Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from Leucaena leucocephala Bark

Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard.

Antioxidant, antimicrobial and cytotoxic potential of condensed tannins from Leucaena leucocephala hybrid-Rendang

Condensed tannins(CTs)are one of the promising compounds due to their potentially health-promoting qualities.In this study,CTs were extracted from a Leucaena leucocephala hybrid-Rendang and subjected to various biological studies including antioxidant(using Ferric reducing antioxidant power(FRAP),DPPH and ABTS radical scavenging assay),anti-microbial(against different pathogens)and cytotoxic activities(toward human breast adenocarcinoma(MCF-7),human colon carcinoma(HT29),human cervical carcinoma(HeLa)and human liver carcinoma(HepG2)cell lines)in cancer cells through in vitro experiments.The structural characteristics and purity of CTs extract were determined using 13C NMR.The results showed that CTs exhibited higher in vitro antioxidant activities(2257.12±80.55 mg TEAC/g extract,605.3±1.82 mg TEAC/g extract and 1014.03±1.20 mg TEAC/g extract in FRAP,ABTS and DPPH assay,respectively)and demonstrated anti-microbial activities toward selected Gram’s positive and Gram’s negative bacteria tested with MIC and MBC value at 6.25–50 mg/mL.Furthermore,among other selected cancer cells,CTs also demonstrated cytotoxic activity toward human breast cancer cells(MCF-7)(IC50=38.33±2.08mg/mL).Characteristic of apoptosis such as cell shrinkage,nuclear condensation and apoptotic bodies were shown in MCF-7.These preliminary investigations have provided scientific rationale to use CTs as an alternative therapy for various oxidative and inflammatory associated diseases.©2016 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Landscape Ecological Evaluation on the Artificial Forest of Leucaena leucocephala——Taking the Example of Xiaokua Hill of Yuanmou

Based on the theory of ecology, this article conducted a landscape ecological evaluation on Leucaena leucocephala artificial forest in the add-hot valley, Yuanmou Xiaokua hill, using a combination method of qualitative analysis and landscape comprehensive evaluation. The comprehensive evaluation indexes of landscape include forest coverage, biodiversity, stability, soil erosion, environmental quality, availability, scientific research characteristic, economic benefits. Using AHP （analytical hierarchy process）, determine the grade of ecological evaluation factors and the weight of evaluation index and calculate the CEI （comprehensive evaluation index） on ecological evaluation. Evaluation results showed that the area CEI was 0.714 225, a better quality of the ecological level, but biodiversity indicators was the lowest. To sum up, it was difficult to maintain ecological restoration effectiveness and process but also guarantee a good biodiversity in the add-hot valleys. We must reasonably arrange the alien species and the native species, in order to obtain a stable and sustainable eco-system.

Genetic analysis of growth and wood variations in Leucaena leucocephala (Lam.) de Wit.

We selected 28 populations of Leucaena leucocephala from different geographical locations in the states of Andhra Pradesh, Tamil Nadu and Orissa of India on the basis of height and girth at breast height （GBH）. We evaluated fiber length, optical density, wall thickness, vessel element length, vessel element diameter, specific gravity and lignin of these populations of L. leucocephala in different sites. Populations had significant variations for all growth, wood and paper parameters. Girth at breast height （GBH） and specific gravity were the most important pa- rameters for heritability and genetic gain, respectively. The minimum heritability was reported for vessel element length and genetic gain for fiber length. The populations were grouped into six clusters, cluster II had maximum number of populations （14） and clusters IV and VI had one population each. GBH contributed maximum of 34.39 % towards total divergence followed by specific gravity （14.02%）. An economic technique to produce quality seed by establishing seed orchards with genetically divergent parents was suggested. The hybridization among the populations selected from diverse clusters could produce greater heterosis needed for higher growth and suitable wood and paper manu- facturing parameters.

Yield-density effects on growth and biomass partitioning in Leucaena leucocephala seedlings

Experiments were conducted to study the effects of density on growth and biomass partitioning of Leucaena leucocephala seedlings.Four plantations with densities of 10,000,20,000,40,000,and 80,000 seedlings ha^-1 were evaluated only from 15 to 25 months after planting.At 15 months,crown height and width decreased with increasing density.Seedling height/dbh ratios increased with increasing density.Biomass increased with greater density according to the yield–density effect equation,which was evident for all densities.With increasing age,biomass division to branches and leaves increased,whereas partitioning to roots decreased in the 10,000 and 20,000 seedlings ha-1 plantings.Partitioning to branches and leaves remained relatively steady,while partitioning to roots increased in the 40,000 and 80,000 seedlings ha^-1 plantings.Biomass division into stem and bark components remained relatively steady in all densities.Yield–density and organ yield–density curves shifted upward with increasing seedling age on a log–log graph throughout the experimental period.

金沙江干热河谷新银合欢(Leucaena leucocephala)的光合与荧光特征干湿季对比研究

为了研究引进树种对干热河谷环境的适应性,以生长于干热河谷野外环境中的新银合欢(Leucaena leucocephala)为研究对象,研究分析了其在湿季(7月)和干季(11月)的光合生理特征和叶绿素荧光特征。结果表明:(1)在Pn-Ci响应曲线中,当Ci<150μmol/mol,干季的净光合速率(Net photosynthetic rate,Pn)高于湿季,而当Ci>150μmol/mol,干季的Pn低于湿季;(2)相较于湿季,干季的初始羧化效率(Initial carboxylation efficiency,CE)、光合能力(Photosynthetic capacity,Amax)、CO2补偿点(CO2 compensation point,Γ)、光呼吸速率(Photorespiration rate,Rp)、最大羧化速率(Maximum carboxylation rate,Vcmax)、最大电子传递速率(Maximum electron transport rate,Jmax)、磷酸丙糖利用率(Triose phosphates utilization rate,TPU)、Jmax/Vcmax、气孔限制值(Stomatal limitation,Ls)和叶片饱和水汽压差(Vapor pressure deficit,VPD)均显著下降(P<0.05),而暗呼吸速率(Dark respiration rate,Rd)、胞间CO2浓度(Intercellular CO2 concentration,Ci)、气孔导度(Stomatal conductance,Gs)、蒸腾速率(Transpiration rate,Tr)、饱和光下最大净光合速率(Light-saturated net photosynthetic rate,Pnmax)和水分利用效率(Water use efficiency,WUE)则显著上升(P<0.05);(3)干季的PSII实际光化学效率(Actual photochemical efficiency of PSII,ФPSII),光化学猝灭系数(Photochemical fluorescence quenching,qP),电子传递效率(Electron transport rate,ETR)较湿季出现显著下降(P<0.05),非光化学猝灭系数(Non-photochemical fluorescence quenching,NPQ)显著增加(P<0.05);(4)叶绿素荧光参数的ФPSII、NPQ、ETR与各光合生理指标相关性较强。在干热河谷地区,气孔限制是影响新银合欢湿季光合速率的主要因素;而非气孔限制是影响其干季光合速率的主要因素。

Effects of sludge on germination and initial growth performance of Leucaena leucocephala seedlings in the nursery

研究被执行决定污泥的不同类型的影响(市政，工业；居住) 在地萌芽上，生长；L 的生节。在托儿所的 leucocephala 幼苗。在种子播种前，污泥的不同联合与滋养的缺乏的自然森林土被合并。领域萌芽，生节地位；幼苗的物理生长参数(射击；根长度，活力索引，领子直径，叶数字，新鲜；弄干射击的重量；根；全部的干燥生物资源增长) 在三以后被记录；六月种子播种。地萌芽，生节地位；生长参数在与控制相比与污泥修改的土壤显著地被改变。小瘤的最高的数字从与居住污泥(1:1 ) 修改的土壤被记录；最高新鲜；干燥小瘤重量也在三从一样的联合被发现；六个月旧的幼苗。在生长参数的情况下，最高的生长从土壤被记录；与控制相比的居住污泥(1:1 ) 联合。从学习，与居住污泥(1:1 ) 修改的土壤提供更好的地萌芽，这能被推荐，生长；L 的小瘤形成。在降级的土壤的 leucocephala。

Steroids from the Whole Plants of Leucaena Leucocephala

Four steroids, 5α,8α-epidioxy-(24ξ)-ergosta-6,22-dien-3β-ol (1), β-sitosterol (2), β-sitostenone (3), and stigmastenone (4), along with 10 known compounds were isolated from the whole plants of Leucaena leucocephala (Leguminosae). 1, Lupeol (5), 1,3-dipalmitoyl-2-oleoylglycerol (6), methylparabene (8) and isovanillic acid (9) were found for the first time from the species. The structure of these compounds were characterized and identified by spectra analyses.

Polyprenol from the Whole Plants of Leucaena leucocephala

Ficaprenol-11 (polyprenol) (1), squalene (2), lupeol (3), ?-sitostenone (4), trans-coumaric acid (5), cis-coumaric acid (6) pheophytin-a (7), pheophorbide a methyl ester (8), methyl-132-hydroxy-(132-S)- pheophorbide-b (9) and aristo-phyll-C (10) were isolated from the whole plants of Leucaena leucocephala (Leguminosae). Among them, 1 and 2 was found for the first time from this species. The structure of these compounds were characterized and identified by spectra analyses.

Fine Root Distribution Pattern of Different Aged Leucaena leucocephala Trees in Debris Flow Source Area in Jiangjia Gully, China

Fine root is critical to restrain soil erosion and its distribution pattern is of great influence on the restraining effects. This study studied the fine root biomass(Br) distribution of different aged Leucaena leucocephala(5, 10, 15 years) in debris flow source area in Jiangjia Gully by digging downward to the bottom at different distances to stem in three directions on slope. The results showed the Br increased dramatically by 143% from 5 years to 10 years and then rose slowly by 38% from 10 years to 15 years. The Br of 5 years was significantly asymmetric between uphill and alonghill directions, but there was little difference among directions for other ages, and a concentration trend appeared to exist in downhill and alonghill directions. Moreover, fine root(D≤1 mm) was significantly heavier than that of fine root(1mm<D≤2 mm), playing a leading role in the vertical distribution of the whole fine root, with a logarithmic or an exponential function. The results presented may shed light on fine root distribution pattern and evaluation of its effect on slope stability in debris flow source area.

Molecular cloning and characterization of two differentially expressed Cellulose synthase gene isoforms in <i>Leucaena leucocephala</i>: A pulp yielding tree species

Leucaena leucocephala is fast growing leguminous tree species, acclimatized to variety of soil and climatic conditions. It is widely used for pulp production in India. Pulp mainly consists of cellulose, which is a simple polymer of unbranched β-1, 4-linked glucan chains. The polymerization of glucose residues into a β-1, 4-linked backbone is catalysed by the enzyme cellulose synthase (CesA). Here, cDNAs encoding CesA genes from Leucaena were isolated and characterized. The two complete cDNAs of 3.228 kb and 3.222 kb encoding CesA gene from L. leucocephala were designated as Ll-7CesA (FJ871987) and Ll-8CesA (GQ267555) respectively. In-silico studies showed that Ll-7CesA has 95.2% identities and Ll- 8CesA has 95.8% identities with Acacia mangium CesA2. Phylogenetic analysis revealed significant similarity with known dicot CesA genes. The deduced amino acid sequence of both CesA genes contained the conserved D, D, D, QxxRW motif, eight membrane spanning regions and a putative zinc binding domain, which are characteristic of glycosyltransferases. DNA blot analysis suggested, CesA gene to be in multiple copies in Leucaena genome. Semi quantitative and quantitative real-time PCR expression analysis of Ll-7CesA gene showed more expression in stem than leaf and not detected in root where as Ll-8CesA gene was expressed more in stem than leaf and root. Overall Ll-8CesA was expressed in all tested tissues and could be involved in active cellulose biosynthesis.

银合欢种子萌发特性及其影响因素研究

为了解银合欢Leucaena leucocephala的种群扩散机制,并为其规模化繁殖育苗和生态修复上的合理利用提供技术支持,研究分析其3种成熟阶段果实和种子的形态特征、鲜重和含水量,种子在不同温度、光照中的萌发情况,以及播种基质和6-BA、GA_(3)溶液对种子萌发的影响。结果表明:幼嫩荚果的种子粒数最多,平均为19.30粒,含水量最高,为61.88%;中熟荚果的鲜重最大,为42.09 g。幼嫩种子的含水量最高,为73.10%;中熟种子的鲜重最重,百粒重为7.04 g。种子在25℃和常温(昼25~35℃/夜18~25℃)的萌发率和萌发指数最高,为萌发的较适温度,且光照下萌发率显著比黑暗高,种子为需光性种子。中熟种子萌发率和萌发指数最高,其次是幼嫩种子,完熟种子最小。将完熟种子播种于不同基质中,出苗率最高的为营养土,其次是园土,砂中最低。100 mg/L GA_(3)和10 mg/L 6-BA溶液浸泡24 h对完熟种子的萌发具有显著的促进作用(P<0.05),而300~700 mg/L的GA_(3)和30~70 mg/L浓度的6-BA溶液反而有抑制作用。

Optimization of South China 5 Cassava-Leucaena Protein Feed Production by Kombucha in Solid-State Fermentation

[Objective] To optimize solid-state fermentation of South China 5 （SC5） cassava-leucaena protein feed by kombucha. [Method] The SC5 cassava-leucaena protein feed was fermented by kombucha. The fermentation conditions were optimized. [ Result] The optimum conditions of solid-state fermentation were as follows： cassava and leucaena weight ratio, 7：3; fermentation time, 6 d; kombucha volume, 10 ml; fermentation temperature, 30 ℃; and water volume, 200 ml. The content of crude protein in feed was substantially increased and reached 23.64%. [ Conclusion] The optimized fermentation process greatly improves utilization of the SC5 cassava-leucaena protein feed.

新银合欢林土壤理化性质–微生物生物量耦合协调关系研究

研究采用空间代替时间序列的方法,通过方差分析、相关性分析和偏最小二乘路径模型探究向家坝工程扰动区6种不同龄级新银合欢林土壤理化性质与微生物生物量的耦合协调关系。结果表明:①原生草地群落(A1,无新银合欢群落)土壤含水量、养分水平和微生物生物量均最高,新银合欢入侵后在草灌阶段土壤含水量、养分水平和微生物生物量显著下降。新银合欢成为灌丛时(A3,新银合欢2 a群落)土壤含水率、有机碳、全氮、全磷、微生物生物量碳氮含量分别下降为A1群落的51.2%、33.9%、31.6%、27.1%、72.8%和61.5%,pH上升至8.16,使得土壤更为碱化。②土壤微生物生物量碳与土壤含水率显著相关(P<0.05),土壤微生物生物量碳氮比与pH呈显著相关;土壤含水率、养分水平和微生物生物量三者之间相互影响且作用显著,高土壤含水率有利于土壤养分与微生物生物量的存在和转化。③原生样地结构稳定,协调度D较高(0.7162);新银合欢入侵后,协调度随着新银合欢林龄增大呈现波动下降,至A4群落(新银合欢3~4 a)时协调度降至最小值(0.5012);在乔木阶段土壤养分与微生物生物量缓慢增加且趋于稳定,协调度缓慢上升,最终在新银合欢纯林时稳定趋于勉强协调发展类型。因此,针对不同龄级新银合欢林,要根据不同恢复阶段的土壤生境条件采取不同调控措施,在植被恢复的物种搭配选择上应注重草灌结合,促进土壤以及整个生态系统的健康发展。

土壤种子库与矿业废弃地植被恢复研究:定居植物对重金属的吸收和再分配

研究了从引入的土壤种子库中所萌发 ,并成功在铅锌尾矿上定居的 4个优势种植物 ,雀稗 (Paspalumthunbergii)、双穗雀稗 (P.distichum)、黄花稔 (Sida rhombifolia)和银合欢 (L eucaena leucocephala) ,对重金属的吸收及其在体内的再分配。植物组织中铜 (Cu)和锌 (Zn)的浓度 ,除了雀稗和双穗雀稗根中的锌浓度分别为 34 4.2 m g· kg- 1和 331.9m g· kg- 1显得较高外 ,其余仍属植物体内正常水平范围 (Zn:2 7～ 15 0 m g· kg- 1 ,Cu:5～ 30 m g· kg- 1 )。草本植物雀稗、双穗雀稗和黄花稔对有毒重金属元素铅 (Pb)的吸收表现出不同的模式 ,Pb在地上部与地下部分的浓度比以雀稗最低 (为 0 .2 0 9) ,表明雀稗所吸收的 Pb大部分被滞留在根部 ,使之较少影响到地上部茎叶的光合作用功能及生长 ,从而使植物对重金属 Pb环境更具耐性。相反 ,双穗雀稗和黄花稔则较高 (分别为 0 .5 0 9和0 .6 5 3) ,显示所吸收的 Pb较多地被转移到便于收获移走的地上部分 ,因而具有较大的植物修复潜力(Phytorem ediation potential)。木本植物银合欢 ,所吸收的重金属 Pb总量的 80 %以上是积累在根、茎的皮和木质部及枝条部分 ,只有 15 %左右分布在叶片中。这表明随着生长 ,有越来越多的 Pb被吸收和累积在更新周期较长的器官中 ,只?

干旱胁迫对坡柳等抗旱树种幼苗膜脂过氧化及保护酶活性的影响

以金沙江干热河谷主要树种坡柳、银合欢、山毛豆实生幼苗为材料,通过盆栽苗自然干旱胁迫,同时以浇水处理为对照,研究了干旱胁迫对坡柳、银合欢、山毛豆3个树种丙二醛含量、膜相对透性及保护酶活性的影响。结果表明,干旱胁迫下3个树种幼苗的细胞膜透性、MDA及SOD,POD酶活性都发生了变化,只是变化的幅度和进程不同。干旱胁迫对银合欢膜系统损伤生成的主要降解产物不是MDA;山毛豆清除活性氧毒害作用主要不是通过SOD和POD的作用;通过叶片相对保水力测定及膜透性、MDA相对含量、酶活性变化情况的分析,3个树种中坡柳耐旱性最强,其次为银合欢,山毛豆居后。

银合欢硬实种子处理方法研究

采用7种不同方法对银合欢Leucaena leucocephala种子进行处理,结果表明,用98%的浓硫酸对银合欢种子进行处理5 min效果最好,发芽率达86%;其次是水温80℃浸种10 min,发芽率达74%;80℃高温干燥10 min和机械摩擦种皮效果比较差,发芽率仅19.3%和15.3%;酒精、40%的氢氧化钠、不同浓度萘乙酸(NAA)浸种对银合欢的发芽率没有影响,最佳处理的大田试验结果与实验室结果相吻合。

泥石流频发区人工恢复新银合欢林种内竞争--以云南东川蒋家沟流域为例

采用Hegyi单木竞争指数模型和张跃西改进单木竞争指数模型,于2006年在云南省昆明市陈川区蒋家沟,对干热河谷泥石流频发区人工恢复新银合欢林种内竞争强度进行定量分析。结果表明:无论是内圈还是外圈新银合欢种内竞争强度随林木径级的增大而减小,内圈的竞争强度要大于外圈;内圈竞争强度与对象木胸径之间的关系近似服从双曲线函数关系,外圈竞争强度与对象木的胸径之间的关系近似服从幂函数关系;两个竞争指数模型均能较好地反映干热河谷区新银合欢人工恢复林种内竞争强度,但Hegyi单木竞争指数模型的适用性优于张跃西改进单木竞争模型。

新银合欢篱对紫色土坡地土壤有机碳固持的作用

土壤有机碳的固持对保持土壤肥力以及缓解全球温室效应具有重要意义。通过田间定位试验,探讨了新银合欢(Leucaena leucocephala)篱对10°和15°的紫色土农耕地(玉米地)和经济林地(油桃地)表层(0—20cm)土壤有机碳积累的影响。结果表明:种植3a的新银合欢篱的10°和15°农耕地、10°经济林地土壤有机碳密度分别比相应的无植物篱的对照地提高41.53%、43.29%、32.15%。经济林处理土壤有机碳含量、有机碳密度、呼吸强度显著大于农耕地处理;10°比15°农耕地更有利于土壤有机碳、呼吸速率及微生物量碳提高;农耕地比经济林地更利于微生物生物量维持。各处理下坡比上坡更利于土壤有机碳蓄积,且土壤呼吸强度提高,但土壤微生物商基本相同。不同处理下,土壤有机碳与土壤理化性质相关性各不相同:定植新银合欢篱的10°和15°农耕地、10°经济林地土壤有机碳与有机质含量、土壤微生物碳有极显著的相关性,与全钾呈正相关,与pH负相关;定植新银合欢篱的10°和15°农耕地呼吸强度与有机碳相关关系均达到了极显著性,10°经济林地呼吸强度与有机碳显著相关;土壤微生物指标变化与有机碳的变化趋势一致,能反映土壤质量变化。阐明定植新银合欢篱利于土壤有机碳固持,且能增强土壤微生物活性,提高土壤质量。