柳树幼苗渗透调节物质对中、碱性钠盐响应的差异性

世界土壤盐渍化问题日益严重.中国拥有面积广大的盐碱地,它严重地制约着中国农业的可持续发展.中国北方内陆盐碱地土壤含有NaCl、Na2SO4、Na2CO3、NaHCO3 多种盐分,类型复杂多样.柳树是我国重要的造林绿化和水土保持乡土树种,对改良盐碱地美化生态环境具有重要作用,因此研究柳树耐碱性及其适应盐碱生理差异性具有重要意义.以盐柳1号（Salix psammophila）为试验材料,分别以中性盐NaCl 和Na2SO4、碱性盐NaHCO3 和Na2CO3 混合模拟盐、碱胁迫（两者物质的量比均为9∶1）,各设计了5 个梯度处理,总共胁迫14 d 后,研究盐与碱胁迫下柳树幼苗叶片含水量、脯氨酸、可溶性糖和可溶性蛋白的变化情况.结果表明：随着盐浓度的升高柳树叶片中的含水量呈减少趋势,在碱性盐胁迫下叶片含水量下降趋势更大,盐浓度达到200 mmol·L^-1 时,叶片含水量达到最低为23.8%,仅为对照的32%（P〈0.01）达到极显著性差异,并且相比于中性盐在碱性盐胁迫下叶片损失水分更多.同样在碱性盐胁迫情况下随着盐浓度升高,柳树叶片中的三种渗透调节物质脯氨酸、可溶性糖和可溶性蛋白含量均增加,其中,碱性盐浓度达到200 mmol·L^-1 时植物叶片中脯氨酸质量分数为100.38 μg·g^-1 达到最大值为对照的3.18 倍（P〈0.01）达到极显著性差异,为同浓度中性盐胁迫下的1.57 倍（P〈0.05）.当碱性盐浓度达到150 mmol·L^-1 时,柳树叶片可溶性糖质量分数是2.4 mg·g^-1 为对照的1.86 倍（P〈0.05）达到显著性差异水平,为同等浓度中性盐胁迫下的1.69 倍（P〈0.05）,叶片可溶性蛋白质量分数为7.84 mg·g-1 为对照的1.67 倍（P〈0.05）差异显著,为同等浓度中性盐胁迫下的1.56 倍（P〈0.05）.综上所述,从渗透胁迫角度分析,碱性盐胁迫比中性盐胁迫是两种不同性质的胁迫,并且碱胁迫对柳树造成的危害损伤更大.

Comparative Effects of Salt and Alkali Stresses on Plant Physiology of Willow

At present, soil salinization has become an increasingly serious concern in the world. Large areas of saline alkali land inChina are a heavy constraint to the sustainable development of agriculture. In Northern China, saline alkali soil contains varied typesof salt ion, such as NaCl, Na2SO4, Na2CO3, and NaHCO3. Willow is a very important tree species for afforestation and conservingsoil and water, which is often used to improve ecological environment of saline alkali land, so that it is of significance to study thesalt and alkali stress on the plant physiology of willow. Salinization and alkalization of soil is a widespread environment problem,which could be divided into salt-stress and alkali-stress in terms of the salt characteristics. In fact, the destructive results caused byalkali-stress are more serious than those by salt-stress. A willow cultivar YanLiu 1（Salix psammophila） was used to study the stressconditions of 6 salinities and 6 alkalities simulated by mixing two neutral salts （NaCl and Na2SO4） and two alkaline salts （NaHCO3and Na2CO3） in the molar ratio of 9∶1 respectively with 14 days’ stress. The concentration range of treatment was set between 50and 200 mmol·L-1 for salt and alkali stress. The results showed that the content of leaf water all decreased with increasingconcentration of salt and alkali treatment, and more water was lost from the leaf under the alkali stress; when the alkali salt stressreached the 200mmol/L, the leaf water content was a minimum of 23.8%, which was 32% of the control（P〈0.01）. This reachedextremely significant difference, and more water content was lost than that under the salt stress. Similarly, with increasing alkali saltconcentration and under alkaline salt stress, the proline, soluble sugar and soluble protein in the leaf grew. When the alkali saltconcentration reached to 200 mmol·L^-1, the content of proline was 100.38 μg·g-1 which was 3.18 times of the control（P〈0.01）,reaching extremely significant difference, and was 1.57 times of