田间增加紫外线（UV）辐射对大豆幼苗生长和光合作用的影响

 两个增加的UV(UV-AB，280～400nm)辐射强度分别相当于大气臭氧减少3.6％和5.1％时增加的UV-B辐射。UV辐射增强明显降低大豆的株高、叶面积、干重、水分含量和叶绿素含量，大豆生长受抑程度随人工UV光源照射时间和强度增加而增强，是增加UV辐射剂量的累积效应，叶绿素b的降幅大于叶绿素a，表明UV辐射对大豆幼苗捕光色素的破坏较严重。同时，增加UV辐射还使大豆幼苗的表观光合速率、蒸腾速率、水分利用效率、气孔导度下降，作用效果与辐射强度正相关。与生长等比较，UV辐射条件下，冠／根比值减少幅度不大。分析认为，大豆幼苗生长和光合能力的下降可以使植物避免或减轻UV辐射的进一步伤害，对植物适应UV辐射有利。

EFFECTS OF SUPPLEMENTAL ULTRAVIOLET (UV) RADIATION ON THE GROWTH AND PHOTOSYNTHESIS OF SOYBEAN GROWING IN THE FIELD

Soybean seedlings were subjected to two treatments of enhanced UV radiation simulating 3.6 % and 5.1% deletions in the ozone layer, respectively, in a field experiment. The significant decreases in plant height, leaf area, dry matter weight , water and chlorophyll content of the seedlings were observed. The inhabitation of growth of the plants depended on the time and density of UV radiation, showing a cumulative effect of UV radiation dose. The decrease in chl. b more than that in chl. a indicates that UV radiation damaged light-harvesting pigment substantially. A higher density of UV radiation lead smaller values of apparent photosynthetic rate, transpiration rate, water use efficiency (WUE) and stomata conductance of plants. The decrease in the shoot/root ratio was far less than that in the growth of the plants growing under supplemental UV radiation. The present work shows that the reduced growth and photosynthesis of the plants could avoid or lighten the further injury due to UV radiation, it benefits plant to adapt itself to en-chanced UV radiation.