土壤紧实胁迫对黄瓜碳水化合物代谢的影响

用容重分别为1.25 g/cm3(疏松土壤,即对照)和1.55 g/cm3(紧实土壤)的土壤进行盆栽试验,研究了土壤紧实胁迫对“津春4号”黄瓜(Cucumis sativusL.)不同生育期叶片和根系碳水化合物代谢的影响,以探讨土壤紧实胁迫对黄瓜生长产生影响的机理.结果表明,在土壤紧实胁迫条件下,黄瓜不同生育期叶片的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著下降,胞间CO2浓度(Ci)显著升高,光合作用受到抑制；叶片中蔗糖磷酸合成酶(SPS)活性显著降低,蔗糖合成酶(SS)、酸性转化酶(AI)和中性转化酶(NI)活性显著增强,蔗糖、葡萄糖、果糖和淀粉含量显著增加,蔗糖的合成与输出受到抑制；不同生育期根系SPS、AI和NI活性显著下降,而SS活性显著增强,蔗糖、葡萄糖和果糖含量显著增加,淀粉含量基本不变.这表明,土壤紧实胁迫抑制了黄瓜叶片中同化物的合成和输出,降低了碳水化合物向根系中的输入,阻碍了根系对碳水化合物的利用,使植株矮小,产量下降.

Effects of soil compaction stress on carbohydrate metabolism of cucumber

In this work, Soils with 1.25 g/cm³ (loose soil, CK) and 1.55 g/cm³ (compacted soil) bulk density were experimented on growing cucumber (Cucumis sativus L.) plants in pots. Effects of soil compaction stress on carbohydrate metabolism of leaves and roots of cucumber cultivar, Jinchun 4, at different growth and development stages were studied for discussing influence mechanism of soil compaction stress on cucumber growth. The results show that under the soil compaction stress, the net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of cucumber leaves are decreased significantly, while the intercellular CO2 concentration (Ci) is increased markedly at different growth and development stages. Thereby, photosynthesis is hampered. The activity of sucrose phosphate synthase (SPS) of cucumber leaves is decreased significantly, while the sucrose synthase (SS), acid invertase (AI) and alkaline invertase (NI) activities are promoted remarkably in the compacted soil treatment. Furthermore, the contents of sucrose, glucose, fructose and starch are also increased markedly, and the synthesis and export of sucrose in leaves are restrained. In roots, the activities of SPS, AI and NI are decreased significantly, while the SS activity is obviously promoted. Moreover, the contents of sucrose, glucose and fructose are also increased strikingly, while the starch content is almost constant. These results indicate that under the soil compaction stress, the synthesis and export of photosynthate of source leaves are remarkably constrained, meanwhile, the import and utilization of carbohydrate of roots are reduced. As a result, the inhibition for plant growth and yield formation occur.