荆芥幼苗对盐胁迫的生理响应

Physiological Responses of Schizonepeta tenuifolia Briq. Seedlings to Salt Stress

为探究盐胁迫对荆芥幼苗生理特性的影响,采用盆栽砂培试验,研究不同浓度盐胁迫(0、25、50、75和100 mmol·L^(-1) NaCl)下荆芥幼苗生长、质膜稳定性、渗透调节、抗氧化酶系统、离子吸收和分配的变化。结果表明,随着盐浓度的增加,荆芥盐害指数逐渐升高,幼苗株高增加速率和比叶面积均逐渐降低,单株干重和叶绿素含量均呈先增加后减少的趋势,且均在25 mmol·L^(-1) NaCl处理下达到最大;叶片中丙二醛(MDA)含量和电解质渗漏率均显著增加;可溶性蛋白和脯氨酸含量均呈先增加后减少趋势,且分别在50和75 mmol·L^(-1) NaCl处理下达到最大,而可溶性糖含量则不断上升;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性均呈先上升后下降的趋势,在25 mmol·L^(-1) NaCl处理下达到最大,而过氧化物酶(POD)活性则持续下降。盐胁迫下,荆芥的根、茎、叶大量积累Na^+,但主要集中在地上部分,同时各部位K^+、Ca^(2+)含量及K^+/Na^+、Ca^(2+)/Na^+值均显著下降。综上,荆芥幼苗对盐胁迫极为敏感,但对低浓度的盐胁迫(25 mmol·L^(-1) NaCl)具有一定的耐受性。本研究结果为荆芥的规范化栽培和抗逆驯化研究奠定了理论基础。

In order to study the effects of salt stress on the physiology of Schizonepeta tenuifolia Briq., seedlings were transplanted into pots with quartz sands and then subjected to 0, 25, 50, 75, 100 mmol·L^-1 NaCl. Changes of the growth, membrane stability, osmotic adjustment, antioxidant enzyme system and ion absorption and distribution of S. tenuifolia seedlings were then studied. The results showed that as salt concentration increased, salt injury index of S. tenuifolia seedlings rose gradually, increasing rate of plant height and specific leaf area decreased, but the dry weight and chlorophyll content increased initially and then reduced, in which both indexes were the highest at 25 mmol·L^-1 NaCl. Malondialdehyde content and electrolyte leakage percentage were induced to increase significantly by salt treatment. Contents of soluble protein and proline increased and then decreased as concentration rose further, in which they were the highest at 50 and 75 mmol·L^-1 NaCl, respectively, while a continuously rising trend in soluble sugar content was shown;the activities of superoxide dismutase(SOD) and catalase(CAT) were enhanced at 25 mmol·L^-1 NaCl but then inhibited at higher concentrations, while that of peroxidase(POD) declined continuously. Under salt stress, accumulation of Na+ in root, stem and leaf was enhanced, especially in the aerial parts, but K^+ and Ca^2+ content, K^+/Na^+, Ca^2+/Na^+ decreased remarkably. In summary, S. tenuifolia seedlings were sensitive to salt stress, but could be tolerant of mild salt stress(25 mmol·L^-1 NaCl). This study provides a theoretical basis for the standardized cultivation, stress resistance and domestication research ofS. tenuifolia.