Incidence and viability of Acremonium endophytes in tall fescue accessions from North Spain

The tall fescue (Festuca arundinacea Schreb.) seed collection of the Centro de Investigaciones Agrarias de Mabegondo was surveyed to determine Acremonium infection rates. One hundred seeds from each of 19 accessions were microscopically examined for endophyte. Seventeen accessions (90%) contained endophyte with a range of 7 to 100%. Leaf sheaths of seedlings from the infected accessions were examined to determine the percentage of infection with viable endophyte. Only seven (41%) of the seventeen infected accessions collected and stored in 1995 at 4°C and 45–50% relative humidity contained viable endophyte with a range of 70 to 100%. While existing germplasm collections of Festuca arundinacea can provide only a small basis of Acremonium germplasm for study, newly collected Festuca arundinacea accessions will offer a greater diversity of Acremonium genotypes.     

Pedological and geomorphological cycles in a catena of Galicia (NW Spain)

A catena developed on gabbro in Galicia, N.W. Spain, was studied. The methods utilized, consisting of macro- and microscopic mineralogical and morphological observation, allowed the identification of different features produced by the action of pedological and geomorphological processes. The application of Butler's K cycle concept allows a relative sequence of events to be established in which pedogenetic processes are integrated within the general framework of the evolutionary history of the slope. Five K cycles could be recognized, beginning with a phase of deep weathering and ending with the present phase of incipient soil formation. In between feature a.o. phases of solifluxion, the formation of an argillic horizon and the development of a stoneline.     

Mobility of sulphate in experimentally acidified soils from Galicia (NW Spain)

Retention of S0₄ ^2? was investigated in Galician soils throughout an intense regime of acidification. Experiments consisted of the addition of an H2SO4 solution (pH 2.7) to columns of 6 soils of contrasting properties over 1, 2, or 5 months. Leachates were obtained continuously throughout the experiment for analysis, and analysis made of the solid fractions after 1, 2 or 5 months. The greatest capacities for retention of S0₄ ^2? were found in soil developed from serpentine and micaschist; the lowest in soils from granite, slate and sandy sediments. The surface horizons, especially those rich in organic matter, displayed low retention of 5042-. The amount of S0₄ ^2? adsorbed throughout the experiment depended on the content of crystalline forms of Fe and with the Fe and Al extracted with dithionite-citrate.The low retention of S0₄ ^2? in the organic horizons and the slightly negative relation with the organic matter suggest an inhibitory effect of the organic matter on the S0₄ ^2? retention process. Results of the study show, that under conditions of moderate acidity, SO₄ ^2? retention occurs in the form of adsorption; in strongly acidic conditions, the precipitation of aluminium-sulphate minerals may provide an additional retention mechanism.     

Mineralogical variability in weathering microsystems of a granitic outcrop of Galicia (Spain)

Several products of weathering have been studied in a granitic outcrop in Galicia (N.W. Spain). Alteration took place under a humid temperate climate. The various materials and the microsystems in which they occur are: (1) fissures containing gibbsite and/or 1:1 sheet silicates of varying degrees of crystallinity, (2) fissures containing 2:1 sheet silicates of beidellite type, (3) encrustations of siliceous material showing varying degrees of structural order, with or without organic matter, and (4) encrustations of non-crystalline matter composed chiefly of Al, P and Si.The results demonstrate the importance of considering the different microsystems which contribute to the formation of secondary products in a given weathering system.     

Ammonia volatilization from nitrogen fertilizers surface-applied to corn (Zea mays) and grass pasture (Dactylis glomerata)

Summary The major agronomic concern with NH₃ loss from urea-containing fertilizers is the effect of these losses on crop yields and N fertilizer efficiency. In this 2-year study, NH₃ volatilization from surface-applied N fertilizers was measured in the field, and the effects of the NH₃ losses detected on corn (Zea mays L.) and orchardgrass (Dactylis glomerata L.) yield and N uptake were determined. For corn, NH₄NO₃ (AN), a urea-AN solution (UAN), or urea, were surface-broadcast at rates of 0, 56 and 112 kg N ha^–1 on a Plano silt loam (Typic Argiudoll) and on a Fayette silt loam (Typic Hapludalf). Urea and AN (0 and 67 kg N ha^–1) were surface-applied to grass pasture on the Fayette silt loam. Significant NH₃ losses from urea-containing N sources were detected in one of four corn experiments (12%–16% of applied N) and in both experiments with grass pasture (9%–19% of applied N). When these losses occurred, corn grain yields with UAN and urea were 1.0 and 1.5 Mg ha^–1, respectively, lower than yields with AN, and orchardgrass dry matter yields with urea were 0.27 to 0.74 Mg ha^–1 lower than with AN. Significant differences in crop N uptake between N sources were detected, but apparent NH₃ loss based on N uptake differences was not equal to field measurements of NH₃ loss. Rainfall following N application markedly influenced NH₃ volatilization. In corn experiments, NH₃ loss was low and yields with all N sources were similar when at least 2.5 mm of rainfall occurred within 4 days after N application. Rainfall within 3 days after N application did not prevent significant yield reductions due to NH₃ loss from urea in grass pasture experiments.     

Potassium fixation in suspensions of soils of Galicia (N.W. Spain)

Abstract

Potassium (K) fixation in soils treated with K‐rich fertilizer is important in limiting leaching of this ion, and thus the risk of high salinity in waters. We studied this capacity for aqueous suspensions of a group of soils of Galicia (N.W. Spain) and found that fixation increased with K dosage, increased slightly with contact time, and decreased with increasing temperature (between 3 and 40°C). Potassium fixation was barely influenced by the mineralogy of the clay fraction but was greater in soils with greater fine particle content. Modified Freundlich equation successfully modelled the effects of K addition, temperature, and contact time on fixation. The influence of temperature was greater in illitic soils than in mixed soils. The results indicate that Galician soils have little capacity for K fixation.     

Expedition to the south-western Hissar Mountains (Southern Uzbekistan) for collecting plant genetic resources in 1995

A joint exploring mission has been carried out by staff members of the Institute of Botany of the Uzbek Academy of Sciences, Takent and the Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, in July/August 1995 to study plant genetic resources in a remote mountainous area of south-western Hissar, Uzbekistan. Subsistence farmers of the Tupalang basin are still growing a great number of landraces and local varieties, which could be investigated for the first time in that area. In total 238 accessions, mainly of cereals, vegetables, pulses, spices and medicinal plants, were collected. Of special interest has been indigenous material of wheat, barley, turnip, chickpea, pea, lentil, small-seeded linseed as well as some wild spices and medicinal plants.     

Throughfall,runoff and soil erosion after prescribed burning in gorse shrubland in Galicia (NW Spain)

The first‐year effect of two different prescribed burning treatments on throughfall, runoff and soil erosion was evaluated in gorse shrubland (Ulex europaeus L.) in Galicia (NW Spain). The treatments compared were: intense burn, light burn and control (no burn). Accumulated annual throughfall represented between the 81 and 87 per cent of total rainfall in intensely burned and lightly burned areas, respectively, whereas in the unburnt areas it was 60 per cent. No significant differences between burning treatments were found for the annual throughfall. However, runoff was significantly greater in intensely burned plots (1·5‐times) than in lightly burned plots. Burning also resulted in a significant increase in runoff (between 2·5 and 1·7‐times, respectively) compared with controls. Total soil losses were small in all treatments, but the intense burn caused significantly greater soil erosion (5·8‐times) compared with the unburned areas. Soil losses after the light burn did not significantly differ from the control although they were higher (2·3‐times). The relationships obtained between erosion and several rainfall parameters were significantly different in burned areas compared to the control. The same response was observed for runoff. Annual erosion losses showed a strong dependence on percentage of bare soil even for small values of this variable. Litter thickness was also a very important variable influencing on erosion rates. This study indicated that by combining ignition techniques and high litter moisture content to maintain the percentage of bare soil below 85 per cent, soil erosion was low. Nevertheless, this result was constrained by the low rainfall that occurred during the study. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of management and climate on biochemical properties of grassland soils from Galicia (NW Spain)

Biochemical properties are considered to be the best indicators available at present for assessing soil quality. However, there are still many gaps in our knowledge about how these properties are affected by abiotic factors and how these factors interact with soil management. With the aim of understanding how climate and soil management affect soil biochemical properties in grasslands soils from a temperate-humid area (Galicia, NW Spain), a total of 60 soils were analyzed for several microbial and biochemical properties. Grasslands were divided into groups according to the type of management applied (native compared with intensive) and to the climate in the area where they were sampled (Mediterranean subhumid with centroeuropean drift climate compared with Atlantic climate). We found that management had a greater influence on soil biochemical properties than climate. Altitude, which strongly influences climate in the region where the soils were analyzed, was found to be a significant factor that affected most soil biochemical properties. In conclusion, the results show that microbially-mediated processes are greatly affected by both, management and abiotic factors and that, for some properties (like net N mineralization and cellulase and casein-protease activities), abiotic factors can have an important influence on soil biochemical properties.     

Laboratory study of phosphate desorption kinetics in soils of Galicia (N.W. Spain)

Abstract

The kinetics of phosphate (P) desorption from surface horizons of 31 soils of Galicia (N.W. Spain) varied with the dose of added P (D = doses studied were equivalent to 200, 500, 1000, and 2000 μg P per g soil) and the soil‐P contact time (T = 7,180, and 360 days). Kinetic data for P desorption in aqueous suspensions of soil were fitted by zero order (Z), first order (F), second order (S), parabolic diffusion (PD), Elovich‐type (ET), and two‐constant equation (TC). TC equations gave the best fits (mean r² = 0.947±0.082). In linearized plots of Z, ET, and PD equations, the slope (K), which gives a measure of the rate of P desorption, increases with D and decreases with increasing T. In corresponding plots of F, S, and TC equations, K describes the constancy of the rate as P desorption progresses, and decreases with increasing D and increases with T. The y‐intercept of the above plots corresponded to a function of Co (the concentration of initially desorbable phosphate) in all cases. For all equations, Co increases dis‐ proportionately with D and exponentially with T. Since the kinetic parameters Co and K vary with sorption conditions, they cannot be considered characteristic of the tendency of a soil to release phosphate. A modified Freundlich equation with independent variables T, D, and t (soil‐water contact time) was also fitted to the kinetic data (mean R² = 0.959+0.031); the exponents (ß1, ß2, and ß3, respectively) of these independent variables indicate how each one influences P desorption in a given soil.     

Distribution of four major forms of potassium in soils of Galicia (N.W. Spain)

Abstract

The potassium (K) status of a group of Galician natural soils was evaluated, and the equilibria between the four main K forms were examined. The results indicated that the Galician soils studied contained a large mineral K fraction (97% of total K), and a smaller fraction of labile K forms, composed of non‐exchangeable (2%), exchangeable K and solution K (1%). For these soils, the exchangeable K was 38% of the non‐exchangeable K, which was consistent with the moderate development of these soils. The equilibrium between solution K and exchangeable K was displaced towards solution K.     

Preliminary chemometric study on the use of honey as an environmental marker in Galicia (northwestern Spain)

Thirteen metal elements were determined in 40 honey samples from Galicia with different environmental origins: rural, urban, and industrial areas. The data set of the honey metallic profiles was studied with a double purpose: first, to make a preliminary evaluation of honey as an environmental indicator in Galicia with the aim of monitoring pollution and, second, to compare the different capabilities of diverse pattern recognition prediction procedures for modeling the environmental surrounding of the hive. A certain level of similarity for urban and industrial samples was obtained using principal component analysis and cluster analysis, whereas significant differences for urban and industrial honeys were found in relation to rural honey samples. Different classification rules to associate metal content of honeys with their environmental surrounding were obtained by chemometric pattern recognition procedures. In general, the classification methods developed by neural networks provided better results than the traditional pattern recognition procedures. The metal profiles of honey seem to provide sufficient information to enable categorization criteria for classifying samples according to their environmental surrounding. Thus, honey could be a potential pollution indicator for the Galician area.     

Status and distribution of the Mediterranean monk seal Monachus monachus on the Cabo Blanco peninsula (Western Sahara-Mauritania) in 1993–1994

The current geographical distribution of the Mediterranean monk seal Monachus monachus colony inhabiting the Cabo Blanco peninsula (Western Sahara-Mauritania) is described. Its distribution range has apparently not changed since surveys conducted in 1984–1988. Sightings of adults on the Tarf el Guerguerat coast, 20 km north of the known breeding caves, suggests the existence of other possible breeding groups further north. Two caves used by the seals are described for the first time. A review of historical trends in cave occupation by seals made it possible (1) to locate the so-called ‘maternity cave’, last reported in 1949; and (2) to establish that the colony, since its discovery, has occupied at least eight caves, five of which have collapsed. An index of population size based on counts of individuals of identified morphological types indicates that, during 1993–1994, the colony was composed of c.113–165 individuals (excluding pups), a larger number than previously assumed. Counting of seals at times of maximum haul-out is proposed as a tool to monitor population trends, although it is considered unreliable for estimating absolute numbers.     

Geochemistry of Aluminium and Iron in Mine Soils from As Pontes,Galicia (N.W. Spain)

The geochemical processes influencing iron and aluminium mobilization and immobilization processes in mine soils are discussed. The study was carried out on 11 soils from the As Pontes mine dump, in the process of reclamation. The soils differ in age, spoils nature, reclamation tasks and type of vegetation, covering a wide range of physico-chemical conditions. Oxalate and pyrophosphate extractable Al and Fe (Alo, Alp, Feo, Fep), and dithionite extractable Fe (Fed) were analysed. These fractions were related to the solution Al and Fe forms and contents and to other soil properties (Eh, pH, sulfides, organic matter, cation exchange capacity, and composition of the soil solution). Alo ranged between 2.2 and 111.2 cmolc kg-1; 5 to 80% of this Alo was organic aluminium (Alp). Fed ranged between 8.5 and 215.6 cmolc kg-1; 20 to 70% was poorly-criystalline iron (Feo). The solution concentrations of Al and Fe ranged between <0.1 and 319.2, and between <0.1 and 46.7 mg L-1, respectively. The results showed that the spoil nature (mostly carbonaceous clays and slates differing in sulfide content) and the reclamation tasks undertaken (topsoiling, liming with fly ash) determine the forms and contents of Al and Fe in the solid phase as well as in the soil solution and also its distribution between the solid and liquid phases.     

Conservation strategies and management guidelines for wild Prunus genetic resources in Andalusia, Spain

Six species of the genus Prunus occur inAndalusia. Matters regarding their ecology, ethnobotanical aspectsand conservation are discussed, as well as knowledge about thegermplasm of those species with greater economic importance and theirdegree of conservation, namely: P.avium, P.mahaleb and P.insititia. Various conservation measures areproposed for wild germplasm and for the germplasm of local varieties:a) conservation efforts should target the best populations,except in the case of P.avium and P.insititia, where every individual should beaddressed, including both wild and local cultivars; b) theDehesa del Camarate (Sierra Nevada) is proposed as an areafor in situ germplasm conservation; c) theawareness of the importance of Prunus germplasmshould be increased among forest workers, environmental managers andthe public; d) some silvicultural techniques are proposed, suchas mixed Prunus patches, hedge treatment,Z-tree selection at the early stages and the protection ofroot suckers; e) improved, selected P.avium and P.mahaleb germplasm should be used at highlyproductive sites since these two species can be cultivated as highvalue timber trees; f) some Prunus speciescan also provide profitable NTFPs in the region. Details regardingdifferent collection areas are covered. Finally, some topics arerecommended for scientific research. Three tables and a distributionmap of Prunus species in Andalusia areincluded.     

Large-scale correlates of alien plant invasion in Catalonia (NE of Spain)

Identification of the main correlates of the invasion process is a fundamental step in alien species management at the regional scale. This paper explores the main climatic, territorial, and anthropic correlates of alien plant species richness and percentage in Catalonia (NE of Spain), by means of GIS techniques. We used floristic data collected in FLORACAT per UTM 10 km × 10 km to set up the number and the percentage of alien species. The association of these variables with climate, topography, landscape, human settlement, and geographic position was explored by means of stepwise regression models applied on the axes obtained from principal component analysis. The significance of the resulting correlates was tested using the modified t test of Dutilleul to remove the effects of spatial autocorrelation. PCA reduced the 22 variables to 12 principal components (PC) that explained 90% of the cumulative variance. Regression models were highly significant and captured a high proportion of total variance (adjusted r² = 0.70 for alien species richness and r² = 0.56 for alien species percentage). Both alien species richness and percentage were mainly correlated to PC summarising variables concerning climate, habitat and landscape heterogeneity, and potential anthropogenic disturbance. However, while these PC exhibited similar weights on alien species richness, species percentage was mainly determined by climate. Implications for conservation are discussed considering a future scenario of climate warming and increasing land use change in Mediterranean areas.     

Use of prolamine polymorphism in studying genetic resources of forage grasses

Summary Electrophoresis of single seed prolamines was used for the analysis ofLolium perenne L.,Festuca pratensis Huds., andDactylis glomerata L. populations. Identification and registration of populations was carried out according to the frequencies of occurrence of genotypes with corresponding types of prolamine banding patterns. The publication sums up the problems of applied use of molecular markers for identification and registration of world genetic resources of forage grasses, analysis of the dynamics of population composition and other problems of plant growing, genetics, breeding and seed control. The approaches mentioned in the article are promising for their use in genetic banks as well as at the institutions which store collections of genetic resources of given crops and at universities and breeding stations.     

Isolation of amoebae of the genera Naegleria and Acanthamoeba from public fountains in Galicia (N.W. Spain)

Tests for free-living amoebae in water from 11 public fountains in Galicia were conducted at two seasons of the year, winter and summer. Only one fountain gave a negative result for the presence of amoebae in both samples. Twenty five strains were isolated, 14 belonging to the genus Acanthamoeba and 10 to the genus Naegleria. The Acanthamoeba strains were made up of the species A. polyphaga, A. quina, A. castellanii and A. paradivionensis. No relation was found between temperature, presence of free chlorine in the water and whether the water was drinkable and the presence or absence of amoebae, nor with the number of strains present in the water samples. The pathogenic capacity of the strains isolated from the genera Naegleria and Acanthamoeba was tested in vivo. It was found that of the 22 strains that would grow at 37 °C, 4 (3 strains of Acanthamoeba and 1 of Naegleria) caused the death of a statistically significant number of mice that had been inoculated intracerebrally, and the presence of amoebae was confirmed in the brains of all the animals inoculated. Intranasal inoculation caused less mice deaths than intracerebral inoculation, and less organs were found containing amoebae.     

Comparison of indirect methods for the determination of percent exchangeable aluminium in acid soils of Galicia (NW Spain)

Abstract

Ten easily determined soil parameters related to soil acidity were evaluated for their potential to provide simple, indirect estimates of the exchangeable aluminium percentage (PAL). These parameters were correlated with the PAL in 0.6N BaCl₂ extracts of soils collected from lime trials on 4 different parent materials. Six rates of lime (0, 0.75, 1.5, 3, 6, 12 t/ha) were added 3–4 years prior to collection of the samples. The soil parameters examined were the pH of soil suspensions with SMP, Woodruff and New Woodruff buffer solutions; the pH of 1, 5 and 10mM CaCl₂ and 0.6N BaCl₂ soil extracts, and the aluminium content of 1, 5 and 10mM CaCl₂ soil extracts. The best correlations with the exchangeable aluminium percentage for all soils considered, were those based on the aluminium content of the 5mM CaCl₂ extract (r=0.976, n=24) followed by the pH of the 0.6N BaCl₂ extract (r=0.945, n= 24). Both these methods are suggested as reliable indirect estimates of soil exchangeable alumimium percentage where availability of staff or equipment restrict direct determinations.