Nodulation and growth of black locust (Robinia pseudoacacia) on a desurfaced soil inoculated with a local Rhizobium isolate

Nodulation and nitrogen fixation of black locust (Robinia pseudoacacia L.), a legume tree broadly used in Argentina for urban and agricultural afforestation, was studied in hydroponic culture. The development of seedlings inoculated with a local strain of Rhizobium, highly specific for R. pseudoacacia, was also compared with respect to non-inoculated but N-fertilised seedlings. This strain produced fast nodulation and high crop yield and leaf N content. Already nodulated plants with the local Rhizobium strain were assayed for growth in a greenhouse pot experiment with soil from a field where topsoil has been removed for industrial purposes, whilst pots with non-desurfaced soil from the same field were used as control. Non-inoculated plants were also grown in either control or desurfaced soil. Inoculated plants developed better than non-inoculated plants in desurfaced soil, and in control soil as well, suggesting that the symbiosis was able to overcome the nutrient limitation of the desurfaced soil. Non-inoculated plants were nodulated by native soil born Rhizobium, either in control or desurfaced soil, but they showed low final nitrogen leaf content and low nitrogen fixation activity, suggesting that native rhizobia were ineffective.     

黄土丘陵区刺槐人工林土壤养分特征及演变

为了探明黄土丘陵沟壑区人工林土壤养分状况及其演变规律,应用时空互代的方法,以刺槐林为代表,对该区不同利用年限的人工林土壤养分特征及其时空变化等进行了系统研究。结果表明,黄土丘陵区人工林土壤肥力处于低水平;人工林表层土壤养分中有机质和速效磷的空间变异性较大;坡度、坡向、坡位等环境因子对土壤养分有一定的影响。随利用年限的增加,人工林土壤全氮,有机质、碱解氮、速效钾含量及土壤养分指数均增加,与利用年限有极显著的相关性,其变化趋势符合y=axb模型。全氮,有机质和碱解氮随利用年限的增加量不显著,而速效钾每经过10年就有显著增加,全磷和速效磷含量则保持相对衡定的水平。黄土丘陵区人工林地土壤有机质、全氮、碱解氮、速效钾及养分指数年增长率分别约为0.20g.kg、0.01g.kg、0.69mg.kg、2.27mg.kg和0.04。该区人工林地土壤有机质、全氮、碱解氮及养分指数约需50年、速效钾约需30年可达到中上等养分水平。     

Effect of toasting intensity at cooperage on phenolic compounds in acacia (Robinia pseudoacacia) heartwood

The phenolic composition of heartwood from Robinia pseudoacacia, commonly known as false acacia, before and after toasting in cooperage was studied by HPLC-DAD and HPLC-DAD/ESI-MS/MS. A total of 41 flavonoid and nonflavonoid compounds were identified, some tentatively, and quantified. Seasoned acacia wood showed high concentrations of flavonoid and low levels of nonflavonoid compounds, the main compounds being the dihydroflavonols dihydrorobinetin, fustin, tetrahydroxy, and trihydroxymethoxy dihydroflavonol, the flavonol robinetin, the flavanones robtin and butin, and a leucorobinetinidin, none of which are found in oak wood. The low molecular weight (LMW) phenolic compounds present also differed from those found in oak, since compounds with a β-resorcylic structure, gallic related compounds, protocatechuic aldehyde, and some hydroxycinnamic compounds are included, but only a little gallic and ellagic acid. Toasting changed the chromatographic profiles of extracts spectacularly. Thus, the toasted acacia wood contributed flavonoids and condensed tannins (prorobinetin type) in inverse proportion to toasting intensity, while LMW phenolic compounds were directly proportional to toasting intensity, except for gallic and ellagic acid and related compounds. Even though toasting reduced differences between oak and acacia, particular characteristics of this wood must be taken into account when considering its use in cooperage: the presence of flavonoids and compounds with β-resorcylic structure and the absence of hydrolyzable tannins.     

林木细根分布规律与土壤水分响应关系研究

通过野外调查和室内分析,对渭北黄土高原主要造林树种的根系分布特征和土壤水分的季节变化规律进行研究.结果表明:林地土壤水分可以划分为土壤水分活跃层、土壤水分稳定利用层和土壤水分稳定层3个层次,不同立地不同层次上的土壤含水量具有不同的时空分布特征.对不同立地条件上林木根系分布特征的研究结果表明,不同立地上刺槐根系的空间分布特征具有明显差异,阴坡立地上的刺槐根系具有更大的分布空间.进一步的分析结果表明,土壤水分的变化规律与根系的分布特征有密切的关系,适宜的水分环境可以保证根系得到充分的牛长发育,扩大水分养分的吸收空间,使林木的地上部分表现出更大的生产力,反之则降低林木生产力.     

A large diversity of non-rhizobial endophytes found in legume root nodules in Flanders (Belgium)

We analysed the genetic properties of non-rhizobial root nodule endophytes (NRE) isolated from indigenous legumes in Flanders. In total, 654 isolates were obtained from 30 different plant species within the Faboideae legume subfamily. Partial sequencing of the 16S rRNA gene revealed a large diversity of different taxa from the classes Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmibacteria, Flavobacteria and Sphingobacteria. Many of the isolates belonged to the genera Bacillus (17.9%) and Pseudomonas (15.9%). No symbiosis (nodC) or nitrogen fixation related genes (nifH) could be detected amongst the isolates, which indicate the endophytic nature of the bacteria. Statistical analysis grouped the investigated plant species into six clusters according to the presence of particular NRE. However, no correlations could be found within these six clusters towards plant tribes or ecoregions the plants had been sampled from. Cluster analysis of the ecoregions according to the presence of NRE, revealed correlations between bacterial genera and those areas. However, groups present in the ecoregions did not correlate with the groups present in the different plant clusters. When combining our previous study on rhizobial diversity recovered from the same sampling campaign (De Meyer et al., 2011) with the current study, 84.1% of the isolates belonged to the traditional rhizobia groups and only 15.9% were NRE. The Loamy ecoregion yielded the lowest number of culturable NRE (8.04%) and the Campine ecoregion the highest number (24.19%). The present study highlights the frequent presence of these NRE in root nodules. The occurrence of certain rhizobia was correlated with the presence of particular NRE, suggesting their presence may not be accidental, however their functions remain unclear at this point.     

栽培对黑土线虫营养群体的空间分布的影响

Geostatistics combined with GIS was applied to assess the spatial distribution of nematode trophic groups following two contrasting soil uses in the black soil region of Northeast China.Two plots,one with fallow for 12 years and the other cultivated,were marked on regular square grids with 2-m spacing.Soil samples were collected from each sampling point,nematodes were extracted from these samples and classified into four trophic groups:bacterivores,fungivores,plant parasites,and omnivores/predators.The numbers of total nematodes and trophic groups analyzed had normal distributions on both fallow and cultivated plots.The absolute abundances of total nematodes and trophic groups were observed to be much nore homogeneous on cultivated plot than on fallow one.Geostatistical analysis showed that the densities of total nematodes and trophic groups on both fallow and cultivated plots exhibited spatial dekpendence at the sampled scale and their experimental semivariograms were adjusted to a spherical or exponential model,except those of bacterivores and fungivores oncultivated plot.The spatial distribution of nematode trophic groups was found to be different for the two land uses,indicating that cultivation changed the native condition for soil nematode activities.     

冬枣黑斑病空间格局及抽样技术研究

冬枣黑斑病已成为威胁冬枣安全生产的主要病害.本文应用Taylor的幂法则、Iwao m*-m回归分析法及6个聚集指标, 对冬枣黑斑病空间分布类型和抽样技术进行了研究, 并进行了影响因素分析.结果表明:冬枣黑斑病在果实和叶片两个空间阶元都属于聚集分布, 分布的基本成分是个体群, 其聚集性随个体密度增大而增加.在果实和叶片两个空间阶元上, 聚集都与致病菌本身习性和环境因素有关.运用Iwao m*-m回归中的两个参数α和β, 确定了不同精度下的理论抽样数及序贯抽样数.     

Genetic diversity of taro (Colocasia esculenta (L.) Schott) in Vanuatu (Oceania): an appraisal of the distribution of allelic diversity (DAD) with SSR markers

In Vanuatu, an oceanic archipelago located in south-west Pacific, taro (Colocasia esculenta (L.) Schott) is one of the staple crops. An eco-geographical survey of its genetic resources was conducted in ten villages, each located on a different island. A sample of 344 landraces referred as the National Sample (NS) was collected. Its genetic diversity was assessed using nine microsatellites markers and then was compared with an International Core Sample (ICS) that was previously distributed in the ten villages of the study in order to test the geographical distribution of allelic diversity as an effective mean for the on-farm conservation of root crops. The ICS was composed of 41 accessions, including 23 originating from South-East Asia. The molecular dataset revealed in the NS (1) 324 distinct multilocus genotypes, (2) six genetic clusters mainly differentiated by rare alleles, (3) a geographical structure of the genetic resources of taro based, within each village, on the dominance of one or two of these clusters rather that their exclusivity, and (4) an analogy between the patterns of dominant clusters between villages and the past and present social networks. In addition, accessions from the ICS revealed 52 new alleles. Based on these findings, we formulate hypotheses regarding the processes involved in the genetic diversification of taro in Vanuatu. We also discuss the use of this set of microsatellite markers along with the molecular dataset obtained from this study as effective tools to monitor the diversity and evolution of taro in the future.     

Desorption and distribution of pentachlorophenol (PCP) on aged black carbon containing sediment

Purpose

There is a strong affinity between organic compounds and black carbon (BC) in sediments, but the release of adsorbed organic compounds from BC may vary with the duration of contaminant–sediment contact (i.e., aging). The objective of this paper was to evaluate the effect of the application of rice straw carbon (RC) on the control of hydrophobic ionizable organic compounds (HIOCs) pollution and investigate whether aging affects the release of adsorbed pentachlorophenol (PCP) in RC-amended sediment.

Materials and methods

Two experiments were conducted in this study: Tenax-mediated desorption kinetics experiment and PCP’s distribution experiment over aging time. The Tenax-mediated desorption kinetics data were fit with a modified two-domain model. PCP’s distribution pools in sediment involves water soluble (F ₁), 48 h desorption (F ₂), 432 h desorption minus 48 h desorption (F ₃), strongly complexed (F ₄), and nonextractable fractions (F ₅).

Results and discussion

A good fit of the desorption kinetics data was obtained with the modified two-domain model, and R ² ranged from 0.979 to 0.999. The presence of RC in the sediment reduced the rapid and slow desorption fractions (F _rap and F _slow) as well as the rapid and slow rates of desorption of PCP (k _rap and k _slow) from the sediment, and the RC also increased the desorption-resistant fraction (F _r ). F _rap and F _slow both increased, while F _r decreased after aging. The PCP content of F ₁, F ₂, and F ₃ increased but decreased in F ₄ and F ₅ with contact time. Furthermore, the segregation of PCP varied less with aging time in sediments with 2.0 % RC than in sediments with 0.5 % RC.

Conclusions

RC played a dominant role in hindering PCP mass transfer and reducing PCP availability in sediments. After the RC-amended sediment was aged for 98 days, the PCP was released more easily and became more readily available, which was attributed primarily to the RC–sediment aging rather than of the PCP–sediment aging. Furthermore, 0.5 % RC is not sufficient to control PCP release from sediments, and 2.0 % RC is needed to fix PCP in sediments over long periods of time.     

Genetic diversity analysis and character associations in black cumin (Nigella sativa L.) based on agro-morphological and phytochemical traits

Black cumin (Nigella sativa L.) is one of the important medicinal plants that used in food and pharmaceutical industries. In the present study, 32 Iran endemic black cumin genotypes were evaluated through randomized complete block design with three replications in 2016 and 2017 growing seasons to determine the extent of genetic diversity and character associations for agro-morphological and phytochemical traits. Results showed the significant differences between genotypes for all traits studied. Clustering analysis using agro-morphological and phytochemical traits grouped genotypes into the two distinct groups. The values of percentage of essential oil and fatty oil content varied from 0.65 to 0.1.36% and 25.30% to 35.02% between genotypes, respectively. The highest seed yield and fatty oil yield obtained for Arak genotype. GC and GC/MS analyses of essential oil and fatty oil compositions of the Arak genotype revealed that p-cymene and linoleic acid were main components, respectively. Stepwise regression analysis revealed that shoot dry mass, days to ripening and seed length were the most important traits associated with seed yield, fatty oil yield and essential oil yield. Hence, these traits can be considered as important indicators for early selection for seed yield and quality in black cumin breeding programs.     

Distribution and phenotypic characteristics of common bean (Phaseolus vulgaris L.) nodulating bacteria in diverse soils

ABSTRACT

Bacteria were isolated from the root nodules using common bean as a trap host. Growth and morphological characteristics of the bacterial isolates were described on yeast extract mannitol mineral salts agar and broth media. The results showed that over 67% of the isolates produced extracellular polysaccharide with an entire margin and convex elevation. The others differentiated into cream yellow, cream white and milky white colouration with colony area ranging from 0.8 to 26?mm². The population levels of bacteria nodulating common bean varied in soils and were not affected by the cropping system. However, selected soil parameters greatly influenced the occurrence and distribution of these bacteria. The isolation of indigenous bacteria in all the soils with different cropping systems is an indication that the soils are favourable for nitrogen fixation. Based on the differences in cultural characteristics of the isolates, our data demonstrate the presence of high diversity of bacteria associated with bean nodules.     

坡度和刺槐覆盖对黄土坡面产流产沙影响的模拟降雨研究

 选用处于黄土高原的山西省吉县蔡家川刺槐覆盖坡面的表层土壤,栽植刺槐幼林后进行人工降雨模拟试验,对比研究不同坡度对刺槐覆盖坡面和裸露坡面的产流和侵蚀产沙的影响。结果表明:当降雨强度一定时,在一定的坡度范围内,随着坡度增加,开始产流时间提前,径流的速度加快,树冠截留率减小,径流量增大,侵蚀量、含沙量增加;刺槐林树冠截留率与坡度的关系为I=29.556α-0.311（R2=0.9874）;刺槐覆盖坡面侵蚀量与坡度之间的关系为W=0.116 84α3.005 9（R2=0.9795）;同一坡度条件下,裸露坡面比刺槐覆盖坡面径流平均速度高15%～25%,径流量高15%～48%,侵蚀量高10%～117%,平均含沙量高55.5%～133.0%。     

Genetic diversity of African wild rice (Oryza longistaminata Chev. et Roehr) at the edge of its distribution

Ethiopia is at the edge of the distribution for African wild rice, Oryza longistaminata. Here, chloroplast (cp) and simple sequence repeat (SSR) markers were applied to wild rice accessions in Ethiopia to evaluate how they differ from control O. longistaminata, O. barthii and O. glaberrima accessions which originated from African countries. Based on the cp genomes of African wild rice species, maternally inherited cpINDEL markers were developed. The cp indels helped to elucidate 20 plastid types. African cultivated rice shared a particular plastid type with one of annual O. barthii. Parts of northern wild rice in Ethiopia shared Type 6 with control O. longistaminata. The north group shared another type with parts of the south group. The 16 SSR markers amplified a total of 155 alleles in 215 rice accessions, with mean allelic richness of 9.688 per locus, observed heterozygosity of 0.241, expected heterozygosity of 0.724, polymorphic information content of 0.700, and a significant genetic differentiation of 0.215. Both cpINDEL and nuclear markers analyses suggested that wild rice in Ethiopia belongs to O. longistaminata. However, they carry both a unique plastid type and different population structure from control O. longistaminata collected from other areas in Africa. We concluded that the edge of its distribution maintains unique variation. These populations are regarded as valuable genetic resources for future rice breeding.

     

Genetic diversity among watermelon (Citrullus lanatus and Citrullus colocynthis) accessions

Genetic diversity was estimated among 42 U.S. PlantIntroduction (PI) accessions of the genusCitrullus (of these, 34 PIs are reported tohave disease resistance), and 5 watermelon cultivars, using 30RAPD primers. These primers produced 662 RAPD markers that could berated with high confidence. Based on these markers, geneticsimilarity coefficients were calculated and a dendrogram wasconstructed using the unweighted pair-group method witharithmetic average (UPGMA). The analysis delineated threemajor clusters. The first cluster consisted of a group of fivewatermelon cultivars, a group of C.lanatus var. lanatusaccessions, and a group of C.lanatus var. lanatusaccessions that contained some C.lanatus var. citroidesgenes. The second cluster consisted of the C.lanatus var. citroidesaccessions, while the third cluster consisted of theC. colocynthis accessions.The two C. lanatus clustersdifferentiated from each other and from the C.colocynthis cluster at the level of 58.8%and 38.9% genetic similarity, respectively. Assessment ofgenetic diversity among accessions that have been reported to havedisease resistance indicated that resistance to either anthracnose,downy mildew, powdery mildew, or watermelon mosaic virus is foundamong all major groups of Citrullus PIs.Additionally, resistance to gummy stem blight or Fusarium wilt mayexist among C. lanatus var.citroides PIs. This study demonstrates thatmolecular markers can be useful in assessing genetic diversity, andin sorting Citrullus PIs into phylogeneticgroups prior to their evaluation for disease or pestresistance.     

4种经济鲍遗传多样性与分化的研究

应用聚丙烯酰胺凝胶电泳技术研究盘鲍(Haliotis discus discus)、皱纹盘鲍(H.discus hannai)、九孔鲍(H.diversicolor supertexta)养殖群体和杂色鲍(H.diversicolor diversicolor)自然群体遗传多样性与分化结果表明,4种经济鲍的遗传多样性较低,盘鲍群体平均每位点等位基因数目、多态位点百分数(P0.99%)、观察杂合度和期望杂合度分别为1.2、16.67、0.109和0.061,皱纹盘鲍群体分别为1.10、11.11、0.093和0.056,杂色鲍群体分别为1.44、33.33、0.106和0.118,九孔鲍群体分别为1.50、33.33、0.135和0.128。盘鲍在Mdh-1位点上符合H-W平衡标准(P>0.05),而在位点Est-3(F=-0.753)和Sod-1-1(F=-1.000)上表现出杂合子过量;皱纹盘鲍在位点Est-3符合H-W平衡标准(P>0.05),而在位点Est-3(F=-0.371)和Sod-1(F=-1.000)上表现出杂合子过量;杂色鲍在位点Est-3、Mdh-1和Amy-1上符合H-W平衡标准(P>0.05),而在位点Aat-1(F=-0.486)和Mdh-1(F=-0.210)上表现出杂合子过量,在位点Est-2(F=0.597)、Amy-1(F=0.330)和Me-1(F=1.000)上表现出杂合子缺失,九孔鲍在位点Est-3、Sdh-2、Amy-1和Mdh-1上符合H-W平衡标准(P>0.05),而在位点Aat-1(F=-0.477)和Amy-1(F=-0.149)上表现出杂合子过量,在位点Est-2(F=0.540)上表现出杂合子缺失。盘鲍和皱纹盘鲍的遗传距离为0.055,九孔鲍和杂色鲍的遗传距离为0.016。     

不同载体菌肥对刺槐光合特性及土壤养分、细菌群落的影响

为探究接种粘质沙雷氏菌（Serratia marcescens N1.14）X-45和不同载体基质固态发酵制备而成的菌肥的应用效果,并以此为结果筛选出可有效替代珍稀资源泥炭发挥肥效的载体,本研究设置7个处理：未施肥对照组（CK）、泥炭对照组（T0）、秸秆组（T1）、麦麸组（T2）、秸秆∶麦麸=1∶1组（T3）、秸秆∶麦麸∶棉籽壳=1∶1∶1组（T4）、秸秆∶麦麸∶豆饼=1∶1∶1组（T5）,通过盆栽试验测定不同菌肥施用下刺槐（Robinia pseudoacacia L.）的光合特性参数和土壤养分含量,采集效果较好菌肥处理下的根际土样本进行16S rDNA高通量测序。结果表明,与泥炭对照相比,除单一载体秸秆外,其余载体处理均可不同程度地改善刺槐光合特性及土壤营养环境,其中以T3、T4应用效果最显著,光合特性参数和土壤养分含量提升明显。基于16S rDNA高通量测序的刺槐根际土微生物多样性结果显示,菌肥的施入可显著改善土壤菌群结构和组成,提升益生菌群Actinomadura和Mesorhizobium的相对丰度,同时其丰度与水解氮、有效磷含量呈正相关,与pH值、速效钾含量呈负相关,即土壤...     

Genetic diversity of the earthworm Octolasion tyrtaeum (Lumbricidae,Annelida)

Octolasion tyrtaeum (Savigny, 1826), a cosmopolite earthworm species widespread around the world, is known to consist of two morphologically distinct forms, small (4–8 cm long) and large (10–14 cm) ones that sometimes are found in sympatry. It was demonstrated that these forms belong to significantly divergent mtDNA lineages, which suggests that the differences among these forms are caused by genetic factors. However, these results were in contrast to the allozyme analyses, and nobody has demonstrated that differences among these lineages exist on nuclear level as well.We analyzed mitochondrial cox1 and cox2 and nuclear ITS2 sequences of O. tyrtaeum specimens from various regions of Russia, Belarus, and Kazakhstan. Our sample only included individuals belonging to the small form, however, we found both genetic lineages described by earlier studies, and, in addition, discovered a new genetic lineage. Nuclear ribosomal sequences confirmed that the differences between these lineages are deep. We also found one example of incongruence for several individuals whose mitochondrial sequences belonged to the “small” lineage, but nuclear ITS2 fell into a separate branch on the phylogenetic tree. In addition, O. tyrtaeum was found to be paraphyletic with respect to the closely related species O. cyaneum (Rosa, 1884).     

The diversity of rhizobia nodulating chickpea (Cicer arietinum) under water deficiency as a source of more efficient inoculants

Chickpea is an important pulse crop grown mainly in the arid and semi-arid regions. The effect of water deficiency on nodulation, biomass production, and competition for nodule occupancy was evaluated in three different soils with two chickpea cultivars, Amdoun I and Chetoui. Two watering regimes were considered; a control that was irrigated three times per week and a water-deficient treatment that was irrigated only one time a week. Results showed that water deficiency significantly decreased the nodule number and the shoot dry weight for both cultivars. Root-nodule bacteria were isolated and characterized by PCR-RFLP of 16S rDNA and nifD-K intergenic spacer. The results show that water deficiency affects the diversity of nodulating rhizobia. The nodulation by Mesorhizobium mediterraneum was reduced while inefficient nodulation by Ensifer meliloti was favoured. In both treatments, chickpea was preferentially nodulated by nifD-K type N6. Analysis for NaCl tolerance showed that most of rhizobia nodulating chickpea under water deficiency are NaCl tolerant. Inoculation with the selected salt-tolerant strain of M. mediterraneum LILM10 increased significantly nodule number and grain yield in the field.     

滨海盐碱地刺槐白蜡混交林土壤酶与养分相关性研究

研究了刺槐、绒毛白蜡纯林及其混交林中不同土层在不同季节的土壤养分含量、土壤酶活性的变化。结果表明：各林分间的土壤养分含量和土壤酶活性在各个季节和土层均表现出差异。经统计分析．土壤酶活性和土壤养分含量在不同季节呈显著相关关系。土壤酶活性和土壤养分含量在土层中的分布有一定的规律性,总的来说,随着土层逐渐加深,土壤酶活性逐渐减弱,土壤养分含量逐渐下降。混交林中各土层的pH值和含盐量都低于纯林相应值,并且在树木生长、土壤养分和土壤酶活性上．混交林优于纯林。     

Genetic diversity of the African hexaploid species Solanum scabrum Mill. and Solanum nigrum L. (Solanaceae)

Two hexaploid species of Solanum sect. Solanum are present in Africa: Solanum scabrum and S. nigrum. Solanum scabrum is a widely cultivated species and is used as a leafy vegetable, as a source of medicine and as a source of ink dye. In previous studies a wide range of morphological diversity has been reported in this species and in some studies subspecies have been proposed. Subspecies are also recognized in S. nigrum. However, it has not been established whether or not the morphological differences are reflected at the genomic level. The present study applies AFLPs to study the genetic diversity in S. scabrum and its relationship to geographical provenance, morphological differences and the possible existence of subspecies within S. scabrum and S. nigrum. The data obtained were analyzed with cluster analysis (using UPGMA and NJ). The results indicate that the genetic variation within S. scabrum was higher within accessions than between accessions. Accessions did not cluster according to their geographical provenance, indicating that accessions from different geographical areas were not significantly different genetically. The clustering reflected neither morphological differences nor domestication status (cultivated or wild). The morphological differences exhibited by S. scabrum could be due to selection by farmers for different plant types. The AFLP derived clustering pattern did not segregate the subspecies recognized in S. scabrum and S. nigrum into separate subclusters.