NaCl胁迫对黄瓜幼苗生长及光合作用特征的影响

以碧春黄瓜为材料,研究了不同浓度NaCl处理对黄瓜幼苗生长、叶片光合作用特性、以及脯氨酸和丙二醛含量的影响。结果表明:10 mmol/L NaCl处理促进了黄瓜幼苗生长,但高浓度NaCl(≥25 mmol/L)处理下,黄瓜幼苗的生物量、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、光系统II电子传递量子效率(ΦPSⅡ)和叶绿素含量均随着浓度增加下降,气孔限制值(LS)、MDA和脯氨酸含量则随着浓度增加而上升;但NaCl处理对光化学效率(Fv/Fm)影响不大。由此说明,低浓度NaCl处理促进了黄瓜幼苗的生长,且NaCl浓度低于100 mmol/L时也未引起黄瓜幼苗叶片光抑制的发生,其光合作用下降的主要原因是叶绿素含量下降以及气孔限制,并且脯氨酸含量的增加也起到增强其抗性的作用。

EFFECTS OF NACL STRESS ON PLANT GROWTH AND PHOTOSYNTHETIC CHARACTERISTICS IN THE CUCUMBER SEEDLING

Cucumber （Cucumis sativus L. Bichun） cultivars were grown in nutrient solutions with five NaCl levels （0,10,25,50,100 mmol＆#183;L-1）for the investigation of plant growth, photosynthetic and chlorophyll fluorescence parameters, and proline and MDA contents in seedling leaves. The results showed that 10 mmol/L NaCl treatment increased plant growth, high-level NaCl （≥25 mmol/L） treatment decreased the plant biomass, net photosynthetic rate （Pn）, stomatal conductance （Gs）, intracellular CO2 （Ci）, quantum yield of PSII （ΦPSII） and chlorophyll content. Stomatal limitation（Ls）, proline and MDA contents increased with NaCl treated concentration. However, photochemical efficiency of PSII （Fv/Fm） was not affected by NaCl treatment. It is concluded that low-level NaCl treatment increased plant growth. However, the decrease of chlorophyll content and stomatal closure lead to the decrease of plant photosynthesis, but photosynthetic structure was not damaged by NaCl stress≤（ 100 mmol/L）. Seedling of cucumber could improve the ability of salt tolerance by increasing proline content.