【作者】 王一；

【导师】 曹敏建；

【作者基本信息】 沈阳农业大学 ， 作物学， 2011， 博士

【摘要】 干旱是制约作物产量形成的重要因素,培育耐旱的玉米品种是抵御干旱提高产量的有效途径之一。而玉米品种耐旱能力的大小由其亲本自交系耐旱性的强弱来决定,深入研究耐旱性玉米自交系的耐旱生理机制,对选育玉米耐旱品种和抗旱栽培具有重要的意义。本文以两个耐旱性不同的玉米自交系为试验材料,苗期采用PEG-6000模拟干旱设置不同程度的胁迫水平,对植株形态、生理生化特性、解剖结构及水分吸收利用效率等方面进行了比较研究,结果如下：1.干旱胁迫下两个玉米自交系生长发育的差异干旱胁迫抑制了玉米自交系地上部的生长发育：在干旱胁迫下,两个玉米自交系的株高、叶面积都较对照有不同程度的降低,植株地上部干物重的增长也受到不同程度的抑制,其抑制程度随胁迫时间的延长与胁迫程度的增加而增加。耐旱玉米自交系各项指标受干旱胁迫抑制的程度小于干旱敏感玉米自交系。干旱胁迫影响了玉米自交系根系的的生长发育：在5mmol/L PEG-6000的处理浓度下,两个玉米自交系的根总长、根系表面积、根系平均直径与对照相比有着不同程度的增加,耐旱玉米自交系的增加幅度显著高于干旱敏感玉米自交系；在10mmol/L、15mmol/L处理浓度下,两个玉米自交系的根总长、根系表面积、根系平均直径则随PEG-6000处理浓度的增加而降低,耐旱玉米自交系各指标的下降幅度显著低于干旱敏感玉米自交系。在干旱胁迫发生时,地上部首先受害,而根系仍能生长,根冠比增大。随着胁迫时间的延长,根系生长逐渐受到抑制。2.干旱胁迫下两个玉米自交系渗透调节物质的差异干旱胁迫下,两个玉米自交系叶片、根系中的可溶性糖、脯氨酸的含量均随着干旱程度的增加与胁迫时间的延长而增加,耐旱性玉米自交系这两项指标的增加幅度均显著高于干旱敏感玉米自交系。两个玉米自交系叶片、根系中的可溶性蛋白含量则是随着干旱程度的增加与胁迫时间的延长而减小,耐旱玉米自交系的下降幅度显著低于干旱敏感玉米自交系。干旱条件下,根系中三个指标的含量均高于叶片中的含量。3.干旱胁迫下两个玉米自交系脂膜透性、膜脂过氧化程度及保护酶活性的差异干旱胁迫下,两个玉米自交系叶片、.根系中的相对电导率值、MDA含量均随胁迫浓度的增加而增加,根系中的相对电导率值、MDA的含量更大一些；两个玉米自交系叶片、根系中的SOD、POD、CAT三种保护酶活性均高于正常生长条件下的活性,并且随着胁迫程度的增加而增强,随着胁迫时间的延长而呈“先升后降”的趋势,并在第6天出现峰值。耐旱性玉米自交系的增加幅度显著高于干旱敏感玉米自交系,降低幅度小于干旱敏感玉米自交系。并且,干旱胁迫下,根系中SOD、POD、CAT的活性均大于叶片中的活性。4.干旱胁迫下两个玉米自交系光合生理特性的差异干旱胁迫下,两个玉米自交系叶片胞间CO2浓度均逐渐升高,净光合速率、气孔导度与蒸腾速率均逐渐下降,认为非气孔因子限制是导致光合速率下降的一个主要原因。两个玉米自交系叶片中叶绿素a含量、叶绿素b含量、叶绿素a+b含量均随胁迫程度的增加而增加,原因之一可能是由于干旱致使植物细胞壁加厚,细胞伸长受抑制,但细胞分裂正常进行,因而单位面积上的含量就有所升高；原因之二可能是干旱使叶片相对含水量下降,进而导致单位重量上的叶绿素含量有所提高。两个玉米自交系叶片的初始荧光Fo均随胁迫程度的增加而升高,可变荧光Fv、Fv/Fo、Fv/Fm、PI值随胁迫程度的增加而明显降低；耐旱玉米自交系的下降幅度显著小于干旱敏感玉米自交系。干旱胁迫下,耐旱玉米自交系的Fm增加,而干旱敏感玉米自交系的Fm减少；干旱敏感玉米自交系的Area随着干旱胁迫程度的增加而增加,耐旱玉米自交系的Area则随着干旱胁迫程度的增加而减小。与干旱敏感玉米自交系相比,耐旱玉米自交系的PSⅡ在干旱条件下仍保持较高的电子传递能力和较强的光合性能。5.干旱胁迫下两个玉米自交系解剖结构的差异两个玉米自交系叶片的解剖结构在干旱胁迫下具有品系间差异,耐旱玉米自交系的叶片较薄,表皮细胞、维管束鞘细胞比较发达,导管面积也较大。干旱胁迫下,随着胁迫浓度的增加,耐旱玉米自交系以上各指标的下降幅度不明显,而干旱敏感玉米自交系下降幅度较大。干旱胁迫下,两个玉米自交系根系的皮层厚度与导管直径均随胁迫程度的增加而减小,耐旱玉米自交系皮层厚度的降低幅度高于干旱敏感玉米自交系,导管直径的降低幅度低于干旱敏感玉米自交系；耐旱玉米自交系根系皮层厚度占根系直径的比例较小,干旱敏感玉米自交系根系皮层厚度占根系直径的比例较大。6.干旱胁迫下两个玉米自交系根系吸水能力及植株水分利用效率的差异干旱肋迫下,两个玉米自交系根系的吸水能力及植株水分利用效率均随胁迫的增加而减小,耐旱玉米自交系的下降幅度显著小于干旱敏感玉米自交系自交系。更多还原

【Abstract】 Drought is one of the main limiting factors for crop yield forming. It is one of the effective approaches to develop drought-tolerant maize hybrids. Due to the difference of drought-tolerance among various inbred lines, it is necessary to further study on the physiological foundation to develop drought-tolerant hybrids and to improve crop cultivated technology. Two inbred lines of different drought-tolerance were selected to use in this study. The drought stress simulation was used with PEG-6000 at different stress levels. The objectives were to research the differences on plant morphology, physiological characteristics, micro-structure and WUE during seedlings in Maize inbred lines. The results were as follows:1. Differences in growth and development between two maize inbred lines under drought stressDrought limited the above-ground growth and development of maize inbred lines. Under drought stress, the plant height and leaf area were decreased, and the above-ground dry matters were limited to different extents. The limiting degree was increased with the stress time extending and the stress degree increasing. The effects in drought-tolerant inbred line were less than those in drought-susceptible inbred lines.Drought affected the growth and development of root system between two maize inbred lines. Comparing with the CK, the total length, surface area, mean diameter of roots of two inbred lines were increased at 5mmol/L, but those of drought-tolerant inbred line were significance increased than drought-susceptible inbred lines. As the concentration of PEG-6000 was 10mmol/L and 15mmol/L, the total length, surface area, and mean diameter of roots were decreased with the increase of treatment contents. When the drought stress occurred, the above-ground parts were damaged first, but the roots were still growing. As stress prolonged, the root growth was inhibited.2. Differences in osmotic adjustment matters between two maize inbred lines under drought stressUnder drought stress, the soluble carbohydrate and proline in leaf and root of two inbred lines were increased with the interments of drought severity and stress time. The increasing range of drought-tolerant line was much more than those of drought-susceptible line, and the contents of soluble carbohydrate, proline and soluble protein in root were more than those in leaf.3. Differences in lipid membrane permeability, lipid peroxidation and protective enzyme between two maize inbred lines under drought stressThe relative conductivity value and MDA content were increased with the increment of stress under drought stress, especially in root. The activities of three protective enzymes SOD, POD and CAT under drought were higher than under normal growing condition. This showed the tendency as’up to down’with the interment of stress severity and time. The increasing range of drought-tolerant inbred line was more than that of drought-susceptible line, but the decreased range was less than drought-susceptible line. The activities of SOD, POD and CAT in root were higher than in leaf.4. Differences in photosynthetic physiological characteristics between two maize inbred lines under drought stressUnder drought stress, the intercellular CO2 content in leaf was increased, but the net photosynthetic rate, stoma conductivity and transpiration rate were decreased, which was indicating that the no-stoma factors were maybe the main reason for the reduction of photosynthetic rate.The contents of chlorophyll a, chlorophyll b, and chlorophyll a+b were increased with the increments of stress due to the increase of cell wall thickness, as well as the inhibition of cell elongation which increased the amount of chlorophyll per unit area; another reason was that the decrease of relative water in leaf led to increase of content in unit weight.The initial Florence Fo in leaf of two inbred lines were increased with the stress increased, but the Fv, Fv/Fo, Fv/Fm, and PI value were decreased. The decreased range of drought-tolerant inbred line was less than that of drought-susceptible line. The Fm was increased in drought-tolerant line, but it was decreased in drought-susceptible inbred line. The area of drought-susceptible line was increased but the area of resistant line was decreased with the increment of drought stress. The PSⅡof drought-tolerant inbred line maintained higher electron transportation ability and photosynthesis. 5. Differences in micro-structure between two maize inbred linesThe drought-tolerant inbred line was characterized with thick leaf, developed mesophyll cell and bundle sheath cell under drought stress. Furthermore, the decreasing ranges of leaf thickness, mesophyll cell and bundle sheath cell areas were not obvious with the increase of drought, but the drought-susceptible line were significantly decreased.The vessel diameter and cortex thickness were decreased with the increment of stress, and the decreased range of drought-tolerant line was greater than that of drought-susceptible line. For the drought-tolerant line, the cortex thickness took less portion of root diameter, but it was on the contrary for drought-susceptible line.6. Differences in ability of water absorption and WUE between two maize inbred linesThe ability of water absorption and WUE were decreased with the increment of stress, and decreasing range of drought-tolerant maize inbred line was less than that of drought-susceptible line.更多还原