【作者】 王辉；

【导师】 袁玉欣； 李玉灵；

【作者基本信息】 河北农业大学 ， 森林培育， 2009， 硕士

【摘要】 刺槐是我国北方最重要的造林树种之一,连栽导致地力衰退。刺槐自毒作用是导致刺槐林地力衰退、生产力下降的重要原因之一。本文首先分析了刺槐枯落物和根际土壤化感物质对刺槐种子发芽及其幼苗的化感效应,验证自毒作用的存在;然后在此基础上分别研究了刺槐枯落物、刺槐根际土和臭椿根际土对1年生刺槐幼苗的外部形态指标和部分生理指标的影响,探讨臭椿与刺槐混交林分中,臭椿对刺槐的影响,而且通过刺槐与主要混交树种种间生化作用的研究,解决刺槐连栽障碍问题,实现刺槐林地的可持续经营,防止刺槐连栽生产力下降在理论上和实践上都具有重要的理论参考价值及实践意义。研究结果表明:(1)刺槐根际土、刺槐枯落物和臭椿根际土浸提液对刺槐种子发芽率和种子活力以及幼苗根长影响基本都是在低浓度时呈抑制作用但达不到显著水平,甚至有的表现为促进作用,在浓度较高时抑制作用增大,并逐渐达到显著水平,到0.2 gDW?ml-1时基本完全抑制种子的萌发和幼苗根长的生长。无论在那个浓度时,三个浸提液对刺槐种子的抑制作用一般表现为:刺槐根际土﹥刺槐枯落物﹥臭椿根际土。3种浸提液对刺槐幼苗生长的促进作用大于对种子萌发的促进作用。(2)臭椿根际土浸提液对1年生刺槐幼苗苗高和地径生长的影响很大,在浓度较低时(0.005 gDW?ml-1和0.01 gDW?ml-1),能促进刺槐幼苗的生长,但是随着浓度的逐渐增大,促进作用逐渐转变为抑制作用,并且抑制作用逐渐增强,到0.1 gDW?ml-1时,抑制作用达到显著水平。刺槐根际土浸提液对自身幼苗在低浓度时作用不明显,只有在浓度较高时才呈抑制作用,并且抑制作用都大于相同浓度下臭椿根际土的抑制作用。臭椿根际土浸提液对刺槐苗高的作用与刺槐根际土的作用差异较大,对苗高的抑制作用比对地径的抑制作用小。(3)刺槐根际土对刺槐的光合作用有抑制作用,并且浓度越大抑制作用越显著。臭椿根际土对刺槐幼苗光合作用也有抑制作用,但是比刺槐根际土的抑制作用小,甚至在浓度很低时有不显著的促进作用。(4)刺槐根际土浸提液对刺槐幼苗叶片叶绿素a和叶绿素b的合成都有抑制作用,对叶绿素a的抑制作用大于对叶绿素b的作用,刺槐根际土浸提液对叶绿素的形成造成破坏,对叶绿素的合成与分解之间的平衡产生影响。臭椿根际土浸提液对叶绿素a和叶绿素b主要的作用为促进作用,只有在浓度很低(0.005 gDW?ml-1)表现出了一定的抑制作用,但效果并不显著,在其他浓度的影响下,叶绿素含量都有一定程度的增加。(5)刺槐和臭椿对刺槐幼苗细胞膜透性有一定的影响,但影响并不大,随着浓度的增加,细胞膜透性逐渐变大,但是变化缓慢,当浓度达到0.1 gDW?ml-1时刺槐根际土浸提液对刺槐幼苗电导率的影响达到显著水平。并且无论在何种浓度下,臭椿根际土浸提液对刺槐幼苗细胞膜的破坏作用总小于刺槐根际土浸提液对其的影响,因此臭椿根际土对刺槐幼苗细胞膜的破坏作用要比刺槐自身根际土的破坏作用小。(6)在刺槐根际土和臭椿根际土浸提液的作用下,刺槐幼苗细胞的超氧化物歧化酶和过氧化物酶的活性总体上是上升的,只有在浓度较低时才呈现出降低的作用。在化感物质的作用下,植物的细胞受到影响,或细胞的膜系统受到损害,细胞的超氧化物歧化酶的活性升高,过氧化物酶活性也上升,但变化幅度较小,并且臭椿根际土作用的水平显著小于刺槐本身的作用。所以随着浓度的升高,两种浸提液对刺槐的生长逐渐转变为抑制作用,并且刺槐根际土的抑制作用一直比臭椿大。(7)刺槐根际土浸提液对可溶性糖含量的影响并不大,在自毒作用下,刺槐幼苗的可溶性糖含量增加很少,而臭椿作用下的刺槐幼苗的可溶性糖含量明显增加,随着浓度的增大,含量逐渐增多。臭椿化感作用刺激刺槐幼苗糖分的积累,可以在一定程度上提高刺槐抗胁迫的能力,有助于以后的快速生长。在两种浸提液的作用下,刺槐幼苗细胞中的丙二醛含量都有一定程度的增加,两种浸提液对细胞膜系统都有一定的破坏作用。但是在低浓度(0.005 gDW?ml-1)下,刺槐幼苗细胞中丙二醛的含量有所下降或上升很少,随浓度的增加,细胞膜受破坏程度逐渐增加,并且臭椿根际土浸提液对刺槐细胞膜的破坏作用要比刺槐根际土的破坏作用小。(8)在低浓度下,游离脯氨酸的含量降低,随着浓度的升高,脯氨酸的含量逐渐增加。一般在相同浓度下,刺槐根际土浸提液作用的刺槐幼苗的脯氨酸含量较高,刺槐根际土浸提液对刺槐幼苗的抑制作用较大。当浓度达到0.1 gDW?ml-1时,两种根际土浸提液对刺槐幼苗的作用大小接近一致,可见,当浓度比较大时,两种植物根际土浸提液对刺槐幼苗的生长有相似的抑制作用。更多还原

【Abstract】 Robinia pseudoacacia is one of the most important reforestation trees in northern China. The field investigation suggested that Robinia pseudoacacia had poor establishment and low productivity, and would lead to soil degradation when grown after it again. So, the bioassays seed germination was used to assays the effect of Robinia pseudoacacia rhizosphere soil, Robinia pseudoacacia litter and Ailanthus altissima rhizosphere soil allelochemicals extracted by different solvent on Robinia pseudoacacia seed germination and growth of seedling. To verify the existence of autointoxicational; and then on this basis to study the effection of Robinia pseudoacacia litter, Robinia pseudoacacia rhizosphere soil and Ailanthus altissima rhizosphere soil on external form of Robinia pseudoacacia seedlings and some physiological indicators. Explore the relation between Robinia pseudoacacia and Ailanthus altissima , and it have great theoretical and practical significance of reference value that resolve the issue of Robinia pseudoacacia plantation obstacles and achieve the sustainable management of woodlands Robinia pseudoacacia, Robinia pseudoacacia plantation to prevent a decline in productivity Through the research on the main role in various biological and chemical reactions between Robinia pseudoacacia with others. The results show that:(1) The extract of Robinia pseudoacacia rhizosphere soil, Robinia pseudoacacia litter and Ailanthus altissima rhizosphere soil can inhibit effect at low concentrations but less than significant level on Robinia pseudoacacia seed germination rate、seed vigor and seedling root length, and even some of the performance of to promote the role of inhibition in the higher concentration increased and gradually reached a significant level, to 0.2 gDW?ml-1 basically completely inhibited seed germination and seedling root length growth.No matter in what concentration, the three extracts on the inhibition of Robinia pseudoacacia in general as follows: Robinia pseudoacacia rhizosphere soil> litter Robinia pseudoacacia> Ailanthus altissima rhizosphere soil. Three extracts of Robinia pseudoacacia seedling growth than on the promotion of the role of promoting the role of seed germination.(2) The effect of Ailanthus altissima rhizosphere soil extract on the one-year-old Robinia pseudoacacia seedling height and diameter growth is large, low concentration (0.005 gDW?ml-1 and 0.01 gDW?ml-1), to promote Robinia pseudoacacia seedlings growth, but with increasing concentration, and promote the role of inhibition gradually changed, and inhibition gradually increased, to 0.1gDW?ml-1 when the level of inhibition was significant. The effect of Robinia pseudoacacia rhizosphere soil extract on its own seedlings role at low concentrations was not obvious, only when in higher concentrations were inhibitory, and inhibitory concentration greater than the same rhizosphere soil Ailanthus altissima inhibition. Ailanthus altissima rhizosphere soil and Robinia pseudoacacia rhizosphere soil play different role on the effect of Robinia pseudoacacia height, and the inhibition on height than on the diameter.(3) Robinia pseudoacacia rhizosphere soil can inhibit photosynthesis of itself, and the concentration of the more significant the greater the inhibition. Ailanthus altissima rhizosphere soil extract also can inhibit photosynthesis of Robinia pseudoacacia seedlings, but smaller than Robinia pseudoacacia rhizosphere soil in the inhibition of, even in low concentrations have no significant role in promoting(4) Robinia pseudoacacia rhizosphere soil extract have inhibition on the synthesis chlorophyll a and chlorophyll b of Robinia pseudoacacia seedlings,and the inhibition of chlorophyll a is greater than to chlorophyll b. The Robinia pseudoacacia rhizosphere soil extract can cause damage to the formation of the chlorophyll and impact the balance between synthesis and decomposition of chlorophyll. Ailanthus altissima rhizosphere soil extracts for chlorophyll a and chlorophyll b main role is to advance the role, only in very low concentrations (0.005 gDW?ml-1) show a certain degree of inhibition of the Agency, the effects are not significant. In other concentrations the influence of chlorophyll content has a certain degree of increase.(5) Robinia pseudoacacia rhizosphere soil extract and Ailanthus altissima rhizosphere soil extract can effect membrane permeability of Robinia pseudoacacia seedlings, but not too great, with the increase in concentration, membrane permeability gradually become larger, and slow to change, when the concentration is 0.1gDW?ml-1 the effects of Robinia pseudoacacia rhizosphere soil extract on electrical conductivity of Robinia pseudoacacia seedlings reach a significant level. no matter under what the concentration, the effections Ailanthus altissima rhizosphere soil extract on Robinia pseudoacacia seedlings membrane is less than the destruction of the role of Robinia pseudoacacia rhizosphere soil extract its impact, so the destructive effects of Ailanthus altissima rhizosphere soil to cell membrane of Robinia pseudoacacia seedlings smaller than Robinia pseudoacacia rhizosphere soil.(6) In the impact of Robinia pseudoacacia and Ailanthus altissima rhizosphere soil rhizosphere soil extracts, the cell superoxide dismutase activity and the superoxide dismutase of Robinia pseudoacacia seedlings in general is rising, only when present in low concentrations to reduce. In the role of allelochemicals, the plant cells affected, or cell membrane damaged, cell superoxide dismutase activity increased, peroxidase activity rise, but change less, and effections of Ailanthus altissima rhizosphere soil was significantly less than Ailanthus altissima in itself. So with the increased of concentration both extracts on the growth of Robinia pseudoacacia for the inhibitory effect of a gradual change, And the effection of Robinia pseudoacacia has been obvious than Ailanthus altissima.(7) Robinia pseudoacacia rhizosphere soil extracts of the soluble sugar content did not affect, in the autotoxicity, the increased of soluble sugar content of Robinia pseudoacacia small, but the increased significantly under Ailanthus altissima, As the concentration increases, the content increased gradually. Allelopathy of Ailanthus altissima can stimulate the accumulation of sugar of Robinia pseudoacacia, which improve the ability of Robinia pseudoacacia Anti-Stress to a certain extent, contribute to the rapid growth of the future.In both the effects of extracts, cells MDA in Robinia pseudoacacia seedlings have a certain increase. In two extracts of the cell membrane systems have a certain degree of damage. However, in low concentration (0.005gDW?ml-1), the cells MDA in Robinia pseudoacacia seedlings declined or increased very little, the damage of membrane gradually increased, and the destructive effects of Ailanthus altissima rhizosphere soil extract to Robinia pseudoacacia membrane less than Robinia pseudoacacia rhizosphere soil in the destructive effects.(8)In low concentration, the free proline content lower, with the higher concentration, a gradual increase in proline content. Generally in the same concentration, Robinia pseudoacacia seedlings with a high level of proline under the effection of Robinia pseudoacacia rhizosphere soil extract. So the inhibition of Robinia pseudoacacia rhizosphere soil extracts on Robinia pseudoacacia seedlings is larger. When the concentration reached 0.1 gDW?ml-1, the effection of two rhizosphere soil extracts close to the same size, we can see that when the concentration of relatively large, the two extracts on the growth of Robinia pseudoacacia seedlings have similar inhibitory effect.更多还原