Effects of metal pollution on the earthwormdendrobaena rubida (Sav.) in acidified soils

Survival of adultDendrobaena rubida, cocoon production, cocoon viability, and growth of juveniles were examined in laboratory experiments when the worms were reared in acidified and metal polluted soils. Solutions of Cu, Cd and Pb were added to give total concentrations of 10, 100 and 500 μg g^?1 in soils with a pH of 4.5, 5.5 and 6.5. Adult tissues, hatchlings and cocoons were analyzed for metals. D. rubida survived poorly in soils with low pH, especially in combination with Pb or Cu, which accumulated in seminal vesicles and cerebral ganglion. Cocoon production was halved when pH was lowered from 6.5 to 4.5 and metals reduced the cocoon number even more in the most acid soils. Hatching success was lower than 20 % in acidified soils. In contrast, the number of hatchlings increased when pH decreased and peaked in soils polluted with Cd. While low pH reduced the embryonic development time, metals prolonged it. Juveniles grew slowly and died early at low pH.     

Soil organic matter distribution and microaggregate characteristics as affected by agricultural management and earthworm activity

Stable microaggregates can physically protect occluded soil organic matter (SOM) against decomposition. We studied the effects of agricultural management on the amount and characteristics of microaggregates and on SOM distribution in a marine loam soil in the Netherlands. Three long‐term farming systems were compared: a permanent pasture, a conventional‐arable system and an organic‐arable system. Whole soil samples were separated into microaggregates (53–250 µm), 20–53 µm and < 20 µm organo‐mineral fractions, sand and particulate organic matter, after complete disruption of macroaggregates. Equal amounts of microaggregates were isolated, irrespective of management. However, microaggregates from the pasture contained a larger fraction of total soil organic C and were more stable than microaggregates from the two arable fields, suggesting greater SOM stabilization in microaggregates under pasture. Moreover, differences in the relative contribution of coarse silt (> 20 µm) versus fine mineral particles in the microaggregates of the different management systems demonstrate that different types of microaggregates were isolated. These results, in combination with micromorphological study of thin sections, indicate that the great earthworm activity under permanent pasture is an important factor explaining the presence of very stable microaggregates that are relatively enriched in organic C and fine mineral particles. Despite a distinctly greater total SOM content and earthworm activity in the organic‐ versus the conventional‐arable system, differences in microaggregate characteristics between both arable systems were small. The formation of stable and strongly organic C‐enriched microaggregates seems much less effective under arable conditions than under pasture. This might be related to differences in earthworm species' composition, SOM characteristics and/or mechanical disturbance between pasture and arable land.     

Riboflavin content in the coelomocytes of contrasting earthworm species is differentially affected by edaphic variables including organic matter and metal content

The riboflavin content in extruded coelomocyte lysates derived from Dendrodrilus rubidus may serve as a sensitive bioindicator of soil metal pollution: the vitamin (B2) content has previously been found to be high in worms from unpolluted soil but low in worms inhabiting Zn/Pb mine soils, aerially deposited Ni-contaminated soil, and in worms experimentally transferred from clean soil to the metalliferous field soils. The aim of the present work was to extend these observations by comparing the number and riboflavin composition of coelomocytes retrieved from three lumbricid species (Allolobophora chlorotica, Dendrobaena veneta, Eisenia andrei) after 4-week exposures to an unpolluted commercial soil, two geochemically contrasting unpolluted field soils, and two different Zn/Pb/Cd-polluted soils from the Bukowno district in South Poland. Whilst eco-physiologically contrasting, these three earthworm species share the trait of possessing relatively high numbers of eleocytes, a category of immune-competent coelomocyte rich in autofluorescent riboflavin. Spectroflurometric analysis indicated that coelomocyte riboflavin content in worms maintained in strongly metalliferous soils or in unpolluted sandy-clay and loamy-sand soils was increased in coleomocytes from epigeic D. veneta and E. andrei species, whilst was decreased in endogeic A. chlorotica. In conclusion, the riboflavin content of earthworm coelomocytes is affected in species-specific ways by edaphic variables, including organic matter and metal pollution.     

Clone distribution of the earthworm Eiseniella tetraedra (Sav.) (Oligochaeta: Lumbricidae) across an altitudinal gradient on subarctic mountains of NW Europe

In earlier studies, we have shown that clone diversity of the parthenogenetic earthworm Eiseniella tetraedra increases from the upper reaches of rivers in northern Sweden towards their mouths. Now we survey brooks in the Scandes Mountains in the watershed between Sweden and Norway where major rivers originate. Using starch gel enzyme electrophoresis, we found 37 clones in a total catch of 379 individuals from six mountains. The most abundant clone made up 48.3% of the individuals collected. It was present on most mountains and was found at different elevations. In comparison with other clones it may represent a general-purpose genotype adapted to environmental conditions ranging from alpine through to subalpine to boreal habitats in the mountains. Diversity of clone assemblages decreased with increasing elevation. On four mountains, one to two clones were found at higher elevations. Passive downstream dispersal of E. tetraedra propagules from wider areas of the mountains was responsible for the more diverse clone pools in the lower reaches of the brooks (i.e., “small rivers behave like large ones”). Two clone groups, which deviated from the norm clone in their number of enzyme variants, were evenly distributed among different elevations. Therefore, we could not correlate genotype differences (i.e., adaptation of clones to mountain elevations). Clone pool similarities among the mountains were low on average (range 0–58%) but in a cluster of four mountains, similarities varied from 46% to 58%. Clone pool similarities between different elevations of the same mountain ranged from 27% to 83%. One mountain brook was sampled over 3 years to assess clone turnover. Only the norm clone was found in upstream habitats but it and three other clones were recorded downstream in at least 2 years. Ten clones were found once in the latter habitat as well.     

长期施肥黑土微生物区系及功能多样性的变化

Black soil （Mollisol） is one of the main soil types in northeastern China. Biolog and polymerase chain reactiondenaturing gradient gel electrophoresis （PCR-DGGE） methods were used to examine the influence of various fertilizer combinations on the structure and function of the bacterial community in a black soil collected from Harbin, Heilongjiang Province. Biolog results showed that substrate richness and catabolic diversity of the soil bacterial community were the greatest in the chemical fertilizer and chemical fertilizer＋manure treatments. The metabolic ability of the bacterial community in the manure treatment was similar to the control. DGGE fingerprinting indicated similarity in the distribution of most 16S rDNA bands among all treatments, suggesting that microorganisms with those bands were stable and not influenced by fertilization. However, chemical fertilizer increased the diversity of soil bacterial community. Principal com- ponent analysis of Biolog and DGGE data revealed that the structure and function of the bacterial community were similar in the control and manure treatments, suggesting that the application of manure increased the soil microbial population, but had no effect on the bacterial community structure. Catabolic function was similar in the chemical fertilizer and chemical fertilizer＋manure treatments, but the composition structure of the soil microbes differed between them. The use of chemical fertilizers could result in a decline in the catabolic activity of fast-growing or eutrophic bacteria.     

Genetic diversity and systematic relationships in sweetpotato (Ipomoea batatas (L.) Lam.) and related species as revealed by RAPD analysis

Summary Fifteen 10mer primers, in combination with the Stoffel fragment, were used to detect random amplified polymorphic DNA (RAPDs) among 26 accessions of sweetpotato (I. batatas (L.) Lam.) from Oceania, Peru, the Philippines, and the United States and between 8 Ipomoea species from section Batatas. Phenetic and principal coordinate analysis of the 56 polymorphisms detected within the hexaploid I. batatas clearly delineated the South Pacific and the Peruvian sweetpotato lines. The two U.S. cultivars clustered with the Oceanic materials. Cladistic and phenetic analysis of 8 Ipomoea species supports previously published phylogenies based on morphological and RFLP data. Among the species examined, I. tabascana, I. trifida and the tetraploid forms of I. batatas from Mexico and Ecuador, including I. batatas var. apiculata, are the taxa most closely related to the cultivated hexaploid I. batatas. These findings support the utility of RAPD markers for evaluating genetic diversity in sweetpotato and for establishing taxonomic and evolutionary relationships in Ipomoea.     

Genetic diversity and population structure of vegetable soybean (Glycine max (L.) Merr.) in China as revealed by SSR markers

Vegetable soybean is a kind of value-added specialty soybean serving as vegetable or snacks. Understanding the genetic structure of vegetable soybean is a key point for further utilization in breeding programs. In the present study, the genetic structure and diversity of 100 vegetable soybean accessions planted in China was analyzed using 53 simple sequence repeat (SSR) markers. A total of 296 alleles were detected with an average of 5.6 alleles per SSR locus. The polymorphism information content (PIC) values of SSR markers ranged from 0.074 to 0.831, with an average of 0.573. Nei’s genetic distance between accessions ranged from 0 to 0.9434 with an average of 0.6286. These vegetable soybean germplasms could be divided into 8 subgroups based on STRUCTURE analysis, or 11 subgroups based on unweighted pair group method with arithmetic average (UPGMA) cluster. Further comparison showed that the UPGMA subgroups and STRUCTURE subgroups were in fact highly consistent. Germplasms in each classified groups showed great consistency with their origins, seed coat colors or pedigrees. Genetic relationships among germplasm panels that initially came from different geographical regions were also analyzed. Germplasm panels from China Mainland, Taiwan Island and Japan were highly similar to each other with the similarities of over 98 %. Molecular data and cluster analysis also showed that germplasms from China Mainland are more diverse than those from other areas. These results gave us a deep insight into the genetic structure of vegetable soybeans in China and will help us to improve the breeding strategies.     

Maize (Zea mays L.) yield and soil properties as affected by no tillage in the black soils of China

A four-year tillage experiment on maize was conducted in the high latitude region of Northeast of China. The main objective of this study was to investigate the effects of different field tillage practices on maize grain yield, soil physical properties, and soil water and temperature dynamics in Northeast of China. The tillage practices included moldboard plow tillage (MOT), rotary tillage (ROT), reduced tillage (RET), combined tillage (COT), and no tillage (NOT). The surface soil water content at depths of 0–20 cm was higher under NOT compared with other tillage practices, but not different at the deeper soil depths in 2011. The soil temperatures under NOT and RET were lower than those under moldboard plow tillage and ROT at depths of 5 and 15 cm, respectively, measured at 9:00 am in 2005. From the hourly dynamics of soil temperature, the differences among the tillage practices mainly appeared during the daytime (from 8:00 am to 7:00 pm). Among all the practices, the average daily soil temperature under ROT was the highest, while that under NOT was the lowest. MOT, ROT, and RET had higher soil accumulative infiltration compared with NOT and COT. The surface soil bulk density under NOT was higher than or equal to that under the other four tillage practices. The maize yields under NOT were the lowest among all the tillage practices for three years straight. Meanwhile, the yields under MOT were the highest, which were about 47%, 61%, and 38% higher than those under NOT. NOT practice is not recommended for use in spring-planted maize under the high latitude humid cool climate Mollisol region in Northeast of China.     

Genetic diversity in the Lima bean (Phaseolus lunatus L.) as revealed by chloroplast DNA (cpDNA) variations

Genetic diversity in the Lima bean (P. lunatus L.) was assessed bymeans of two chloroplast DNA probes. Based on data obtained from 152accessions including wild forms and landraces, the two separateMesoamerican and Andean groups were confirmed and a transition poolof genetic diversity was observed in the two botanical formsconsistent with their distribution range. Three primary centres ofgenetic diversity and one secondary diversification spot are proposedfor the wild Lima bean whereas only two domestication sites areunderlined for the landraces. The importance of human intervention inwidening the distribution range and the genetic diversity inlandraces is discussed.     

Biological nitrogen fixation in faba bean (Vicia faba L.) in the Ethiopian highlands as affected by P fertilization and inoculation

 N₂ fixation by leguminous crops is a relatively low-cost alternative to N fertilizer for small-holder farmers in developing countries. N₂ fixation in faba bean (Vicia faba L.) as affected by P fertilization (0 and 20 kg P ha^–1) and inoculation (uninoculated and inoculated) with Rhizobium leguminosarium biovar viciae (strain S-18) was studied using the ¹⁵N isotope dilution method in the southeastern Ethiopian highlands at three sites differing in soil conditions and length of growing period. Nodulation at the late flowering stage was significantly influenced by P and inoculation only at the location exhibiting the lowest soil P and pH levels. The percentage of N derived from the atmosphere ranged from 66 to 74%, 58 to 74% and 62 to 73% with a corresponding total amount of N₂ fixed ranging from 169 to 210 kg N ha^–1, 139 to 184 kg N ha^–1 and 147 to 174 kg N ha^–1 at Bekoji, Kulumsa and Asasa, respectively. The total N₂ fixed was not significantly affected by P fertilizer or inoculation across all locations, and there was no interaction between the factors. However, at all three locations, N₂ fixation was highly positively correlated with the dry matter production and total N yield of faba bean. Soil N balances after faba bean were positive (12–58 kg N ha^–1) relative to the highly negative N balances (–9–44 kg N ha^–1) following wheat (Triticum aestivum L.), highlighting the importance of rotation with faba bean in the cereal-based cropping systems of Ethiopia. Received: 13 January 2000     

Compositional changes in 'Bartlett' pear ( Pyrus communis L.) cell wall polysaccharides as affected by sunlight conditions

Preharvest conditions can have a great impact on fruit quality attributes and postharvest responses. Firmness is an important quality attribute in pear, and excessive softening increases susceptibility to bruising and decay, thus limiting fruit postharvest life. Textural characteristics of fruits are determined at least in part by cell wall structure and disassembly. Few studies have analyzed the influence of fruit preharvest environment in softening, cell wall composition, and degradation. In the current work 'Bartlett' pears grown either facing the sun (S) or in the shade (H) were harvested and stored for 13 days at 20 °C. An evaluation of fruit soluble solids, acidity, color, starch degradation, firmness, cell wall yield, pectin and matrix glycan solubilization, depolymerization, and monosaccharide composition was carried out. Sun-exposed pears showed more advanced color development and similar levels of starch degradation, sugars, and acids than shaded fruit. Sunlight-grown pears were at harvest firmer than shade-grown pears. Both fruit groups softened during storage at 20 °C, but even after ripening, sun-exposed pears remained firmer. Sunlight exposure did not have a great impact on pectin molecular weight. Instead, at harvest a higher proportion of water-solubilized uronic acids and alkali-solubilized neutral sugars and a larger mean molecular size of tightly bound glycans was found in sun-exposed pears. During ripening cell wall catabolism took place in both sun- and shade-grown pears, but pectin solubilization was clearly delayed in sun-exposed fruit. This was associated with decreased removal of RG I-arabinan side chains rather than with reduced depolymerization.     

Iron nutrition of sunflower(Helianthus annuus L.) as affected by various levels of p and ZN

The effects of various P and Zn levels on iron nutrition of sunflower (Helianthus annuus L.c.v. Record) were studied in two separate experiments in nutrient solution under greenhouse conditions.

In the first experiment, sunflower was grown in nutrient solutions containing four levels of P(1.5, 2.5, 3.5 and 4.5 mM/l) and three levels of Fe(0.25, 0.75, and 1.5 ppm) as FeCl₃ or FeEDDHA. In the second experiment (following the first experiment), the treatments were three P levels (0.75, 1.50 and 3.00 mM/l), three Fe levels (0.25, 0.75 and 1.5 ppm) as FeEDDHA and three Zn levels (0.1, 0.2 and 0.4 ppm).

The plants receiving Fe‐chelate, except for 0.25 ppm Fe, showed no symptoms of iron chlorosis. With inorganic Fe treatments, iron chlorosis appeared after 7–10 days depending on P level, but except for 0.25 ppm Fe which remained chlorotic, plants recovered completely within 3–4 days thereafter due to pH regulating mechanism of sunflower under iron stress condition. With both sources of Fe, chlorosis was associated with high P:Fe ratio.

Increased P and Fe levels in nutrient solution resulted in general increases in the dry weights of roots and shoots. The Fe concentration of shoots, except in few instances, was not affected by P levels, indicating that the sunflower cultivar used in this experiment could utilize inorganic Fe as well as Fe‐chelate under our experimental conditions.

Increasing P levels caused significant increases in Mn content of the shoots as 0.25 and 0.75 ppm inorganic Fe³⁺. Increased Fe levels increased shoot Mn content with inorganic Fe and decreased it with Fe‐chelate. The effects of P, Fe and Zn on sunflower indicated an antagonistic effect of Zn on 1.5 ppm Fe for all P levels. Increased Zn levels in nutrient solution generally increased Zn content of the shoots without having any marked effect on their Mn content.     

Changes in the odorants of boiled carp fillet (Cyprinus carpio L.) as affected by increasing methionine levels in feed

Sixty common carp in groups of five in four tanks per treatment were given three diets containing different increasing amounts of methionine. The aroma extract dilution analysis (AEDA) of the boiled carp fillets resulted in 32 odorants, of which 26 were identified. Ten compounds were quantified using an internal standard (IS), and the very low concentrations of 2-acetyl-1-pyrroline, (Z)-1, 5-octadien-3-one, and methional were calculated by the nasally determined detection limit. The concentration of methional seemed to increase with increasing methionine in the diet. Because the unstable methional could be converted by beta-elimination into methanethiol, the impact resulting in an off-flavor was investigated by headspace analysis. The investigation revealed no difference in the methanethiol contents between the treatments with the lowest and highest methionine supplies.     

Transport of labile carbon in runoff as affected by land use and rainfall characteristics

The mobilization of organic carbon (C) by water erosion could impact the terrestrial C budget, but the magnitude and direction of that impact remain uncertain due to a lack of data regarding the fates and quality of eroded C. A study was conducted to monitor total organic C and mineralizable C (MinC) in eroded materials from watersheds under no till (NT), chisel till (CT), disk till low input (DT-LI), pasture and forest. The DT-LI treatment relies on manure application and legume cover crops to partly supply the N needed when corn is grown, and on cultivation to reduce the use of herbicides. Each watershed was instrumented with a flume and a Coshocton wheel sampler for runoff measurement. Carbon dioxide (CO₂) evolved during incubation (115 days) of runoff samples was fitted to a first-order decomposition model to derive MinC. Annual soil (6.2 Mg ha⁻¹) and organic C (113.8 kg C ha⁻¹) losses were twice as much in the DT-LI than in the other watersheds (<2.7 Mg soil ha⁻¹, <60 kg C ha⁻¹). More than management practices, rainfall class (based on intensity and energy) was a better controller of sediment C concentration and biodegradability. Sediment collected during the low-intensity (fall/winter) storms contained more organic C (37 g C kg⁻¹) and MinC (30–40% of sediment C) than materials displaced during the high-intensity summer storms (22.1 g C kg⁻¹ and 13%, respectively). These results suggest a more selective detachment and sorting of labile C fractions during low-intensity storms. However, despite the control of low-intensity storm on sediment C concentration and quality, increased soil loss with high-energy rainfall suggests that a few infrequent but high-energy storms could determine the overall impact of erosional events on terrestrial C cycling.     

长期施磷黑土中磷的吸附–解吸特征及其影响因素

  【目的】  比较长期不施磷与施磷黑土对外源磷的吸附–解吸特征,为黑土区磷素管理提供理论基础。  【方法】  供试黑土长期定位试验位于吉林省公主岭市,始于1990年。2018年选择其中不施肥(CK),施氮钾肥(NK),施氮磷钾肥(NPK)和氮磷钾+有机肥(NPK+M) 4个处理小区,采集0—20、20—40和40—60 cm土层的土壤样品,分析了土壤理化性质,采用恒温平衡法测定了土壤磷的吸附–解吸特征,并由此计算得到磷最大吸附量(Q_m)、吸附亲和力常数(K_Q)、最大缓冲容量(MBC)、磷吸附饱和度(DPS)、最大解吸量(D_m)和解吸率(D_r)。  【结果】  随着平衡溶液中磷浓度的增加,磷的吸附量与解吸量均呈先快速增加后逐渐趋于平衡的过程。与不施磷处理(CK和NK)土壤相比,施磷处理(NPK、NPK+M)减少了磷的吸附量,增加了磷的解吸量。与不施磷处理相比,施磷处理在0—60 cm剖面上的Q_m和MBC值分别降低了4.94%～63.46%和15.90%～75.18%,D_r值增加了8.52%～474.0%,以NPK+M处理变化量最大。施磷处理比不施磷处理在0—60 cm土壤剖面上全磷和有机质含量分别增加了34.40%～145.5%和12.77%～50.07%,游离态铁铝氧化物(Fe_d+Al_d)含量降低了5.14%～11.35%。冗余分析表明,不施磷处理土壤的有机质、Fe_d+Al_d和全磷,以及施磷处理中的Fe_d+Al_d、络合态铁铝氧化物(Fe_p+Al_p)、pH和有机质是影响磷吸附解吸特征参数的主要土壤因子,分别解释了不施磷和施磷处理全部变异的77.59%和90.62%。土壤有效磷(Olsen-P)与磷吸附饱和度(DPS)相关关系表明,所研究的黑土DPS环境界限值为8%左右,NPK+M处理中3个土层的DPS_M-P值(由Mehlich-3 浸提的磷、铁和铝计算)为7.77%～25.96%,DPS_O-P值(由Olsen-P和Q_m计算)为17.24%～24.75%,均高于此环境界限值,具有磷素流失的风险。  【结论】  长期施磷降低了黑土对外源磷的吸附量,增加了磷解吸量。长期不施磷肥,土壤对磷的吸附和解吸主要受有机质、游离态铁铝氧化物的影响。而长期施肥,特别是有机肥与化肥配合处理,土壤中游离态和络合态铁铝氧化物、有机质及pH是影响磷吸附解吸特征的主要因素。     

Glucosinolate concentration in turnip (Brassica rapa ssp. rapifera L.) roots as affected by nitrogen and sulfur supply

Three greenhouse pot experiments were conducted with four different nitrogen (N) treatments (80, 160, 240, and 320 kg ha (-1)) in combination with three sulfur (S) treatments (10, 20, and 60 kg ha (-1)) to study the effects of combined N and S supply on glucosinolate concentration and composition in turnip roots. Total glucosinolate concentration varied widely from 9.7 (N 320S 10) to 91.6 (N 160S 60) mg (100 g) (-1) root fresh weight (FW) and individual glucosinolate concentrations were increased with increasing S supply regardless of the N treatment, whereas enhanced N supply (160 - 320 N ha (-1)) at the high S level (60 kg ha (-1)) did not affect total glucosinolate concentration. In contrast, assumingly attributed to the individual glucosinolate biosynthesis concentration of N-containing tryptophan-derived indole glucosinolate was highest with increased N supply, whereas S-containing methionine-derived aromatic and aliphatic glucosinolates decreased with increasing N supply combined at low S level (10-20 kg ha (-1)).     

Genetic diversity in cowpea [Vigna unguiculata (L.) Walp.] as revealed by RAPD markers

The present study, using RAPD analysis, was undertaken to characterize genetic variation in domesticated cowpea and its wild progenitor, as well as their relationships. The materials used consisted of 26 domesticated accessions, including accessions from each of the five cultivar-group, and 30 wild/weedy accessions, including accessions from West, East and southern Africa. A total of 28 primers generated 202 RAPD bands. One hundred and eight bands were polymorphic among the domesticated compared to 181 among wild/weedy cowpea accessions. Wild accessions were more diverse in East Africa, which is the likely area of origin of V. unguiculata var. spontanea. Var. spontanea is supposed to have spread westward and southward, with a loss of variability, loss counterbalanceed in southern Africa by introgressions with local perennial subspecies. Although the variabilty of domesticated cowpea was the highest ever recorded, cultivar-groups were poorly resolved, and several results obtained with isozyme data were not confirmed here. However primitive cultivars were more diverse than evolved cultivars, which still suggests two consecutive bottlenecks within domesticated cowpea evolution. As isozymes and AFLP markers, although with a larger number of markers, RAPD data confirmed the single domestication hypothesis, the gap between wild and domesticated cowpea, and the widespread introgression phenomena between wild and domesticated cowpea.