《植物生理学报》 2018, 54(9): 1409-1416
摘 要：采用温室盆栽试验, 研究不同浓度(0、50、100、150、200和250 mmol·L-1) NaCl处理对蒺藜苜蓿(Medicago truncatula)生长发育及共生结瘤的影响。结果表明: 在共生固氮和施加氮肥两种条件下, 低浓度(50 mmol·L-1)NaCl处理对苜蓿生长发育均没有明显影响; 随着NaCl浓度的升高, 苜蓿生长受到明显的抑制, 且抑制程度与NaCl浓度呈正相关; 对比两种条件下苜蓿生长受盐胁迫的程度发现, 施氮处理的苜蓿的各项生长指标普遍优于共生固氮的苜蓿, 表明后者对盐胁迫更敏感。进一步研究NaCl胁迫对苜蓿共生结瘤的影响发现盐浓度≥100 mmol·L-1时, 随着浓度的升高, 根瘤数量不断减少, 根瘤不断变小, 同时固氮区细胞数量也相应减少。可见, 苜蓿能够耐受低浓度的盐胁迫, 但中高浓度(≥100 mmol·L-1)盐胁迫显著抑制了其生长发育及共生结瘤过程, 这一结果为盐地苜蓿育种及栽培提供理论指导。
关键词：苜蓿; NaCl胁迫; 生长; 共生结瘤
Corresponding author: YU Liang-Liang; E-mail: firstname.lastname@example.org
Abstract:The effects of different concentrations (0, 50, 100, 150, 200, and 250 mmol·L-1) of NaCl on growth and symbiotic nodulation in Medicago truncatula in a pot experiment were studied. The results showed that: in both conditions of symbiotic nitrogen fixation and application of nitrogen fertilizer, no influence of the low concentration (50 mmol·L-1) of NaCl on the growth and development of medicago plants was observed; however, growth of medicago was obviously repressed as the NaCl concentration increased, and the repression effects positively correlated with NaCl concentrations. Further analysis of the effects of NaCl stress on the growth of medicago grown under the above two conditions revealed that growth parameters of medicago treated with nitrogen fertilizer were better than those of medicago inoculated with rhizobia, indicating that symbiotic medicago plants were more sensitive to salinity stress. The effects of NaCl stress on symbiotic nodulation of medicago were also investigated. The results showed that as the NaCl concentration (≥100 mmol·L-1) increased, both nodule number and size decreased, and accordingly cells in N-fixing zone of the nodules reduced. Taken together, our results demonstrate that growth and nodulation of medicago are tolerant to low salinity stress, but are repressed by higher concentration of NaCl (≥100 mmol·L-1). These results provide useful information for medicago breading and cultivation in saline lands.
Key words: medicago; NaCl stress; growth; symbiotic nodulation
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