Abstract: This paper deals with the variation law of photosynthetic rates of Eupatorium adenophorum Spreng and the relation between the variation law and I main enviromental factors. The difference of its photosynthetic rates was compared , with some farm crops. The main results are as follows: 1. E. adenophorum is a herbaceous plant of C3 type and sun inclining to shade. The light saturation point is about 40000 Ix. The compensation point is about 700 Ix. The CO2 compensation point is about 80 ppm. 2. The maximum net photosynthetic rate of E. adenophorum is about 23 CO2 mg.dm^-2.h-1. The diurnal variation law of its photosynthetic rates exhibits a curve with double peak (main peak at about 10 : 00 and secondary peak at about 16: 00). Its photosynthetic rate keeps higher level for a long time in a year. 3. The change in the soil moisture content affects leaf's photosynthetic rate obviously. The photosynthetic rate of E. adenophorum grown in vegetable soil approximates to zero when the soil moisture content is reduced to 17, and what is more, the photosynthetic rate of the plant undergone drought tieatment on the third day after lewatering is 53 as much as the normal ones. Accordig to the above experimental results and climate characteristics which the dry and rain season aie very distinct in the harmed area, it seems that the dry season (from October to next February) is better time for controlling E. adenophorum.

Key words: Eupatorium adenophorum

摘要： 本文研究了紫茎泽兰（Eupatorium adenophorum Spreng）光合作用强度的变化规律及其与环境主要生态因子的关系，比较了它与某些农作物叶片净光合速率的差异，得到如下结果：1.紫茎泽兰是一种阳性偏阴的C3 类草本植物，其光合作用的光饱和点约为40000 lX，光补偿点约为700 lx，且具有80 ppm左右的CO2 补偿点。2．紫茎泽兰的最大净光合速率能达到23毫克CO2 ／平方分米·时左右，叶片净光合速率的日变化规律呈双峰曲线型（主峰在10时左右，次峰在16时左右）。在一年中有较长的时间，它的光合速率保持着较高的水平。3．生长在一般菜园土上的紫茎泽兰，当土壤含水量降至17％左右时，叶片光合速率接近0；而且，受过干旱处理的紫茎泽兰植株，在恢复供水后的第三天，其光合速率只达到原来的53％。根据以上结果，结合受紫茎泽兰危害地区干湿季分明的特点，提出干季是防除紫茎泽兰的最佳季节。

关键词: 紫茎泽兰, 光合速率, 光饱和点, 光补偿点, CO2补偿点, 土壤含水量