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干旱胁迫下外源钙对桂西北喀斯特地区青冈栎种子萌发的影响
邓 平1, 吴 敏2, 赵 英,等2
1.玉林师范学院 桂东南珍稀经济物种保护利用重点实验室培育基地,西北农林科技大学 林学院;2.玉林师范学院 桂东南珍稀经济物种保护利用重点实验室培育基地
摘要:
【目的】研究喀斯特地区土壤中交换性钙离子对干旱胁迫条件下青冈栎种子萌发特性以及有机渗透调节物质、抗氧化酶活性的影响,探明青冈栎种子在干旱胁迫条件下萌发所需的最佳外源钙浓度,为在喀斯特地区进行青冈栎的推广造林、植被恢复与重建提供理论参考。【方法】以大小相近、饱满的青冈栎种子为供试对象,采用双因素设计试验,即干旱胁迫和添加CaCl2 2个因素,其中干旱胁迫共设6个水平,环境水势分别为0,-0.1,-0.3,-0.6,-0.9,-1.2 MPa,对应PEG-6000质量浓度分别为0,50,125,200,250和300 g/L;添加CaCl2共设4个水平,对应CaCl2浓度分别为0,10,20,30 mmol/L,进行完全组合设计,共设24个处理,测定不同处理青冈栎种子萌发参数(萌发率、萌发势、萌发指数和活性指数),丙二醛(MDA)和有机渗透调节物质(可溶性糖、可溶性蛋白、游离脯氨酸)含量以及抗氧化酶(SOD、POD、CAT、APX)活性,用隶属函数法对不同处理青冈栎种子的耐旱性进行综合评价。【结果】(1)外源CaCl2、干旱胁迫及其交互作用对青冈栎种子各萌发参数均有极显著影响。在环境水势为-0.3 MPa、CaCl2浓度为10 mmol/L 组合处理下,各萌发参数值均达到最大;在环境水势为-1.2 MPa、CaCl2浓度为30 mmol/L组合处理下,种子停止萌发。(2)外源CaCl2、干旱胁迫及其交互作用对青冈栎种子萌发生理生化参数及抗氧化酶活性均有显著影响。同一外源CaCl2下,MDA含量随干旱胁迫的加剧而显著增加;在同一环境水势下,随着CaCl2浓度的增加,MDA含量呈先下降后上升的趋势。当环境水势为0 MPa时,随着CaCl2浓度的增大,有机渗透调节物质含量总体呈增加趋势;当环境水势为-0.1~-1.2 MPa时,在同一环境水势下,随CaCl2浓度的增大,有机渗透调节物质含量均呈先增加后减少的趋势。当环境水势为0 MPa时,与无钙组相比,CaCl2处理组的SOD活性无明显变化,而POD、CAT、APX活性则明显升高;当环境水势为-0.1~-1.2 MPa时,在同一环境水势下,随CaCl2浓度的增大,抗氧化酶(SOD、POD、CAT、APX)活性均呈现先升高后降低的趋势。(3)利用隶属函数法计算可知,当环境水势为-0.3 MPa、CaCl2浓度为10 mmol/L时,对应隶属函数加权平均值最高,青冈栎种子的耐旱性得以有效提高。【结论】在喀斯特地区利用青冈栎种子播种育苗时,播种前用10 mmol/L CaCl2浸种可以提高种子的耐旱性。
关键词:  青冈栎  种子萌发  干旱胁迫  外源钙  喀斯特地区
DOI:
分类号:
基金项目:国家自然科学基金项目(31560124,31800205);广西自然科学基金项目(2015GXNSFBA13913);广西高校科学技术研究项目(KY2015YB246,2017KY0539);大学生创新创业训练计划项目(20170606128,20170606246)
Effects of exogenous calcium on seed germination of Cyclobalanopsis glauca in Karst area of Northwestern Guangxi under draught stress
DENG Ping,WU Min,ZHAO Ying,et al
Abstract:
【Objective】The effects of exchangeable calcium ions in soils of Karst area on seed germination characteristics,organic osmotic adjustment substances and antioxidant enzyme activities of Cyclobalanopsis glauca under drought stress were studied,and the optimal exogenous Ca2+ concentration for germination of Cyclobalanopsis glauca seeds was investigated.The research would provide reference for the promotion of afforestation,vegetation restoration and reconstruction in Karst areas.【Method】The Cyclobalanopsis glauca seeds with similar size and fullness were selected for two factor experiment including drought stress and addition of CaCl2.Six environmental water potentials (0,-0.1,-0.3,-0.6,-0.9 and -1.2 MPa) were simulated using different concentrations of polyethylene glycol (PEG)-6000 (0,50,125,200,250 and 300 g/L),and exogenous calcium with four different concentrations (0,10,20 and 30 mmol/L CaCl2) was installed to simulate calcium rich soil environment.A total of 24 treatments were conducted to determine germination characteristics (germination rate,germination potential,germination index and vigor index),contents of malondialdehyde (MDA) and organic osmotic adjustment substances (free proline,soluble sugar and soluble protein) and activities of antioxidant enzymes (superoxide dismutase (SOD),peroxidase (POD),catalase (CAT),and ascorbate peroxidase (APX)).Subordinate function analysis was also carried out for comprehensive evaluation of drought tolerance of Cyclobalanopsis glauca seeds in different treatments.【Result】(1) Exogenous CaCl2,drought stress and their interactions had significant effects on germination parameters of Cyclobalanopsis glauca seeds.All the germination parameters reached maximum when environmental water potential was -0.3 MPa and CaCl2 concentration was 10 mmol/L.Seeds stopped germination when the environmental water potential was -1.2 MPa and CaCl2 concentration was 30 mmol/L.(2) Exogenous CaCl2,drought stress and their interactions had significant effects on physiology and biochemistry parameters and antioxidant protective enzymes of Cyclobalanopsis glauca seeds.MDA content increased significantly with increase of drought stress under same exogenous CaCl2.MDA content decreased first and then increased with the increase of CaCl2 concentration under same environmental water potential.When environmental water potential was 0 MPa,the contents of organic osmotic adjustment substances tended to increase with the increase of CaCl2 concentration.When environmental water potential was -0.1--1.2 MPa,the contents of osmotic adjustment substances increased first and then decreased with the increase of CaCl2 concentration under same environmental water potential.When environmental water potential was 0 MPa,POD,CAT and APX activities in CaCl2 treatment groups increased significantly compared with calcium free groups,while there was no significant change in SOD activity.When environmental water potential was -0.1--1.2 MPa,the activities of antioxidant protective enzymes (SOD,POD,CAT and APX) increased first and then decreased with the increase of CaCl2 concentration under same environmental water potential.(3) The result of subordinate function analysis showed that the weighted average of subordinate function was the highest when environmental water potential was -0.3 MPa and CaCl2 concentration was 10 mmol/L,and the drought tolerance of Cyclobalanopsis glauca seeds was effectively improved.【Conclusion】Soaking seeds with 10 mmol/L CaCl2 before sowing can increase drought tolerance of Cyclobalanopsis glauca seeds in Karst areas.
Key words:  Cyclobalanopsis glauca  seed germination  drought stress  exogenous Ca2+  Karst area

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