The Study Of Plant Phenotypic Plasticity And Stability

Phenotypic plasticity has become an important concept in ecology,evolutionary and developmental biology.Despite the numerous relevant literatures,we are still far away from fully understanding the phenomenon of plant phenotypic plasticity.This is associated with the complicacy of environmental factors and plant responses in natural habitats,as well as the variability of plasticity itself.By virtue of both field and indoor experimental approaches,targeted on an annual species of Abutilon theophrasti M.,this thesis studied its plasticity in biomass allocation,allometric growth,morphological traits,plant architecture,the relationships of plasticity with integration,canalization and developmental stability in in response to population density,as well as effects of soil conditions and growth stage on responses of theses facets to density;cotyledon plasticity and stability of multiple annual species in response to light and seeding depth;effects of early extreme experiences,plant-plant interactions on the responses to water conditions of multiple perennial species.The strategies and implications of plant adapting to environments through phenotypic plasticity and stability as well as the variation of plasticity were discussed,and important results obtained in research are as follows.1.The plasticity of A.theophrasti in response to population density demonstrated that:density-induced plasticity of allometric relationships among modules and developmental trajectory may be apparent plasticity,while density-induced variation of plant size can be true plasticity;the plastic responses of plant individuals to increased density experienced a transformation from true plasticity to apparent plasticity:as plants grew,density first affected the strategy of biomass allocation,then growth rate;the results that morphological response to density varied with soil conditions and growth stages revealed the increase of density can induce multiple different responses in a single trait,suggesting the complicacy of plant plasticity in response to biotic environments and the importance of the influences of abiotic factors;high density can induce different responses in different layers,reflecting strategies of energy trade-off among different layers,reproduction-delay and below-ground space-orientation for modular populations in response to density.2.The relationships between phenotypic plasticity and stability suggested:the production of individual plasticity is associated with the enhance of phenotypic integration and attenuation of population canalization,and this trend will be more pronounced under resource-sufficient environment and intensified competition;phenotypic plasticity and canalization may not only share some common mechanisms,but also be controlled by separate mechanisms;the level of trait FA is more likely to reflect the growth rate of a plant individual,rather than the level of its developmental stability;higher FA is associated with greater within-population variation,lower degree of potential plasticity under relatively favorable environments,whereas the level of FA,within-population variation is more likely to cooperate with plasticity under stressful environments.3.Research of the variability of plasticity itself demonstrated that:early inundation or drought experience can enhance subsequent relative growth of plants in extreme conditions,and the degree of such effects is correlated with the species' habitat range and invasiveness;plants under competition with conspecific or heterospecific neighbors may be less able to produce active response to abiotic environments at whole-plant level,but still can make local adjustments,and conspecific neighbors can promote the above-ground response to dry vs.wet conditions,while heterospecific neighbors are more likely to promote below-ground growth.Such ability of modulating plasticity may be more important than short-term plasticity in adapting to environmental heterogeneity...