The Study On Plant Growth Plasticity

This paper presented a new classification of plant plasticity, and this method was used to research on three annual plants Xanthium sibiricum Parin., Fagopyrum esculentum Moench. and Datura stramonium L. under density and sowing date treatments. The morphological plasticities, biomass allocations and meristem allocations were studied to reveal the differences of plasticities of different plant traits under different environments.1. According to allometric slope and constant, we divided plant plasticity into four categories:1.1 Relationship plasticity: the size dependences of traits disappear as the environment changes;1.2 Scale index plasticity: allometric scale index (slope) is significantly different in different environmental conditions;1.3 Constant feature plasticity: allometric scale index is not significantly different, but the characteristics constant (interception) is significantly different;1.4 Growth rate plasticity: allometric scale index and characteristics constant are not significantly different, but the growth rate is different.2. Morphological plasticity was affected by the following factors:2.1 The responses of different morphological traits to environment were different. Under density restriction condition, crown was relationship plasticity, the number of leaves was constant feature plasticity, and diameter was growth rate plasticity.2.2 The responses of plant morphological traits to different environments were various. Crown was relationship plasticity under density restriction condition, but was not the same type of plasticity under sowing date treatments.2.3 Allometric relationship is influenced by the indicator of plant size. Allometry is to study the relationship between characteristics and size, however the size can be described by total biomass, and in some cases by height. Our research found that both in the density or sowing date treatments, the dependence of traits on the total biomass was significantly higher than on height, indicating that if size is expressed by the total biomass, the plasticity of morphological features was smaller.2.4 The plasticities of branch and branch angle were different among different type of branching.3. The allocation of biomass plasticity was small than morphological traits plasticity. As well as morphological characteristics, the allocation of biomass plasticity was affect by the environment, different part of biomass, and the indicators of size. The allocation of biomass plasticity was higher under different sowing date treatments than density treatments. Reproduction biomass plasticity was higher than stem, root and leaf plasticities. The dependence of biomass allocation on total biomass was higher than on height.4. Meristiem allocation is an effective method to investigate plant allocation strategies and plasticity. Different architectures have different possibilities for, and different constraints on, plasticity of meristem allocation in response to competition. Reproductive allocation appeared to be the least plastic allocation pattern.