镉胁迫对107杨幼苗光合作用和干物质分配的影响

Effects of Cadmium Stress on Leaf Photosynthesis and Dry Matter Allocation of Populus×euramericana(Dode)Guineir cv. 'Neva'

以1年生107杨幼苗为材料,采用盆栽试验方法研究了不同镉浓度处理对107杨苗叶片光合作用和干物质分配的影响。结果表明:107杨1年生苗在镉处理10 d内,50、100、150、200 mg·kg-1浓度处理的叶片净光合速率表现为先大幅下降后逐步回升的变化规律,与对照相比,下降的最大幅度分别达17.1%、17.8%、23.9%、24.7%,镉胁迫浓度越大苗木所受胁迫程度越重,在镉胁迫1 d时,净光合速率大幅下降的原因主要是发生了由气孔因素为主导的光合限制;胁迫第10～40天内,50～200 mg·kg-1浓度处理的叶片净光合速率与对照的差异不显著;胁迫处理40 d后,仅200 mg·kg-1镉浓度处理对苗木净光合速率具显著抑制作用,150 mg·kg-1镉浓度对107杨净光合速率的影响可能是一个重要的阀值。镉胁迫条件下,107杨苗茎部干物质分配比率随着处理浓度的增大而增大,根部则随处理浓度的增大而下降,高浓度200 mg·kg-1处理能导致苗木根冠比大幅度下降,使苗木根系生长受到严重阻碍。

The effects of cadmium stress on leaf photosynthesis and dry matter allocation for one-year-old seedlings of Populus × euramericana（Dode）Guineir cv.＇Neva＇ were studied through potted cultivation.The results showed that in the early 10 days of cadmium stress,the net photosynthetic rates（Pn） of seedlings of four trial treatments greatly decreased at first followed by relatively slow various increase,relative to contrast,the treatments of 50,100,150 and 200 mg·kg-1 respectively had the maximum reduction of 17.1%,17.8%,23.9%,and 24.7%.The higher the concentration of cadmium stress was,the bigger the descending depth was.The main factor that caused the descending of Pn was the occurrence of photosynthesis restriction induced by stoma restriction.At the stage of 10-40 d after treatment,different cadmium concentration treatment had no significant difference.After treatment time arrived at 60 d and 80 d,200 mg·kg-1 cadmium stress had significant effect on Pn,the others didn＇t arrive at significant levels.The cadmium concentration of 150 mg·kg-1 might be the key threshold for photosynthesis of P.× euramericana（Dode）Guineir cv.＇Neva＇.The stem allocation ratio of P.× euramericana（Dode）Guineir cv.＇Neva＇ seedlings increased with the increasing cadmium concentration,while the root allocation ratio decreased with the increasing cadmium concentration,the treatment of 200 mg·kg-1 could significantly decrease the root-shoot ratio of seedlings,and greatly baffle the growth of roots.