【作者】 林武星；

【导师】 洪伟；

【作者基本信息】 福建农林大学 ， 森林培育， 2005， 博士

【摘要】 木麻黄防护林存在连栽生产力下降、防护功能衰退的突出问题。基于木麻黄更新困难的问题,许多学者从木麻黄品种退化、病虫害频发和土壤理化性质改变等方面对木麻黄更新后生产力下降的原因进行大量的研究。而对于木麻黄存在自身他感作用,亦即木麻黄产生对本种有抑制作用的物质引起自身生长抑制的研究较少,前人曾采用不同浓度的木麻黄小枝浸提液处理木麻黄幼苗研究木麻黄自身他感作用,结果发现随着浸提液浓度增大,木麻黄幼苗生长受到抑制作用加强,而且对幼苗根生长的抑制作用尤为明显,并从木麻黄小枝浸提液中分离鉴定出他感物质为黄酮类衍生物。但对于木麻黄通过根系分泌、枯枝分解等途径产生自身他感作用物质抑制自身生长、木麻黄自身他感作用物质对木麻黄生理生化的影响,以及木麻黄自身他感作用的影响因素和缓解措施的研究尚处于空白。为此,以木麻黄实生苗木为受体材料,木麻黄根系、新鲜叶、枯落叶和表层土壤浸提液为木麻黄自身他感作用物,采用水培方法,研究木麻黄自身他感作用物对木麻黄苗木生长、营养吸收、碳代谢、活性氧代谢及内源激素的影响,探讨木麻黄自身他感作用的影响因素和缓解措施。这对于及时弄清自身他感作用物质对木麻黄生理生化的影响,探明木麻黄更新障碍的原因以及采取相应的措施对木麻黄自毒作用进行调控以提高木麻黄更新生产力,确保木麻黄林地持续利用和木麻黄防护林体系建设顺利实施均有重大而又深远意义。 1 木麻黄自身他感作用物对木麻黄幼苗生长的影响 采用15年生实生木麻黄的根系、新鲜叶、枯落叶及表层土壤水浸液处理木麻黄实生苗,研究木麻黄自身他感作用物对其幼苗生长的影响,结果表明:木麻黄各种器官的水浸液对其幼苗的苗高和地径生长、苗根重量和活力、叶和茎重量均起抑制作用,并且随水浸液浓度增大,抑制作用增强。木麻黄不同器官相同浓度的水浸液对幼苗生长的抑制程度表现为根>新鲜叶>枯落叶>表层土壤。说明木麻黄能通过根泌、叶淋、枯落叶分解等途更多还原

【Abstract】 Proplems of decline of productivity and protective function due to continous plantation exist in Casuarina equisetifolia shelfer-forest. Many scholars have been studying on the causes for decline of productivity of Casuarina after regeneration from these aspects such as decline of species , insect pest and changing of soil physical and chemical character in recent few decades. However, The research on Casuarina self-allelopathy to cause the decline of productivity of Casuarina was rarely reported. Ms. Deng Guilan reported in 1996 that the leaves extracts of Casuarina could inhibited the growth of Casuarina seedlings. Moreover, she isolated and identified five self-allelochemicals from leaves extract. But the studies on that Casuarina can produce self-allelochemicals to inhibit itself growth through root and litter leaves, self-allelochemicals affect physiology and biochemical of Casuarina, effect factors and relief measures on Casuarina self-allelopathy have never been carried out.This research paper studied the effects of Casuarina allelochemicals on the growth , nutritional absorption , Carbon, AOS and endogenous hormone, the factors to affect Casuarina self-allelopathy and the measure of Casuarina self-allelopathy relief through using the seedlings of Casuarina as experimental material and water extract of roots, fresh leaves, litters and surface soil of middle age Casuarina as allelochemicals and method of nutritional culture. The main results were submitted as follows:1 Effects of allelochemicals of Casuarina on the growth of Casuarina seedlings Using water extract of roots, fresh leaves, litters and surface soil of 15-year old Casuarina to handle Casurina seedlings. The results showed that water extract of various organs of Casuarina inhibited the growth of seedlings height and diameter, weight and activity of root, weight of leaves and stems, and this inhibition was strengthened with the increasing of water extract concentration. The inhibition extent of water extract on the growth of seedlingsshowed that roots>fresh leaves>litter>surface soil. It indicated that Casuarina can produce allelochemicals to inhibit itself growth through roots, leaves, litter, and allelochemicals keep jn the soil to affect the growth of next generation. 2 Effects of allelochemicals of Casuarina on nutritional absorption2.1 Under low concentrative water extract (1:40 and 1:20) of roots, the content of P in seedling roots increased 26.3% and 28.8%compared with CK while high concentration (l:10and 1:5) made the content of P reduced 5.1% and 28.8% which indicated that low concentrative allelochemicals promoted the absorption of P of seedling roots while high concentrative allelochemicals inhibited the absorption of P. The content of P in seedling stems and leaves reduced with the increasing of the concentration of Casuarina root water extract. The above mentioned showed that allelochemicals inhibited the absorption of P of Casuarina seedling stems and leaves and prevented the transportation of P from roots to stems and leaves.2.2 Low concentrative water extract of Casuarina roots promoted the absorption of K of seedling roots and stems while high concentrative extract inhibited the absorption and transportation of K. The content of K in seedling roots increased 11.4% when the concentration of water extract was 1:40. Then with the increasing of root water extract, the content of K in the root decreased. The content of K in seedling roots reduced 59.1 %^ 80.1 % and 175% when the concentration of root extract was 1:20. And the content of K reduced with the increasing of water extract of roots. The content of K in the stems reduced 24.4% and 74.9% compared with CK when root extract of Casuarina were 1:10 and 1:5. The content of K in seedling leaves dramatically reduced with the increasing of root extract. The content of K reduced 15.8% to 167.6% compared with CK. The above mentioned showed that allelochemicals could inhibit the absorption of seedlings on K. But low concentration of allelochemicals promoted the absorption of K of seedling roots and stems.2.3 The content of Ca and Mg of seedlings reduced dramatically under water extract of roots. The content of Ca in seedling roots > stems and leaves reduced 31.6%~122.6% ^ 35.5%~226.7%and 34.0%~176.8% respectively compared with CK and the content of Mg declined 90.4%~180.2%, 6.7%~31.4%and 23.7%~I76.7% respectively. The above mentioned indicated that allelochemicals inhibited Casuarina seedlings to absorb Ca and Mg. Moreover, the higher the concentration of allelochemicals, the stronger the inhibition.2.4 Under water extract of Casuarina root, the content of Fe in seedling leaves continuously declined with 4.0%~108.3% compared with CK while it in the roots and stems added 3.7% and 5.3% respectively compared with CK when water extract of seedling roots was 1:40. However, the content of Fe in roots and stems of seedlings reduced 35.0%~107.7% and 35.7%~146.8% respectively when the concentration of water extract of roots was more than 1:40. The content of Cu of seedling stems and leaves increased 33.8%~48.0% and 38.4%~49.1% when the concentration of water extract of seedling roots was less than 1:20 while it declined 35.5%~49.0% and 97.6%~105.0% respectively when the concentration of water extract of roots was more than 1:20. However, the content of Cu in seedling roots reduced 12.7%~214.4% compared with CK with the increasing of water extract of roots. The content of Mn in seedling roots and leaves declined 32.4%~212.1% and 22.3%~151.9% respectively with the increasing of water extract of Casuarian roots. Low concentrationl:40and 1:20) of water extract of roots caused the content of seedling stem to increase 22.5% and 44.4% respectively compared with CK while high concentration (1:10and l:5)made the content of Mn decline 72.6%~134.8%. The content of Zn in roots> stems and leaves of seedlings reduced 15.9%~276.3%> 31.6%~99.6% and 5.7%~110.2% respectively.It could be concluded that self-allelochemicals Casuarina produced inhibited seedlings of Casuarina to absorb the nutrition from the soil. The reason was that self-allelochemicals of Casuarina poisoned the roots of Casuarina seedlings which reduced the activity of Casuarinaseedlings. However, the fact that low concentration allelochemicals promoted seedlings to absorbed some nutrition perhaps was related to the defensive response that seedlings made under the stimulation of allelochemicals.3 Effects of self-allelochemicals of Casuarina on Carbon of Casuarina seedlings3.1 self-allelochemicals declined the content of Chi of seedlings. Self-allelochemicals reduced the content of Chi a, band a/b. Meanwhile, the extent of declining of Chi a> b and a/b was strengthened with the increasing of the concentration of allelochemicals. The content of Chi a > b and (a+b) of leaves(unit.Fw) of seedlings reduced 9.09%~68.77% ^ 5.76%~60.27%and 7.45%~54.9% respectively, and Chi a/b reduced 5.76%~60.27%. The declining of Chi is unfavorable to photosynthesis of Casuarina. The extent of Chi a declining was more than Chi b which was obvious when the concentration of allelochemicals was high. The content of Chi mainly a reduced largely when the concentration of allelochemicals was high.3.2 Photosynthesis efficiency of seedlings reduced under self-alleiopathy of Casuarina. net photosynthetic rate, light staturation point, CO2 staturation point, carboxylation efficiency and photophosphorylation activities of casuarinas were reduced under self-allelopathy and glycolate oxidase activities were strengthened .3.3 The accumulation of C in seedlings of Casuarina declined under self-allelopathy the content and accumulation of C of casuarinas were declined and content of total soluble sugars in casuarinas roots and items were increased under self-allelopathy, while content of total soluble sugars in casuarinas leaves was increased under low concentration of self-allelopathy, but high one caused its dropping.4 Effects of self-allelochemicals of Casuarina on AOS and endogenous hormone of seedlings 4.1 the content of the growth promoting hormones of seedlings declined under self-allelopathy of Casuarian.the content of the growth promoting hormones in leaves and roots of casuarina IAA> GF^ iPAs and ZRs decreased under self-allelopathy and the content ofdecreasing was strengthened with the increasing of concentration of self-allelopathy. And the balance of endogenous hormones were broken and the content of ABA increased as well as ABA/lAA,ABA/GA,ABA/iPAs and ABA/ZRs. Under self-allelopathy, the increment and biomass of roots,items and leaves of casuarina has close relation to the reducing of content of IAA,GR,iPAs and ZRs.increasing of content of ABA and the damage of the balance of endogenous hormones.4.2 the balance of AOS was damaged and AOS greatly acumulated in the casuarina under self-allelopathy. It showed that permeability of plasma membrane increased construction and function of membrane were damaged . The content of MDA increased and membrane lipid peroxidation became serious.The producing speed of O2" and the content of H2O2 in leaves cells increased, and the balance of AOS on producing and clearing was broken. AOS acumulated greatly in leaves cells.The defense system of AOS was damaged and the activity of SOD,CAT,GR and POD decreasd as well as the ability of cells on clearing O{ and H2O2. 5 Effect factors and relief of self-allelopathy of Casuarina5.1 Selection of proper clone of Casuarina relieved self-allelopathy of Casuarina. Inhibition of self-allelochemicals of different clone of Casuarina on seedlings and resistance of different clone seedlings on allelochemicals of Casuarina were different. The inhibition extent of allelochemicals of experimental clone showed seed breeding >clone Dongl> clone Pingl>clone Yue601>clone Yue701. Clone Yue501> clone Yue701 and clone Huil had high resistance and adaptability. In practical plantation, Casuarina could relieve to inhibit its growth because of self-allelopathy through selecting clone Yue50k Yue601 , Yue701 and Hui 1 to plant.5.2 Density of stand affected Casuarina self-allelopathy. Low density relieved the growth inhibition of Casuarina. Under high density, Casuarina strengthened the producing of self-allelochemicals and the growth inhibition, relieved photosynthesis and Pn. Moreover,更多还原