【作者】 杨洋；

【导师】 张凤华； 时增凯；

【作者基本信息】 石河子大学 ， 农业硕士（专业学位）， 2020， 硕士

【摘要】 土壤盐碱化是全球范围内普遍存在的环境问题,严重影响作物的生长和发育,限制作物的产量和品质,开发经济生态效益高的耐盐碱作物资源越来越受到广泛关注,本试验采用盆栽试验,在复合盐碱胁迫下种植油菜,分析油菜幼苗生长、渗透调节、光合参数、离子运输等生理生化特性,探索油菜苗期对盐碱胁迫的生理响应机制,为进一步揭示油菜的耐盐机理提供理论依据。主要结论如下:（1）不同程度盐碱胁迫对油菜幼苗生长及光合参数的影响。随着复合盐碱胁迫程度的增加,中、重度处理与轻度处理相比,油菜幼苗株高根长表现为降低趋势,苗前期分别降低25.50%、41.83%及37.04%、46.30%;苗后期株高与根长降低幅度减少。随着盐胁迫增加,油菜幼苗叶片净光合速率、气孔导度及蒸腾速率均表现为先降低后升高,胞间CO₂则表现出降低趋势。与苗前期相比,重度胁迫下降低幅度最大,分别为45.3%、74.9%、46.7%、44.2%。盐碱胁迫抑制油菜生长及光合参数,苗前期抑制程度高于苗后期,且重度盐碱胁迫抑制程度更为明显。（2）不同程度盐碱胁迫对油菜幼苗可溶性糖、脯氨酸含量的影响。随着复合盐碱胁迫程度的增加,油菜幼苗叶片中可溶性糖含量呈现降低趋势,其中苗后期高于苗前期,分别是苗前期的115.6%、139.8%、52.9%;脯氨酸含量在苗前期,表现为先增加后降低,苗后期呈现降低趋势,且苗后期是苗前期的318.8%、210.1%、181.0%。油菜幼苗在受到盐碱胁迫时,苗前期表现出渗透胁迫,后期体内开始适应并积累脯氨酸、可溶性糖作出相应的调节。（3）不同程度盐碱胁迫对油菜幼苗体内保护酶活性的影响。随着盐碱程度的增大,苗后期与苗前期相比,SOD与POD酶活性降低,CAT酶活性升高,且苗后期分别是苗前期的98.4%、90.6%、96.2%,36.6%、38.1%、60.9%,79.9%、131.1%、2460.3%。盐碱胁迫下,油菜幼苗在苗前期,通过增加SOD和POD酶活性,从而清除胁迫所产生的超氧负离子自由基和H₂O₂,而在苗后期,则通过提高CAT酶活性降低氧化损伤,从而适应其逆境。（4）盐碱胁迫对油菜幼苗体内离子吸收、运输的影响。不同程度盐碱胁迫下,苗前期,茎叶中积累的Na⁺大于根部,且含量分别是根中的45.63倍、1.02倍和2.63倍,Na⁺/K⁺、Na⁺/Mg²⁺比值大于根部,而Na⁺/Ca²⁺比值小于根;苗后期,茎叶中积累的Na⁺小于根部,尤其在中、重度胁迫下,Na⁺/K⁺、Na⁺/Ca²⁺比值小于根部,Na⁺/Mg²⁺比值大于根部。复合盐碱胁迫下,苗前期油菜幼苗体内离子通过区域化分布,优先将Na⁺积累在茎叶,保证根的正常生长;苗后期将Na⁺截留在根部,保证其它营养元素被运输到茎叶,维持幼苗体内离子平衡。（5）不同程度盐碱胁迫对微生物多样性的影响。随着盐碱程度的增加,土壤细菌多样性降低;细菌群落结构随盐碱胁迫程度的增加呈明显的梯度变化,其中轻度和中度盐碱土细菌群落结构相似,与重度盐碱土细菌群落结构差异较大。更多还原

【Abstract】 Soil salinization is a widespread environmental problem worldwide,which severely affects the growth and development of crops,limits the quality and yield of crops,and develops economic and ecological benefits of saline-tolerant crop resources that have received increasing attention.This experiment uses Pot experiment,planting rape under complex saline-alkali stress,analyzing physiological and biochemical characteristics of rape seedling growth,osmotic adjustment,photosynthetic parameters,ion transport,etc.,exploring the physiological response mechanism of rapeseed to salt-alkali stress in order to further reveal the salt tolerance of rape The mechanism provides a theoretical basis.The main conclusions are as follows:（1）Effects of different levels of saline-alkali stress on photosynthetic parameters and biomass of rape seedlings.With the increase of the degree of combined saline-alkali stress,the net photosynthetic rate,stomatal conductance and transpiration rate of rapeseed seedlings decreased first and then increased,and intercellular CO₂ showed a downward trend.Compared with the pre-emergence stage,the decline was the largest under severe stress,which were 45.3%,74.9%,46.7%,and 44.2%,respectively.Rapeseed seedlings showed a decreasing root height,Compared with the mild and moderate treatments,the pre-emergence stage was reduced by 25.50%,41.83%,37.04%,and 46.30%;the post-emergence stage was reduced by 21.55%,15.19%,9.09%,and17.05%,respectively.Saline-alkali stress inhibited the increase of photosynthetic parameters and plant height and root length in rapeseed.The degree of inhibition at the early seedling stage was higher than that at the later stage of seedling,and the degree of severe saline-alkali stress inhibition was more obvious.（2）Effects of different levels of saline-alkali stress on soluble sugar and proline content in rape seedlings.With the increase of salinity,the soluble sugar content in the leaves of rapeseed seedlings showed a decreasing trend,in which the late seedling stage was higher than the pre-seedling stage,which were 115.6%,139.8%,and 52.9%of the pre-seedling stage;In order to increase first and then decrease,the post-emergence stage showed a downward trend,and the latter stage was 318.8%,210.1%,and 181.0%of the pre-emergence stage.When rapeseed seedlings were subjected to saline-alkali stress,they showed osmotic stress in the early stage of seedlings,and later in the body began to adapt and accumulate proline and soluble sugar to make corresponding adjustments.（3）Effects of different levels of saline-alkali stress on protective enzyme activities in rape seedlings.With the increase of salinity,the activities of SOD and POD enzymes decreased in the late seedling stage compared with the pre-seedling stage.Activity increased,and the increase was 79.9%,131.1%,2460.3%.Under saline-alkali stress,rape seedlings in the early stage of seedlings can increase their SOD and POD enzyme activities to remove the superoxide anion free radicals and H2O2 produced by stress,while in the later stage of seedlings,they can increase CAT enzyme activity to reduce oxidative damage and adapt its adversity.（4）The effects of saline-alkali stress on ion absorption and transportation in rapeseed seedlings.Under different levels of saline-alkali stress,Na⁺accumulated in the stems and leaves was larger than that in the roots at the early seedling stage,and the contents of the stems and leaves were 45.63,1.02,and 2.63 times that of the roots,respectively.The ratio is larger than the root,and the ratio of Na⁺/Ca²⁺is smaller than that of the root.In the late seedling period,the accumulated Na⁺in stems and leaves is smaller than the root,especially under moderate and severe stress,the ratios of Na⁺/K⁺,Na⁺/Ca²⁺are smaller than the root,and the ratio of Na⁺/Mg²⁺is larger than the root.Under compound saline-alkali stress,the ions in rapeseed seedlings in the early stage of seedlings are distributed regionally,and Na⁺is preferentially accumulated in the stems and leaves to ensure the normal growth of the roots;Na⁺is trapped in the roots in the late stage of seedlings to ensure that other nutrients are transported to the stems and leaves.Maintain ion balance in seedlings.（5）Effects of different levels of saline-alkali stress on soil pH and microbial diversity.When rapeseed grows to the five-leaf stage under salt stress,the pH of the soil decreases compared to before planting;as the degree of saline-alkali increases,the soil bacterial diversity decreases;the structure of the bacterial community significantly increases with the increase of saline-alkali stress The gradient structure of bacterial communities in mild and moderate saline-alkali soils is similar,and the structure of bacterial communities in severe saline-alkali soils is quite different.更多还原