玉米根系形态对土壤Cd和芘复合污染的响应

Response of maize (Zea mays L.) root morphology to Cd and pyrene contamination in soil

植物根系在逆境胁迫下通过改变其形态及分布来适应不利的生长环境,根系的形态变化是植物适应外界环境(特别是土壤环境)的一个重要机制。采用盆栽模拟试验探讨了Cd+芘复合污染对两种基因型玉米(ZeamaysL.)(白玉米和黑玉米)根系形态学参数(根长、根表面积、根体积、根平均直径及不同根直径等级分布)的定量化影响。与对照未污染相比,Cd+芘复合污染显著降低了白玉米和黑玉米茎叶和根的生物量,特别是根的生物量。Cd+芘复合污染对白玉米生物量的抑制要比对黑玉米要灵敏。与未污染相比,Cd+芘复合污染下白玉米和黑玉米的根长稍有增长,根表面积、根平均直径和根体积减小,但两处理间差异不显著。白玉米和黑玉米每一级根直径的根长在Cd+芘复合污染和未污染处理间没有显著差异。白玉米和黑玉米>0.60mm的根的根表面积在Cd+芘复合污染下显著降低。此研究结果为重金属-多环芳烃复合污染土壤植物毒理效应和植物修复技术的进一步研究奠定基础。

The plants could control root morphology and distribution to adjust the toxic effect. Change of root morphology is an important mechanism of plant adapting to toxic stress in soil environment Cd and pyrene were studied as combined contamination to explore effects in two maize （Zea rnays L.） genotypes on root morphology at an early growth stage in a pot experiment. Qualitative root parameters like specific root length （SRL）, specific root surface area （SRA）, specific root volume （SRV）, average root diameter （ARD）, and distribution of root diameter classes of maize were evaluated. Shoot and root biomass of white maize and black maize significantly decreased in Cd and pyrene contaminated soil than that in uncontaminated soil, especially for root biomass. The inhibitive effects of Cd and pyrenc combined contamination on biomass of white maize was more sensitive than that of black maize. SRL was slightly higher of white maize and black maize in Cd and pyrene contaminated soil than that in uncontaminated soil. SRA, ARD and SRV of white maize and black maize decreased in Cd and pyrene contaminated soil compared to control, but the difference was not significant between the two treatments. There was no significant difference of SRL in each diameter classes of white maize and black maize between Cd and pyrene contaminated treatment and uncontaminated treatment. The SRA of root diameter class 4 （〉0.60 mm） of white maize and black maize was significantly decreased in Cd and pyrene contaminated soil than that in uncontaminated soil. The result lays foundations for the further study the toxic effect on plant and phytoremediation of heavy metal and polycyclic aromatic hydrocarbons combined contamination in soil.