盐、干旱胁迫对沙蒿种子萌发与幼苗生理特性的影响

Effect of salt and drought stresses on seed germina⁃ tion and seedling physiological characteristics of Artemisia desertorum

摘要:

【目的】探明盐、干旱胁迫对沙蒿（Artemisia desertorum）种子萌发与幼苗生理生化特性的影响，找到沙蒿对盐、干旱胁迫的耐受阈值，以利于逆境条件下保障种子萌发和幼苗的生长。【方法】以沙蒿种子为材料，在 25 ℃下对其进行不同浓度 NaCl （50、100、150、200 和 300 mmol/L）和 PEG-6000 溶液 （5、10、15、20 和 25%）胁迫处理，测定种子萌发率、幼苗生物量、渗透调节物质含量以及抗氧化酶活性。 【结果】低浓度 NaCl（＜50 mmol/L）和 PEG-6000（＜15%）对种子萌发和幼苗生长（根长、株高和鲜重） 抑制不显著或具有一定的促进效果，而高浓度（＞50 mmol/L 和＞15%）则具有显著的抑制作用。防御响应的渗透调节物质（可溶性糖、蛋白质和脯氨酸）含量和活性氧清除酶（SOD、POD、CAT 和 APX）活性在低浓度胁迫范围内逐渐增加，在极端胁迫浓度范围内显著下降；膜脂过氧化最终产物丙二醛的含量持续增加。【结论】沙蒿种子萌发与幼苗形态建成对 NaCl 和 PEG-6000 胁迫的耐受阈值分别小于 50 mmol/L 和 15%。

Abstract:

【Objective】 To investigate the effect of salt and drought stresses on seed germination and seedling physiological characteristics of Artemisia desertorum，as well as find out their critical points for stress tolerance，this will be favor of ensuring seed germination and seedling growth under adverse conditions.【Method】 The experiments were conducted on germination rate，seedling biomass，the content of osmotic adjustment substances and antioxidant enzyme activities in A. desertorum at different treatments with NaCl （50，100，150，200 and 300 mmol/L） and PEG- 6000（v/v，5%，10%，15%，20% and 25%） at 25 ℃ .【Result】 The germination rate and seedling growth （root length，plant height and fresh weight） was slightly inhibited or improved at lower concentrations of NaCl （＜50 mmol/L） and PEG-6000（＜15%），while they were significantly inhibited at higher concentrations. The content of os- motic adjustment substances （soluble sugar，protein and proline） and the activities of oxygen scavenging enzymes （SOD，POD，CAT and APX） exhibited a gradual increase with lower concentrations of NaCl and PEG-6000，while they decreased significantly with higher concentrations. The content of malondialdehyde that is an end product of membrane lipid peroxidation increased in response to the NaCl and PEG - 6000 stresses.【Conclusion】 The critical concentrations of NaCl and PEG-6000 for seed germination and seedling morphogenesis of A. desertorum were less than 50 mmol/L and 15%，respectively. These findings provide useful references for the improvement of the seed ger- mination rate and seedling survival rate. The results have revealed the adaptation mechanism to salt and drought stresses which helps with protecting the germplasm resource of A. desertorum.