中文摘要：

为了探讨外源硫化氢（H_2S）对黄瓜耐冷性的调控机理,以‘津优3号’黄瓜为试材,叶面喷施H_2S供体硫氢化钠（NaHS）,以清水处理为对照,研究H_2S对温度变化的响应,以及对黄瓜叶片光合作用和抗氧化系统的影响。结果表明：随着日光温室内气温降低和低温持续时间的延长,黄瓜叶片的H_2S含量及D–/L–半胱氨酸脱巯基酶（CDes）活性先升高,后降低;光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）、核酮糖–1,5–二磷酸羧化酶（RuBPCase）活性,以及暗下光系统Ⅱ最大光化学效率（F_v/_F_m）、光下实际光化学效率（Φ_（PSⅡ））、电子传递效率（ETR）和光化学猝灭（q_P）逐渐降低,胞间CO_2浓度（Ci）、初始荧光（F_o）和非光化学猝灭（NPQ）趋于升高。低温胁迫可使MDA含量增加,超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）活性先升高后降低。与对照相比,NaHS处理叶片的H_2S含量和CDes活性及P_n、G_s、T_r、RuBPCase活性、F_v/_Fm、Φ_（PSⅡ）、ETR和q_P明显升高,C_i、F_o和NPQ显著降低。低温下NaHS处理的MDA含量显著低于对照,而SOD、POD、CAT、APX和GR活性明显高于对照。NaHS处理的黄瓜产量比对照增加15.3%。可见CDes催化合成H_2S受低温胁迫诱导,外源H_2S可增强活性氧清除能力,减轻低温对黄瓜叶片光合机构的伤害。

英文摘要：

The purpose of this paper is to investigate the regulation mechanism of exogenous hydrogen sulfide（H_2S）on chilling tolerance in cucumber（Cucumis sativa L.）plants.‘Jinyou 3＇cucumber plants were used as materials. The respond of H_2S to temperature and the effect of sodium hydrosulfide（NaHS,the donor of H_2S）on photosynthesis and antioxidant system in cucumber were investigated, with distilled water as the control. The results showed that H_2S content and D-/L-cysteine desulfhydrase（CDes）activity increased at first and then decreased as the temperature decreased and lasted. Low temperature led to decrease in photosynthetic rate（P_n）,stomatal conductance（G_s）,transpiration rate（T_r）,ribulose bisphosphate carboxylic enzyme（RuBPCase）activity,maximum photochemical efficiency of PSⅡ in darkness（F_v/F_m）,actual photochemical efficiency of PSⅡ（Φ_（PSⅡ））,electron transport rate（ETR）and photochemical quenching（q_P）,while increase in intercellular CO_2 concentration（C_i）,initial fluorescence（Fo）and non-photochemical quenching（NPQ）. Low temperature increased malondialdehyde（MDA）content. The superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）,ascorbate peroxidase（APX）and glutathione reductase（GR）activities increased in the early days of chilling stress,but subsequently decreased. Compared with the control,the NaHS treated leaves showed significantly higher H_2S content,CDes activity,P_n,G_s,T_r,RuBPCase activity,F_v/F_m,Φ_（PSⅡ）,ETR and q_P,whereas markedly lower C_i,F_o and NPQ. NaHS caused a significant decrease in MDA content,but an increase in SOD,POD,CAT,APX and GR activities. The yield of NaHS-treated cucumber plants was 15.3% higher than that of the control. This indicated that H_2S which is catalyzed by CDes was induced by chilling stress. Exogenous H_2S can enhance the ROS scavenging activity,and alleviate the injury of photosynthetic apparatus in cucumber leaves against low temperature.