小冰麦(Triticum aestivum-Agropyron intermedium)对盐胁迫和碱胁迫的生理响应

Physiological Response of Xiaobingmai (Triticum aestivum-Agropyron intermedium) to Salt-Stress and Alkali-Stress

将两种中性盐(NaCl和Na2SO4)和两种碱性盐(NaHCO3和Na2CO3)按摩尔质量比1∶1混合,在60～300mmolL-1盐浓度内模拟出5种强度的盐胁迫条件,在30～180mmolL-1盐浓度内模拟出6种强度的碱胁迫条件,并以此对小冰麦苗胁迫处理12d。测定相对生长率(RGR)、含水量、丙二醛(MDA)、电解质外渗率、叶绿素、类胡萝卜素6项胁变指标和Na+、K+、脯氨酸、甜菜碱、有机酸5种溶质含量。结果表明,碱胁迫下小冰麦的各项胁变反应均明显大于盐胁迫下。在本试验条件下,小冰麦可耐受的最高盐胁迫浓度为300mmolL-1,而碱胁迫仅为150mmolL-1。碱胁迫造成小冰麦光合色素含量急剧下降,可能是其危害甚于盐胁迫的原因之一。碱胁迫下有机酸大量积累可能是小冰麦响应碱胁迫的特殊生理机制。试验结果证明盐、碱胁迫是两种性质不同的胁迫,不仅对植物的作用机制不同,而且植物的适应机制也不同。

Land salinization-alkalization is a widespread environmental problem. The problem can be further classified, in terms of the salt characteristics, into salt-stress and alkali-stress. In fact, the destructive effects caused by alkali-stress is more serious than that by salt-stress. However, the information about alkali-stress is little up to the present. The resistance to salt and alkali stresses is stronger in Xiaobingmai （ Triticum aestivum -Agropyron intermedium） than in other varieties of wheat. The cultivar Xiaobingmai 33 has been planted over some salt-alkalized areas, but its resistance to salt and alkali stresses is few studied yet. Therefore, Xiaobingmai 33 was chosen as the experimental materials to explore its physiological response to salt and alkali stresses and the difference between salt-stress and alkali-stress. The seedlings of Xiaohingmai 33 were treated for 12 days under five conditions of salt-stress and six conditions of alkali-stress, which were established by mixing NaC1 and Na2 SOa or NaHCO3 and Na2 CO3 at 1 ： 1 molar ratio respectively. The concentration range of treatments was from 60 to 300 mmol L^-1 for the salt-stress, and 30 to 180mmol L^-1 for the alkali-stress. Six strain indices including relative growth rate （RGR）, water content, malondialdehyde （MDA） content, electrolyte leakage rate, chlorophyll content, and carotenoid content, and the contents of five solute including Na^＋ , K^＋ , praline, betain, and organic acid, were determined. The physiological responses of Xiaobingmai 33 to salt-stress and alkali-stress were analyzed and compared in order to further identify the difference of both stresses. The results showed that the decrease extents of RGR and water content and the increase extents of MDA and electrolyte leakage rate under-alkali stress were greater than those under salt-stress with increasing stress intensity. The contents of chlorophyll and carotenoid didn＇ t change under salt stress, but decreased sharply under alkali-stress. Under both stresses, the contents of Na^＋ , praline, and betain increased, while K^＋ content decreased, and the changing degree under saltstress was higher than that under alkali stress. In addition, organic acid content increased significantly under alkali-stress, but decreased slightly under salt-stress. In conclusion, all the strain responses to alkali-stress were more marked than those to salt-stress. The maximum concentration for Xiaobingmai 33 in resistance to salt-stress was 300 mmol·L^-1, and that to alkali-stress was only 150 mmol·L^-1 under the present experimental conditions. Alkali-stress caused great decrease of photosynthetic pigment content, which might be one of the reasons that the effect of alkali-stress was more severe than that of salt-stress. The accumulation of organic acids might be a special physiological mechanism of Xiaobingmai response to alkali-stress. The present study indicate that salt-stress and alkali-stress are two different stresses, not only in their effects on plant, but also in the response of plant to them.