关键词: 紫花苜蓿, 冻融循环＋盐碱胁迫, 营养器官, 矿质离子, 离子稳态平衡

Abstract: Freezing and thawing often occur in spring in saline areas of the Northeast China. In order to explore the effects of freeze-thaw and saline-alkali stress on the absorption and transport of mineral ions in alfalfa,in this study,'Longmu 807’alfalfa seedlings were used as test materials to investigate the effects of the freeze-thaw cycle (freezing-thaw cycle,FT) and freeze-thaw cycle + saline-alkali (freezing-thaw cycle and saline-alkali,FT+SA) stresses on the mineral elements absorption and transportation in the vegetative organs of alfalfa seedlings. The results showed that under FT and FT+SA stresses,the content of Na⁺in roots of alfalfa seedlings increased,while the content of Na⁺ in stems and leaves decreased;however,the contents of K⁺,Ca²⁺,Mg²⁺,Fe³⁺,Mn²⁺,Zn²⁺,Cu²⁺and the ratios of K⁺/Na⁺,Ca²⁺/Na⁺,Mg²⁺/Na⁺decreased in root,stem and leaf,and the reduction level under FT+SA stress was higher than that under FT stress. The selective transport capacity of Mg²⁺in roots is higher than that of K⁺ and Ca²⁺,and the K⁺ transport capacity from stems to leaves is higher than that of Mg²⁺and Ca²⁺. Ability to limiting Na⁺ and inhibiting K⁺,Ca²⁺,Mg²⁺ selective transport in the root,and the ability of stem to selectively transport K⁺,Ca²⁺,Mg²⁺to leaves is higher under FT+SA stress than those under FT stress. The correlation between the ions is relatively high,which jointly maintains the ion balance of the plant. Under FT and FT+SA stresses,the distribution and transportation of the above mineral ions were affected in roots,stems and leaves of alfalfa seedlings,which was related to the cold and saline-alkali resistance of alfalfa seedlings.

Key words: Alfalfa, Freezing-thaw cycle and saline-alkali stress, Vegetative organ, Mineral ion, Ion steady-state equilibrium