为建立一种既可高效结瘤固氮, 又具有一定产量的大豆(Glycine max)营养液栽培系统, 设计并进行了2个试验。首先在不同供氮条件下, 研究了接种根瘤菌对大豆的结瘤状况、固氮能力、生物量及产量的影响。结果表明, 供氮过高或过低, 均影响大豆生长、产量形成及根瘤固氮; 并且植物生长所需的最适供氮水平远高于生物固氮所需的最适供氮水平。此外, 大豆生物固氮活性最高的时期在生殖期第一期(R1期)之前。由此推断, 大豆R1期前, 供应较低的氮, 有利于根瘤形成及固氮; 而从R1期起, 应提高供氮水平, 以促进植物生长及产量的形成。在此基础上开展第2个试验, 对供氮条件进行了优化处理(即R1期前低氮供应、R1期开始中氮供应)。结果表明, 与持续供应高氮相比, 优化供氮处理不仅可获得较多固氮酶活性较高的大根瘤, 还能保持较好的生长、获得更高的百粒重及维持80%左右的产量。研究结果不仅可为高效研究大豆根瘤共生固氮提供营养液配方, 还可为大豆高产高效栽培提供试验依据。

To establish a nutrient solution system for soybean cultivation with effective nodulation and relatively high yield, we first evaluated the effect of nitrogen (N) content and rhizobia inoculation on soybean growth, yield and biological nitrogen fixation (BNF). Too high or too low N supply affected soybean growth, yield and N₂ fixation capacity. Also, the required optimal N level was much higher for plant growth than that of BNF. Furthermore, the highest nitrogenase activity in soybean occurred before the first stage of reproduction (R1 stage). Thus, the enzyme activity could facilitate nodule formation and N₂ fixation with a lower N supply before the R1 stage and a higher N supply afterward to promote plant growth and yield in soybean. A second experiment was conducted to optimize N supply (i.e., low N supply before R1 and medium N supply at the beginning of R1). As compared with continuously supplied high N, the optimal scheme promoted BNF with more and larger nodules with higher nitrogenase activity and also maintained a good growth performance with higher 100 grain weight and about sustained 80% of soybean yield. These results provide a reference for nutrient receipt for soybean BNF study as well as soybean production for high yield and nutrient efficiency.