翅果油树的生态学特征及其根瘤固氮活性的研究

翅果油树是中国放线菌结瘤植物资源中一种具有较高经济价值的稀有油料树种。作者对其生态学特征以及多种生态因子与其根瘤固氮活性的关系进行了调查和研究。 研究结果表明:在生长季节内,翅果油树根瘤的固氮活性呈双驼峰状变化。在6月出现一个高峰、9月出现一个次高峰。这种季节性变化,是受各种生态因子和寄主植物体内代谢因素所制约的。温度对根瘤固氮活性有明显影响;光合作用強度与固氮活性密切相关,但并不呈同步关系;有性生殖生长在不同季节对根瘤固氮活性的影响,是由于二者对光合作用产物发生竞争的结果。种植翅果油树可以明显地提高林地内的氮素含量,12年生人工林和20年生人工改造林分别比荒坡自然植被下的土壤含氮量提高75％和99％。

STUDIES OF ECOLOGICAL CHARACTERISTICS AND NITROGENASE ACTIVITV OF ROOT NODULES OF ELAEAGNUS MOLLIS DIELS

Elaeagnus mollis Diels is a rare oil tree of high economic values in actinorhi-zal plant resources in China. Its ecological characteristics and the relations between ecological factors and the nodular nitrogenase activity were surveyed and studied.Surveying results indicated that the origin of Elaegnus mollis Diels is from warm temperat zone and semi-arid climate zone and it grows in drab soil of low mountain and hilly land. This species is characterised by a high tolerance to drought, cold and barren and a high adaptability. Developing this species in middle reaches of the Yellow River and some Eerious soil erosion regions in China is of high economical and ecological benefits.Research results indicated that the nitrogenase activity of root nodules in Elaeagnus mollis Diels during the growing seasons shows two periods of high rate, the first in June, and the second in September. The seaeonal variations of nitrogenase activity are restricted by ecological factors and metabolic factors of host plant. The influence of temperature on nodular nitrogenase activity is obvious. Photosynthetic intensity is in close relation with nitrogenase activity, but without synchronism. The influence of sexual reproductive growth on nitrogenase activity during different seasons is due to the result of competition for photosynthate allocation between both. Planting Elaeagnus mollis dramatically increased the nitrogen content of soil in woodland. Soil nitrogen contents under 12 year-old artificial forest and 20 year-old artificially transformed forest increased by 75% and 99% over those of natural Vegetation on a waste slope, respectively.