干旱与复水对马铃薯块茎膨大期碳氮转运的影响

为探讨干旱及复水对马铃薯块茎膨大期碳氮物质转运影响的生理机制，采用盆栽控水法研究了干旱胁迫、旱后复水过程中马铃薯叶片与块茎中碳水化合物、氮素同化物以及碳氮转运相关酶活性的变化规律。结果表明：干旱胁迫下马铃薯叶片蔗糖磷酸合成酶（SPS）活性显著增强，增幅为54.9%，可溶性糖与蔗糖含量显著增加，分别增加84%、25%；块茎蔗糖与淀粉含量显著下降，分别降低25%、11.8%。复水后叶片可溶性糖含量变化较小，叶片SPS活性仍保持较高水平；块茎中蔗糖合成酶（SS）活性下降6.25%(P＜0.05)，蔗糖与淀粉含量分别增加21.8%、29.8%。干旱胁迫下马铃薯叶片中硝酸还原酶（NR）活性下降49.3%，谷氨酰胺合成酶（GS）活性与对照差异不显著，叶片游离氨基酸与可溶性蛋白质含量分别降低29.4%、38.4%，全氮含量降低13%；块茎中游离氨基酸与可溶性蛋白质含量增加16.8%、270.9%。复水后叶片中NR与GS活性高出对照3.5%、12.1%，叶片游离氨基酸、可溶性蛋白质以及全氮含量仍保持较低水平；块茎游离氨基酸、可溶性蛋白含量较高，增幅分别为24.6%、178.4%，全氮含量增加，与对照差异不显著。说明干旱胁迫显著阻碍了马铃薯碳水化合物与氮素同化物的合成与转运，使马铃薯叶片碳水化合物积累，但干旱促进了氮素向块茎转运，块茎中的碳氮比下降；复水后马铃薯植株能够快速修复干旱胁迫造成的损伤，表现为块茎中淀粉含量增多，块茎碳氮比增加。

Effects of drought stress and rehydration on carbon and nitrogen translocation in potato tuber swelling stage

To explore the physiological mechanism of carbon and nitrogen transport in potato tuber swelling stage to the drought stress and rehydration treatment, using potted plant experiment to study the changes of carbohydrates, nitrogen assimilates, and enzyme activity in potato leaves and tubers during drought stress and rehydration after drought. The results indicated that the activity of sucrose phosphate synthase (SPS) in potato leaves increased by 54.9%, and the contents of soluble sugar and sucrose increased by 84% and 25%, respectively during drought stress; the content of sucrose and starch in tuber decreased by 25% and 11.8%, respectively. After rehydration, the content of soluble sugar in leaves changed slightly, and the activity of SPS in leaves remained high; the sucrose synthase (SS) activity in tubers decreased by 6.25%, sucrose and starch content increased by 21.8% and 29.8%, respectively. Under drought stress, the activity of nitrate reductase (NR) in potato leaves decreased by 49.3%, while the activity of glutamine synthase (GS) was not significantly different from that of control. The content of free amino acid, soluble protein, and total nitrogen in potato leaves decreased by 29.4%, 38.4%, and 13%, respectively. The content of free amino acid and soluble protein in tubers increased by 16.8% and 270.9%, respectively. After rehydration, the activities of NR and GS in leaves were significantly higher than those in the control by 3.5% and 12.1%. The contents of free amino acids, soluble proteins, and total nitrogen in leaves remained low. The contents of free amino acids and soluble proteins in tubers increased by 24.6% and 178.4%, respectively, with no significant difference from those in the control. The results showed that drought stress significantly hindered the synthesis and transport of carbohydrates and nitrogen assimilates in potato leaves, and accumulated carbohydrates in potato leaves, but, drought stress promoted the transport of nitrogen to tubers, and decreased the ratio of carbon to nitrogen in tubers. The potato plants could quickly repair the damage caused by drought stress after rehydration, which showed that starch content in tubers increased and the ratio of carbon to nitrogen in tubers increased.