Measurement of in situ Phosphorus Availability in Acidified Soils using Iron-Infused Resin     

Karolina Tahovská  Petr Čapek  Hana Šantrůčková  Jiří Kaňa  Jiří Kopáček 《Communications in Soil Science and Plant Analysis》2016,47(4):487-494

A hybrid anion resin was tested for in situ phosphorus (P) availability measurement in soils of two stands recovering from acidification and having different P-sorption characteristics. The phosphate (P-PO₄) sorption capacity of the resin (before saturation) was 48 µmol g^?1. Sorption and elution were tested under P-PO₄ concentrations common in acidic soils (0–0.42 mmol l^?1) either with or without the presence of sulfate (0.2 mmol l^?1). The efficiency of P-PO₄ sorption was independent of the sulfate and was 100 ± 0.2% (n = 56, ± SD). The P-PO₄ recovery stabilized after six elution steps (each: 50 ml of 0.5 M sodium hydroxide, resin/solution 5:1). The efficiency of P-PO₄ recovery was 80 ± 7% and was used to evaluate field measurements. We determined the amount of P-PO₄ in the field using resin bags in three consecutive years. The results indicate that bioavailable P is negatively related to the soil ability to retain P.  相似文献   

Occurrence of (+)- and (-)-gossypol in wild species of cotton and in Gossypium hirsutum Var. marie-galante (Watt) Hutchinson     

Stipanovic RD  Puckhaber LS  Bell AA  Percival AE  Jacobs J 《Journal of agricultural and food chemistry》2005,53(16):6266-6271

Gossypol occurs as a mixture of enantiomers in cottonseed. These enantiomers exhibit different biological activities. The (-)-enantiomer is toxic to animals, but it has potential medicinal uses. Therefore, cottonseed with >95% (-)-gossypol could have biopharmaceutical applications. The (+)-enantiomer shows little, if any, toxicity to nonruminant animals. Thus, cottonseed with >95% (+)-gossypol could be more readily utilized as a feed for nonruminants. The (+)- to (-)-gossypol ratio in commercial Upland (Gossypium hirsutum) cottonseed is usually about 3:2, whereas that in commercial Pima cottonseed (Gossypium barbadense) is approximately 2:3. Herein are reported the (+)- to (-)-gossypol ratios in the seed from 28 wild species of cotton (194 accessions), 94 accessions of G. hirsutum var. marie-galante, and 3 domesticated species (11 accessions). It was found that some or all of the accessions of Gossypium darwinii, Gossypium sturtianum, Gossypium areysianum, Gossypium longicalyx, Gossypium harknessii, and Gossypium costulatum produce an excess of (-)-gossypol but none >65%. At least one accession of Gossypium anomalum, Gossypium mustelinum, Gossypium gossypioides, and Gossypium capitis-viridis contained >94% (+)-gossypol. One of the 94 accessions of G. hirsutum var. marie-galante (i.e., no. 2469) contained 97% (+)-gossypol.  相似文献   

Effect of clear-cutting on the understory vegetation,soil and diversity of litter beetles in scots pine-dominated forest     

Laima Česonienė  Remigijus Daubaras  Vytautas Tamutis  Vilma Kaškonienė  Paulius Kaškonas  Vidas Stakėnas 《Journal of Sustainable Forestry》2013,32(8):791-808

Currently, the aim of modern forest management is not only timber production but also the protection of biodiversity. The initial effects of clear-cut logging on forest understory vegetation, soil and the diversity of litter beetles have been studied. We examined unstudied effects of clear-cutting disturbance on understory vascular plant species abundance, forest soils, and understory vegetation nutrients as well as beetle diversity one year after clear-cutting. Substantial changes in the prominence values and above-ground mass of forest-related vascular plant and moss species were detected. Clear-cuttings resulted in fast appearance of new light-loving plant species. The significant decrease in understory plant biomass influenced the reduction of nutrient pools in clear-cut areas after one year. The clear-cut logging negatively influenced the richness of species and the number of individuals of stenobiontic forest-related beetles in the forest litter. However, forest clear-cuttings were beneficial for eurytopic and open land species.  相似文献   

Molekulargenetische Analyse des ‘Maschanzker’/‘Borsdorfer’‐Sortenkomplexes     

Alberto Storti  Hans–Joachim Bannier  Christian Holler  Bernd Kajtna  Thomas Rühmer  Alois Wilfling  Claudio Soldavini  Josef Dalla Via  Sanja Baric 《Erwerbs-Obstbau》2013,55(3-4):99-107

‘Maschanzker’ is one of the best-known old apple cultivars in Austria and in the 19th century this variety also played an important role in the fruit production of South Tyrol (Northern Italy). ‘Maschanzker’ is believed to originate from one of the oldest German apple vari­eties ‘Borsdorfer’, which is even considered a synonym. However, since the denomination ‘Maschanzker’ is part of the name of a number of more or less similar types of apple, this study aimed at investigating the synonymy and homonymy as well as the relationships within and between different accessions of ‘Maschanzker’, ‘Borsdorfer’ and ‘Edelborsdorfer’ by employing 14 microsatellite DNA markers. A total of 38 accessions from several collections in Europe were analysed and 14 different genotypes were identified, which were assigned to three groups. Our data suggest a series of parent-offspring connections within the here defined Maschanzker group and the Edelborsdorfer group, while no closer relationship was evident to or among the accessions of the Borsdorfer group. Molecular genetic analyses thus provide fundamental data which can serve as a basis for the pomological revision of the ‘Maschanzker’/‘Borsdorfer’ cultivar complex.  相似文献   

Vertical and horizontal water redistribution in Norway spruce (Picea abies) roots in the Moravian Upland     

Nadezhdina N  Cermák J  Gaspárek J  Nadezhdin V  Prax A 《Tree physiology》2006,26(10):1277-1288

Hydraulic redistribution (HR) by roots of large Norway spruce (Picea abies (L.) Karst.) trees was investigated by means of sap flow measurements made with the heat field deformation method. Irrigation was applied to a limited portion of the root system to steepen gradients of water potential in the soil and thus enhance rates of HR. On completion of the sap flow measurements, and to aid in their interpretation, the structure of the root system of seven of the investigated trees was exposed to a depth of 30 cm with a supersonic air-stream (air-spade). Before irrigation, vertical redistribution of water was observed in large coarse roots and some adjacent small lateral roots. Immediately after localized irrigation, horizontal redistribution of water from watered roots to dry roots via the stem base was demonstrated. The amount of horizontal distribution depended on the position of the receiving roots relative to the watered roots and the absorbing area of the watered root. No redistribution from watered roots via dry soil to roots of neighboring trees was detected. Responses of sap flow to localized irrigation were more pronounced in small lateral roots than in large branching roots where release and uptake of water are integrated. Sap flow measurements with multi-point sensors along radii in large lateral roots demonstrated water extraction from different soil horizons. We conclude that synchronous measurements of sap flow in both small and large lateral roots are needed to study water absorption and transport in tree root systems.  相似文献   

Twelve-year investigation of copper soil concentrations shows that vineyards are at risk     

Andrej Simončič  Janez Sušin  Marjan Šinkovec  Robert Leskovšek  Franc Čuš  Vida Žnidaršič Pongrac 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(5):381-394

During the period 2004–2015, the upper soil layer (0–20?cm) was sampled in eight agricultural production areas in Slovenia. Overall, 53, 249, 169, 139, and 413 samples were respectively taken from vegetable fields, arable cropland, hop fields, orchards, and vineyards. Copper was measured in the aqua-regia extracts of these samples using flame atomic absorption spectrometry. The minimum, maximum, average, and median concentrations were calculated for five land uses and for all eight production areas in Slovenia. Sample portions below and/or above the limit, warning, and critical concentrations of 60, 100, and 300?mg/kg, respectively, were calculated as well. The results were compared for different land uses and production areas and showed that the copper concentrations in the vegetable, arable crop, and hop fields and orchards did not exceed the critical concentration. In addition, the copper concentrations in the vineyards exceeded the critical concentration but the maximum copper concentration (508?mg/kg) was still lower than the concentrations reported from other vine-growing Mediterranean countries. Also, the copper concentrations in hop fields exhibited an increasing trend in the Celje (and Maribor) area(s).  相似文献   

Efficacy of fungicides on Hymenoscyphus fraxineus and their potential for control of ash dieback in forest nurseries          下载免费PDF全文

M. Hrabětová  K. Černý  D. Zahradník  L. Havrdová 《Forest Pathology》2017,47(2)

Twenty‐six commercial formulations of fungicides at six concentrations were evaluated in vitro for their efficacy on mycelial growth of Hymenoscyphus fraxineus (anamorph Chalara fraxinea). The results are presented as EC₅₀, EC₉₀ and minimal inhibitory concentration values; the comparisons with the recommended application concentrations showed that 10 of the 26 fungicides were highly effective in their ability to inhibit the mycelial growth of the pathogen. The eight most effective fungicides identified based on multiple comparisons analysis were azoxystrobin, bitertanol, captan (in two‐component preparation with trifloxystrobin), difenoconazole, kresoxim‐methyl, spiroxamine (in multicomponent preparation with tebuconazole and triadimenol), tebuconazole and trifloxystrobin. Azoxystrobin, difenoconazole, kresoxim‐methyl, mancozeb, myclobutanil, pyrimethanil, tebuconazole and trifloxystrobin were selected to verify their effectiveness in in planta tests. During two field tests in nurseries, it was found out that tebuconazole (triazole), trifloxystrobin and kresoxim‐methyl (strobilurins) and mancozeb (dithiocarbamate) were significantly effective against H. fraxineus. The best results were gained with tebuconazole, when mean percentage of diseased saplings was 16.3%, whereas in the control, it was 63.6%. The combination and alternation of fungicides from the triazole, strobilurine and dithiocarbamate chemical groups should be an effective tool for protecting ash saplings in forest nurseries. Moreover, exact timing of the treatment reflecting rainfall and development of first symptoms in the foliage will be also important.  相似文献   

不同物理形态开食料对犊牛生长发育、瘤胃发酵及血液指标的影响     

杜超  甄玉国  KERTZ Alois Francis  沈旖帆  卜登攀 《动物营养学报》2017,29(6)

本试验在湿热条件下,探究饲喂不同物理形态的开食料对犊牛生长发育、瘤胃发酵及血液指标的影响。试验采用36头荷斯坦母犊牛,随机分为3组(每组12头),分别自由采食颗粒状开食料(PSA)、粉末状开食料(PSB)和多颗粒状开食料(TS)。试验期63 d,其中1~42日龄为正常饲喂牛奶时期(断奶前期);43~49日龄为断奶期;50~63日龄为断奶后期。开食料从犊牛5日龄开始自由采食。在1、42、49以及63日龄晨饲前进行采血和称重,49和63日龄晨饲前胃管法采集瘤胃液。试验期间每天记录采食量和温湿度指数。结果表明,在湿热环境下:1)断奶期和断奶后2周TS组开食料干物质采食量、平均日增重和重料比高于PSA和PSB组,PSB组最低,但差异不显著(P0.05)。2)TS组犊牛初次反刍时间较PSA组提前3.8日龄,较PSB组提前4.7日龄,差异均显著(P0.05)。63日龄时,TS组瘤胃液氨氮含量显著低于PSA组(P0.05)。3)42日龄时PSA组犊牛血液免疫球蛋白G含量显著高于TS组(P0.05)。4)TS组犊牛初始腹泻时间较PSA和PSB组分别晚0.44和1.75日龄,但无统计学差异(P0.05),TS组腹泻率最低。综合得出,湿热环境下,多颗粒状开食料较颗粒状开食料和粉末状开食料更能促进犊牛的生长发育,使犊牛尽早产生反刍行为,从而加快瘤胃功能的完善  相似文献   

Common ragweed (Ambrosia artemisiifolia) dry matter allocation and partitioning under different nitrogen and density levels     

ROBERT LESKOVŠEK  AVISHEK DATTA  STEVAN Z. KNEZEVIC  ANDREJ SIMONČIČ 《Weed Biology and Management》2012,12(2):98-108

Dry matter partitioning and allocation is a major determinant of plant growth and its competitiveness. Common ragweed (Ambrosia artemisiifolia) is a troublesome agronomic weed species and it is also a major health concern in Europe and many other countries because of its rapid spreading and production of allergenic pollen. A field experiment was conducted in 2009 to determine the effect of nitrogen fertilizer levels (0, 100, and 200 kg ha^?1) and plant density levels (1.3, 6.6, and 13.2 plants per m²) on the leaf, stem dry matter partitioning, and dry matter allocation of ragweed. With an increasing density, the stem partitioning coefficient increased, whereas the leaf partitioning coefficient decreased. The addition of nitrogen had a limited effect on the leaf and stem dry matter partitioning. The root dry matter production decreased with an increasing density and was not influenced by the addition of nitrogen. Under intraspecific competition, ragweed exhibited a stronger above‐ground competition intensity than below the ground, which resulted in a greater root : shoot ratio, compared to the low‐density stands. The level of nitrogen influenced the vertical leaf, stem, and total dry matter distribution, with a greater allocation to the top stratum of the plants, thus increasing their competition for light. The biomass allocation of ragweed to the roots in response to the nitrogen supply exhibited a low plasticity, compared to the shoots, which displayed a high plasticity. The results of this study suggested that, under intraspecific conditions and with an increasing nitrogen supply, ragweed would be more competitive in above‐ground resource acquisition.  相似文献   

United States Department of Agriculture-Agricultural Research Service studies on polyketide toxins of Fusarium oxysporum f sp vasinfectum: potential targets for disease control     

Bell AA  Wheeler MH  Liu J  Stipanovic RD  Puckhaber LS  Orta H 《Pest management science》2003,59(6-7):736-747

A group of 133 isolates of the cotton wilt pathogen Fusarium oxysporum Schlecht f sp vasinfectum (Atk) Sny & Hans, representing five races and 20 vegetative compatibility groups within race 1 were used to determine the identity, biosynthetic regulation and taxonomic distribution of polyketide toxins produced by this pathogen. All isolates of F oxysporum f sp vasinfectum produced and secreted the nonaketide naphthazarin quinones, bikaverin and norbikaverin. Most isolates of race 1 (previously denoted as races 1, 2 and 6; and also called race A) also synthesized the heptaketide naphthoquinones, nectriafurone, anhydrofusarubin lactol and 5-O-methyljavanicin. Nine avirulent isolates of F oxysporum from Upland cotton roots, three isolates of race 3 of F oxysporum f sp vasinfectum, and four isolates of F oxysporum f sp vasinfectum from Australia, all of which previously failed to cause disease of Upland cotton (Gossypium hirsutum L) in stem-puncture assays, also failed to synthesize or secrete more than trace amounts of the heptaketide compounds. These results indicate that the heptaketides may have a unique role in the virulence of race 1 to Upland cotton. The synthesis of all polyketide toxins by ATCC isolate 24908 of F oxysporum f sp vasinfectum was regulated by pH, carbon/nitrogen ratios, and availability of calcium in media. Synthesis was greatest below pH 7.0 and increased progressively as carbon/nitrogen ratios were increased by decreasing the amounts of nitrogen added to media. The nonaketides were the major polyketides accumulated in synthetic media at pH 4.5 and below, whereas the heptaketides were predominant at pH 5.0 and above. The heptaketides were the major polyketides formed when 10 F oxysporum f sp vasinfectum race 1 isolates were grown on sterilized stems of Fusarium wilt-susceptible cotton cultivars, but these compounds were not produced on sorghum grain cultures. Both groups of polyketide toxins were apparently secreted by F oxysporum f sp vasinfectum, since half of the toxin in 2-day-old shake culture was present in the supernatant. Secretion was enhanced by calcium. Glutamine and glutamic acid inhibited both nonaketide and heptaketide syntheses, even at low nitrogen  相似文献