【作者】 石喜；

【导师】 王密侠；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2009， 硕士

【摘要】 水分是影响作物生长的主要因子之一,水分亏缺条件下作物的生理生态特性发生了较大变化,体现了作物对水分因子的响应。本文以盆栽玉米为试材,对玉米水分亏缺的生理生化响应及补偿效应进行研究。主要研究内容包括:(1)研究玉米苗期和拔节期不同程度的水分亏缺对玉米株高、叶面积、蒸腾速率和光合速率、耗水规律及水分利用效率的影响及复水后的补偿效应;(2)探讨不同程度的水分亏缺对叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、丙二醛(MDA)、脯氨酸(Pro)及叶绿素等生理指标的影响及复水后的补偿作用;(3)研究不同程度的水分亏缺叶片和根系中脱落酸(ABA)含量的变化、H2O2的累积及复水后的变化,并利用扫描电子显微技术研究了不同水分处理时气孔结构及不定次生根根毛的变化特征。研究获得了以下主要结论:1、苗期和拔节期不同的水分亏缺抑制株高的增长、叶面积的扩展和干物质的累积,抑制程度与水分亏缺程度一致。复水后的株高、叶面积和干物质均表现出了不同程度的补偿效应,尤其以苗期亏缺的株高补偿最为明显,生育结束时轻度、中度和重度处理的株高均出现了超越补偿。苗期水分亏缺的根系活力和根冠比随亏缺程度的加重而增大,说明苗期水分亏缺对根的影响小于对冠的影响,复水后亏缺处理的根系活力仍然保持较高水平,而根冠比都低于对照,说明分配到冠的干物质比例增大,体现了地上部位的补偿作用。两个阶段的水分亏缺在生育后期的死叶个数均少于对照处理的,说明水分亏缺降低了叶片衰减速度,有利于后期的生长。2、苗期水分亏缺影响了光合特性的变化,水分亏缺下光合速率和蒸腾速率都下降,而叶片的水分利用效率相应有所提高。复水后短时间内(10天),除了轻度处理的光合速率略高于对照,其余受处理的光合速率和蒸腾速率均低于对照。在两个阶段进行水分亏缺均减少植株耗水量,水分亏缺复水后减少了蒸腾耗水量的同时提高了水分利用效率。3、水分亏缺对玉米抗氧化系统及渗透调节等产生了很大的影响,随着水分亏缺程度的加重,Pro含量、POD活性及MDA含量显著增加,SOD活性先升后降,叶绿素含量持续减少。复水后的Pro含量、POD活性与对照无显著差异,SOD活性的趋势与处理时一致,而MDA含量依然是重度处理最高,轻度和中度处理的MDA含量略低于对照,叶绿素含量受处理的到后期甚至高于对照。这说明水分亏缺条件下能诱导抗氧化防护酶活性,增强植物抗氧化的保护能力。4、玉米根系和叶片中ABA随水分亏缺程度加重含量增加,叶片保卫细胞中H2O2大量累积,说明H2O2在气孔运动中起着关键作用。复水后,玉米叶片中ABA含量有所降低,而根系中的ABA含量仍然保持较高浓度,叶片的H2O2的累积量均降低。新发现不同程度水分亏缺能诱导根尖不同组织累积H2O2,对照处理累积在根冠区,轻度处理累积在根冠和分生组织区,中度和重度处理积累在根冠,分生组织和伸长组织区,各种处理根毛区均没有H2O2累积。5、叶子表皮与根毛分布特点通过电子显微镜观察,表明水分亏缺导致叶片表皮形态结构发生变化,正常和轻度处理的表皮表面光滑,有两种类型的叶表皮毛,而中度和重度处理的叶表皮细胞表面两种类型的表皮毛消失,在表皮细胞表面重新形成大量的绒状物。次生根根毛随着水分亏缺程度的加重,根毛在数量上呈增多趋势,正常和轻度处理的根毛短而少,而中度和重度水分处理的根毛长而密,但水分亏缺诱导根毛增长有阈值。更多还原

【Abstract】 Soil moisture is the main factor to affect the crops grows. The crops’ physiological and ecology characteristic has changed obviously under water deficit. In this paper the effects of water deficit on physiological and biochemical response and compensation effect are studied by carrying out the potted experiments. The main research content includes:(1)Study the effects of seedling and jointing water deficit on plant height, leaf area, photosynthetic rate, transpiration rate, water consumption rule, WUE and compensation effect after rewatering.(2)Discuss the effects of water deficit in varying degrees on superoxide dismutase(SOD), peroxide(POD), malondialdehyde(MDA), proline(Pro) and chlorophyll and compensation effect after rewatering.(3)Study the ABA content, H2O2 accumulation on leaf and root system under different water deficit and rewatering, and use the scanning electron microscopy to research the stomatal and root hair’s change under different water deficit. The main results are as follows:1. Seedling and jointing water deficit obviously restricts the plant growth, leaf area expansion and dry matter accumulation, and the restriction degree is closely related to water deficit degree. After rewatering, the plant height, leaf area and dry matter accumulation are compensated on defferent degree. Especially the plant height compensation on seedling deficit is most obvious. The plant height of light treat, mild treat and severe treat is higher than the contrast at the end stage. With the increase of degree of water deficit, the root/crown ratio and root activity are increased, which explained that the influence on the root is smaller than the crown on seedling water deficit. The root activity is still maintained the high level, but the root/crown ratio is lower than the contrast. It showed that the crown’s dry material proportion has increased, which manifest the compensation on the ground spot. The number of dead leaf on water deficit of two stages is shorter than the contrast treat. It showed that the water deficit reduce the leaf weaken speed and it advantage to later period’s growth.2. The photosynthetic rate and transpiration rate are decreased under water deficit, but the water use efficiency is correspondingly improved. In a short time after rewatering(10days), other photosynthetic rate and transpiration rate are all lower than the contrast except for the photosynthetic of light treat is higher than the contrast. Tow stages’water deficit is decreased the plant water consumption, at the same time raised the water use efficiency.3. Water deficit has changed great influence on the oxidation resistance system and the osmotic regulation. With the increase of degree of water deficit, the proline content, peroxide activity and malondialdehyde content are significantly improved, the superoxide dismutase activity is increased at first, and then decreased, but the chlorophyll content is decreased continuously. After rewatering, the proline content and peroxide activity has no significant difference to the contrast, the trend of superoxide dismutase activity is consistent with the treatment, but the malondialdehyde content which the severe treat is maintained the highest level, the light treat and mild treat are slightly lower than the contrast, and the chlorophyll content which treated is even higher than the contrast to the later period. The results indicated that the water deficit can induce the activity of oxidation resistance protection enzyme, and enhance the protection capacity of plant antioxidant.4. With the increase of degree of deficit, the ABA content on leaf and root is raised. The H2O2 massive accumulated in the leaf guard cell show that H2O2 is playing the crucial role in the stomatal movement. After rewatering, the leaf’s ABA content has reduces, but the root’s ABA content still maintaines the high density, and the leaf’s H2O2 density has reduces. It is a recent discovery that varying degree content water deficit can induce the root different organization to accumulate H2O2. The contrast in the root cap area, the light treat accumulates in the root cap and the meristematic tissue area, and the mild and severe treat accumulates in the root cap, meristematic tissue area and the elongated structure area. Each kind of treat has not H2O2 to accumulate in the root hair area.5. Through the electron microscope to observe the distribution characteristic of leaf epidermis and root hair, which indicated that the shape of leaf’s epidermis structure is changed. The epidermis surface of contrast and light treat is luminous and has two types of epidermis hair. But the mild and severe treat has not two types of epidermis hair and forms the massive fabric shape in the epidermal cell surface. With the increase of degree of deficit, the tendency of secondary root hair is increased in quantity. The root of contrast and light treat is short and few, mild and severe treat is long and dense, but the water deficit inducing root hair growth has threshold value.更多还原