water, density, pruning, trampling and other factors affected the formation of tiller structure and the proportion of two types of tillers. Among them, the treatment of water significantly limited the blade length, width, branch diameter distribution of tillers, tiller number, bunch diameter. The treatment of density significantly affected the number of diameter of the bunch. The treatment of pruning significantly increased the leaf size and specific leaf area, node location of a leaf. The treatment of trampling profoundly affected the leaf length, width, node location of a leaf and above ground biomass. In the dense conditions, some of these ecological factors profoundly affected the tiller structure and the number. The fertilizer factor enhanced the performance of tillers in terms of some morphological indices and decreased the number of dead leaves.In addition, some phenomena frequently appeared in the practices, such as bald spots, aging, temperature and others of the lawn of tall fescue grass, were explained and analyzed. The results of this study are of valuable in terms of maintenance and management practices of the tall fescue lawn.