大豆-根瘤菌共生体系光合与固氮关系研究

水培大豆和田间生长的大豆,接种根瘤菌 Rhizobium B16-11C 后植株全氮含量、叶片叶绿素含量和净光合速率及种子产量都明显增加。比较 Clark 大豆的结瘤品系和不结瘤品系获类似结果。摘除根瘤后3天内叶片净光合速率无明显变化。大豆植株遮阴、去叶或切掉地上部导致根瘤活性明显下降。但去豆荚不能提高根瘤固氮的比活性。根瘤活性的日变化不能用根瘤蔗糖、淀粉含量或周围温度的变化来解释,其控制因子尚待深入研究。

STUDIES ON THE RELATIONSHIP BETWEEN PHOTOSYN-THESIS AND NITROGEN FIXATION IN THE SYMBIOTIC SYSTEM OF SOYBEAN AND NODULE BACTERIA(RHIZOBIUM)

The relationship between photosynthesis of soybean and nitrogen fixation of the nodules by symbiotic Rhizobium was studied.The contents of total nitrogen and chlorophyll,the net pho- tosynthetic rate and seed yield of soybean were much higher in either hydroponically cul- tivated or field-grown plants inoculated with Rhizobiurn B16-11C(or Clark no(?)ating strain)than in control without inoculation(or Clark non-nodulating strain).These results show that the symbiotic nitrogen fixation has a beneficial effect on photosynthesis.However,the effect was indirect and slow so that there was no change in the net photosynthetic rate of the soybean leaves until three days after removing nodules from the soybean roots. On the other hand,decreasing the photosynthate supply to nodule by shade,defoliation or shoot removal of the soybean,the nodule activity declined significantly.It seems that the supply of photosynthate to root nodule is a limiting factor for symbiotic nitrogen fixation.However, the diurnal variation of the nodule activity could not be explained by change neither in the contents of sucrose and starch of the root nodules nor in the ambient temperature.The factor controlling the diurnal variation deserves further Study.