NaCl胁迫对甜瓜叶片气体交换和叶绿素荧光特性的影响

以两个变种甜瓜幼苗为材料,在人工控制条件下研究了NaCl胁迫对甜瓜叶片气体交换和叶绿素荧光特性的影响。结果表明,盐胁迫降低了甜瓜叶片光合色素含量、净光合速率、蒸腾速率、气孔导度和PSⅡ最大光化学效率、PSⅡ潜在活性、PSⅡ电子传递量子效率和光化学猝灭系数,使非光化学猝灭系数升高。在≤50 mmol·L-1 NaCl胁迫下,甜瓜叶片光合速率降低主要由气孔因素引起,而在NaCl浓度≥100 mmol·L-1条件下则以非气孔限制因素为主。

Effect of NaCl Stress on Gas Exchange and Chlorophyll Fluorescence of Cucumis melo Seedlings

Muskmelon seedlings, cv. Huanghemi and Baishami, were employed to study the effect of NaCl stress on photosynthesis, chlorophyll contents and chlorophyll fluorescence parameters. The results indicated that net photosynthetic rate ( Pn ), transpiration rate ( Tr ), stomatal conductance ( Gs ), maximum photochemical efficiency of PSⅡ( Fv / Fm ), potential activity of PSⅡ ( Fv / Fo ), quantum efficiency of non-cyclic electron transport of PSⅡ(ΦPSⅡ) and photochemical quenching( qP ) decreased, while non-photochemical quenching( qN ) increased under NaCl stress, especially under high concentrations in both varieties. When NaCl concentration was ≤50 mmol·L~(-1), intercellular CO_2concentration ( Ci ) decreased, while stomatal limitation value ( Ls ) increased. In contrast, Ci increased but Ls decreased when NaCl concentration was ≥100 mmol·L~(-1). The results indicated that photosynthesis of muskmelon was limited by stomatal factor under slight NaCl stress, but mainly by non-stomatal factors under severe NaCl stress.