铝胁迫对西瓜幼苗光合及叶绿素荧光特性的影响

摘要

In the study,two watermelon varieties Zaomiwang (ZM)and Zaochunhongyu (HY)seedlings were used as materials to investigate the effect of aluminum(Al)on growth and physiological characteristics under differ-ent Al concentrations (0,250,500,1 000,1 500 μmol /L)treatment in order to find out the impact of aluminum stress on photosynthetic characteristics of watermelon.Changes in root length and biomass results showed that ZM was more sensitive to Al than HY.Effects on photosynthesis for the followed three aspects:Chlorophyll content of HY increased in the Al treatment.Chlorophyll content of ZM was higher than contrast only when Al concentration was 250 μmol /L.Chlorophyll a /b content of HY intended to decrease as long as the Al concentration increased;In the Al treatment,when concentration lower than 500 μmol /L the stomatal conductance (Gs),intercellular CO2 con-centration (Ci),net photosynthetic rate (Pn)and transpiration rate (Tr)of ZM was effected more obviously than those of HY.When Al concentration was above 1 000 μmol /L,the value of these four items all intended to fall down;Changes of Chlorophyll fluorescence in these two watermelon variety in the Al treatment (without Al3 + =250μmol /L concentration)were as follow:original fluorescence (Fo),maximum fluorescence (Fm),potential photo-chemical efficiency (Fv /Fo),photochemical maximum efficiency of PS Ⅱ (Fv /Fm)and the ability of leaves to transform energy Y(Ⅱ)decreased,while non-photochemical quenching (NPQ)increased,and leaves maintained a high actinic light energy distribution by adjusting the heat dissipation;In addition,photochemical quenching coeffi-cient (qP)and electron transport rate (ETR)decreased.At Al3 +≤250 μmol /L concentration,the four parameters of HY:Fo,Fm,Fv /Fo,Fv /Fm was more stable;with aluminum concentration increases,the electron transfer rate was less affected,NPQ relatively constant,that is able to maintain a constant light protection.%为了探明铝胁迫对西瓜光合特性的影响。以西瓜品种早蜜王（ZM）、早春红玉（HY）为材料，研究不同浓度铝（0，250，500，1000，1500μmol ／L）处理下西瓜幼苗生长指标、叶绿素含量、光合特性及叶绿素荧光参数的变化。随铝浓度升高，铝处理对两西瓜品种幼苗根长及生物量的影响基本都表现为“先促后抑”，且对 ZM的抑制作用较 HY 更明显。对光合作用的影响主要有以下3个方面：铝处理下 HY 叶绿素含量均高于对照，ZM 叶绿素含量仅在低浓度（250μmol ／L）铝处理下高于对照；HY 叶绿素 a ／b 随铝浓度升高呈下降趋势；Al3＋≤500μmol ／L 的铝处理下，ZM 气孔导度、胞间 CO2浓度、净光合速率、蒸腾速率受影响程度较 HY 明显，在 Al3＋≥1000μmol ／L 处理下，HY、ZM的4个参数均呈降低趋势。在大于250μmol ／L 的铝处理下，两西瓜品种在铝胁迫下荧光参数变化表现为：初始荧光（Fo）、最大荧光（Fm）、潜在光化学活性（Fv ／Fo）、最大光化学效率（Fv ／Fm）和实际量子产量 Y（Ⅱ）下降，非光化学猝灭（NPQ）上升，光化学猝灭（qP）与 PSⅡ电子传递速率（ETR）降低。HY 较 ZM 耐铝在荧光参数变化上表现为：低浓度胁迫（250μmol ／L）下，Fo、Fm、Fv ／Fo、Fv ／Fm 更加稳定；电子传递速率受铝处理影响较小，非光化学猝灭（NPQ）在不同浓度铝处理下较为恒定，即能够维持恒定的光保护能力。