NaCl胁迫对超大甜椒种子萌发及幼苗生长的影响

Seed Germination and Seedling Growth of Sweet Pepper under NaCl Stress

以超大甜椒种子和幼苗为材料,采用水培法研究低、中、高浓度(50、150、250 mmol·L-1)NaCl胁迫对其种子萌发和幼苗生长的影响.结果显示:(1)低浓度NaCl处理促进种子萌发,而中、高浓度NaCl处理抑制种子萌发;NaCl处理第18天时,高浓度NaCl处理植株全部死亡,其余各处理植株苗高、叶面积、地上部鲜重和干重均随处理浓度升高而下降,但低浓度NaCl能刺激超大甜椒的根系生长.(2)低、中浓度NaCl处理时,植株叶绿素含量未受到大的影响,类胡萝卜素含量却随胁迫时间延长微量升高;在盐胁迫7 d的周期内,低、中浓度NaCl处理植株MDA含量、SOD活性和可溶性糖含量均随浓度升高及时间延长显著增加,脯氨酸含量在低浓度下变化不明显而中浓度下显著升高;在高浓度NaCl处理3 d中,MDA含量急剧升高,SOD活性先升高后下降,脯氨酸和可溶性糖含量显著增加.研究发现,NaCl胁迫浓度越高对超大甜椒种子萌发和幼苗生长的抑制效应越明显;低中浓度NaCl处理幼苗能通过自身的抗氧化酶清除系统和渗透调节物质来抵抗胁迫引起伤害,类胡萝卜素可能也有一定的抗胁迫作用,而高浓度NaCl处理增加了膜脂过氧化程度,严重影响了活性氧和渗透调节物质的正常代谢.

The effects of NaCl stress on germination and growth of sweet pepper were investigated by water culture method.The results showed：the seed germination was promoted under the treatment of 50 mmol·L^-1 NaCl.While the seed germination was inhibited when the concentrations of NaCl were higher than 50 mmol·L^-1.At the 18th day after NaCl stress,except that 250 mmol·L^-1 NaCl stress caused the seedling＇s death,the height,leaf area,fresh weight and dry weight of seedlings decreased under 50 mmol·L^-1 and 150 mmol·L^-1 NaCl stress relative to the controls.However,the root growth was promoted by 50 mmol·L^-1 NaCl stress.The content of chlorophyll was mild changed when NaCl concentration ≤150 mmol·L^-1 NaCl,as well as carotenoid to improve the capacity of sweet pepper to salt stress.During the 7 d NaCl stress under 50 and 150 mmol·L^-1 NaCl stress,the content of MDA,activity of SOD and the content of soluble sugar significantly increased with higher NaCl concentration,and the contents of proline significantly increased except for 50 mmol·L^-1 NaCl.Under 250 mmol·L^-1 NaCl stress（only 3 d）,the contents of MDA,proline and soluble sugar significantly increased.The activities of SOD increased under low concentration and declined under higher concentration.These results indicated：the higher NaCl concentration,the more obvious inhibition.Under 50 mmol·L^-1 and 150 mmol·L^-1 NaCl stress,SOD was important in scavenging active oxygen species,and proline and soluble sugar were main osmoregulation substances,as well as carotenoid played a role.That membrane lipid peroxidation was serious under 250 mmol·L^-1 NaCl stress suggested that normal metabolism of reactive oxygen species and osmoticum were disturbed under such stress.