【作者】 郭伟；

【导师】 王庆祥；

【作者基本信息】 沈阳农业大学 ， 作物学， 2011， 博士

【摘要】 本研究采用NaCl、Na2SO4、NaHCO3和Na2CO3四种盐,模拟了20种盐度、碱度不同的复杂盐碱条件,通过主成分分析,确定Na+浓度、C032-浓度和pH值为盐碱环境对小麦形成胁迫影响的代表性因子。在此基础上,选用5种不同浓度的NaCl和Na2CO3,对经过腐植酸浸种处理的水培小麦幼苗进行胁迫处理,通过对种子萌发、碳氮代谢、光合作用、离子稳态、抗氧化系统和根际环境的研究,探讨盐、碱胁迫的不同作用机理,以及腐植酸对小麦耐盐碱性的调控效应。结果表明：1.随盐碱胁迫离子浓度的增加,尤其是C032-比例的增加,使种子吸水能力减弱,α-淀粉酶活性降低,胚根生长受阻,种子活力下降,发芽速度迟缓,发芽强度变弱,最终降低了发芽率。小麦出苗后,通过降低根系总的吸收面积,增加活跃吸收面积,增强根系活力,提高对K+吸收能力,维系叶片高的K/Na比和苯丙氨酸解氨酶活性,缓解由高浓度盐碱形成的环境压力。2.盐碱胁迫下幼苗通过增强叶片蔗糖磷酸合成酶活性,提高蔗糖含量,积累可溶性糖,降低渗透势,维持质膜完整性。幼苗的防御机制随着胁迫浓度的提高而降低,叶片可溶性糖含量降低,硝态氮含量减少,内源硝酸还原酶活性降低,谷氨酰胺合成酶活性增强,可溶性蛋白质浓度降低。尤其是碱胁迫的危害强于盐胁迫,其对谷氨酰胺合成酶活性影响更大,形成比盐胁迫更高的铵态氮积累。3.盐碱胁迫导致小麦幼苗根系内丙二醛积累量进一步加大,过氧化物酶活性增强,超氧化物歧化酶活性降低,而叶片中游离脯氨酸含量增加,过氧化氢酶活性升高,过氧化物酶活性降低,超氧化物歧化酶活性先升后降。碱胁迫处理的抗氧化酶系活性高于同浓度的盐胁迫处理。随着盐碱胁迫浓度的增加,活性氧的产生及清除系统的平衡遭到破坏,叶片与根系电导率显著提高。4.在短时期的盐碱胁迫下,气孔导度下降,叶片蒸腾速率和水分利用效率降低,而胞间二氧化碳浓度升高,气孔限制值减小,净光合速率下降,叶绿素含量降低。随盐碱胁迫程度的增强,叶片光合速率的下降,根际磷浓度增加,Ca2+、Mg2+浓度降低,C1-浓度变化减小,NSCCs活性受到抑制,Na+的吸收比率降低,K+/Na+比值提高,大部分酯类释放减少,抑制醇类和烷类的分泌。尤其碱性环境下可溶态的Ca2+、Mg2+含量显著降低,根系大量分泌对二甲苯、间二甲苯、邻苯二甲酸二异丁酯。5.腐植酸浸种增强萌发种子α-淀粉酶活性,促进根系生长,提高了小麦幼苗的根冠比,加速可溶性糖积累,及向根系的运输,提高根系的蔗糖／果糖比,以降低根系渗透势,增强根系吸收能力。6.盐碱胁迫下腐植酸浸种增加了小麦幼苗可溶性蛋白质积累,降低了叶片谷氨酰胺合成酶和硝酸还原酶活性,降低氮素转化,而提高蔗糖磷酸合成酶活性,增加可溶性糖和谷胱甘肽含量,提高超氧化物歧化酶和过氧化氢酶活性,加强了对氧自由基的清除,降低膜脂过氧化程度,尤其是对碱胁迫下幼苗碳氮代谢和抗氧化能力的调控效应更显著。7.腐植酸浸种同时增强K+专性和NSCCs吸收,降低了根际Na+的浓度,提高根际K+/Na+,增强对Ca2+、Mg2+的活化,提高了叶片气孔导度,降低胞间二氧化碳浓度,通过调节气孔因素和根际离子平衡,提高盐碱胁迫下小麦的光合速率和矿质养分的吸收能力。研究认为,盐碱胁迫抑制了小麦种子萌发和幼苗生长,尤其是CO32-的水解形成的高pH值胁迫,以及CO32-本身对根际与细胞微环境离子稳态的破坏作用,致使碱胁迫对小麦幼苗生长的损伤强于盐碱胁迫,而腐植酸浸种强化了小麦的耐盐机制,但其调控效应受小麦基因型影响。更多还原

【Abstract】 Four kinds of salt including NaCl,Na2SO4,NaHCO3 and Na2CO3 are used to simulate 20 kinds of different salinity-alkalinity conditions. The concentration of Na+, CO32- and pH are identified as typical factors by principal component analysis that the effect of salt-alkali environment to wheat stress in the paper. On this basis, five different concentrations of NaCl and Na2CO3 are selected for stress treatments of water cultivation wheat seedlings after soaking the seed by humic acid, different action mechanism of salinity-alkalinity stress and control effects of humid acid to saline alkali tolerance of wheat are discussed by the research of seed germination, carbon and nitrogen metabolism, photosynthesis, ion steady-state, antioxidation system and rhizosphere environment.The results show that high salt concentration, especially increasing proportion of CO32-decreased water absorption capacity andα-amylase activity, inhibited radicle growth, reduced seed vigor, slowed the germination speed, weakened sprout strength, finally decreased germination rate. After wheat emerge, decreasing total absorption area of root, increasing active absorption area, root vigor and absorption capacity of K+ maintained high K/Na and the activity of phenylalanine aminolyase(PAL) in leaves and relieved enviornment pressure by high concentrations of salinity-alkalinity.Seedling maintained plasma membrane integrity under salinity-alkalinity stress by improved the activity of sucrose phosphate synthase(SPS), increasing the content of sucrose, the accumulation of soluble sugar and decreasing osmotic potential. Defense mechanism of seedling decreased with increasing stress concentration, which the content of soluble sugar, endogenous nitrate reductases activity and the concentration of soluble protein decreased, nitrate nitrogen reduced, the activity of glutamine synthase increased. Especially the harm of alkali stress is stronger than salt stress which has a greater effect on the activity of glutamine synthelase(GS), and produce higher accumulation of ammonium nitrogen than salt stress.The accumulation of malondialdehyde(MDA)in root and seedling increased further under salinity-alkalinity stress, the activity of peroxidase (POD) enhanced, the activity of super oxide dlsmutase(SOD) decreased, however, the proline content increased, the activity of CAT improved, the activity of POD decreased and the activity of SOD first rises then descends in leaves. The activity of antioxidant enzymes under alkali stress are higher than that under salt stress with same concentration. The production of active oxygen and balance of removing system are broken which improved conductivity of root and leaves dramaticlly by increasing salinity-alkalinity stress concentration. Stomatal conductance, transpiration rate and water use efficiency decreased, however, intercellular carbon dioxide concentration increased, Ls and chlorophyll content decreased, net photosynthetic rate decilined under salinity-alkalinity stress of short time. photosynthetic rate of leaves decreased, phosphate concentrations in rhizosphere increased, however, the concentration of Ca2+, Mg2+ and concentration variation of Cl- decreased, inhibited the NSCCs activity, decreased absorption rate of Na+, improved K+/Na+. The content of soluble Ca2+ and Mg2+ decreased dramatically and root secreted largely p-xylene, m-xylene and DIBP especially under alkali environment. However, the release of esters decreased, and inhibited the secretion of alcohols and alkanes.Soaking seed by humic acid enhanced a-amylase activity of germinating seed, and improved root shoot ratio of seedling, promoted the accumulation of soluble sugar, enhanced sugar transportation to root, improved the ratio of sucrose to fructose in order to osmotic potential of root and enhance root absorptive capacity by strengthen of root growth.Soaking seed by humic acid enhanced the accumulation of soluble protein of seedling, decreased nitrogen tranformation and the activity of GS and nitrate reductase(NR) under salinity-alkalinity stress, however, improved the activity of SPS, SOD and catalase, increased the contwnt of soluble sugar and glutathione (GSH), enhanced elimination to oxygen free radicals, decreased lipid peroxidation. In addition, control effect of humic acid is more markedly for carbon and nitrogen metabolism and oxidation resistance of seedling under alkali stress.Soaking seed by humic acid enhanced the absorptionof K+and NSCCs, decreased the absorption of Na+ and ntercellular carbon dioxide concentration, increased the K+/Na+ of rhizosphere and stomatal conductance of leaves, improved the activation of Ca2+ and Mg2+, photosynthetic rate and absorption capacity of mineral nutrition of wheat are improved by regulating stomatal factors and rhizosphere ions balance under salinity-alkalinity stress.The study show that the harm to wheat seedling under alkali stress is stronger than that under salt stress by high pH stress as a result of CO32- hydrolyzation and damaging effects of CO32- to rhizosphere and cell microenvironment ion steady. However, soaking seed by humic acid intensify salt resistance mechanism, but control effects was influenced by genotype of wheat.更多还原