【作者】 杨凤娟；

【导师】 王秀峰；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2006， 博士

【摘要】 目前在探讨植物抗盐机制方面已取得了长足进展,但多以NaCl处理作为研究手段。温室土壤次生盐渍化的阴离子类型以NO₃^-为主,而温室土壤中NO₃^-积累造成蔬菜伤害的内部机理尚缺乏深入系统的研究。本课题在已有研究基础上,采用水培技术,设定营养液中不同NO₃^-浓度处理7d,进一步探讨土壤中NO₃^-过量积累对黄瓜的伤害机理,以及在NO₃^-胁迫条件下,NO₃^-在黄瓜器官内的分布,对黄瓜幼苗生理生化特性、离子跨膜运输功能蛋白活性及对细胞内Ca2+水平变化的影响,为改良根际环境,减轻盐渍化危害奠定理论基础。主要结果如下: 1.利用15N示踪技术研究黄瓜对氮素的吸收、分配及利用特性:土壤盆栽黄瓜幼苗在4叶1心和6叶1心期,在一定程度上,随NO₃^-浓度的增加,有利于幼苗生长,故干物质积累量有所增加,叶片中N含量增加。随生育期的延长（抽蔓期和结果期）,黄瓜根系积聚大量N,植株长势明显受抑,甚至出现萎蔫枯死现象。NO₃^-胁迫下,4个生育期黄瓜植株对15N的利用率均比对照显著降低,但N2（900Kg·hm-2）处理下,整株从肥料中吸收的N量均高于对照,这说明随NO₃^-浓度的增加,植株对氮的吸收仍呈上升趋势,适宜氮肥用量（对照）下,并不能满足黄瓜对氮肥的吸收。黄瓜吸收的氮素在各器官中的分配差异显著,叶片中的分配率在各个生育期均最高。2. NO₃^-胁迫对黄瓜幼苗生理生化特性的影响:（1）采用水培技术,设定营养液中不同NO₃^-浓度处理7d, NO₃^-浓度为56 mmol·L-1处理区,株高和叶面积绝对增加量显著高于对照,说明在低浓度NO₃^-处理区,稍微增加NO₃^-有利于植株的生长。但若NO₃^-浓度高于140 mmol·L-1,开始出现萎蔫和干枯现象。所有处理下,叶片和根系含水量均比对照降低,但差异不显著;地上部和地下部干物重也均低于对照,随处理浓度的增加差异达极显著水平。说明NO₃^-对植株的胁迫效应随处理浓度的增加而增大。根冠比均极显著高于对照,是因为地下部的下降幅度明显小于地上部的缘故。（2）采用水培技术,设定营养液中不同NO₃^-浓度处理7d,当NO₃^-处理浓度在56⁹8 mmol·L-1范围内,叶片中膜脂过氧化产物MDA含量和电解质相对渗漏率逐渐升高,保护酶除CAT外,其它酶（SOD、POD及APX）活性均比对照有所降低;NO₃^-浓度高于140 mmol·L-1时, MDA含量和电解质相对渗透率有所降低,保护酶SOD和POD活性升高。而根中变化规律与叶中相反。更多还原

【Abstract】 At present, we had lots of achievements on plant salt resistance mechanism, but most of them regarded NaCl as means of researching. The main anion of the soil salinization of the greenhouse was NO₃^-, but interior mechanisms of vegetable damage led by NO₃^- accumulation in greenhouse soil were short of systemic research.On the basis of present study, this subject will probe into the injury mechanism to the cucumber of NO₃^- excessive accumulation in greenhouse soil. We will clarity the distribution of NO₃^- in cucumber organ and the effects of NO₃^- stress on physiological and biochemical indexes, ion transmembrane transportation function protein activity and subcellular Ca2+ distribution in cucumber seedling, in order to establish theory basis to improve rhizosphere condition and lighten alkali-saline injury. The main results obtained were presented as follows:1. The absorption, distribution and utilization of cucumber to nitrogen by 15N tracer technology under NO₃^- stressIn four leaves and six leaves stages, a certain extent, it showed that higher NO₃^- favored growth and development of cucumber plants with increasing of NO₃^- , plant dry matter accumulations and N contents increased. With the growth of cucumber （vine and fruit stages）, the large accumulations of N in roots caused the growth inhibition of cucumber plants, even the appearance of wilt. N distribution changed with the growth and development center of cucumber. N utilization efficiency significantly decreased under NO₃^- stress. However, plant N content of N2 （900Kg pure nitrogen per ha.） absorbed from fertilizer was higher than control （450Kg pure nitrogen per ha.）, which suggested optimum nitrogen fertilization （450Kg pure nitrogen per ha.） could not satisfy the N need of the plant growth. N partitioning in the cucumber plant organs had significantly differences, and N partitioning in the leaf was highest in all the growth stages.2. Effects of NO₃^- stress on physiological and biochemical index of cucumber seedlings（1） Plant height and area of leaves expanded much more than control under 56 mmol·L-1 NO₃^- concentrations after 7 days of treatment, which showed that it favored growth and development of cucumber plants when nitrate was slightly added based on low-level更多还原