Cd胁迫和增强UV-B辐射对大豆根系分泌物的影响  

EFFECT OF CADMIUM AND ENHANCED UV-B RADIATION ON SOYBEAN ROOT EXCRETION

作　　者：强维亚[1] 陈拓[2] 汤红官[1] 冯虎元[1] 安黎哲[1,2] 王勋陵[1] 

机构地区：[1]兰州大学生命科学学院,干旱农业生态国家重点实验室,兰州730000 [2]中国科学院寒区旱区环境与工程研究所,兰州730000

出　　处：《植物生态学报》2003年第3期293-298,共6页Chinese Journal of Plant Ecology

基　　金：中国科学院知识创新工程重大项目 (KZCX1_10_0 2 );国家自然科学基金项目( 30 170 186 );中国科学院冰芯与寒区环境开放实验室知识创新工程项目 ( 2 10 50 6 )

摘　　要：镉 (Cd)污染和增强紫外线_B(UV_B)辐射对大豆 (Glycinemax)根系分泌物变化的研究表明 ,Cd污染促进了大豆根系有机化合物 (如有机酸、氨基酸、多肽和酰胺等 )的分泌 ,但该分泌作用受增强UV_B辐射的抑制。根系有机硫分泌只受较强胁迫条件促进 ,较高浓度Cd和较强的UV_B辐射对大豆根系有机硫分泌有协同促进作用。氮素含量主要受Cd胁迫影响 ,其变化可能有两方面原因 :1 )Cd胁迫下根系对有机含氮化合物 ,主要是多肽、氨基酸和酰胺的分泌增加 ;2 )Cd胁迫减少了根系对氮素的吸收 ,引起根际环境中残留氮素的升高。增强UV_B辐射对根际环境中氮素有一定影响 ,但不显著。研究结果表明了增强UV_B辐射在一定程度上影响Cd胁迫下大豆根系有机化合物的分泌作用 。An increase in ultraviolet_B (UV_B, 280_315 nm) radiation reaching the earth's surface due to depletion of the stratospheric ozone layer and heavy metal pollution due to industrial waste have become serious concerns. In order to understand the influence of enhanced UV_B radiation and heavy metal pollution on plant root growth, physiological metabolism, and tolerance to heavy metals, the effect of cadmium (Cd) associated with enhanced UV_B radiation on the excretion activity of soybean root was investigated. The full amounts of nitrogen, organic carbon, and sulfur excreted by soybean ( Glycine max ) root exposed to Cd 2+ pollution, enhanced UV_B radiation and both in combination were measured using the Kjeldahl method and a CS_344 carbon and sulfur system (LECO USA). The results showed that Cd 2+ could enhance root excretion of organic carbon, but the excretion was inhibited by enhanced UV_B radiation. Excretion of organic sulfur compounds was only accelerated by severe stress, that is a combination of higher Cd 2+ concentration and stronger UV_B radiation had a synergistic effect on excretion. Nitrogen content was mainly affected by Cd 2+ . The possible reasons were: 1) Cd 2+ pollution promoted roots to excrete more organic nitrogen compounds, such as amino acids and polypeptides; 2) Cd 2+ decreased absorption ability of roots, and nitrogen uptake from rhizosphere was reduced, thereby resulting in an increase in nitrogen content in the environment of the root. Nitrogen content in the environment could also be affected by enhanced UV_B radiation, but this effect was insignificant. The results indicated that UV_B radiation could alter the composition and proportion of root excretions, and, perhaps, affect plant tolerance to Cd 2+ stress.

关 键 词：CD胁迫 UV-B辐射 大豆 根系 分泌物 镉污染 

分 类 号：X173[环境科学与工程—环境科学]