Distribution of Accumulated Aluminum and Changes in Cell Wall Polysaccharides in Eucalyptus camaldulensis and Melaleuca cajuputi under Aluminum Stress

Distribution of aluminum (Al) within plant components and Al-induced changes in cell wall polysaccharides in root tips of Eucalyptus camaldulensis Dehnh. seedlings were compared with those of Melaleuca cajuputi Powell. In E. camaldulensis, 0.5 mM Al (pH 4.2 for 40 d) reduced plant dry weight by 50%, increased callose concentration in the root tips and induced leaf necrosis. In comparison with M. cajuputi, Al concentrations were higher in roots and leaves of E. camaldulensis on both a fresh weight basis and in the cell sap, but were lower in the cell wall. Al increased pectin, hemicellulose and cellulose concentration in the cell walls of E. camaldulensis root tips. Al-induced leaf necrosis and growth reduction in E. camaldulensis is discussed in the context of potentially toxic concentrations of Al in plant tissue and changes in polysaccharide content which could reduce water and nutrient uptake and cell wall extensibility in roots.     

Changes in Cell Wall Polysaccharides and Hydroxycinnamates in Wheat Roots by Aluminum Stress at Higher Calcium Supply

The present study was conducted to investigate the cell-wall polysaccharides and hydroxycinnamates in wheat plants (Triticum aestivum L.) under aluminum (Al) stress at a higher level of calcium (Ca) supply. Seedlings were grown in nutrient solution for 7 d and then subjected to treatment solutions containing Al (0 or 100 μM) and Ca (0 or 2500 μM) in a 500 μM CaCl ₂ solution at pH 4.5 for 8 d. Calcium treatment (2500 μM) improved root growth significantly under Al-stress conditions. The contents of pectin and hemicellulose in roots were increased under Al-stress conditions, and this increase was conspicuous in the hemicellulosic fraction. The increase in the hemicellulose was attributed to increases in arabinose, xylose, and glucose in neutral sugars. High Ca treatment decreased these contents in Al-stressed cell walls. Aluminum treatment increased the content of ferulic acid, whereas Ca treatment with Al reduced the content. These results suggest that Al may modify the mechanical properties of cell-wall polysaccharides by enhancing the synthesis of arabinoxylan, β-glucan, and ferulic acid in the cell wall. High Ca treatment may maintain the normal synthesis of these materials even under Al-stress conditions.     

猕猴桃果实贮藏期间细胞壁多糖物质降解特性及组织结构差异分析

为了深入了解猕猴桃果实采后细胞壁多糖物质降解及组织结构变化与果实贮藏性的关系,本研究以红阳和华特猕猴桃果实为试材,对25和4℃贮藏期间的细胞壁多糖物质含量及果胶降解酶活性进行测定,并比较两品种果实在25℃贮藏期间的细胞显微结构和钙组分含量差异。结果表明,在25和4℃贮藏条件下,随着贮藏时间的延长,红阳和华特猕猴桃果实中半纤维素（HCL）、纤维素（CL）和共价结合型果胶（CSP）含量不断降低,水溶性果胶（WSP）含量不断上升,离子结合型果胶（ISP）含量相对稳定。红阳猕猴桃各细胞壁多糖组分含量变化速度较快。两品种猕猴桃果实硬度均与WSP含量呈显著负相关,与CSP含量呈显著正相关。果胶降解酶活性检测结果显示,25℃贮藏前期,红阳猕猴桃中果胶酸裂解酶（PL）和β-半乳糖苷酶（β-Gal）活性显著高于华特;贮藏中后期,红阳中果胶甲酯酶（PME）活性显著高于华特。4℃贮藏期间,红阳中PME活性仍显著高于华特;4℃贮藏前期,红阳中β-Gal活性与华特无显著差异,而PL活性低于华特。相关性分析表明,25℃贮藏期间,与红阳和华特果实软化显著相关的果胶降解酶分别是PME和PL;4℃贮藏期间,与华特果实软...     

铝毒胁迫下磷对荞麦根系铝形态和分布的影响

以2个荞麦（Fagopyrum esculentum Moench）品种＂江西荞麦＂（铝耐性）和＂内蒙荞麦＂（铝敏感）为材料,采用水培法,研究铝毒胁迫下磷对荞麦根系总铝和单核2种形态以及Al在根尖和细胞壁中的分布情况的影响。结果表明,与200μmol/L Al处理相比,1.0mmol/L磷预处理分别使江西荞麦和内蒙荞麦的相对根长增加了24.4%和35.9%,根系总Al含量分别降低了18.2%和22.5%,根系单核Al含量分别降低了95%和63.2%。根尖细胞壁荧光检测结果为在单Al胁迫下细胞壁的荧光强度最大,1.0mmol/L磷预处理大幅度减弱细胞壁的荧光强度。表明外源磷供应可降低根系总Al和单核Al含量,使毒性形态的铝转化为无毒形态,以及减少Al在根尖以及细胞壁的积累,以缓解Al对根伸长的抑制,提高荞麦根系的抗铝毒害能力。     

草酸处理对桂七芒果冷害及细胞壁代谢的影响

为探讨草酸处理对低温冷藏下芒果冷害及细胞壁代谢的影响,本试验以桂七芒果果实为试材,采用5 mmol·L^-1草酸溶液浸泡处理,以清水浸泡处理为对照,并于4℃贮藏,分析芒果的冷害指数、丙二醛(MDA)含量、相对电导率、硬度、细胞壁物质含量、细胞壁代谢酶的变化。结果表明,与对照组相比,草酸处理显著降低了低温贮藏14 d后桂七芒果果实冷害指数、MDA含量、相对电导率、原果胶和纤维素含量,显著降低了低温贮藏28 d后果实的硬度;显著提高了低温贮藏14 d后果实水溶性果胶含量及多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、纤维素酶(Cx)活性,显著提高了贮藏21 d后果实β-半乳糖苷酶(β-Gal)活性。综上所述,草酸处理能减轻桂七芒果冷害,维持采后果实细胞壁降解酶较高活性和水溶性果胶含量。本研究为揭示草酸减轻芒果果实冷害机制提供了依据,可为草酸应用于其他冷敏型果实的贮藏保鲜提供理论参考。     

小麦根尖细胞壁对铝的吸附/解吸特性及其与耐铝性的关系

研究了耐铝性明显差异的2个小麦基因型西矮麦1号(耐性)和辐84系(敏感)根系对铝毒胁迫的反应与根尖细胞壁组分以及细胞壁对铝的吸附和解吸的关系。结果表明,30mol/L.AlCl3可迅速抑制小麦根系伸长,但对辐84系根系伸长的抑制更为明显,且小麦根系相对伸长率随着铝浓度的提高而急剧降低。在30mol/L.AlCl3处理24h后,西矮麦1号根系伸长的抑制率为33.3%,而辐84系根系伸长的抑制率高达70.9%。小麦距根尖0～10.mm根段的铝含量和细胞壁中果胶糖醛酸含量显著高于10～20.mm根段,且前者对铝的累积吸附量明显大于后者;在0～10.mm根段,敏感基因型果胶含量高于耐性基因型,其根尖含铝量及根尖细胞壁对铝的吸附量都要大于后者。采用1.0.mol/L.NH3.H2O对细胞壁预处理2.h降低果胶甲基酯化程度后,耐性和敏感基因型根尖细胞壁对铝的累积吸附量分别降低了17.1%和20.9%,但对铝的累积解吸率没有影响。由此可见,小麦根尖是铝毒的主要位点,细胞壁果胶含量和果胶甲基酯化程度可能是导致不同小麦基因型根尖细胞壁对铝吸附量、铝积累量的差异及其对铝毒胁迫反应的差异的重要原因。     

不同蔬菜对镉的吸收累积及亚细胞分布

采用营养液培养,基于叶绿体分离方法,研究了不同种类蔬菜对镉吸收、运输和亚细胞的分布规律。结果表明,蔬菜在不同浓度镉的营养液中培养1周后,蔬菜生物量没有产生显著差异,而不同种类的蔬菜生物量差异较大。镉在蔬菜叶片中大部分存在于细胞壁中,占总量的62％～85％,少量存在于原生质（不含叶绿体）和叶绿体中;随着营养液中镉浓度的增加,各组分中镉的含量明显增加,但分配比例变化不大。各种蔬菜根中镉的含量高于地上部镉含量;随着镉浓度的增加,根中镉分配比例从44％-59％降低至27％～38％;不同蔬菜根部对镉的吸收能力及镉向地上部转移的能力有显著性差异。     

Soil rehabilitation through afforestation: evaluation of the performance of Eucalyptus and pine plantations in a Nigerian Savanna environment

On the outskirts of Zaria, northern Nigeria, Eucalyptus camaldulensis and Pinus oocarpa plantations have been established to satisfy both land rehabilitation and agroindustrial objectives. Soils of the plantations and adjacent unafforested degraded sites where major influences from soil type and management were minimal were sampled to provide data for a parallel investigation of the effect of afforestation on soil rehabilitation. Three adjacent age–grade plantations in respect of each tree species were involved. These are 6, 13 and 27 years for eucalyptus, and 7, 15 and 25 years for pines. Results obtained showed that the rate of soil regeneration in the context of present silvicultural practices is extremely slow. Of the soil parameter studies, only organic matter shows significant improvement within the examined time frame. The soil texture, bulk density, infiltration rate, nutrient elements and pH showed only slight improvement. There was little evidence to suggest that either of the tree species had a more beneficial effect on the soil than the other. The significance of the results is discussed in terms of land‐use decision and policies in Nigeria towards a sustainable afforestation programme. Copyright © 2001 John Wiley & Sons, Ltd.     

铝胁迫下硝普钠对黑麦和小麦根尖细胞壁铝吸附的影响

用一氧化氮供体硝普钠(sodium nitroprusside,SNP)处理铝胁迫下的黑麦和小麦幼苗,探讨铝胁迫和铝胁迫下外源NO对黑麦和小麦根尖细胞壁铝吸附的影响。结果表明:铝显著抑制黑麦和小麦根的伸长生长,小麦受抑制更为严重;SNP处理可缓解铝对黑麦和小麦根伸长生长的抑制作用,1 mmol/L SNP处理最有效。小麦根尖对铝的吸附量和吸附速率显著高于黑麦的,1 mmol/L SNP处理显著降低小麦和黑麦细胞壁对铝的吸附量,使根尖铝含量显著下降。铝与根尖细胞壁的结合是导致植物铝毒害的重要原因,而降低根尖细胞壁对铝的吸附是外源NO缓解铝毒害的重要机制。     

铝胁迫对油菜根系形态和生理指标的影响

为探讨油菜幼苗在不同浓度铝胁迫下的生理响应,以2个耐铝毒差异显著的油菜品种(耐铝品种R178和铝敏感品种S169)为试验材料,在营养液培养条件下,共设置0(对照)、50、100、150、200和 300 μmol·L^-1 6个铝(pH值4.5)处理,研究铝胁迫对油菜根系形态及生理指标的影响。结果表明,50 μmol·L^-1铝处理下R178各根系形态指标与对照相比均无显著差异,而S169根系各形态指标与对照均差异显著,其中总根尖数随着铝处理浓度的增加呈先升高后降低的趋势,其他根系指标均随着铝处理浓度的增加呈逐渐减少的趋势,300 μmol·L^-1铝处理下,2个品种的主根相对伸长率较对照分别减少65.7%和79.7%。随着铝处理浓度的增加,2个品种幼苗根系中可溶性蛋白和脯氨酸含量均呈先升高后降低的趋势,叶片中可溶性蛋白含量呈降低趋势,而脯氨酸含量则呈升高的趋势。铝胁迫导致2个品种幼苗根系和叶片的质膜透性显著增加,300 μmol·L^-1铝处理下R178和S169根系相对电解质外渗率较对照分别增加54%和59%,叶片中分别增加82%和90%,同一处理下R178根系和叶片电解质外渗率均小于S169。随着铝处理浓度的增加,2个品种根系中的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均呈先增加后降低的趋势;R178叶片中SOD活性呈增加趋势,而S169则呈先增加后降低的趋势,且在200 μmol·L^-1时达到最大值;2个品种叶片中的POD、CAT和抗坏血酸过氧化物酶(APX)活性均呈先增加后降低的趋势。综上,铝胁迫显著抑制了油菜根系生长,破坏了细胞质膜的完整性,油菜幼苗通过蛋白质和脯氨酸含量的积累以及保护酶活性的增高抵抗铝胁迫。本研究结果为耐铝油菜资源筛选和新品种选育提供了理论依据。     

Changes in soil properties related to conversion of savannah woodland into pine and eucalyptus plantations,Northern Nigeria

Soil properties associated with six age-grade plantations of Pinus oocarpa Schiede and Eucalyptus camaldulensis Dehnh., respectively, including nearby natural vegetation, were compared in the savannah zone of Nigeria. The soil organic matter, total nitrogen and exchangeable nutrients first show declining values with the increasing age of the plantation, then an increase and finally steady or declining values in the 0–15 cm soil depth. Usually the differences between the two youngest plantations and the oldest plantations, and the natural vegetation, were significant. In the 20–30 cm soil depth the properties showed a decrease or steady values over time, with the three oldest plantations showing significant differences from the natural vegetation. The soil pH showed an increased acidity over time. There was little difference in the soil properties between the two tree species. The implications of the results are discussed in relation to sustaining productivity and soil fertility. © 1998 John Wiley & Sons, Ltd.     

不同施肥模式下红壤性水稻土中磷的分布及其有效性

研究了不同施肥模式下红壤性水稻土中磷的分布及其有效性。结果表明,随团聚体粒径从大到小的变化,红壤性水稻土全磷含量在不同施肥模式下均表现出先上升后下降的趋势,在5～2 mm粒径团聚体中出现一个峰值;有效磷含量表现出先缓慢上升后迅速下降的特征,在5～2 mm粒径团聚体中出现一个大峰值;在施磷处理中,磷的有效率表现出先缓慢上升后迅速下降的特征,分别在5～2 mm和0.5～0.25 mm粒径团聚体中出现一个大峰值和一个小峰值,但在无磷处理中,磷的有效率表现出逐渐下降的趋势,只在0.5～0.25 mm粒径团聚体中出现一个小峰值。研究表明,长期施加磷肥,尤其与有机物还田相结合,会促使土壤全磷富集于>1 mm粒径团聚体,显著提高>2 mm粒径团聚体中有效磷含量与磷的有效性;在磷肥不足的情况下,减少磷肥施入量,结合有机物还田也能取得较好的效果;即使没有磷肥施入,实行秸秆还田也能在一定程度上提高土壤磷的有效性。     

花江峡谷不同植被类型下土壤水分时空分布特征

花江峡谷是一个严重石漠化的喀斯特峡谷,水分是花江峡谷植物生长发育的主要限制因子,故在花江峡谷区如何选择适当的植被类型是充分利用降水和防止水土流失的一个重要环节。通过研究花江峡谷区不同植被类型下土壤水分的时空分布特征,探讨适合该区生态修复的植被类型,为峡谷区生态建设与水土保持提供依据。研究结果表明:(1)在空间分布上,多年生的柚木对土壤深层水分的影响较大;花椒树(特别是长势好的花椒树木)对土壤水分的保持具有明显作用。(2)在时间分布上,各种植被类型下的土壤含水量均随降雨量的多少而升降,但进入12月份在降雨量最低的情况下,花椒的土壤含水量甚至出现升高的现象,反映了花椒特有的保持水土、涵养水源的作用。研究结果证明大面积种植花椒树有利于提高研究区的生态、经济效益。     

不同土地利用方式对黑土有机无机复合体的影响

采用超声波分散、颗粒大小分组法研究不同土地利用方式下黑土有机无机复合体组成及有机碳的分布特征。不同土地利用方式下黑土均以细砂级复合体为主,有机碳含量随粒径增加而减少,C/N比随粒径增加而增加。NP和NPM处理比NF处理土壤<20μm粒级复合体含量减少,>20μm复合体含量增加;草地与裸地相比<20μm粒级复合体含量减少,>20μm复合体含量增加。土地利用方式不同,土壤固碳的机制是不同的,草地生态系统的土壤固碳潜力高于农田土壤。施肥和有机质的输入使土壤各粒级复合体中的有机碳含量增加;使>20μm粒级复合体固持的SOC量比例增加,表明在土壤有机质含量增加的情况下,有机质有向大粒级复合体的积累增加。     

Distribution of K,Na and Cl in Root and Leaf Cells of Soybean and Cucumber Plants Grown under Salinity Conditions

The element contents in the compartments of root and leaf cells of soybean and cucumber plants grown for 8 d in a nutrient solution containing 50 mM NaCl, 25 mM CaCl₂ or 50 mM NaCl+4.75 mM CaSO₄ were examined by X-ray microanalysis of freeze-substituted dry sections. Sodium accumulated in the vacuoles rather than in the cytoplasm and apoplastic space in the root cells of the soybean plants, leading to the difficulty in the transport of Na to leaves in soybean. Salt injury of soybean is considered to be caused by the accumulation of Cl at high concentrations in all the compartments of root and leaf cells. In contrast, the accumulation of Na in the cytoplasm of the root and leaf cells might disturb the metabolism and lead to the occurrence of salt toxicity in cucumber plants, which are tolerant to Cl due to the stimulation of Cl accumulation in vacuoles when the Ca concentration was high in nutrient media.     

卧龙地区针叶林及亚高山灌丛对降雨的雨滴谱及能量的影响

在运用色斑法研究岷江冷杉及川滇高山栎灌丛林下的雨滴滴谱及降雨动能的基础上,探讨了上述两个生态系统林冠雨谱特征及降雨动能削减特征,比较了3种雨滴终速计算方法的适用性。结果表明:两种生态系统树冠层对降雨动能的改变作用有一定差异,灌丛林下的降雨动能一般小于林外降雨动能,而且雨强增大时灌从对动能的削减作用更加明显一些;但针叶林下的降雨动能却显著高于林外降雨动能,雨强增大时林下的降雨动能比有下降的趋势。在计算雨滴终速时,比较好的计算方法为Beard经验公式法,沙玉清公式(及修正的牛顿公式)法。     

Effects of Zinc Application on Growth,Absorption and Distribution of Mineral Nutrients Under Salinity Stress in Soybean (Glycine Max L.)

The purpose of the present work was to evaluate effects of zinc application on growth and uptake and distribution of mineral nutrients under salinity stress [0, 33, 66, and 99 mM sodium chloride (NaCl)] in soybean plants. Results showed that, salinity levels caused a significant decrease in shoot dry and fresh weight in non-zinc application plants. Whereas, zinc application on plants exposed to salinity stress improved the shoot dry and fresh weight. Potassium (K) concentration, K/sodium (Na) and calcium (Ca)/Na ratios significantly decreased, while sodium (Na) concentration increased in root, shoot, and seed as soil salinity increased. Phosphorus (P) concentration significantly decreased in shoot under salinity stress. Moreover, calcium (Ca) significantly decreased in root, but increased in seed with increased salinization. Iron (Fe) concentration significantly decreased in all organs of plant (root, shoot, and seed) in response to salinity levels. Zinc (Zn) concentration of plant was not significantly affected by salinity stress. Copper (Cu) concentration significantly decreased by salinity in root. Nonetheless, manganese (Mn) concentration of root, shoot, and seed was not affected by experimental treatments. Zinc application increased Ca/Na (shoot and seed) ratio and K (shoot and seed), P (shoot), Ca (root and seed), Zn (root, shoot, and seed) and Fe (root and shoot) concentration in soybean plants under salinity stress. Zinc application decreased Na concentration in shoot tissue.     

内陆干旱区不同灌溉制度对盐碱地滴灌土壤盐分离子分布的影响

通过田间试验研究覆膜滴灌条件下不同灌溉制度对土壤盐分分布的影响。试验通过控制滴头正下方20 cm处的土壤基质势下限进行灌溉,共设5个水平的土壤基质势处理:-5 kPa(S1)、-10 kPa(S2)、-15 kPa(S3)、-20 kPa(S4)和-25kPa(S5),每个处理重复3次,按随机区组布置。结果表明:不同土壤基质势控制对盐渍土中盐分分布有显著影响,不同土壤盐分离子的分布各不相同。其中Na+与Cl-容易被淋洗,两个生长季后,各处理土壤中Na+与Cl-含量有显著降低,并且土壤基质势控制越高淋洗效果越好。SO42-与HCO3-的淋洗效果主要受离子浓度影响,第一年淋洗效果较第二年明显。Mg2+与Ca2+不易随水移动,各处理无明显差异。经过两个生长季的灌溉淋洗,各处理土壤SAR值与全盐含量均有显著降低,根区内SAR值与全盐含量的降低幅度均在50%以上。研究结果对内陆干旱区盐碱地水盐调控和灌溉制度的制定具有理论意义和应用价值。     

外源NO对Ca(NO_3)_2胁迫下番茄幼苗PSII功能及光能分配利用的影响

为探讨外源NO缓解番茄幼苗次生盐渍伤害的光合生理机制,以秦丰保冠番茄幼苗为试材,在水培条件下,利用叶绿素荧光动力学技术研究喷施NO供体硝普钠(SNP)对80 mmol·L-1Ca(NO_3)_2胁迫下番茄幼苗PSII光化学效率、激发能分配和天线色素吸收光能利用的影响。结果表明,喷施SNP有效缓解了Ca(NO_3)_2胁迫对PSII的损伤,使第15天番茄幼苗叶片的PSII最大光化学效率(F_v/F_m)、天线转化效率(F_v'/F_m')、实际光化学效率(ΦPSII)、光化学荧光猝灭系数(q P)及吸收光能用于进行光化学反应(P)和非光化学耗散(Ex)的份额分别较胁迫处理显著提高了4.93%、39.31%、92.84%、39.00%、92.83%和10.33%;初始荧光(Fo)、非光化学荧光猝灭系数(NPQ)、双光系统间激发能分配不平衡偏离系数(β/α-1)和天线热耗散的份额(D)分别较胁迫处理显著降低了7.20%、13.22%、43.09%和24.70%。综上,外源NO能通过改善PSII光化学活性和增强PSII反应中心的非光化学耗散减轻Ca(NO_3)_2胁迫造成的光抑制,进而提高番茄幼苗的耐盐能力。本研究结果为利用外源NO缓解蔬菜设施生产的次生盐渍障碍提供了理论和技术依据。     

硅酸盐对污染土壤铬、铅形态和小白菜吸收分布及其健康风险的影响

为保障蔬菜的品质安全,通过土壤盆裁试验,研究硅酸盐对Cr、Pb单一污染及Cr-Pb复合污染土壤中小白菜(Brassica chinensis)的生物量、土壤中Cr、Pb形态及小白菜体内Cr、Pb积累量的影响.结果表明,在受到较高水平的Cr～Pb污染时,小白菜对Pb的富集能力要明显高于Cr,被小白菜吸收的Cr、Pb都主要累积在根部.施用硅酸盐能通过减少土壤中有效态Cr、Pb的含量,从而减少小白菜对Cr、Pb的吸收,且施用效果明显,其中2.0 g/kg效果最好,但该处理严重抑制小白菜生长,不适于生产应用.而Si_1处理(1.00 g/kg)能在不影响产量的前提下极显著地降低小白菜茎中Cr、Pb的质量分数,并使叶中Pb的质量分数降至国家标准限量值附近或低于限量值,因此该处理在生产上极具应用前景.