重金属铅胁迫对刺槐幼苗生长及铅离子转运特性的影响

为了解刺槐Robinia pseudoacacia对铅胁迫的耐受程度与耐受机制，以刺槐幼苗为研究对象，用硝酸铅溶液浇灌处理，研究幼苗的生长特性、组织铅离子质量分数（μg·g-1）及离子转运特征。结果表明:250 mg·L-1铅处理对刺槐幼苗的茎高、地径、干质量、鲜质量等有一定的促进作用；在中高铅离子质量浓度（≥500 mg·L-1）下，刺槐幼苗的生长受到抑制。随着铅处理质量浓度的增加，幼苗根系铅离子质量分数显著上升（P < 0.05）；茎部铅质量分数先升后降；叶中铅质量分数大体呈现降低趋势；叶/茎离子转运率急剧下降（P < 0.05）；（叶+茎）/根、茎/根离子转运率先升后降。通过多元回归分析，发现根系铅质量分数、（叶+茎）/根离子转运对幼苗干物质积累影响最大；茎部铅离子质量分数、根茎间铅离子转运对幼苗地径、苗高生长影响最大。图 3 表 2 参23

Growth and ion transport with Pb stress in Robinia pseudoacacia seedlings

To explore Robinia pseudoacacia (Black Locust) tolerance and mechanism to lead(Pb) stress, R. pseudoacacia seedlings were first watered with solutions of Pb(NO₃)₂ dissolved in distilled water. Then, properties of growth, lead concentration(μg·g-1), and ion transfer in stressed seedlings were analyzed using multivariate linear regression analysis, Ducan multiple comparison and single factor test design with treatments of 250, 500, 1 000 and 1 500 mg·L-1 and 3 replications. Experimental results showed that 250 mg·L-1 of Pb(NO₃)₂ solution slightly promoted height, stem diameter, and seedling dry and fresh weights, but these decreased when lead concentration was subsequently increased. Lead content significantly increased (P < 0.05) with accumulation found in roots; seedling stems showed a lead increase(P < 0.05) and a subsequent decrease (P < 0.05). In stressed seedlings leaf concentration declined in these treatments of 250 to 1 500 mg·L-1. In addition, the lead ion transfer-ratio for stem to leaf significantly declined (P < 0.05). However, as lead concentration increased, the root to stem and root to both stem and leaf concentration increased (P < 0.05) and then decreased (P < 0.05). The multivariate linear regression analysis, showed that the most important factors affecting accumulation of dry biomass were 1) lead concentration in roots and 2) ion transfer ratio of root to both stem and leaf. Also in stressed seedlings lead concentration in stems and ion transfer ratio of root to stem the most significantly affected (P < 0.05) growth of height and of stem diameter. It was drawn that lead accumulation in root and inhibition of its transfer could prevent leaves from damage deriving from lead stress, and they would be the tolerance mechanism to lead stress for Robinia pseudoacacia seedlings.Ch, 3 fig. 2 tab. 23 ref.]