外源亚精胺对盐胁迫下甜瓜幼苗光合和超微结构的影响

Effects of exogenous spermidine on photosynthetic characteristics and ultra structure of salt-stressed muskmelon seedlings

为探讨盐胁迫下甜瓜的耐盐机制,在PC板温室采用无土栽培的方式,以黄金蜜为品种,研究了添加不同浓度的亚精胺对NaCl胁迫下甜瓜幼苗的相对电导率、光合色素含量、光合参数、荧光参数及叶绿体超微结构的影响。结果表明,喷施不同浓度外源亚精胺显著缓解了盐胁迫下甜瓜幼苗叶片的电解质渗透率的升高,提高了叶绿素a、b含量和类胡萝卜素含量,保持了较高的光合作用能力;添加外源亚精胺提高了盐胁迫下甜瓜幼苗叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、最大光化学效率(Fv/Fm)、有效光化学效率(Fv'/Fm')、潜在活性(Fv/Fo)、PSⅡ量子产额(фPSⅡ)和光化学猝灭系数(qP),降低了非光化学猝灭系数(NPQ),维持了较高的光系统Ⅱ活性;同时,添加外源亚精胺有利于维护膜系统结构的稳定,缓解盐胁迫对叶绿体结构的破坏,从而保护光合系统。亚精胺浓度为1.0 mmol/L时缓解盐胁迫对甜瓜伤害的效果最好。

The effects of different concentrations of spermidine on relative electric conductivity, photosynthetic pigment content, photosynthetic parameters, fluorescence parameters and ultra structure of soilless-cultured muskmelon seedlings under salt stress were investigated in PC greenhouse. Under NaC1 stress, exogenous spermidine slowed clown the rise of electrolyte leakage, increased photosynthetic pigment contents, net photo synthetic rate （ Pn ）, respiration rate （ Tr ）, stomatal conductance（ Gs ）, intercellar CO2 concentration（ Ci ）, maximum quantum efficiency（ Fv/Fm ） , effective quantum efficiency （ Fv ＇/Fm＇ ）, potential activity （ Fv/Fo ）, quantum yield （ ФPS II ） and photo chemical quenching coefficient （ qP）, and decreased non-photochemical quenching coeffieient（NPQ）, which maintained higher PS II activity of muskmelon seedling leaves. Meanwhile, exogenous spermidine maintained morphology and integrity of membrane system structure, and alleviated the damage of chloroplast caused by NaCl stress, resulting in protecting photosynthetic system of muskmelon. 1.0 mmol/L spermidine was the best for alleviating damage of salt to muskmelon seedling leaves.