华荠苧响应不同土壤水分的表型可塑性

Phenotypic plasticity of growth and morphology in Mosla chinensis responds to diverse relative soil water content

研究了土壤相对含水量分别为 1 0 0 %、80 %、60 %、40 %和 30 %水分条件下华荠 ( Mosla chinensis)生长和形态的表型可塑性。结果表明 :成年植株的生物量积累、形态参数、单株叶绿素总含量及穗重等都在60 %相对含水量条件下最高 ;当土壤相对含水量从 30 %提高到 60 %时 ,分配到枝和根的生物量随之增加 ,分配到叶的生物量减少 ,土壤相对含水量再提高时 ,情况则相反 ;生殖比率随土壤相对含水量的下降而升高 ,30 %处理最大 ,1 0 0 %处理最小。这些结果说明华荠的适宜水分生态位是中偏湿的土壤环境。华荠通过器官生物量分配和形态结构调整对不同土壤水分产生可塑性响应 ,并以提高生殖比率的策略来适应干旱胁迫。

The phenotypic plasticity, biomass, morphology, chlorophyll content and reproductive allocation (RA) of Mosla chinensis were studied in five soil water treatments, which were the relative water content (RWC) of holding capacities (WHC) in soil (100%, 80%, 60%, 40% and 30%). The root, shoot, branch and leaf biomass were positively correlated with RWC increase from 30%～80% of WHC; however, biomass declined at 100% WHC. Highest ratios of fresh weight to biomass in branch and leaf were observed at 80% WHC. M. chinensis allocated more mass to stem and root than to leaf when RWC increased from 30% to 60% WHC; an opposite trend was observed at RWC >60% WHC. Its height, canopy range, proximal diameter, total branch length and the amount of the first class branch increased as water supply increased from 30%, reaching the climax at 80% WHC. The highest chlorophyll contents were observed at 40% and 60% WHC. The highest ear mass was found at 60% WHC, but the reproductive allocation increased from 0.29 to 0.51 with RWC decreased. The overall results indicated that M. chinensis had a high plasticity response to water supply; optimum condition of soil water was RWC at 60% WHC. It is drought resistant by increasing the relative biomass of reproductive organs to somatic biomass.