Abstract: This paper deals with the characteristics of light-photosynthesis, temperature-photosynthesis,relative humidity-photosynthesis,diurnal changes of photosynthetic rate, and effects of irrigation for Melilo toides ruthenica under natural conditions.The results obtained are as follows: 1.The diurnal changes of photosynthetic rate of M.ruthenica population belong to noon-sescent type un der normal weather condition.The peak valve at afternoon was lower 64 % than morning, their type were changed by influence of different weather conditions.2.The population photosynthetic rate increased (or decreased) with the increased (or decreased) of light intensity and temperature before 8 o’clock (after 17 o’clock), and declined with moisture declined at noon time under fine-weather condition.The change range of population photosynthetic rate were different with change of light intensity and tem perature below light saturation point under different weather conditions.The slope was bigger at over cast than other weather conditions.3.The light saturature point of M.rethenica population was lower than some other plants, and the pho tosynthctic ability of population of over cast weather condition were higher than sunshine or shawdy.4.The photosynthesis were rised, and the type of diurnal change of photosynthesis were changed due to irrigation.According to photosynthetic ecological characteristics of M.ruthenica population, showed that it may be classified as a C₃ type plant, and is a good material for mixture with grasses.

Key words: Melilotoides ruthenica, Photosynthesis, Ecology characteristics

摘要： 本文在不同天气条件下研究扁蓿豆(Melilotoides ruthenica)的光合-光,光合-温和光合-湿的关系,种群光合的日变化以及灌水对种群光合生态特性的影响。结果如下:1.在一般天气条件下,扁蓿豆种群光合的日变化属于中午降低类型。下午的高峰值比上午低64%。在不同天气条件下日变化类型有所变化。在阴天或晴天灌水后,种群光合速率则无中午降低现象。2.在上午高峰值以前和下午高峰值以后,种群光合速率主受光照强度和温度的影响,随着光强和温度的升降而增减。而在中午前后虽然光照强度和温度较高,但光合速率反而下降,其主要原因是湿度减小所致。在不同天气条件下,种群光合速率的变化幅度有所区别,以阴天的斜率较大。3.扁蓿豆种群的光饱和点较低。阴天的比晴天高40%左右。上午的光合量比下午高105%。4.灌水可提高种群目光合量的56.52%,使光合日变化类型由双峰变为单峰曲线。根据以上光合生态特性,可以认为扁信是属于C₃阴性植物,并为其作为优良的野生混植材料提供可靠的依据。

关键词: 扁蓿豆, 光合作用, 生态特性