镉和增强紫外线-B辐射复合作用对大豆生长的影响

研究了Cd^2+和增强紫外线-B(UV-B)辐射以及二者复合胁迫(Cd+UV-B)对大豆生长、光合作用、抗氧化酶活性和吲哚乙酸(IAA)氧化酶活性的影响，结果表明，UV-B辐射对大豆生长较CA^2+有更明显的抑制作用，主要是降低了光合作用，生物量减小；抑制节间的分化和伸长，节间减少，株高降低。UV-B辐射对POD、SOD活性有显著诱导作用，而Cd^2+明显颉颃UV-B对POD活性的诱导并抑制IAA氧化酶活性．在复合作用下，植物体内IAA氧化酶和POD活性较UV-B单独作用下显著降低，这两种酶活性降低会引起植物体内IAA含量升高，同时光合作用略有升高，这是株高和生物量较UV-B作用下有所增加的重要原因,复合胁迫还增强了对根伸长生长的抑制作用，根长度较对照显著降低(P<0．05)。IAA氧化酶和POD活性变化以及光合强度变化与大豆株高和生物量变化密切相关，这也是复合胁迫影响大豆生长状况的重要因素。

Effect of the combination of cadmium and UV-B radiation on soybean growth

This paper studied the characteristics of soybean growth under the stress of Cd,UV-B radiation and their combination.The results showed that UV-B radiation gave a more pronounced inhibition on soybean growth than cadmium.Under UV-B radiation,the internode differentiation and elongation were inhibited,the internode and plant height were reduced,and the activities of SOD and POD had an apparent increase.Cd 2 could antagonize the effect of UV-B radiation on POD activity,and inhibit indole-3-acetic acid(IAA)oxidase activity.A significant decrease of POD and IAA oxidase activities in soybean was detected when exposed to combined UV-B and Cd 2 ,compared with UV-B radiation only.The decrease of POD and IAA oxidase activities was related to the increase of IAA contents and photosynthetic activity,which might account for the increases of biomass and plant height.Moreover,the combined stress enhanced the inhibition of root growth,and significantly decreased root length.The IAA oxidase and POD activities and photosynthesis rate might be the crucial factors determining the pattern of soybean growth under the stress of Cd 2 in combination with UV-B radiation.