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草业学报 ›› 2025, Vol. 34 ›› Issue (11): 66-80.DOI: 10.11686/cyxb2024505

• 研究论文 • 上一篇    下一篇

不同共生效应根瘤菌株对紫花苜蓿光合特性和呼吸代谢的影响

侯文璐(), 康文娟(), 陆保福, 韩宜霖, 关键, 王晶晶   

  1. 甘肃农业大学草业学院,草业生态系统教育部重点实验室,中-美草地畜牧业可持续发展研究中心,甘肃 兰州 730070
  • 收稿日期:2024-12-23 修回日期:2025-02-17 出版日期:2025-11-20 发布日期:2025-10-09
  • 通讯作者: 康文娟
  • 作者简介:E-mail: kangwj@gsau.edu.cn
    侯文璐(2001-),女,甘肃定西人,在读硕士。E-mail: 3262639782@qq.com
  • 基金资助:
    苜蓿燕麦高产种质创新和品种选育子课题(03324007);财政部和农业农村部:国家现代农业产业技术体系(CARS-34)

Effects of rhizobial strains with different symbiotic effects on the photosynthetic characteristics and respiratory metabolism of alfalfa

Wen-lu HOU(), Wen-juan KANG(), Bao-fu LU, Yi-lin HAN, Jian GUAN, Jing-jing WANG   

  1. Pratacultural College,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem of Ministry of Education,Sino-U. S. Centers for Grazing Land Ecosystem Sustainability,Lanzhou 730070,China
  • Received:2024-12-23 Revised:2025-02-17 Online:2025-11-20 Published:2025-10-09
  • Contact: Wen-juan KANG

摘要:

为探究紫花苜蓿-根瘤菌共生系统结瘤固氮对紫花苜蓿的光合特性、呼吸代谢以及植株生物量积累的影响,以根瘤菌株LL2和QL5分别侵染‘甘农9号’紫花苜蓿,比较接种根瘤菌后紫花苜蓿的结瘤固氮能力、植株表型、光合特性和呼吸代谢等指标的差异。结果表明:1)接种根瘤菌株LL2后植株单株有效根瘤数(7个)、固氮酶活性(0.29 μmol·g-1·h-1)、豆血红蛋白含量(0.76 mg·g-1)显著高于接种根瘤菌株QL5处理,前者紫花苜蓿的地上干重、株高、叶面积均显著提升,说明根瘤菌株LL2是‘甘农9号’紫花苜蓿的高效匹配菌株,QL5是低效匹配菌株。2)接种高效根瘤菌株LL2后植株的气体交换参数、叶绿素含量、叶绿素荧光参数、光合产物显著高于接种低效根瘤菌株QL5处理。3)接种根瘤菌株LL2后植株的ATP含量、ATP合成酶、己糖激酶、异柠檬酸脱氢酶、6-磷酸葡萄糖脱氢酶、6-磷酸葡萄糖酸脱氢酶活性显著高于接种根瘤菌株QL5处理,呼吸速率显著小于QL5处理。4)地上干重与蒸腾速率(相关系数为0.72)、淀粉含量(0.83)、ATP合成酶活性(0.72)呈显著正相关(P<0.05),与呼吸速率呈负相关(0.66);结瘤固氮能力与净光合速率(0.83)、可溶性糖含量(0.79)呈极显著正相关(P<0.01),与叶绿素(a+b)含量(0.76)、6-磷酸葡萄糖脱氢酶活性(0.85)呈显著正相关(P<0.05),与呼吸速率呈负相关。5)接种高效匹配根瘤菌株LL2的植株单位光照时间下产生的单位干重(0.06 g·h-1)显著高于接种根瘤菌株QL5的处理(0.03 g·h-1)。综上,高效匹配根瘤菌株LL2可通过提高结瘤和固氮能力促进植株对氮素的固定,为植株光合和呼吸提供更多的氮素能源,进而增加光合产物,降低呼吸速率,促进植株代谢循环,最终积累更高的生物量。

关键词: 紫花苜蓿, 根瘤菌, 共生固氮, 光合特性, 能量, 呼吸代谢

Abstract:

In order to explore the effects of nodulation and nitrogen fixation on the photosynthetic characteristics, respiratory metabolism, and plant biomass accumulation of alfalfa (Medicago sativa) plants in alfalfa-rhizobium symbiotic system, two Sinorhizobium meliloti strains, LL2 and QL5, were used to infect the M. sativa cultivar‘Gannong No. 9’, and the differences in nodulation and nitrogen-fixation ability, the phenotype, photosynthetic characteristics, and respiratory metabolism of alfalfa plants after inoculation with LL2 and QL5 were compared. The results showed that: 1) Compared with plants inoculated with S. meliloti QL5, those inoculated with S. meliloti LL2 formed significantly more effective nodules per plant (7), and the nodules showed significantly higher nitrogenase activity (0.29 μmol·g-1·h-1) and leghemoglobin content (0.76 mg·g-1). The aboveground dry weight, plant height, and leaf area of alfalfa plants were greater in those inoculated with S. meliloti LL2 than in those inoculated with QL5, indicating that S. meliloti LL2 was a well-matched strain for M. sativa ‘Gannong No. 9’ and S. meliloti QL5 was a poorly matched strain. 2) The values of gas exchange and the contents of chlorophyll and chlorophyll fluorescence parameters and photosynthetic products were significantly higher in plants inoculated with the high-efficiency strain LL2 than in those inoculated with the low-efficiency strain QL5. 3) The adenosine triphosphate (ATP) content and the activities of ATP synthase, hexokinase, isocitrate dehydrogenase, 6-phosphogluconate dehydrogenase, and glucose-6-phosphate dehydrogenase were significantly higher, and the respiration rate was significantly lower, in plants inoculated with strain LL2 than in those inoculated with strain QL5. 4) There was a significant positive correlation between aboveground dry weight and transpiration rate (correlation coefficient, 0.72), starch content (0.83), and ATP synthase activity (0.72) (P<0.05); and a negative correlation between the aboveground dry weight and respiration rate (0.66). The nodule nitrogen-fixation ability was extremelly significantly positively correlated with net photosynthetic rate (0.83) and soluble sugar content (0.79) (P<0.01); significantly positively correlated with chlorophyll (a+b) content (0.76) and glucose 6-phosphate dehydrogenase activity (0.85) (P<0.05); and negatively correlated with the respiratory rate. 5) The dry weight per unit light time was significantly higher in plants inoculated with the highly efficient rhizobium strain LL2 (0.06 g·h-1) than in plants inoculated with QL5 (0.03 g·h-1). In summary, the well-matched, efficient rhizobial strain promoted nodulation and nitrogen fixation, providing a nitrogen source for enhanced photosynthesis capacity and respiration. This increases the production of photosynthetic products, reduces the respiration rate, and promotes plant metabolism, leading to increased biomass accumulation.

Key words: alfalfa, rhizobium, symbiotic nitrogen fixation, photosynthetic characteristics, energy, respiratory metabolism