关键词: 扁蓿豆, 叶片解剖形态, 茎解剖形态, 耐盐性

Abstract: [Objective] To compare and evaluate the salt tolerance of a new Medicago ruthenica line （LX line） and two registered Medicago ruthenica varieties. [Methods] Seeds of three Medicago ruthenica varieties [LX line, Horqin Sandy Land Medicago ruthenica（B1）, and Tumd Medicago ruthenica （B2）] were subjected to simulated salt stress germination tests using NaCl solutions at concentrations of 30 mmol/L （T1）, 60 mmol/L （T2）, and 90 mmol/L （T3）, with an equal volume of distilled water treatment as the control. Germination rate, root length, shoot length, fresh weight, and dry weight were measured. Using paraffin sectioning, the anatomical structures of leaves and stems were observed to analyze differences between the new line and the other two. [Results] With increasing NaCl concentrations, the germination rate of the LX line initially increased and then decreased but remained higher than that of B1 and B2 varieties. Under T1, T2, and T3 conditions, root length and shoot length ranked as LX > B2 > B1. Under T1 and T2 conditions, the root-to-shoot ratio （root length/shoot length） of the LX line was higher than that of B1 and B2 varieties. No significant differences （P>0.05） were observed in fresh weight and dry weight between the LX line and B1 or B2 varieties. Regarding leaf anatomical characteristics, the LX line exhibited significantly （P<0.05） greater leaf thickness, vein thickness, mesophyll thickness, upper epidermal thickness, lower epidermal thickness, and palisade tissue thickness compared to those of B1 and B2 varieties, but lower spongy tissue porosity. For stem anatomical characteristics, the LX line showed significantly （P<0.05） smaller vessel diameter, stem pith diameter, xylem thickness, phloem thickness, area of xylem and phloem, and stem cross-sectional area compared to those of B1 and B2 varieties. [Conclusion] The LX line of Medicago ruthenica demonstrates salt-tolerant anatomical structures and salt tolerance, with its seeds capable of superior germination and development under salt stress conditions.

Key words: Medicago ruthenica, leaf anatomy, stem anatomy, salt tolerance