中文摘要：

以小白菜品种‘寒笑’为实验材料,采用营养液栽培法,研究了80 mmol/L硝酸钙胁迫下,叶面喷施0.5mmol/L亚精胺（Spd）对小白菜生长、光合作用及其品质的影响。结果表明,（1）Ca（NO3）2胁迫显著抑制了小白菜幼苗生长,使植株的株高、根长、叶面积、根体积、干鲜重显著降低,而叶面喷施Spd可有效缓解胁迫对生长的抑制。（2）Ca（NO3）2胁迫处理植株叶绿素含量比正常营养液培养处理（对照）显著下降了54.72%,而叶面喷施Spd可以有效缓解Ca（NO3）2胁迫对光合色素含量的抑制,并且使植株类胡萝卜素含量比Ca（NO3）2胁迫处理显著提高53.33%。（3）Ca（NO3）2胁迫显著降低了小白菜幼苗光合作用效率,使植株净光合速率（Pn）比对照显著下降34.45%,而叶面喷施Spd可以有效缓解Ca（NO3）2胁迫对Pn的抑制,使植株Pn比Ca（NO3）2胁迫处理显著提高28.11%。（4）Ca（NO3）2胁迫显著降低了小白菜幼苗品质,其植株维生素C、可溶性糖、可溶性蛋白含量比对照显著降低,同期有机酸、硝酸盐含量却比对照显著升高,而叶面喷施Spd可以显著改善上述小白菜营养指标。研究认为,外源亚精胺可有效缓解Ca（NO3）2胁迫对小白菜生长和光合作用的抑制,提高Ca（NO3）2胁迫环境条件下小白菜的品质。

英文摘要：

‘Hanxiao＇was selected as material to study the effects of 0.5 mmol/L exogenous spermidine（Spd）on the growth and quality of pakchio seedlings under 80mmol/L calcium nitrate stress by hydroponic culture.The results showed that：（1）The stress of 80 mmol/L Ca（NO3）2 significantly reduced plant growth,plant height,root length,leaf area,root volume,fresh and dry weight.Spraying 0.5mmol/L Spd on leaf significantly promoted the growth of seedlings.（2）The stress of 80mmol/L Ca（NO3）2 significantly reduced the contcents of photosynthetic pigments.Compared with CK treatment,chlorophyll content in seedlings declined 54.72% with Ca（NO3）2 treatment.Spraying 0.5mmol/L Spd on leaf significantly promoted the contents of photosynthetic pigments in seedlings.Compared with Ca（NO3）2 treatment,carotenoid cont-cent in seedlings increased 53.33% with NS treatment[Ca（NO3）2＋Spd].（3）The stress of 80 mmol/L Ca（NO3）2significantly reduced photosynthesis.Compared with CK treatment,Pn of seedlings declined34.45% with Ca（NO3）2 treatment.Spraying 0.5 mmol/L Spd on leaf significantly promoted Pnof seedlings.Compared with Ca（NO3）2 treatment,Pnof seedlings increased 28.11% with NS treatment.（4）The stress of 80mmol/L Ca（NO3）2 significantly reduced quality.Compared with CK treatment,the contents of vitamin C,soluble sugar and soluble protein of seedlings significantly declined,nitrate and organic acid significantly increased with Ca（NO3）2 treatment.Spraying 0.5 mmol/L Spd on leaf significantly promoted seedlings above-mentioned nutritive index.These results indicated that exogenous Spd significantly promoted the growth,photosynthesis and improved the quality of pakchoi seedlings under calcium nitrate stress.