盐和PEG模拟干旱胁迫对沙米种子萌发及幼苗生长的影响

Effect of salt and drought simulated by PEG on seed germination and seedling growth of Agriophyllum squarrosum

研究不同浓度盐溶液(NaCl、MgSO4、盐渍土壤)和PEG模拟干旱胁迫对沙米种子吸胀、萌发和幼苗生长的影响,并观察胁迫解除后种子的反应。结果表明:随着NaCl、MgSO4和PEG浓度的升高,沙米种子吸胀率先升后降,种子萌发率呈现不同程度降低,盐渍土壤溶液对萌发率没有显著影响;对沙米种子萌发和幼苗生长的胁迫效应是NaCl>MgSO4>盐渍土壤溶液,沙米种子萌发和幼苗生长能耐受的NaCl胁迫临界阈值是18 g/kg,能耐受一定的MgSO4和较高浓度的盐渍土壤胁迫。随着干旱胁迫的加剧,种子萌发率显著降低,幼苗生长受阻,沙米种子萌发和幼苗生长能耐受的渗透势临界阈值为-0.94MPa。各类盐和PEG模拟干旱胁迫解除后,种子仍具有较高的萌发能力,沙米能适应轻度盐渍土壤生境,但盐化程度过高或极端干旱将抑制沙米种子萌发和幼苗建植。破除种子的休眠、土壤保墒、低盐渍化并覆以沙埋(黑暗条件)种植,是保证沙米存活的关键。

Seed germination and seedling growth of Agriophyllum squarrosum following different concentration of the NaCl,MgSO4 and saline soil solution and that of the PEG-6000 solution were studied,and the restoration germination of seeds was observed.The results showed that water uptake rate of seed increased first and then decreased,and germination percentage decreased with increasing NaCl,MgSO4 and PEG concentration,whereas there was insignificant effect of saline soil solution on germination percentage.The stress effects of salt on seed germination and seedling growth were NaClMgSO4saline soil solution.Seed germination and seedling growth of Agriophyllum squarrosum were sensitive to NaCl stress,in which the lowest permeability threshold was 18 g/kg;seed germination could tolerate stress of higher concentration of saline soil solution.In addition,with increasing of PEG concentration,the germination percentage decreased insignificantly,and seedling growth was restricted,in which the lowest permeability threshold was-0.94 MPa.After removing the stress of salts and PEG,seeds displayed higher germination percentage,indicating that there was osmotic regulation during seed germination to adapt saline and drought habitats.The results imply that Agriophyllum squarrosum can survive in mild saline soil habitat, however,high degree of saline or extreme drought will inhibit seed germination and seedling establishment.We suggest that breaking seed dormancy,keeping soil moisture and low salinity,and sand burial（dark condition） cultivation are the key to guarantee the survival of Agriophyllum squarrosum.