Phenotypic Plasticity Of Experimental Population Of Artemisia Scoparia In The Songnen Plain

The phenotypes of plants depend on genotypes and environments. Plants adoptdifferent adapting strategies responding to different environments so that make full useof resources. The phenotypic plasticity of Artemisia scoparia in morphologicalstructure, resource distribution pattern, reproductive allocation and water-solublecarbohydrate content in roots responding to planting density, cutting frequency andsowing time were studied, which could reveal the adapting strategies responding todifferent environments and the regulation on growth and reproductive allocation of A.scoparia, provide theoretical basis for using A. scoparia reasonably and providescience accumulation for further studying of plant population ecology. During theyears from2010to2011, through field controlled experiments, results showed that:Experimental population of A. scoparia had significant morphological plasticityin different growth conditions. The differences among different density mainly showedthat the crown diameter, the length of roots and the biomass of plants in the area ofhigh density were smaller or less than those in the area of low density. The pattern ofsmall plants in high-density population and big plants in low-density population wasformed basically. The height of plants decreased by cutting, but the biomasses ofmodules of A. scoparia increased by cutting reasonably in some degree, while thenutriments which were needed by growth of A. scoparia could not be supplied timelyin the condition of undue cutting so that restrained material production significantly.The A. scoparia in condition of earlier sowing thrived and had strong reproductiveability, but the number of dormancy modules was less, and it was bad foroverwintering and regreening. The A. scoparia in condition of later sowing were smalland had less dry matter accumulation, but the number of dormancy modules was more,and it was good for overwintering and regreening.The biomass distribution of above-and below-ground modules had the sameregulation in different growth conditions. The ratio of above-and below-groundbiomass decreased significantly with increase of density and cutting frequency anddelay of sowing date, which indicated that the biomass of above-ground modulesdecreased more quickly than below-ground and more biomass was allocated to rootswith increase of pressure of limiting factors.Experimental population of A. scoparia had different reproductive allocationmodel in different growth conditions. In conditions of different density, thereproductive allocation was constant value and the effect of competing for A. scopariawas not significant. The reproductive allocation increased in the condition ofreasonable cutting, while the investment to reproduction decreased or reproductiveallocation ceased in the condition of undue cutting. Responding to different sowingdate, the reproductive allocation decreased significantly until ceased with delay ofsowing date. The water-soluble carbohydrate content affected stress tolerance and regenerationof plants. The water-soluble carbohydrate content in roots of experimental populationof A. scoparia had different variation tendency in different growth conditions. Thedifferences among different density were not significant, but the variations weresignificant in conditions of different cutting frequency and different sowing date,which increased in the condition of reasonable cutting and decreased in the conditionof undue cutting, and in the latest sowing date was significantly higher than others.