【作者】 徐莲珍；

【导师】 张硕新；

【作者基本信息】 西北农林科技大学 ， 生态学， 2008， 硕士

【摘要】 本文以1年生刺槐(Robinia pseudoacacia)、元宝枫(Acer trancatum)和侧柏(Platycladus orientalis)实生苗为试验材料,采用盆栽控水方法,对苗木在水分胁迫下的生长状况、耗水规律、光合作用、保护酶活性及渗透调节物质含量的动态变化等进行了测定,旨在评价和对比各苗木的抗旱能力,建立抗旱评价指标体系,为我国干旱半干旱地区造林树种的选择和营林技术提供理论依据。主要研究结论如下:1)水分胁迫显著抑制了三种苗木的高生长和地径生长,且随着胁迫程度的加剧,苗高和地径生长受到的抑制程度增加。2)各苗木光合速率日变化呈单峰型;刺槐的气孔导度日变化呈单峰型,元宝枫和侧柏的气孔导度日变化为双峰型;随着水分胁迫加剧,光合速率和气孔导度下降,水分利用率不同程度提高;与正常供水相比,在中度和重度水分胁迫下蒸腾速率下降,而在轻度胁迫下升高。随着水分胁迫加剧,三种苗木的Pmax、LSP显著下降,LCP、Rd显著升高,在中度和重度胁迫下刺槐的AQY值显著下降,但水分胁迫对元宝枫和侧柏的AQY值没有显著影响。3)在生长过程中,三种苗木的叶绿素总量持续下降,中度和重度胁迫下叶绿素总含量显著低于正常供水和轻度胁迫下的;正常和轻度胁迫下各树种的叶绿素a/b值先降低后升高,中度和重度胁迫下的持续下降且显著低于正常供水和轻度胁迫下的。4)随着水分胁迫的加剧,三种苗木叶片相对含水量降低,自然饱和亏增大;在相同水分处理下,三种苗木的相对含水量和离体叶片24小时保水力从大到小顺序为侧柏>元宝枫>刺槐。在正常水分条件下,刺槐保持膨压能力最低,侧柏的最高;但是在干旱条件下刺槐通过降低Ψ0π、Ψ100π、RWC0和ROWC0,提高Ψ100π与Ψ0π差值、AWC和RWD0来保持膨压,使得刺槐保持膨压的能力超过元宝枫和侧柏。随着水分胁迫加剧,三种苗木的耗水速率降低,单位面积茎流量从大到小顺序为元宝枫>刺槐>侧柏;刺槐和元宝枫的耗水高峰期出现在8月,侧柏的则在7月。5)随着水分胁迫加剧,三种苗木叶片游离脯氨酸含量、可溶性糖含量显著增加,可溶性蛋白含量显著减少;在整个生长过程中,游离脯氨酸含量与可溶性糖含量极显著正相关,而两者与可溶性蛋白存在弱的负相关。6)随着生长进程和水分胁迫程度加剧,三种苗木叶片中的MDA含量增加;三种酶在不同生长时期表现出不同的酶活性。无论哪种水分条件下,刺槐的酶活性一直维持在较高水平。7)运用模糊数学隶属函数法,对三种苗木在干旱下的适应性和抗旱生产力进行了比较。3种苗木抗旱能力大小依次为元宝枫>侧柏>刺槐。更多还原

【Abstract】 The pot cultured one-year-old seedlings of Robinia pseudoacacia, Acer trancatum and Platycladus orientalis were tested with water grade method to study their physiological biochemical characteristics under water stress. The growth status, water consumption patterns, photosynthesis and dynamics changes of protective enzymes activity and osmotic adjustment substances were measured to evaluate and compare the drought-resistant ability of the three seedlings, based on which evaluation indexes system was established to provide theoretical basis for selecting afforestation tree species and forest management measures in arid and semi-arid area. The results are as follows:(1) The growth of height and ground diameter was inhibited significantly under water stress; and with the aggravation of water stress, the degree of inhibitory increased.(2) The diurnal changes of net photosynthetic rate of the three tree species showed single peak type. The diurnal changes of stomatal conductance of R. pseudoacacia was single peak type and that of A. trancatum and P. orientalis were double peak type. With the enhancement of water stress intensity, the net photosynthetic rate and stomatal conductance were induced and the water use efficiency increased at different degrees. Compared with that under normal water supply, the transpiration rate decreased under medium and sever water stress but increased under light water stress. With increasing degree of water stress, Pmax and LSP of the three seedlings decreased significantly however LCP and Rd increased significantly. AQY values of R. pseudoacacia decreased significantly under medium and sever water stress, but water stress had no significant effects on those of A. trancatum and P. orientalis.(3) During the growth process, the total chlorophyll content of the three seedlings decreased continuously; and the total chlorophyll content in the leaves under medium and sever water stress was significantly lower than those under normal water supply and light water stress. The ratios of Chla and Chlb decreased at first and then increase under normal water supply and light water stress. Chla/Chlb values decreased continuously under medium and sever water stress and were significantly lower than those under normal water supply and light water stress. (4) With the aggravation of water stress, the relative water content of leaves of the three seedlings decreased, and the nature saturated deficit enlarged. Under the same water condition, the relative water content and 24h water retention capacity of isolated leaves of the three seedlings was listed in descending order as follows: P. orientalis >A. trancatum >R. pseudoacacia. The ability of turgor maintenance of R. pseudoacacia was the poorest and that of P. orientalis was the strongest. But R. pseudoacacia made its turgor maintaining ability exceed A. trancatum and P. orientalis through reducingΨ0π,Ψ100π, RWC0 and ROWC0and improving the differential value ofΨ100πandΨ0π, AWC and RWD0. With increasing intensity of water stress, the water consumption rate of the three seedlings decreased and the sap flow rate per area of three seedlings was as follows: A. trancatum > P. orientalis >R. pseudoacacia. The period of the highest water consumption of A. trancatum and R. pseudoacacia was in August, and that of P. orientalis in July.(5) With the aggravation of water stress, the content of free proline and soluble sugar content in the leaves of the three seedlings increased obviously, while the soluble protein content decreased significantly. In the whole growth process, the free proline content was significantly positively correlated with soluble sugar content, but they were weakly negatively correlated with soluble protein content.(6) MDA content of the three seedlings increased with the growth course and the aggravation of water stress. Three enzymes showed different activity at different growth stages. Whether under water stress or not, enzymes activities of R. pseudoacacia were maintained at higher level as compared with other two seedlings.(7) The adaptability and productivity of the three seedlings under water stress were contrasted and compared through subordination function of fuzzy mathematical analysis. The drought-resistant ability of three seedlings was listed in descending order as follows: A. trancatum> P. orientalis> R. pseudoacacia.更多还原