盐敏感甜瓜幼苗生长及生理特性对盐胁迫的响应

Response on Growth,Photosynthetic Performance in Salt-sensitive Melon Seedling Under Salinity Stress

以盐敏感甜瓜品种‘羊角酥’为试验材料,利用不同浓度NaCl(12.5、25.0、37.5、50.0、62.5、75.0 mmol·L-1)进行梯度胁迫处理,探讨盐胁迫对甜瓜生长发育、光合作用、叶绿素荧光、脂质过氧化和抗氧化酶活性的影响,旨在为甜瓜盐胁迫的适应性机制提供参考依据。结果表明:不同浓度NaCl(12.5~75.0 mmol·L-1)处理显著降低株高、叶面积,对茎粗无显著影响;与对照相比,盐胁迫下甜瓜幼苗气孔导度(Gs)和蒸腾速率(Tr)显著降低;随着NaCl浓度增加,丙二醛(MDA)含量显著增加;在62.5、75.0 mmol·L-1浓度下,叶绿素(Chl)含量和电子传递速率(ETR)显著降低,而其它叶绿素荧光参数,如开放PSⅡ中心的激发捕获效率(Fv′/Fm′)、光化学淬灭系数(qP)和非光化学淬灭系数(qN)则略有降低,但差异不显著;盐胁迫下甜瓜叶片中超氧化物歧化酶(SOD)和过氧化物酶(POD)活性的变化趋势与盐浓度无相关性。盐敏感甜瓜品种受低盐浓度(<75.0mmol·L-1)的影响主要表现为幼苗生长势和光合效率的降低。此外,盐浓度过高时(75.0 mmol·L-1),由盐胁迫引起的脂质过氧化很难被酶抗氧化剂完全抵消。

The objective of this study was to investigate the effect of salinity stress on the growth,photosynthesis,chlorophyll fluorescence,lipid peroxidation and antioxidative enzyme activity of salt-sensitive melon(Cucumis melo L.)cultivar,‘Horn Crisp’melon.The results showed that different NaCl concentrations(from 12.5 mmol·L-1 to 75.0 mmol·L-1)significantly reduced the growth attributes including plant height and leaf area,but no significant change on stalk diameter.Salt-stressed melon seedling demonstrated a significant decrease in stomatal gsuctance(Gs)and transpiration rate(Tr)compared to control.Meanwhile,a significant increase in malondialdehye(MDA)was exhibited with increasing of NaCl concentration.Under 62.5 mmol·L-1 and 75.0 mmol·L-1 NaCl,chlorophyll(Chl)content and electron transport rate(ETR)had significantly reduced,while other chlorophyll fluorescence parameters,such as efficiency of excitation capture of open PSⅡcenters(Fv′/Fm′),photochemical quenching(qP)and non-photochemical quenching(qN)emerged a slight reduction but no significance.It was noteworthy that the change trends of antioxidant enzymes superoxide dismutase(SOD)and peroxidase(POD)activities in melon seedling under salt stress revealed no correlation with salt concentration.These results demonstrated that salt-sensitive melon variety was affected by a low saline concentration range(<75.0 mmol·L-1),melon seedling respond to salinity stress rely on reducing growth potential and photosynthetic efficiency.Moreover,lipid peroxidation induced by salt stress was difficult to offset completely by enzymatic antioxidants when NaCl concentration exceeded a certain range.