燕麦对碱胁迫的阳离子响应机制

以耐碱性燕麦品种Vao-9和碱敏感性品种白燕5号为试验材料，采用盆栽法，用25、50、75、100 mmol L^-1碱浓度(Na₂CO₃和NaHCO₃按摩尔比1∶1混合)进行短期(14 d)和长期(28 d)胁迫处理，观测两品种根、茎、叶中Na⁺、K⁺、Ca²⁺、Mg²⁺吸收及分配特点，并从离子平衡吸收与分配角度，探讨燕麦对碱胁迫的生理适应机制。胁迫处理14 d后，燕麦体内Na⁺增加，K⁺下降，Ca²⁺和Mg²⁺变化不大，且两品种间各器官中4种离子的分配比例差异不显著。胁迫处理28 d后，两品种各器官中Na⁺增幅较大，K⁺、Ca²⁺和Mg²⁺降幅较大。Vao-9植株体内Na⁺、Ca²⁺含量大于白燕5号，但K⁺、Mg²⁺含量与白燕5号无显著差异，但两品种间各器官中4种离子的分配特点不同；当胁迫浓度达到100 mmol L^-1时，与白燕5号相比，Vao-9叶片中少分配5.9个百分点Na⁺，多分配13.5个百分点K⁺、28.9Ca²⁺、10.9Mg²⁺，茎中多分配5.4个百分点Na⁺，少分配9.8个百分点K⁺，根中少分配28.9个百分点Ca²⁺、10.9Mg²⁺，因而Vao-9叶片中Na⁺ /K⁺、Na⁺ /Ca²⁺、Na⁺ /Mg²⁺值较白燕5号低。可见，燕麦通过提高阳离子选择吸收及器官分配能力以适应碱胁迫。

Cation-Responsive Mechanisms of Oats to Alkali Stress

In a pot experiment, an alkali-tolerant oat variety, Vao-9, and an alkali-sensitive variety, Baiyan 5, were exposed to 25, 50, 75, and 100 mmol L^-1 of alkali stress (molar ratio of Na₂CO₃-to=NaHCO₃ = 1:1). The contents of Na⁺, K⁺, Ca²⁺, and Mg²⁺ absorbed by oat seedling and their distribution characteristics in root, stem, and leaf were measured after a short-term (14 d) or a long-term (28 d) stress treatment. The objective was to understand the physiological adaptation to alkali stress in oat in the view of ion balance absorption and distribution. After short-term stress, the cation contents in oat plants showed the variations of increased Na⁺, decreased K⁺, and minor changes in Ca²⁺ and Mg²⁺. Besides, the distribution proportions of the four ions in various organs were not significantly different between the two varieties. Compared to short-term stress, long-term stress resulted in larger increase of Na⁺ content and larger decreases of K⁺, Ca²⁺, and Mg²⁺ contents in all organs of both varieties. Vao-9 absorbed more Na⁺ and Ca²⁺ than Baiyan 5, and the absorptions of K⁺ and Mg²⁺ were not significantly different between varieties, but the distribution characteristics of the four ions in various organs were different between the two varieties.Under 100 mmol L^-1 alkali stress, 5.9 percent Na⁺ in leaf were lower distributed and 13.5 percent K⁺, 28.9 Ca²⁺, 10.9 Mg²⁺ more distributed in Vao-9 than in Baiyan 5, 5.4 percent Na⁺ in stem higher and 9.8 K⁺ lower in Vao-9 than in Baiyan 5 , 28.9 Ca²⁺, 10.9 Mg²⁺ in root were lower in Vao-9 than in Baiyan 5, As a result, the Na⁺ content and the ratios of Na⁺/K⁺, Na⁺/Ca²⁺, and Na⁺/Mg²⁺ in leaf were lower in Vao-9 than in Baiyan 5. Clearly, oat plant has the mechanism of selective absorption and distribution of various cations in different organs in response to alkali stress.