【作者】 潘香梅；

【导师】 郁继华；

【作者基本信息】 甘肃农业大学 ， 蔬菜学， 2010， 硕士

【摘要】 本试验以黄瓜(Cucumis sativus L.)幼苗为试材,对其叶面喷施脱落酸溶液,研究了碱胁迫(60 mmol·L-1 Na2CO3)下外源脱落酸(ABA)对黄瓜幼苗生长指标、膜脂过氧化、保护酶活性、气体交换参数、叶绿素含量和叶绿素荧光参数的影响,以期为ABA在黄瓜生产上的应用提供科学依据。试验结果如下:1.碱胁迫显著降低了黄瓜幼苗的株高、根茎叶的干鲜重以及根系活力,但显著增加了黄瓜幼苗的脯氨酸(Pro)含量;外施不同浓度ABA能够缓解碱胁迫下黄瓜幼苗株高、各器官干鲜重和根系活力的降低,并增加Pro含量,其中以5×10-5 mol·L-1的ABA处理效果最好。2.碱胁迫下,黄瓜幼苗叶片的丙二醛(MDA)含量和细胞膜透性增加,通过叶施5×10-5 mol·L-1 ABA可显著降低黄瓜幼苗叶片在碱胁迫下的膜脂过氧化程度和明显缓解对细胞膜的伤害。3.随着碱胁迫时间的延长,黄瓜幼苗叶片的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性呈显著下降趋势,而过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性呈先升高后降低的变化趋势;外施5×10-5 mol·L-1 ABA可提高黄瓜幼苗在碱胁迫下SOD、POD、CAT和APX的活性,从而使叶片抗氧化能力增强。4.碱胁迫降低了黄瓜幼苗的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),提高了其胞间CO2浓度(Ci);通过叶面喷施5×10-5 mol·L-1 ABA提高了碱胁迫下黄瓜幼苗的Pn和Tr,降低了Gs和Ci。5.黄瓜幼苗的叶绿素a、叶绿素b和叶绿素总含量随着碱胁迫处理时间的延长呈先升高后降低的趋势,而叶绿素a/b的变化则是先急剧下降后缓慢上升;外施5×10-5 mol·L-1 ABA可提高黄瓜幼苗在碱胁迫下的叶绿素含量。6.外施5×10-5 mol·L-1 ABA可缓解碱胁迫导致的黄瓜幼苗叶片PSⅡ最大光化学效率(Fv/Fm)、PSⅡ有效光化学效率(Fv’/Fm’)、PSⅡ实际光化学效率(ФPSⅡ)、光化学荧光淬灭系数(qP)、PSⅡ电子传递速率(ETR)、PSⅡ光化学速率(PCR)和PSⅡ用于光化学反应的能量(P)的下降及初始荧光(Fo)、非光化学荧光淬灭系数(NPQ)、天线色素耗散的能量(D)和非光化学耗散的能量(E)的升高,在一定程度上防止Na2CO3胁迫对黄瓜幼苗叶片PSⅡ反应中心的损伤,维持黄瓜幼苗叶片较高的光合活性。更多还原

【Abstract】 By spraying abscisic acid on cucumber (Cucumis sativus L.) seedlings leaves, effects of exogenous abscisic acid on growth index, membrane lipid peroxidation, protective enzymes activities, gas exchange parameters, chlorophyll contents and chlorophyll fluorescence parameters in leaves of cucumber seedlings under alkaline stress were studied in this paper in order to provide scientific bases for ABA appliance in cucumber production. The results were showed below:1. The height of cucumber seedlings were significantly decreased under alkaline stress, and fresh and dry weight of root, stem and leaf and root activity as well, but significantly increased proline contents. It could alleviate the decrease of the height of cucumber seedlings, fresh and dry weight of root, stem and leaf and root activity, and increased proline contents when cucumber seedlings were treated with different concentrations of abscisic acid, which 5×10-5 mol·L-1 is the best for cucumber seedlings.2. Malondialdehyde content and membrane permeability of cucumber seedlings were increased under alkaline stress. After spraying 5×10-5 mol·L-1 abscisic acid on cucumber seedlings leaves, membrane lipid peroxidation was significantly decreased and membrance damage was alleviated.3. With the increasing of alkaline stress time, the activities of superoxide dismutase and catalase were significantly decreased, while the activities of peroxidase and ascorbate peroxidase were increased firstly and then decreased. After spraying 5×10-5 mol·L-1 abscisic acid on cucumber seedlings leaves, the activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase were increased and the antioxidant capacity was enhanced.4. Alkaline stress caused net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate(Tr) of cucumber seedlings were decreased and its intercellular CO2 concentration(Ci) was increased. After spraying 5×10-5 mol·L-1 abscisic acid on cucumber seedlings leaves, net photosynthetic rate and transpiration rate were increased and stomatal conductance and intercellular CO2 concentration were decreased.5. With the increasing of alkaline stress time, the contents of chlorophyll a, chlorophyll b and total contents of chlorophyll were increased firstly and then decreased, but chlorophyll a/b dropped dramticly and then increased slightly. After spraying 5×10-5 mol·L-1 abscisic acid on cucumber seedlings leaves, the contents of chlorophyll were increased.6. After spraying 5×10-5 mol·L-1 abscisic acid on cucumber seedlings leaves, it could efficiently alleviate the decrease of photochemical maximum efficiency of PSⅡ(Fv/Fm), photochemical efficiency of PSⅡ(Fv’/Fm’), actual photochemical efficiency of PSⅡ(ФPSⅡ), photochemical quenching coefficien(tQp), the electron transport rat(eETR), photochemistry rate(PCR)and the ration of absorbed light in photochemistry(P)as well as the increase of minimal fluorescence(Fo), non- photochemical quenching coefficient(NPQ), the ration of thermal dissipation(D)and excess energy(E)in cucumber seedlings induced by alkaline stress.更多还原