【作者】 张国斌；

【导师】 郁继华；

【作者基本信息】 甘肃农业大学 ， 设施作物， 2013， 博士

【摘要】 本文利用生物测定方法，研究了连作1~3年辣椒的土壤和基质浸提液中根系分泌物对小麦、菜豆、黄瓜和辣椒种子萌发和芽苗生长的化感作用，并将连作3年辣椒的土壤和基质浸提液进行组分分离，结合对辣椒种子化感作用的生物测定结果，借助GC-MS分析方法明确了化感优势组分的化感物质；进一步，通过外源SNP（NO供体，150μmol·L-1）和ABA（100μmol·L-1）叶面喷施连作3年土壤和基质浸提液处理下的辣椒幼苗，研究了外源物质缓解自毒作用下辣椒幼苗生长、光合作用、抗氧化酶系统、氮素同化等的生理生化机制。所取得的主要研究结果如下：1.连作1~3年辣椒的土壤和基质浸提液导致小麦、菜豆、黄瓜和辣椒的胚根长、胚芽长、发芽率和芽苗鲜质量不同程度地降低，表现出明显的抑制作用，且抑制作用随着辣椒连作年限的延长而增强，而土壤浸提液的抑制作用明显强于相对应年限的基质浸提液；连作3年的土壤和基质浸提液均对小麦种子萌发和芽苗生长的抑制作用最强，辣椒次之，菜豆再次之，对黄瓜的抑制作用最弱。连作3年辣椒的土壤和基质浸提液中的主要化感物质有差异，土壤浸提液中化感物质主要是3-甲基-1-丁醇、乙二醇、己醛、三甲基戊烷、单（2-乙已基）邻苯二甲酸酯，而基质浸提液中化感物质主要是棕榈酸甲酯、邻苯二甲酸二异丁酯；土壤浸提液乙醚+乙酸乙酯组分的优势化感物质主要是邻苯二甲酸二异丁酯、间苯二甲酸二辛酯、氧化苯乙烯，而基质浸提液乙酸乙酯组分的优势化感物质主要是氧化苯乙烯、邻苯二甲酸二异丁酯，两者含有共同的化感物质邻苯二甲酸二异丁酯。2.土壤和基质浸提液处理导致辣椒幼苗的茎粗、株高、叶长、叶宽、真叶数、鲜干重、根冠比和根系活力降低，其中，茎粗、株高、叶长、根系鲜重、鲜重根冠比、地上部干重、根系干重和根系活力显著低于对照，说明两种浸提液严重抑制了辣椒幼苗的生长和根系活力；NO和ABA明显促进自毒作用下上述指标的增加，NO对自毒作用下辣椒幼苗地上部鲜干重的促进作用强于ABA，而ABA对根系鲜干重的促进作用强于NO；整体来看，对于自毒作用下辣椒幼苗生长指标和根系活力的促进作用，NO显著强于ABA。3.两种浸提液均导致辣椒幼苗叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、原初光能转化效率（Fv/Fm）、光系统Ⅱ电子传递量子效率（ΦPSⅡ）、光化学猝灭系数（qP）、叶绿素含量以及叶绿素a/b显著下降，而胞间CO2浓度（Ci）和非光化学猝灭系数（NPQ）显著上升。外源NO处理显著提高辣椒幼苗叶片的Pn、Gs、Fv/Fm、ΦPSⅡ、qP和叶绿素含量，降低Ci和NPQ，对Tr无显著影响；外源ABA处理显著提高辣椒幼苗叶片的Pn、Fv/Fm、ΦPSⅡ、qP和叶绿素含量，降低Ci和NPQ，对Gs和Tr无显著影响。自毒作用导致辣椒光合速率下降的主要原因是非气孔因素，土壤浸提液处理对辣椒的自毒作用比基质浸提液处理严重；外源NO和ABA通过提高自毒作用下辣椒叶绿素含量，维持较高的光系统Ⅱ活性和光合能力，增强辣椒的抗逆性。4.两种浸提液均导致辣椒幼苗叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性，以及脱氢抗坏血酸（DHA）含量的下降；还原型抗坏血酸（AsA）、脯氨酸（Pro）、可溶性蛋白和丙二醛（MDA）含量，以及相对电导率和AsA/DHA上升；土壤浸提液胁迫程度显著大于基质浸提液。外源NO和ABA处理显著提高辣椒幼苗叶片的SOD、POD和CAT活性，以及Pro和可溶性蛋白含量，降低MDA含量和相对电导率，显著促进AsA含量升高和DHA含量下降，维持较高的AsA/DHA，NO对自毒作用下辣椒幼苗氧化损伤的缓解效应显著好于ABA。外源NO和ABA通过提高自毒作用下辣椒抗氧化酶活性、渗透调节物质含量和AsA/DHA比值，有效地阻止辣椒体内MDA积累和电解质渗漏，缓解自毒作用对辣椒幼苗造成的膜脂过氧化，增强辣椒的抗逆性。5.自毒作用下辣椒幼苗全氮、全磷和全钾含量，以及硝酸还原酶（NR）和谷氨酰胺合成酶（GS）活性下降，铵态氮和硝态氮含量增加。外源施用NO和ABA显著提高了胁迫植株全氮、全磷和全钾含量，降低了无机氮的积累，NO还显著提高了胁迫植株NR和GS活性。表明外源NO和ABA提高了自毒作用下辣椒幼苗的氮还原和同化能力，这可能是其提高植株抗自毒能力的一个重要原因。更多还原

【Abstract】 The allelopathy on seed germination and sprout growth of wheat, kidney bean, cucumber and pepper in root exudates of soil and substrates extracts of1-3years continuous cropping pepper were studied by bioassay methods. Major allelochemicals were identified by GC-MS analyzing methods in the separated components of soil and substrates extracts of3years continuous cropping pepper combined with results of bioassay methods, which held the highest allelopathy on pepper. Further, throughing exogenous SNP (NO donor,150μmol·L-1) and ABA (100μmol·L-1) treated by foliar spray pepper seedlings under soil and substrates extracts, physiological and biochemical mechanisms of nitric oxide (NO) and abscisic acid (ABA) on alleviation to autotoxicity in pepper seedlings were studied, which related to growth, photosynthesis, antioxidant enzyme systems, nitrogen assimilation, and so on. The main results were as folllows:1. Radicle length, shoot length, germination rate and sprout fresh weight of wheat, kidney bean, cucumber and pepper were reduced to different extents with soil and substrates extracts of1-3years continuous cropping pepper treated, which indicated that root exudates suppressed strongly seed germination and sprout growth of four vegetables. Suppression action on seed germination and sprout growth of four vegetables was strengthener with continuous cropping years of pepper prolonged,and that of soil extracts was better obviously that of substrates extracts. Suppression action on seed germination and sprout growth of wheat was strongest among four vegetables of soil and substrates extracts of3years continuous cropping pepper, which was gradually weakened on pepper. kidney bean and cucumber. Major allelochemicals by GC-MS were difference in soil and substrates extracts of3years continuous cropping pepper, and major allelochemicals were3-methyl-1-butanol, ethylene glycol,2,2,4-trimethylpentane,1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester in soil extracts, while major allelochemicals were hexadecanoic acid, methyl ester,1,2-benzenedicarboxylicacid, bis(2-methylpropyl) ester in substrates extracts, we found that soil extracts diethylether+ethylacetate component and substrates extracts ethylacetate component held the highest allelopathy. Finally, the component of soil extracts diethylether+ethylacetate and substrates extracts ethylacetate was analyzed by GC-MS. The result showed that the main allelochemicals were identified as1,2-epoxyethylbenze1,2-benzenedicarboxylicacid, bis(2-methylpropyl) ester,1,2-benzenedicarboxylicac bis(2-methylpropyl) ester in Soil extracts diethylether+ethylacetate component, and the main allelochemicals were identified as acenaphthene,1,2-epoxyethylbenzen,1,2-benzenedicarboxylicacid, bis(2-methylpropyl) ester in Substrates extracts ethylacetate component. Common allelochemical was1,2-Benzenedicarboxylicacid, bis(2-methylpropyl) ester in both components.2. Stem diameter, plant height, leaf length, leaf width, leaf number, fresh and dry weight, ratio of root to top and root activity of pepper seedlings were declined under both soil and substrates extracts, especially, stem diameter, plant height, leaf length, root fresh weight, R/T of fresh weight, top dry weight, root dry weight and root activity were lower significantlly than that under autotoxicity stress, which indicated that both soil and substrates extracts suppressed obviously growth and root activity of pepper seedlings. NO and ABA both promoted obviously increasement of the above index under autotoxicity, and promoting role of NO on top fresh and dry weight of seedlings was stronger than that of ABA, while which of ABA on root fresh and dry weight of seedlings was stronger than that of NO. In all, promoting role of NO on growth index and activity of pepper seedlings was higher significantlly than that of ABA under autotoxicity stress.3. All of soil and substrates extracts reduced Pn, Gs, Tr, Fv/Fm, ΦPS II, qP, chlorophyll content and ratio of chlorophyll a/b obviously, but increased Ci and NPQ significantly. Under autotoxicity stress, exogenous NO treatments significantly increased Pn、Gs、Fv/Fm、ΦPS Ⅱ、qP and chlorophyll content, but reduced Ci and NPQ significantly, and had no obvious influence on Tr. Exogenous ABA treatments significantly increased Pn、Fv/Fm、ΦPS Ⅱ、qP and chlorophyll content, but reduced Ci and NPQ significantly, and had no obvious influence on Gs and Tr under autotoxicity stress. The reduction in net photosynthesis rate caused by autotoxicity stress was considered to be a result of non-stomatal restriction mainly, and autotoxicity on pepper of soil extracts was serious greatly than substrates extracts. Under autotoxicity stress, exogenous NO and ABA application increased chlorophyll content, maintained PSII center activities and photo synthetic capacity, and enhanced autoxicity tolerance in pepper.4. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities, and dehydroascorbate (DHA) content declined under all of soil and substrates extracts stress, while ascorbic acid (AsA), proline (Pro), soluble protein, malondialdehyde (MDA) contents, relative conductivity and AsA/DHA ratio increased. Autotoxicity pepper of soil extracts was serious greatly than that of substrates extracts. NO and Al significantly increased SOD, POD and CAT activities, Pro and soluble protein contents, while reduced MDA content and relative conductivity significantly. At the same time, AsA/DHA ratio was significantly higher through promoting significantly to increase AsA content and decrease DHA content. Alleviate effect to autotoxicity of NO was significantly better than that of ABA in pepper seedlings. The above results suggested that NO and ABA effectively prevented malondialdehyde accumulation and electrolyte leakage, mitigated lipid peroxidation, through increasing antioxidant enzymes activities, osmotic adjustment substance content and AsA/DHA ratio in pepper seedlings under autoxicity stress.5. Total nitrogen, total phosphorus and total potassium content, nitrate reductase (NR) and glutamine synthetase (GS) activities declined under drought stress, while the content of ammonia nitrogen and nitrate nitrogen content increased. Exogenous application of NO and ABA in the condition of autotoxicity stress significantly increased the content of total nitrogen total phosphorus and total potassium, while decreased the accumulation of inorganic nitrogen. Also, NO application obviously increased the activities of NR and GS under autotoxicity stress. The above results suggested that NO and ABA enhanced the ability of nitrogen reduction and assimilation under autotoxicity stress, which might be a key reason for improving the autotoxicity tolerance of plants.更多还原