【作者】 王海珍；

【导师】 梁宗锁；

【作者基本信息】 西北农林科技大学 ， 植物学， 2003， 硕士

【摘要】 本研究以黄土高原四个乡土树种：辽东栎(Quercus liaotungensis)、大叶细裂槭(Acer stenolobum Rehd.var.megalophyllum)、白刺花(狼牙刺Sophora viciifolin)和虎榛子(Ostryopsis davidiana)为实验材料，在盆栽模拟土壤干旱环境下，研究了不同土壤水分条件下四个乡土树种幼苗的耗水特性、生长、干物质积累分配的变化规律及各树种不同层次水平的水分利用效率。探讨了不同土壤水分条件下各树种水分代谢、渗透调节物质、保护酶活性、光合作用及光合色素含量的时空变化，旨在揭示四个树种抗旱生理机制的差异并综合评价了四个树种的抗旱性强弱、生态反应和适应机制，取得主要结果如下： 1．四个乡土树种的耗水特性不同。不同树种的最大耗水时期、最高耗水日以及日耗水最高时段有所不同；随土壤水分含量的减少，最高耗水时期、最高耗水日及日耗水高峰有提前的趋势；耗水高峰期多集中6、7、8三个月(白刺花集中在7、8、9三个月)。土壤水分含量高低决定各树种耗水量的多少，总趋势是：适宜水分＞中度干旱＞重度干旱。土壤水分含量对大叶细裂槭耗水量的影响最大，对其它树种影响较小。不同水分处理下耗水量均是白刺花＞辽东栎＞大叶细裂槭＞虎榛子。随土壤水分含量的减少，白刺花和大叶细裂槭的耗水变化幅度较小，虎榛子和辽东栎耗水高峰出现时间提前。白刺花属高耗水高水分利用效率的树种，中度干旱对其耗水量以及耗水规律几乎没有影响，且水分利用效率有所提高。虎榛子属低耗水低水分利用效率树种，耗水系数最大。大叶细裂槭对水分亏缺敏感，但其适应生长的水分范围很宽，属广适性树种，适应性强，成活率在干旱下最高。辽东栎属低耗水高水分利用效率的树种，但其幼苗不耐高温强光，适宜于在林下生长。 2．各树种在不同月份、不同天气状况下的蒸腾速率日变化规律不同。各树种在不同月份、不同天气状况下的蒸腾速率日变化规律不同。不同树种在不同季节、不同天气状况下的蒸腾速率或者是单峰、或者是双峰；在严重干旱下或生长后期，由于气孔的生理调控能力下降而呈不规律的变化。对蒸腾速率与环境因子的相关分析表明，环境因子对树种蒸腾速率影响的大小顺序依次是：光强、气温和相对湿度。不同水分处理下各树种对这3个主要环境因子的反应不同。 3．土壤水分条件对四个树种水分状况的影响不同。大叶细裂槭在干旱胁迫下主要通过增加根系吸水维持较高的叶水势，维持叶片含水量不致于下降过多，具有御旱植物的特点。白刺花则通过一些生理调节方式增加叶片的保水力维持较高的水分含量，具有耐旱植物的特点。虎榛子通过降低叶水势以增强吸水力维持较高的叶水势，但其叶片保水力较差。辽东栎的叶水势变化较平稳，与其叶片组织含水量较稳定有关。综合来看白刺花、辽东栎较抗旱；大叶细裂槭、虎榛子抗旱性较弱。 4．土壤干旱对各树种渗透调节物质以及光合色素含量变化的影响不同。随土壤干旱程度的加剧，各树种叶片中可溶性糖含量均呈上升趋势。游离脯氨酸含量随生长进程以及干旱程度加剧变化较为复杂。四个树种K+含量不同时期不同水分处理变化不同。白刺花K+含量在各处理中均显著高于其它树种，其K+含量与其抗早性成正相关。可溶性蛋白质含量随土壤干旱加剧变化较为复杂，无明显规律。叶绿素总量随干旱胁迫时间延长呈下降趋势，叶绿素b下降而叶绿素a上升，类胡萝卜素的含量及性质较稳定。不同土壤水分条件对各树种保护酶活性、细胞膜结构影响不同。白刺花以其渗透保护性物质提高质膜稳定性，同时其三个保护酶能够相互协同作用降低膜脂过氧化程度减少水分胁迫造成的伤害。虎棒子则通过保持较高的酶活性降低质膜过氧化以维持膜结构的完整性。大叶细裂械对水分胁迫的反应敏感，但其保护酶调节能力较强，对水分亏缺的适应范围很宽。辽东栋幼苗对环境因子的适应性较差，影响其保护酶活性的因素较多，酶活性变幅较大。5.不同土壤水分含量对各树种的生长、干物质分配影响不同。白刺花、大叶细裂械属生长较快的树种，辽东栋、虎棒子属生长较慢的树种，但它们对干旱都具有良好的适应性。树木生长的不同时期，土壤水分对其蒸腾、光合的影响程度不同;不同的树种在相同的时期对土壤水分含量以及其它环境因子的敏感程度也不同。随土壤水分含量变化各树种水分利用效率变化不同。辽东栋属低蒸腾高水分利用效率，梭化效率稳定型树种;大叶细裂械属高蒸腾高光合、梭化效率、水分利用效率较高的树种;虎棒子属生长缓慢耗水少、水分利用效率低的树种;白刺花属高耗水高生长量、高水分利用效率的树种。不同土壤水分条件下环境因子对树木光合速率的影响不同。由通径分析结果表明:适宜水分下光照强度对光合速率影响最大，其次是气温;中度干旱下大气湿度对Pn的直接作用最大，光强次之;重度干旱下大气温度对树种Pn影响最大，其次为大气湿度，光强最小。通过对各生理指标与光合速率的相关和通径分析结果表明，在不同水分处理下，影响Pn的主导因子不同。适宜水分条件下，Gs对Pn的直接作用最大;中度干旱胁迫下Ci成为限制光合作用的主导因子;重度干旱?更多还原

【Abstract】 Using four native species (Acer stenolobum Rehd.var.megalophyllum.Sophora viciifolin,Quercus liaotungensis,Ostryopsis davidiana)of Loess Plateau as experiment materials and Pot culture experiments simulating different soil water status ,this paper mainly deals with water consumption characteristic and growth ,biomass allocation regular and WUE of different level of four native tree species under three different soil water. Time and space change of water metabolism, osmotic adjustment substance, principal protective enzyme activity, photosynthesis and photosynthetic pigment of four tree species of different soil water stress, we expected to discover difference of drought-resistance mechanism and comprehensive evaluateDrought-resistance characteristic of four native tree species are different. By experiment, we discovered ecological responses and adaptability mechanism with soil water stress. This result provided scientific basis of rational chosen tree species and plant construction in Loess Plateau. The mail results are as follows:1. Different soil water content had obvious affected on water consumption of 4 tree species. Time and date of the highest water consumption had notably difference. The highest water consumption of four tree species concentrated on 6,7,8 month. Soil water content decided on water consumption ,the trend is normal water>media stress> severe stress. According to sort with water consumption under different soil water content ,the trend is Sophora viciifolin > Ouercus liaotungensis > Acer stenolobum Rehd.var.megalophyllum>Ostryopsis davidiana . Sophora viciifolin has higher water consumption and WUE characteristic, Ostryopsis davidiana belong to low water consumption and WUE species and has the highest water coefficient. Acer stenolobum Rehdvar.megalophyllum was sensible to soil water deficit, but it grows under widely water condition and fine adaptability and higher survival rate. Quercus liaotungensis has low water consumption and high WUE characteristic and its seedling has weakly resistance on high temperature and strong light.2. Change regular of date transpiration rate of different tree species have obvious different under different month and climate. Transpiration rate of seedling on sun day surpass that of cloudy day and summers surpass autumns. Curve of transpiration rate of different seedling was single or two peaks. Transpiration rate declined with the deepening of soil water stress. Correlation analysis with transpiration and environment elements showed that sunlight has the stronger effect on transpiration rate secondly is air temperature and RH. Different responses to principle environment factor of different tree species under different soil water content.3. Different soil water content has affected water metabolism of 4 trees species. Acer stenolobum Rehdvar.megalophyllum has higher leaf water potential, keeping higher leaf water content. It has drought avoidance characteristic. Ostryopsis davidiana decreased leaf water potential to increase organ water content and has weakly leaf water retention capability. Change of leaf water potential and water content of Ouercus liaotungensis isstable. Sum up, Quercus liaotungensis and Sophora viciifolin has stronger drought-resistance characteristic.4. Different soil water content had obvious affected on osmotic adjustment substance and photosynthetic pigment content of four tree species. Leaf Soluble sugar content of four seedlings ascended with descending soil water content. Chant of leaf praline content has no obvious regular with growing and water deficit. Change of leaf K+ content has notable different with different growth stage and water deficit. Leaf K+ content of Sophora viciifolin has significantly surpassed other seedling; K+ content has positive correlation with drought-resistance. Change of leaf soluble protein content has complex with soil water decreasing. Chlorophyll content descended with prolonging water stress time, Chlorophyll a ascended and更多还原