镉胁迫对桂花生长和养分积累、分配与利用的影响

Effects of cadmium stress on growth and nutrient accumulation,distribution and utilization in Osmanthus fragrans var. thunbergii

桂花(Osmanthus fragrans var.thunbergii)是长江流域镉污染地区普遍栽植兼具绿化、观赏和净化环境等重要价值的园林树种之一。为了解镉胁迫条件下桂花生长适应特性,采用盆栽试验研究了不同镉浓度处理下(CK:0mg·kg-1;I:25mg·kg-1;II:50mg·kg-1;III:100mg·kg-1;IV:200mg·kg-1)一个生长季节内一年生桂花生物量生产、生物量分配格局以及C、N、P积累、分配与利用特征。植物各器官生物量生产及C、N和P积累量均表现出随镉处理浓度的增加而降低的趋势,较高浓度镉处理(II、III、IV)明显抑制了桂花的生物量生产、C、N和P的积累,显著改变了生物量及其C、N和P积累量的分配格局,但相对较低浓度镉处理(I)对桂花生物量生产以及C、N和P的积累与分配特征影响并不显著。一定浓度的镉胁迫处理(I、II、III)表现出提高桂花N的利用效率而降低P的利用效率的趋势,但重度镉胁迫(IV)均降低了桂花N和P的利用效率。结果表明桂花具有一定的抗镉胁迫能力,但较高程度的镉胁迫显著影响了桂花生长及养分格局。

Aims The valuable ornamental plant Osmanthus fragrans var.thunbergii is grown in city gardens and on roadsides in the regions of the Yangtze River Basin,where often it has been contaminated with cadmium.Our objective was to characterize the effects of different cadmium stresses on（a） biomass production,（b） C,N and P accumulation and distribution patterns and（c） N and P use efficiency in O.fragrans var.thunbergii.Methods A controlled pot-experiment was arranged with different treatments of five cadmium concentrations（CK：0,I：25,II：50,III：100,and IV：200 mg·kg^-1）.One-year old O.fragrans var.thunbergii was cultivated in the pots.Biomass production and concentrations of C,N and P in plant components were measured over one growing season.Biomass,distribution of C,N and P and N and P use efficiency were calculated.Important findings Treatments with higher cadmium concentrations（II,III and IV） significantly decreased O.fragrans var.thunbergii biomass and C,N and P accumulation,as well as altered their distribution patterns,but the treatment with lower cadmium concentration（I） had no significant effects.Treatments with lower cadmium concentrations（I,II and III） increased N use efficiency but decreased P use efficiency,and both the lowest N and P use efficiencies were observed under the treatment with the highest cadmium concentration（IV）.Results suggest that O.fragrans var.thunbergii could efficiently adapt to cadmium-contaminated environments by altering nutrient use strategy and biomass distribution pattern.