Phenotypic Plasticity Of Seedlings Of Ten Plants Of Saussurea DC. Of East Of Qinghai-Tibet Plateau Under Different Light And Nutrient Conditions

We examined the effects of light and nutrient on seedling phenotypic plasticity of ten common species of Saussurea DC. on East of Qinghai-Tibet Plateau. Seedling growth and plastic response to light and nutrient treatments were examined, the results showed that:1. The light treatment affected significantly the percent emergence and emergence rate of ten species which difference among species. Percent emergence of few species was affected by nutrient treatment, and higher nutrient condition would inhibit seedling emergence of some species funder specific light environment.2. Light treatment has no effect on survival rate of S.salicifolia and S.parviflora. There were high mortality under full light for other species of Saussurea . Nutrient treatmenthas has few effects on survival rate. As a whole, these ten species of Saussurea DC. have strong survival ability to varied environments.3. The morphological traits show plastic changes to some extent although it differs between species. Stem length and leaf area of seedling increased with light decreasing especially under high nutrition. Special leaf area (SLA) and leaf area rate (1AR) of ten plants of Saussurea DC increased significantly with a decrease of light. Especially for strongly shade- tolerant S.parviflora, SLA and LAR showed highly plastic respons to light treatment.4. The plasticity of functional traits are different among traits and species. Under high nutrient condition ,low light level could decrease the biomass of S.elongata,S.stella,S.japonica, but have no effects on other seven plants of Saussurea DC. Leaf weight ratio (LWR) and root weight ratio (RWR) of four species(S.salicifolia, S.hieracioides, S. elongata, S. purpurascens) did not changed with light under high nutrient condition,whhile LWR and RWR of other three species (S. macrota, S.parviflora, S. japonica)did not changed with light under low nutrient condition. In other case, LWR decreased and RWR increased inhanced light.5. Plant growth plasticity is correlated with natural distribution of species. For plants with narrow ecological range, such as S.parviflora and S. purpurascens, the relative growth rate did not change with light condition, which contrasts wich widely ranged 5. macrota. It shows that plasticity of RGR may affect the distribution of Saussurea plants in nature.6. The plasticity performance of ten species in seedling morphological traits, functional traits and growth can not allount entirely for plant distribution.