烯效唑对低温胁迫下秋茄幼苗光合作用与抗氧化系统的影响

Effect of uniconazole on photosynthesis and antioxidant system in Kandelia obovata seedlings under low temperature stress

以秋茄(Kandelia obovata)幼苗为材料,研究了喷洒0.1 mmol·L^(-1)烯效唑对植株叶片光合作用、叶绿素、荧光特性、抗氧化系统及细胞膜透性的影响。结果表明:烯效唑能显著提高低温胁迫下秋茄幼苗叶片净光合速率(P_n)、气孔导度(G_s)、叶绿素含量和叶绿素a/叶绿素b(Chl a/Chl b)比值,降低胞间CO_2浓度(C_i)和气孔限制值(L_s);同时烯效唑也能显著提高低温胁迫下秋茄幼苗叶片PSⅡ最大光化学效率(F_v/F_m)、实际光化学效率(Φ_(PSⅡ))、光化学猝灭系数(q_P),增加了超氧化物歧化酶(SOD)、过氧化物酶(POD)与抗坏血酸过氧化物酶(APX)活性,反而降低了非光化学猝灭系数(NPQ)、细胞膜透性和丙二醛(MDA)积累,说明烯效唑处理能改善低温胁迫下秋茄植株抗氧化系统运行,增强其植株光合电子传递效率,从而有效促进植株的光合作用,减少低温胁迫对秋茄叶片细胞的伤害。

The effect of uniconazole on leaf photosynthetic characteristics,chlorophyll fluorescence and antioxidant system in Kandelia obovata seedling under cold stress was investigated.Kandelia obovata seedlings were pretreated with 0.1 mmol·L^-1 uniconazole for 7 d,and then exposed to cold stress at day/night of（5/-2）℃ for48 h.Results show that the net photosynthetic rate（Pn）,stomatal conductance（Gs）,chlorophyll content and Chl a/Chl b ratio significantly increased,and intercellular CO2 concentration（Ci） and stomatatal limitation（Ls） were reduced in K obovata leaves by the use of uniconazole.The photochemical efficiency of photosystem Ⅱ（Fv/Fm）,actual photochemical efficiency（ΦPSⅡ） and photochemical quenching cofficient（qP） could be enhanced,but non-photochemical quenching coefficient（NPQ） decreased,in K obovata leaves with uniconazole treatment.In addition,uniconazole alleviated the oxidative damage in leaves of K obovata by reducing cell membrane permeability and lipid peroxidation,and by increasing the activities of superoxide dismutase（SOD）,ascorbate peroxidase（APX） and peroxidase（POD）.Sum up,it indicates that uniconazole alleviates freezing-induced cell damages through regulating the photosynthesis and antioxidant system of K.obovata.