Search
Search Results
-
Modern approaches to assessment of PAHs bioavailability in soil for environmental toxicology research
35-36Views:204The efficiency of TENAX beads sorption method enabling to separate the bioavailable fraction of PAHs in the soil has been estimated. Due to the method the PAHs effects on soil biota have been explored. Laboratory investigations have ascertained possibility of application of TENAX beads sorption for soil quality assessment.
-
Effect of agrotechnical factors on the yield of the Grolim asparagus (Asparagus officinalis L.) hybrid on acidic sandy soil
43-48Views:519Research of blanched asparagus has begun at the University of Debrecen Institutes for Agricultural Research and Educational Farm Research Institutes of Nyíregyháza in 2011. Establishment of the plantation took place in May 2011. The Grolim hybrid was used in the trial, 16 medium plot trial area has been formed under field conditions, with four repetitions and 36 m2 plot size. In the course of our studies, the effect of different nutriment supply methods (untreated, manure, sheep manure compost, fertilizer) has been analysed on the spear yield of the Grolim asparagus hybrid between 2013 and 2017.
In our studies, the beginning of vegetative growth has been recorded upon the constant presence of 10 °C of average soil temperature in the case of the Grolim asparagus hybrid. The beginning and length of spear harvesting are both influenced by the time and dynamics of initial development in spring. During the analysed period, the dates of spear harvesting were various, the earliest being on 23rd March, 2014 and the latest on 23rd April, 2015; the rest of the three years have been varied within this one month interval. The total of heat units required for the vegetative development of spears has been determined; it provides important information for cultivation practice.
Spear yields turned out to be hectic during the analysed period. In 2013 and 2014, yields have surpassed the amount of 50 kg/harvest period/plot in the case of every treatment version. However, in 2015 a significantly lower specific yield has been recorded due to the unfavourable weather conditions in spring; a yield decline of nearly 50% was recorded in the case of the control treatment compared to the previous years. Yield was also lower in the rest of the fertilization treatments compared to 2014; however, in these cases, the degree of yield decrease was around 5–10%, which suggests the yield stabilising effect of fertilization. In 2016, a slight yield increase was measured in comparison with the base year. In 2017, there was a decline of yield in the control treatment; however, the different fertilization treatments resulted in yield increase as compared to previous years.
On the basis of our studies, it is clear that the best yield results have been provided by the artificial fertilization treatment in all of the five analysed years. It was followed by the sheep manure compost and manure treatments in terms of their effect on spear yield. During the three harvesting periods, the lowest yield on acidic sandy soil was recorded in the case of the control treatment. The most remarkable effect of nutriment treatments has been realised in terms of the decreased deviation of yield results, which perfectly represents the yield stabilising effect of nutriment supply in the case of perennial crops – asparagus – as well, even on a poor nutriment supply characteristic sandy soil.
-
Possibilities of mass valuation in land use in Hungary
59-68Views:362Technological development makes it possible to simplify and accelerate decision-making processes by adequately processing and evaluating large volumes of data. Sub-data obtained from large data sets have a very important practical role in asset valuation, forecasting and valuing delineated or difficult-to-map areas, or in the context of portfolio management. Land valuation is a separate segment within asset valuation and it requires a specific methodological approach on behalf of evaluators. In this study, the authors compared the transaction data of arable land and the value of other land use categories. Based on empirical assessments, the authors developed proposals for the fast and cost-effective determination of the value of land use categories other than arable land - mainly meadows and pastures.
-
The Examination of the Effects of Value Modifying Factors on Dairy Farms
36-40Views:166We wish to present a method to quantify the value modifying effects when comparing animal farms. To achieve our objective, multi-variable statistical methods were needed. We used a principal component analysis to originate three separate principal components from nine variables that determine the value of farms. A cluster analysis was carried out in order to classify farms as poor, average and excellent. The question may arise as to which principal components and which variables determine this classification.
After pointing out the significance of variables and principal components in determining the quality of farms, we analysed the relationships between principal components and market prices. Some farms did not show the expected results by the discriminant analysis, so we supposed that the third principal component plays a great role in calculating prices. To prove this supposition, we applied the logistic regression method. This method shows how great a role the principal components play in classifying farms on the basis of price categories. -
The impacts of spring basal and side dressing on maize yield
83-86Views:340The yield potential of maize is very high. According to Tollenaar (1983), maize yield potential is as high as 25 t ha-1 (absolute dry yield) which is the highest among all cereals. In order to fully utilise this high yield potential, proper nutrient replenishment is of chief importance among all agrotechnical factors.
The aim of research was to examine the effect of nitrogen fertiliser applied as basal and side dressing on maize yield.
The measurements were performed at the Látókép experiment site (47° 33’ N, 21° 26’ E, 111 m asl) of the Centre for Agricultural Sciences of the University of Debrecen on mid-heavy calcareous chernozem soil with deep humus layer in an established experiment in 2011, 2012 and 2013. The trial design was split-split-plot with two replications.
Based on the experiment results, it can be established that the nutrient uptake of maize is greatly dependent on the amount of water store in the soil. From the aspect of the development of the maize plant and water supply, the most determinant factor was the distribution of precipitation over the growing season and not the amount precipitation. This is shown by the fact there was only 276 mm precipitation – which was favourably distributed – in 2012 to increase the availability of nutrients and the main average was the highest in this year (14.394 t ha-1).
Spring basal dressing helped maize development in all three years even on chernozem soil which is well supplied with nutrients. Although the effect of side dressing did not result in any yield increase, it could still contribute to mitigating the stress effects caused by environmental factors. Altogether, nutrient supply adapted to the various development stages of maize can favourably affect the success of maize production.
-
Variability examination of photosynthetic pigment content and specific leaf area in individual maize (Zea mays L.) plants
153-157Views:469Currently, maize is one of the most important crops (Zea mays L.) both globally and in Hungary. We compared physiological parameters of a maize genotype – p9903 – at two different experimental sites in a field experiment. Furthermore, we examined these parameters’ variability in individual plants on the leaves with different ages. Absolute chlorophyll content of the leaves were analysed, separately that of chlorophyll a and chlorophyll b. We also measured the absolute carotenoid contents of leaves. Furthermore, we calculated these photosynthetic pigments’ content ratio. Specific leaf area (SLA) and dry matter weight were also measured in order to characterise plant production. The results obviously reflect the decreasing in the efficiency of photosynthetic apparatus on the low yield site. Otherwise, we identify significant differences only in certain cases of leaves.
-
Development of a New Maize (Zea mays L.) Breeding Program
25-30Views:321Genetic manipulation may not replace any conventional method in crop breeding programs, but it can be an important adjunct to them. Plant regeneration via tissue culture is becoming increasingly more common in monocots such as corn (Zea mays L.). In vitro culturability and regeneration ability of corn decreased as homozigosity increased, which suggested that these two attributes were controlled primarily by dominant gene action. Pollen (gametophytic) selection for resistance to aflatoxin in corn can greatly facilitate recurrent selection and screening of germplasm for resistance at a much less cost and shorter time than field testing. Integration of in vivo and in vitro techniques in maize breeding program has been developed to obtain desirable agronomic attributes, speed up the breeding process and enhance the genes responsible for them. The efficiency of anther and tissue cultures in most cereals such as maize and wheat have reached the stage where it can be used in breeding programs to some extent and many new cultivars produced by genetic manipulation have now reached the market.
-
Comparison of growth parameters of 40 varieties/clones short rotation coppice willow (Salix)
99-104Views:242The plantation of willow varieties was established in 2009. The 40 different varieties and clones of Salix were planted at a research field in Kolíňany (Nitra district). The paper evaluates results from the first growing season in 2009. The survival rate of planted cuttings ranged from 55.56 % to 100.00 % after the first year. The lowest survival rate was reached by Terra Nova variety. The stem numbers per plant ranged from 1.17 ±0.37 to 2.53 ±0.98. The average height of one-year old stem varied from 65.82 ±36.60 cm to 225.58 ±68.61 cm. The average stem diameter ranged from 6.90 ±2.63 mm to 14.34 ±3.39 mm. There were statistically very significant differences in parameters of stem height stem diameter and stem numbers per plant among studied varieties/clones. The statistic method used was analysis of variance ANOVA. The varieties were then divided into 6 groups according to their similarity in observed parameters after the first growing season by cluster analysis. The best results were reached by varieties/clones classified in the second group. The survival rate, stem diameter and stem height values of these varieties/clones were above average.
-
Emerging sectors in rural development
65-72Views:241This paper focuses on the innovativeness of rural economy and in particular on the way rural entrepreneurs in endogenous and exogenous sectors make use of their rural environment. building upon the sustainable innovation framework, key strategies for rural development are formulated. the described data refers to the rural innova region (10 rural eu regions). The results show that rural innovation is essentially a process of valorising endogenous potentials by connecting them with exogenous assets.
-
Grassland association stock of plants the examination of the regeneration of a construction
185-191Views:197Due to the drastic change in using the nature like grassland association (one-sided overgrazing – one mowing per a year), by the third year of the experiment in every area, where overgrazing stopped, independently on second sowing and nutrient resupply, Borhidi degradation degree decreased. In the areas where overgrazing with large animal density (sheep) continued, degradation degree was 3.4–5.0 by the third year of the experiment, and Hordeum murinum, which causes animal healthy problems, appeared massively.
-
Leaf reflectance characteristics and yield of spring oat varieties as influenced by varietal divergences and nutritional supply
29-34Views:273Inadequacy of nutrients in the soil and sufficient inaccessibility to nutrients is caused by factors that affect production and productivity of spring oat varieties. Exogenous application of nutrient and real time nutrient assessment can therefore reverse these associated negative consequences. A field experiment was conducted to evaluate the response of spring oat varieties to sulphur and silicon based fertilisation. Eight spring oat varieties, four level of nutrient application was arranged in a split-plot design with three replications. The obtained results showed that foliar application of sulphur improves the grain yield of most nutrients responsive varieties by about 34.7%. However, application of silicon had shown a diminishing return association to grain yield of variety GK Kormorán, GK Pillangó, Lota, Panni. LAI, thousands grain weight, SPAD, NDVI was significantly (p < 0.05) influenced by genetic difference of the tested varieties, developmental plasticity, and nutrient application. Significantly higher grain yield was obtained from the variety Mv Pehely than the other tested varieties. Therefore, it could be inferred that a combined use of nutrient responsive spring oat varieties and sulphur containing fertilisers could be important agronomic practice to improve grain yield and to develop climate resilient oat varieties.
-
Evaluation of water balance in apple and pear trees
193-198Views:609A significant proportion of the aboveground green and dry weight of the plant constitutes the foliage. The canopy is an important factor
of plant growth. On one hand the canopy absorbs the solar energy, which is necessary for the photosynthesis, on the other hand accumulates
the absorbed nutrients by the roots, and the most of the water-loss happens through the foliages. The determination of the full canopy is not
an easy target. In our research we developed a measurement method to determine the leaf area. With the parameters of the examined tree
(leaf length and maximum width) and the data of ADC AM 100 leaf area scanner we determined the k-value, with which we can easily and
fast evaluate the leaf surface. Furthermore we defined from the water balance of compensation lysimeters the cumulative transpiration of
fruit trees and the efficiency of water use of trees. -
Folic acid content of beetroot leaf and root by different growing stages and genotypes
115-119Views:529An increasing interest has been observed of beetroot leaf as a salad component due to recent studies focusing on their nutritional value. The randomized field experiment was carried out on lowland chernozem soil with 6 varieties, 3 replications and 2 sowing dates. Sampling was performed on 23 of August 2018 at the stage of 30 and 50 days of vegetation, where leaf (30 and 50 days) and root (50 days) were collected. Total dry matter, folic acid and nitrate content were evaluated.
The results of this investigation show that higher total dry matter content was measured in the root (8.47–10.30%) compared to the leaf in both developmental stages (6.47–9.20%). Nevertheless, higher folic acid content was found in the young leaves of 30 and 50 days of development (58.77–113.86 µg 100g-1). Among the examined varieties, Bonel has presented great amount of folic acid not only in the leaves (99.35–113.61 µg 100g-1), but also in the root (89.99 µg 100g-1). Finally, lower nitrate content was found in Libero (316.16 mg kg-1) at 30 days and in Akela (340.41 mg kg-1) at 50 days of development. Thereby, fresh consumption of beetroot leaves are highly recommended.
-
Mitochondrial DNA-based diversity study of Hungarian brown hares (Lepus europaeus Pallas 1778)
23-29Views:352The brown hare being an important game species which is widespread across the European continent has been in focus of many population genetic studies. However only a few comprising researches can be found on the diversity of Central-European populations.
The aim of our large scale long term ongoing study is to fill this gap of information on the species by describing the genetic history and structure of the brown hare populations of the area using both mitochondrial DNA markers and genomic skin and hair colour regulating genes.
This article gives forth a part of our results concerning the mitochondrial DNA diversity of Hungarian brown hares based on amplification of a 512 bp long D-loop sequence. N=39 tissue or hair samples have been collected from 15 sampling sites on the Hungarian Great Plain. We have described a high level of haplotype diversity (Hd=0.879±0.044) based on a 410 bp alignment of our sequences. We have found 17 haplotypes within our sample set with the nucleotid diversity of π=0.01167±0.0022. Our ongoing research shows high genetic diversity for the brown hare in the studied region and a second alignment with 156 sequences downloaded from GenBank indicates a geographic pattern of haplotypes among the studied populations though these results need confirmation by our further analyses.
-
Evaluation of population parameters and biometric data of an Eurasian Collared Dove (Streptopelia decaocto Friv.) population in the Great Plain of Hungary
89-92Views:577The Eurasian Collared Dove shows different patterns in density all over Hungary. In some cases, the population has decreased to a lower level, but there are habitats where the population remained stable. Several factors were taken into consideration during the evaluation of this phenomenon. These publications state that the increased urbanization of corvids, the lack of food sources, and the changes in nesting sites caused the decrease in numbers. During our research, we intend to contrast the differences in population structure of Collared Doves that differ from each other in the density of predators presented at nesting sites. As a first step, in this paper, numerous samples (n=118) were taken from a population that is less influenced by corvid species’ nest predation. Our prediction was that the population parameters remained at the level of 1980’s, in which the population of Eurasian Collared Dove has reached its maximum, according to further publications.
During the evaluation process, our data were collected from hunting bags near Nyíregyháza. Results were compared with former publications. We stated that the population structure, such as age and gender distribution remained stable in the evaluated population. In addition, morphometric factors of the collected individuals were also measured, such as weight, wing length, 3rd primary feather, and tail length, which were compared with former surveys. During statistical tests no significant difference was revealed among population parameters, but there were significant differences between most of the morphometric data, (p>0.05).
-
Thinning and final cutting control in black locust (Robinia pseudoacacia L.) stands: a methodological approach – Short communication
43-46Views:202Planning, implementing and inspecting forestry operations require more extent application of certain assessment methods. These methods may need to be improved and, in some cases, their simplification is necessary in order to ease their usage in practice. Knowledge and application of auxiliary tables and functions, data on volume and methods to estimate yields are needed for the planning of any kind of forestry operations, depending on the level of planning. The main purpose of this paper is to propose relatively rapid and simple methods to estimate the volume at thinning and final cutting, and the gross above ground volume at the harvest of black locust (Robinia pseudoacacia L.) stands, as well as to introduce tending operation models tailored for black locust. All these measures could be beneficial to forest authorities and foresters who are responsible for planning and production.
-
Data on the bumblebee assemblages (Apidae: Bombus spp.) lives in lands under agri-environment commitment
31-35Views:479The goal of agri-environmental schemes (AES) and greening programs are protecting and increasing biodiversity in agricultural lands. The evaluation of effectiveness of AES needs further investigations. For the purpose of investigations, species and species groups should be selected which can indicate the effects of changes in landscape use on biodiversity. Bumblebees are good indicators for this purpose.
The role of bumblebees in pollination is well studied but in the case of different crops, much less detailed data are available. In 2018, bumblebee assemblages of 44 sites belonged to 8 different agricultural and semi-natural habitat types were studied in the surroundings of Sajószöged, Tiszaújváros and Derecske.
This study provides new distribution data of 8 bumblebee species in three 10×10 km UTM cells covering the sampling area. According to our results, the alfalfa and red clover fields and semi-natural grasslands has more species rich and abundant bumblebee assemblages than different crop fields (sunflower, oilseed radish and vegetable morrow) and can help protect bumblebee assemblages of agricultural lands. Based on the collected distribution and abundance data, the role of the bumblebees in pollination of the studied crops should be re-evaluated.
-
Marginalisation and Multifunctional Land Use in Hungary
50-61Views:193Our study prepared as a brief version of National Report in the frame of EUROLAN Programme. We deal with the interpretation of some definitions (marginalisation of land use, multifunctionality of land use, marginalisation of agriculture, multifunctionality of agriculture), with sorting and reviewing indicators of marginalisation and finally with the analysis of functions of land use. We suggested a dynamic and a static approach of marginalisation. We can explore the dynamic process by time series and the static (regional) one by cross-section analyses.
It is very hard to explain the perspective of the future of marginalisation of land and of agriculture in Hungary. The process of marginalisation seems faster in the agriculture in the coming years, but it depends on the utilisation of new possibilities given by the EU financial resources and by the Common Market. At this moment agriculture seems one of the big losers of the accession.
In the long term we should face considerable challenges in the land use. It is necessary to take into account that there is a supply market of foods and traditional fibre production world-wide. There are limited possibilities to produce and to market for example biodiesel (fuel), bioethanol, or maybe biogas. Thus the environment and landscape preservation becomes more and more real land use alternatives.
The environmental interpretation of the multifunctionality of land use: activities (functions) of environmental preservation and nature conservation in a certain area, which aim to preserve natural resources by the existing socio-economic conditions.
Preservation of rural landscapes is the task mainly for land-users, who can be commanded by legal means and can be encouraged by economic measures to carry out the above activity. In the recent past measures of „command and control” type regulation were predominant, however nowadays, especially in the developed countries, the role of economic incentives increases.
As a conclusion of our analysis we can state that as long as the main land-dependent activities (agriculture, forestry, housing, tourism, local mining) cease to be viable under an existing socio-economic structure, then it is hardly possible to sustain the rural landscape on an appropriate level by non-commodity products (such as environment preservation, cultural heritage, nature conservation, employment etc.).
1 The study was prepared in the frame of EUROLAN (EU-5 Framework Project), QLK5-CT-2002-02346, as a compiled version of the Hungarian National Report, The national project co-ordinator: Prof. Dr. Gabor Szabo.
A part of places with high ecological values coincides with the areas with unfavourable agricultural endowments and underdeveloped micro-regions. We think so that the marginalisation preserves the non-environmental-sound activities and hinders the development of multifunctional agriculture and this process can change only by joint utilisation of endogenous and exogenous resources and methods. Thus the successful programmes for agri-environmental protection and multifunctional land use can serve the moderation of negative effects of marginalisation or maybe the marginalisation process itself. -
Promising Leuce poplar clones in sandy ridges between the rivers Danube and Tisza in Hungary: a case study
111-113Views:445An intensive integrated research and development work has been carried out on the improvement of Leuce poplars including primarily the native white poplar (Populus alba L.) and its natural hybrid grey poplar (Populus × canescens). More than 70 percent of the Leuce poplar stands can be found on calcareous sandy sites in the Danube–Tisza region, so they play a significant role in the poplar management of this part of the country. The most important task ahead of Hungarian poplar growers is to improve the quality of poplar stands and plantations based on selecting new clones and cultivars. The growth and yield of four promising Leuce poplar clones was evaluated on a marginal site in central Hungary. The clones ‘H 425-4’ (Populus alba L. × Populus alba L.), and ‘H 758’ (Populus alba L. Mosonmagyaróvár 124) seem to be suitable for wood production, while the ‘H 427-3’ (Populus alba L. × Populus alba L. cv. Bolleana) and ‘H 422-9’ (Populus alba L. × Populus grandidentata (Michx)) clones (with decorative stem form) could be better used for tree lines and ornamental plantations.
-
Effect of the claw disorders on production performance in dairy cattle
15-19Views:323The aim of the study was the influence of claw disorders on production traits in dairy cattle. Observed were claw traits as claw angle, claw length, heel index, claw height, claw diagonal and claw width. Right hind claw after functional trimming was evaluated. Occurrence of claw disorders like interdigital dermatitis and heel erosion (IDHE), digital dermatitis (DD) and sole ulcer (SV) as well as the progress of disease were observed. Basic summary and variation statistics was performed by the SAS software. Two herds were included in the study. Holstein dairy cows (n=101) produced 11 875 kg of milk, 468 kg (3.94%) of fat and 396 kg (3.34%) of proteins. Holstein cows were affected with IDHE in 22 cases, with DD in 6 cases and with sole ulcer in 10 cases. Slovak Simmental dairy cows (n=101) produced 5834 kg of milk, 258 kg (4.44%) of fat and 209 kg (3.59%) of proteins. Slovak Simmental cows were affected with IDHE in 8 cases, with DD in 5 cases and with sole ulcer in 19 cases. Observed was that claw disorders caused deviations of milk production.
-
Investment funding programs on dairy farms in Hajdú-Bihar County
11-16Views:294The dairy farming sector needs constant modernization of its buildings, machines and technology in order to maintain its competitiveness and productivity. For the greater scale investments, these companies try to apply for state funds in addition to their own financial sources. Therefore, the investment support system plays a great role by improving the competitiveness and modernity of these farms. In the last 10 years, 7 funding programs were available for dairy farms. In this research, 25 dairy farms were interviewed in Hajdú-Bihar County. The examined farms cover more than 50% of the milk production in Hajdú-Bihar County. The survey questions focused on the investment funding program use of farms between 2007 and 2017 and renewable energy investments including all programs. The results show how many tenders were submitted, how many were successfully evaluated and completed. All farms had at least two successfully evaluated projects. A correlation was found between completed projects by farm size and completed projects. The connection of the modernity index of dairy farms and the completed projects was also shown.
-
Classification of a diffuse heavy metal polluted mining site using a spectral angle mapper
119-123Views:851Characterization of heavy metal polluted abandoned mining sites is complicated, as the spatial distribution of pollutants often changes dramatically.
In our study, a hyperspectral data analysis of the Gyöngyösoroszi abandoned Pb-Zn mine, located in northern Hungary, where Záray (1991) reported serious heavy metal contamination, was carried out using ENVI 4.3. In this area, galena (PbS), goethite (FeO(OH)), jarosite (KFe3(SO4)2(OH)6), sphalerite ((Zn, Fe)S) and pyrite (FeS2) were the predominant minerals in the alteration zones was chosen as the target mineral.
Spectral angle mapper (SAM) and BandMax classification techniques were applied to obtain rule mineral images. Each pixel in these rule images represents the similarity between the corresponding pixels in the hyperspectral image to a reference spectrum.
As a result of hyperspectral imagery the distribution of pyritic minerals (sphalerite, galena) in the area was defined. Both of the mineral formations occur, especially in mine tailings, the area of the ore preparatory, and the Szárazvölgyi flotation sludge reservoir. According to the results, jarosite and goethite have similar distributions to sphalerite and galena. The results showed that hyperspectral remote sensing is an effective tool for the
characterization of Pb, Zn and Fe containing minerals at the examined polluted sites and for modelling the distribution of heavy metals and minerals in extensive areas.
This classification method is a basis of further detailed investigations, based on field measurements, to map the heavy metal distribution of the studied area and to quantify the environmental risks caused by erosion, which include DEM (digital elevation model) and climatic and hydrological data sources. Furthermore, it can be used primarily to support the potentially applicable phytostabilization technique and to isolate hot spots where only ex-situ remediation techniques can be applied. -
The effect of zinc fertilization on the yield and element content of ryegrass
27-31Views:243The effect of Zn fertilization on the yield and Zn, N, P, K, Mg and Mn content of ryegrass was studied in a greenhouse experiment for 8 chernozem soils with three replicates under uniform NPK supply and irrigation. The applied Zn rates were 0, 2.5 and 5 mg/kg Zn. Due to Zn doses the yield incrased significantly. Zn fertilization increased the plant Zn content and decreased the plant P and Mn content significantly. For N, K and Mg there was no significant effect.
-
Interpretation of sustainability in the utilization of renewable energy sources
61-64Views:270The utilization of renewable energy sources (res) is crucial regarding to sustainable reconstruction of energy systems. The target is a balanced, sustainable development of Hungarian energy management considering equally the ecological, social and economic aspects. There are many different technologies of utilization of res varied by sources, conversion processes, size and products. The comparison of each technology and their sustainability assessment are required by the importance of efficient remodeling of energy infrastructure. The group of attributes was composed by numerous important parameters in the course of our analysis with the choice experiment (ce) methodology. The estimation of each attributes’ influence on the individual’s preferences and choices was possible by this method and the preferences of the statistical population was concluded. So thus the utility derived from each attribute was estimated. The result of the ce analysis for the population of experts is demonstrated in the current phase of our research.
-
Rural development: how to measure performance imbalances in agribusiness chains
21-27Views:189No abstract