碱、旱胁迫对乌拉尔甘草种子萌发及幼苗生理特性的影响

Effect of alkaline and drought stress on seed germination and seedling physiological characteristics of Glycyrrhiza uralensis

摘要:

【目的】 探讨碱、旱胁迫对乌拉尔甘草种子萌发和幼苗生长特性的影响，找出乌拉尔甘草对碱、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生长。【方法】 设置不同浓度的Na₂ CO₃ 、 NaHCO₃ 两种碱性盐和PEG-6000处理乌拉尔甘草种子，测定发芽率、发芽势、发芽指数、活力指数、相对盐害率、萌发抗旱指数、胚根长、胚根宽及4种生理指标。【结果】 30 mmol/L浓度的Na₂ CO₃ 和 Na₂ CO₃ 处理对乌拉尔甘草种子萌发具有一定的促进作用，45 mmol/L浓度2种碱性盐处理开始表现出盐害，所有碱性盐对发芽势均表现为抑制作用。5%浓度的PEG-6000处理对五个种子萌发指标均具有显著的促进作用。Na₂ CO₃ 处理对甘草胚根伸长生长没有显著的促进作用，并会显著抑制胚根宽的生长。Na₂ CO₃处理对甘草胚根伸长生长和胚根宽生长均表现为显著的抑制作用。除14%和17% 浓度的PEG-6000处理外，其他浓度对甘草幼苗的伸长生长均表现为显著的促进作用，所有浓度PEG- 6000处理对甘草幼苗的胚根宽生长均无显著的促进作用，轻微的干旱胁迫有利于甘草种子萌发和幼苗生长。MDA含量与NaHCO₃ 处理下甘草幼苗的胚轴长、胚根宽均具有极显著负相关关系，SOD活性与 PEG-6000处理下甘草幼苗的胚轴长、胚根宽均具有极显著负相关关系。【结论】 5%浓度的PEG-6000 处理有利于乌拉尔甘草种子萌发和幼苗生长，乌拉尔甘草种子萌发和幼苗形态建成对Na₂ CO₃ 、 NaHCO₃ 和PEG-6000胁迫的耐受阈值分别小于45、45 mmol/L和8%。乌拉尔甘草幼苗体内MDA含量可作为评价耐受Na₂ CO₃ 处理的生理指标，SOD活性可作为评价耐受PEG-6000的生理指标。

Abstract:

【Objective】 To investigate the effects of alkali and drought stress on the seed germination and seedling growth characteristics of Glycyrrhiza uralensis，and to determine the tolerance thresholds of Glycyrrhiza uralen- sis to these stresses，in order to facilitate seed germination and seedling growth under adverse conditions.【Method】 Set different concentrations of Na₂ CO₃ ，NaHCO₃ ，and PEG-6000 to treat Glycyrrhiza uralensis seeds，and measure germination rate，germination potential，germination index，vigor index，relative salt damage rate，germination drought resistance index radicle length，hypocotyl width，and four physiological indicators.【Result】 Treatment with Na₂ CO₃ and NaHCO3 at a concentration of 30 mmol/L has a certain promoting effect on the germination of Glycyrrhiza ura- lensis seeds. At a concentration of 45 mmol/L，the treatment with both alkaline salts began to show salt damage，and all alkaline salts inhibited germination potential. Treatment with 5% PEG-6000 significantly improvedall five seed germination indicators. Na₂ CO₃ treatment did not significantly promote the elongation growth of Glycyrrhiza uralen- sis embryo roots and significantly inhibited hypocotyl width. NaHCO₃ treatment showed significant inhibitory effects on both the elongation and width growth of Glycyrrhiza uralensis embryo roots. Except for treatments with 14% and 17% concentrations of PEG-6000，all other concentrations significantly promoted the elongation of Glycyrrhiza ura- lensis seedlings. However，noconcentration of PEG-6000 significantly promotedthe width growth of Glycyrrhiza ura- lensis seedlings. Mild drought stress positively affected Glycyrrhiza uralensis seed germination and seedling growth. The MDA content （malondialdehyde） is showed a significant negative correlation with hypocotyl length and embryo roots width of Glycyrrhiza uralensis seedlings under Na₂ CO₃ treatment，while SOD （superoxide dismutase） activity was negatively correlated with the length of hypocotyl and the width of embryo roots of Glycyrrhiza uralensis seedlings under PEG-6000 treatment.【Conclusion】 A 5% concentration of PEG-6000 is beneficial for seed germination and seedling growth in Glycyrrhiza uralensis. The tolerance thresholds of Glycyrrhiza uralensis seed germination and seedling morphogenesis under Na₂ CO₃ ，NaHCO₃，and PEG-6000 stress are less than 45 mmol/L，45 mmol/L，and 8%，respectively. The MDA content in Glycyrrhiza uralensis seedlings can be used as a physiological indicator to evaluate the tolerance to Na₂ CO₃ treatment，while SOD activity serves as a physiological indicator for PEG-6000 tolerance.