【作者】 柯裕州；

【导师】 彭镇华； 张旭东；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2008， 博士

【摘要】 本文在查阅大量文献的基础上,对盐碱地综合治理、植物抗盐性和抗盐机理等方面的国内外研究进展进行综述,并以黄河流域及西北地区常用的桑树砧木—实生桑为研究材料,采用盆栽加盐和大田试验等方式,进行桑树幼苗抗盐性试验,通过对桑树幼苗成活率、光合作用、叶绿素荧光及其他一些指标的测量,系统分析了实生桑的耐盐能力及其幼苗在盐胁迫环境下的生理生化变化过程,并分析其抗盐机理。主要结论如下:(1)实生桑不同阶段的耐盐能力表现为1年生幼苗>种子。种子对盐分的敏感性极强,NaCl浓度为0.1% (g / g﹒干土重),其种子成苗率为9.67%;而NaCl浓度为0.2%,则难以成苗,故在盐碱地的综合治理中难以采用直播的方式进行推广。通过综合评价分析,1年生幼苗NaCl浓度适宜值为0.13%,临界值为0.30%,极限值为0.52%。(2)盐胁迫对桑树幼苗生长发育具有明显的抑制作用,且不同器官对盐胁迫的敏感程度表现为根>茎>叶。实验期间,当NaCl浓度为0.5～0.7%时,桑树幼苗的根系生长下降81.33-92.35%,新梢生长下降70.94-84.62%,叶片生长下降56.18-75.97%。盐胁迫能够显著降低桑树幼苗根冠比,当根冠比低于0.067～0.071时,植株受害极其严重,80%以上的植物枯死。(3)盐胁迫下, 0.1%NaCl处理浓度对桑树幼苗叶片的净光合速率(Pn)具有一定的促进作用;而0.3%、0.5%和0.7%则对Pn具有明显的抑制作用,且造成桑树幼苗Pn降低的效应主要是由非气孔因素控制的。在一定范围内,PAR和CO2浓度的增大可提高Pn。此外,随着NaCl处理浓度增大,Gs、Tr、WUE、Ls下降,而Ci上升。盐胁迫对桑树幼苗叶片的叶绿素荧光参数具有显著影响。试验期间,随NaCl处理浓度增大,Fo呈下降的趋势,但处理之间Fo变化差异不明显;而Fv/Fm、Fv/Fo、Fm和ΦPSⅡ下降,NPQ则先升后降。分析表明,盐胁迫对桑树幼苗光合作用的影响是多方面的,一方面是通过阻碍光合电子传递、降低光化学效率和光能转化效率来抑制植物的光合作用;另一方面则通过破坏细胞膜系统的结构和功能,降低光合酶的活性,引发光合机构的异常。而叶片中Na +和Cl -离子在抑制桑树幼苗的光合作用起主要作用,且Cl -离子的效应大于Na +离子。(4)盐胁迫对桑树幼苗的危害包括离子毒害、营养失衡、产生渗透胁迫和破坏细胞膜结构和功能的完整性,主要表现出植物体内Na+、Cl-的大量累积;植物器官中Ca2+、K+、Mg2+含量下降;K+/ Na+、Ca2+/ Na+、Mg2+/ Na+值急剧减小;器官含水量下降、叶片萎焉;质膜透性增加、MDA含量增大。(5)桑树幼苗对盐胁迫的适应机理可能包括以下四个方面,即离子的区域化作用、离子稳态重建、渗透调节作用和抗氧化保护体系的调节作用,主要表现为:①在器官层次上,桑树幼苗具有明显的Na+区域化作用,且离子的区域化作用具有明显的阈值效应,实生桑1年生幼苗Na+在器官层次上的区域化作用极限值在0.3%～0.5%之间。②试验初期,盐分对根系Ca2+、K+、Mg2+离子的吸收具有一定的促进作用,各个器官Ca2+、K+、Mg2+离子含量的增加,在一定程度上缓解Na+离子毒害,维持一定的K+/ Na+、Ca2+/ Na+、Mg2+/ Na+值,保证代谢的正常进行和植物生存。③Na+和Cl-是桑树幼苗适应盐胁迫主要渗透调节物质,高盐浓度(0.5-0.7%)下,其占实测渗透势的32.53%～66.96%。渗透调节过程中脯氨酸也发挥了重要作用,此外,可能存在其他有机小分子物质来平衡细胞质与液泡之间的渗透。④SOD、CAT和POD活性先升后降,表明了抗氧化酶系统在一定程度上能减轻或缓解盐胁迫对桑树幼苗的迫害。(6)桑树种植后,盐碱地土壤容重下降、土壤砂粒和粘粒含量降低、粉粒含量升高增加,土壤含盐量明显降低,土壤pH值略微减小,这些现象充分说明了土壤理化性质有所改善,保水保墒能力增强。同时,土壤N、P、K,有机质和腐殖质含量、土壤微生物数量和土壤酶活性都呈增大趋势,可见,桑树在盐碱地土壤改良中具有一定的作用。更多还原

【Abstract】 Based on the extensive available literature at home and abroad, this dissertation summarized the research advance on the saline-alkali soil comprehensive management, salt-resistance or salt tolerance and their salt-resistant or salt-tolerant mechanism. In this pot experiments treated with NaCl and the field experiments in the saline-alkali soils, with a common stock of Mulberry - Shishengsang(实生桑)(Morus alba),which adapted to the Yellow River valley and northwestern areas , as experimental materials, seedling emergences of seeds, the survival rate of seedlings, photosynthesis and chlorophyll fluorescence and other indicators were measured, and the physiological and biochemical process of mulberry seedlings in salt stress environment were systematically analyzed, moreover, their salt-resistant mechanism was researched . Main conclusions are as follows:(1) For Mulberry - Shishengsang(实生桑)(Morus alba)at different stages, it showed salt tolerance of 1 year-old seedlings was higher than that of its seeds. NaCl semi-lethal concentration for 1 year-old mulberry seedlings was 0.3% (g / g. DW) or so. Its seeds showed extremely sensitive to salt, and its Seedling emergences was 9.67 % under 0.1% NaCl concentration treatment , while 0 % under 0.2% NaCl concentration, so it is difficult to use and promote them in the saline-alkali soil Comprehensive Management by sowing.(2) Salinity significantly inhibited the growth and development of mulberry seedlings. During the experiments, Salinity significantly inhibited the growth of mulberry leaves, elongation of renewal branches and elongation and formation of lateral roots, and the sensitivity to salt of different organs performed lateral root> renewal branch> leaf. Under NaCl concentration of 0.5 to 0.7%, lateral root augment declined 81.33-92.35%, while that of renewal branches and leaves declined 70.94-84.62% and 56.18-75.97%, respectively. In addition, the root-shoot ratio of mulberry seedlings significantly decreased under salt stress, it showed that the plants suffered extremely seriously, and more than 80% of plants withered, when the root -shoot ratio would be below 0.071 to 0.067.(3) The net photosynthetic rate (Pn) of mulberry seedlings under 0.1% NaCl concentration was above that of control, but it was contrary when under 0.3%, 0.5% and 0.7% NaCl concentration treatments, moreover, net photosynthetic rate gradually decreased with NaCl concentration increasing. It denoted the main factor inhibiting Pn is non-stomatal control. In addition, salinity had significant effects on stomatal conductance(Gs), intercellular CO2 concentrations(Ci),and transpiration rate(Tr), water use efficiency (WUE)and stomatal limiting value (Ls) , and in which Gs, Tr, WUE and Ls dropped, but Ci rose with NaCl concentration increasing. To some extent, enhancing PAR or CO2 concentration may enhancing Pn .Salinity had significant impact on the chlorophyll fluorescence of mulberry seedling leaves. During the experiments, it showed a declining trend for Fo, but the differences of it between various treatments were not obvious with NaCl concentration increasing. Fv / Fm, Fv / Fo, Fm andΦPSⅡdeclined, but NPQ is first increased and then decreased. with NaCl concentration increasing .there may exist many accesses to photosynthesis inhibition of mulberry seedlings for salt stress, one was by hampering photosynthetic electron transfer, reducing the photochemical efficiency and energy conversion efficiency to curb the plant photosynthesis, the other, by destructing the membrane system structure and function, lowering photosynthetic synthase activity and triggering the photosynthesis Reaction Center abnormal. In the end, Na + and Cl - ions played a major role in to curb photosynthesis of mulberry seedlings, and the effect of Cl– ion on inhibiting photo- synthesis was greater than that of Na + ion.(4)The damages of salinity to mulberry (Morus alba) seedlings may attribute to ion toxicity, nutritional imbalance or deficiency, osmotic stress effects and destructible membrane structure and function, which were testified by the negative effects of salinity on mulberry morphology and ecophysiology, such as Na+ and Cl- ion mass cumulation in plants, a decline of Ca2+、K+、Mg2+ ion concentration in mulberry organs, a drop of K+/ Na+, Ca2+/ Na+and Mg2+/ Na+ ratio, a decrease of water moisture, fading mulberry leaves as well as an increase of MDA content and memberane permeability.(5) Adaptability mechanisms of mulberry seedling to salt stress can be included as below: ion compartmentalization, ion homeostasis regeneration, osmotic regulation and antioxidant protection systems self-defense, which could be suggested by the proofs such as①Na + compartmentalization at the organ level had impacts on the salt tolerance of mulberry seedlings, and for 1-year-old mulberry seedlings, its threshold may be between from 0.3% to 0.5%.②In the early-stage of experiments, salinity had a positive impact on Ca2+,K+ and Mg2+ ions uptake and distribution of mulberry seedlings, and K+/ Na+、Ca2+/ Na+、Mg2+/ Na+ ratio can be control to maintain life.③Na+ and Cl- in mulberry seedlings, which occupied 32.53%～66.96% in osmotic potential when treated with 0.5-0.7% NaCl concentrations, may take a major position in the osmotic regulation. For organic substances, proline was an important osmolyte under salt stress condition, and it may act as a mediator of osmotic adjustment. In addition, there may be other organic material to balance the osmotic potential between the cytoplasm and the vacuole.④antioxidant enzymes activity such as SOD, POD and CAT to perform at first increasing and then decreasing may be suggested that antioxidant enzyme system activities, to a certain extent, can reduce or mitigate salt damage to mulberry seedlings under salt stress.(6) After applied to saline-alkali soils, mulberry trees can improve the soil physicochemical properties, enhance soil nutrition contents, decrease salt concentratations, enhance enmyzes activities and multiple soil microbes.更多还原