干旱胁迫对黄瓜幼苗叶绿素含量和光合特性的影响

为了研究干旱胁迫对黄瓜幼苗叶绿素含量和光合特性的影响，以黄瓜幼苗为试材，采用盆栽试验，研究PEG模拟干旱对黄瓜幼苗叶绿素含量和光合特性的影响。结果表明，随着干旱胁迫浓度的提高和胁迫时间的延长，黄瓜幼苗的叶绿素含量、气体交换参数和叶绿素荧光的降幅增大。干旱胁迫1天，5%PEG与对照(CK)之间叶绿素总含量差异不显著，10%、20%PEG处理叶绿素总含量较CK分别降低5.2%、16.3%，干旱胁迫2天，5%、10%、20%PEG处理叶绿素总含量较CK分别降低8.6%、12.0%、37.2%。干旱胁迫1天，CK和5%PEG处理之间Pn、E、Gs差异不显著，CK、5%、10%、20%PEG处理之间Ci差异显著，干旱胁迫2天，CK、5%、10%、20%PEG处理之间Pn、E、Ci差异显著。干旱胁迫2天，5%、10%、20%PEG处理的YIELD较CK分别降低2.4%、8.7%和13.2%，ETR较CK分别降低8.5%、17.6%和40.2%，qP较CK分别降低4.6%、9.3%和12.7%，qN较CK分别降低8.7%、18.1%和66.6%。

Effects of Drought Stress on Chlorophyll Contents and Photosynthetic Characteristics of Cucumber Seedlings

To study the effects of drought stress on chlorophyll contents and photosynthetic characteristics of cucumber seedlings,the author carried pot experiments by using cucumber seedlings as materials to research the effects of PEG imitation drought stress on them.The results showed that the decreasing amplitude of chlorophyll contents,gas exchange parameters and chlorophyll fluorescence characteristics of cucumber seedlings increased by improving drought stress concentration and prolonging stress time.The different of total chlorophyll content between compare（CK） and 5% PEG was indifferent,but their of 10% and 20% PEG treatment decreased by 5.2% and 16.3% respectively than CK at drought stress first day.The total chlorophyll content of 5%,10% and 20% PEG treatment reduced by 8.6%,12.0% and 37.2% respectively than CK at drought stress second day.The different of net photosynthetic rate（Pn）,transpiration rate（E）,stomatal conductance（Gs） between compare（CK） and 5% PEG was indifferent,while the different of intercellular concentrations of carbon dioxide（Ci） among treatments of CK,5%,10% and 20% PEG was different at drought stress first day,but the different of Pn,E and Ci among treatments of CK,5%,10% and 20% PEG was different at drought stress second day.At drought stress second day,the effective photochemical efficiency of PSII（YIELD） of 5%,10% and 20% PEG treatment reduced by 2.4%,8.7% and 13.2% respectively than CK,the photosynthetic electron transfer rate（ETR） reduced by 4.6%,9.3% and 12.7%,while non-photochemical quenching of fluorescence but increased（qN） reduced by 8.7%,18.1% and 66.6%.