Browse

1 - 10 of 6,251 items :

Clear All

Abstract

The impact of regulated drip-irrigation on productivity and fruit quality of tomato ‘Tofane’ has been studied under a warm dry desert climate in southern Algeria. Yield, fruit weight and size, water content and parameters of fruit quality – total soluble solids, phenolic compounds, carotenoids, vitamin C, pH and titratable acidity were determined. Two irrigation treatments were applied in 2012 and 2013: T1, optimal irrigation (100% evapotranspiration – ETc) during the whole growth period (growth stages I, II and III); T2, optimal irrigation during I and II stages, and regulated deficit irrigation (67% ETc) during stage III (from fruit set to full fruit maturity of first and second bunch). T1 treatment during the whole season showed the highest values of soil water potential (Ψsoil), between −0.02 MPa and −0.06 MPa, on depths of 0.3 and 0.6 m, respectively. During stage III, regulated deficit irrigation caused the lowest Ψsoil values, which were between −0.1 MPa and −0.12 MPa on a soil depth of 0.3 and 0.6 m, respectively. Deficit irrigation caused significant decrease of water content in fruits and not significant decrease of fruit weight and size, as well as fruit yield while water saving for irrigation amounted to 10%. Comfort-irrigated tomato plants produced fruits containing significantly higher titratable acidity, total soluble solids and vit. C content. There was a tendency to decrease carotenoid content and increase phenolic content in both years of the study. Due to the possibility of water saving with not significant yield decrease, it seems that the reduction of water use in growth stage III would be an adequate strategy for tomato cultivation in hot, dry climate.

Abstract

A total of 558 specimens of black-bellied anglerfish Lophius budegassa (Spinola, 1807) were collected by the vessels engaged in commercial trawl fishing in the Central Aegean Sea between September 2017 and August 2018 in order to determine age and growth. Ageing was based on growth ring counts of transverse sections of the illicium (first ray of the dorsal fin). By reading the illicium, individuals were found within II-XI age groups. Total lengths and weights ranged between 12.0 – 65.0 cm and 24.5 – 4682.0 g, respectively. Von Bertalanffy growth parameters were estimated for males, females and combined sexes of L. budegassa. The results are compared with previous studies.

Abstract

The properties of biomass-based fuel and combustion tests showed that logging residues are promising renewable energy sources. The data used in this study were collected from four clear-felling areas in Järvselja Training and Experimental Forest Centre, Southeast Estonia in 2013–2014. Logging was carried out by harvesters in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst.), silver birch (Betula pendula Roth.) and black alder (Alnus glutinosa L. Gaertn.) dominated stands with a small admixture of other tree species according to the cut-to-length method and logging residues were placed in heaps. The aim of this research is to assess different characteristics of logging residues (quantity, moisture content, energetic potential, ash content and amount) in clear-felling areas. The highest load of slash was measured on the birch dominated study site, where the dry weight of the logging residues was 29 t ha−1. Only the branch fraction moisture content on the black alder dominated site (35.4%) was clearly different from respective values on other sites (21.6–25.4%). The highest calorific value of the residues was assessed with the residues from the birch dominated site, where in moist sample it was 365 GJ ha−1 and in dry matter 585 GJ ha−1. The heating value of the fresh residues is highest in coniferous trees. The highest ash content in branch segments was registered for the black alder dominated site. Järvselja data indicate higher quality in conifer dominated sites, yet a higher load of logging residues in broadleaf dominated stands.

Abstract

This study focused on the occurrence of xylophagous beetles and nematodes in the different parts of Pinus sylvestris L. trees of different health condition in the pure stands in Zhytomyr region (Central Polissya). Stem fragments with thin, thick and transitional bark, branches and twigs were examined in each of 12 model trees. Xylophagous beetles were identified by adults or by galleries. Nematodes were isolated from wood samples in the laboratory using the Baermann method and identified by morphometric characteristics. Among 10 species of xylophagous beetles, Ips acuminatus (frequency 16.7%; dominance 17.9%) and I. sexdentatus (frequency 11.1%, dominance 54.6%) dominated, which prefer the fragments with thin and thick bark respectively. No xylophagous beetle was found in the healthy and slightly weakened trees. Among 15 nematode species, 40% were saproxylic, 33.3% entomophilic, 13.3% phytophagous, and by 6.7% predators and species associated with fungi. An entomophilic nematodes Cryptaphelenchus macrogaster f. acuminati was common in all parts of stem and branches (frequency of occurrence 25–33.3%). An entomophilic nematodes Parasitorhabditis acuminati and a predator Fuchsia buetschlii acuminati had the highest frequency of occurrence (41.7%) under the thin bark and in the branches. The frequency of these species in colonized with xylophagous insects stem fragments with thin bark was significantly higher than in respective not colonized fragments.

Abstract

There is a significant lack of data for the biological parameters of beluga or great sturgeon, the largest fish in the Caspian Sea. The age, growth and fisheries indices for the stock status of beluga was investigated in the south Caspian Basin of Iran between 1990 and 2011. Fork lengths ranged between 113-420 cm and weights from 8.0 to 725.0 kg. The growth parameters were L = 440 cm, K = 0.027 year−1, t 0 = − 5.8 years. The age at first capture (t c) was 13.1 years. The long-term age composition data showed age up to 63 years, and the ages 12-19 years comprised 76.7% of the total catch. The generation length was 33 years. The values of “KF” were close to 1 or >1, indicating that beluga sturgeon is in a favorable condition in the southern Caspian Sea. The length distribution showed that 24.2% of the catch is comprised of juveniles. Based on the age structure and age at first maturity, recruitment and growth overfishing occurred in beluga stocks. Therefore, increased length or age at first capture in future fishery policies should be implemented. The mega-spawners represented 4.4% of the fish captured and revealed an unhealthy population structure.

Abstract

Growth of forest plantations on soils causes changes in their properties. These changes, their behavior, and magnitude depend on the original soil characteristics and also on the effect of forest plantations being grown. In the steppe zone of Ukraine, Robinia pseudoacacia L. and Quercus robur L. are the woody species most widely used in planting of forest plantations on chernozem soil. Chernozem soil formed exclusively under zonal steppe vegetation and chernozem soil under Robinia pseudoacacia and Quercus robur plantations were studied in this work to analyze the changes in soil properties caused by growth of these tree species. Dry aggregate size distribution, density, particle density, total porosity, organic carbon content, cation exchange capacity, pH values, hydrolytic soil acidity and dry residue, and the available nitrogen, phosphorus, and potassium content were analyzed. The studies found that Robinia pseudoacacia and Quercus robur plantations contribute to an increase in the share of aggregates 2–1 mm in size, as well as formation of aggregate fraction >10 mm, which are completely absent in the Calcic chernozem developed under the steppe vegetation. An increase in the density and particle density, as well as a decrease in the total porosity values were observed under the influence of forest stands studied. This is more common with chernozem under Q. robur plantation. It was found that the carbon percentage decreased in chernozem under the influence of Robinia pseudoacacia growth (on average, 0.4% by a meter-deep layer), but under Quercus robur planting it increased (on average 0.3% by meter-deep layer). Effect of Robinia pseudoacacia plantings on chernozem was also manifested by a decrease in cation exchange capacity (on average, 11 cmol/100 g by a meter-deep layer). The growth of R. pseudoacacia and Quercus robur plantations results in decrease of pH values (0.2 by a meter-deep layer) and increase of hydrolytic soil acidity and dry residue in chernozem water extract. Effect of Robinia pseudoacacia planting leads to a decrease in carbon, nitrogen, and phosphorus content in chernozem. The change in chernozem properties under the influence of Quercus robur plantation is reflected in accumulation of these nutrients. Growth of Robinia pseudoacacia and Quercus robur plantations leads to a decrease in potassium reserves in chernozem, which may indicate its active uptake by these woody species. In general, Q. robur planting is characterized by a large positive effect on the physical and chemical properties of chernozem than Robinia pseudoacacia planting. The findings obtained serve as a ground for making a recommendation for growing Quercus robur plantations under climate conditions of the steppe zone of Ukraine in order to improve the zonal chernozems’ state and fertility.

Abstract

The argan tree is a multi-purpose tree (fruit tree, medicinal, cosmetic, and pastoral plant) found in the semi-arid and arid regions of North Africa. It is under strong human pressure such as the impact of population growth, crop expansion, overgrazing, and wood and fruit exploitation that are also the main causes of desertification in the rest of the world. Over the years, interest in this beneficial tree and demand for its products have increased: especially with the increase in the price of argan oil, which is now one of the most expensive and much in demand oils in the world. This increase has led to many socio-political, economic and cultural changes at the national, regional and local levels, especially in farming behaviour and the habits of the local population. This bibliographic research was therefore conducted in order to analyse the various changes and their consequences on the planning, conservation, and management methods implemented in the argan tree area and their effects on the habits of the local population in order to ensure the sustainability of the Argan Tree Biosphere Reserve in Morocco. Indeed, the aims of this study were, firstly, to analyse the change dynamic of argan forest area in the ABR; and secondly, to investigate the impact of various socio-political, economic and cultural changes resulting from increased prices of argan oil on planning, conservation, and management methods of argan tree ecosystem and on the habits of the local population.

Abstract

Over the years, it has been the subject of discussions whether efficiency-oriented interventions contribute to an equity distribution of wealth across regions and whether equity orientation is a source of inefficiency. While efficiency refers to the maximization of growth in the national economy, convergence-oriented policy is focused on equalizing the level of development at interregional level. The case of Georgia was studied as a developing country facing various challenges in terms of economic growth and regional divergence. This article provides an overview of the economic development trends taking place in the regions of Georgia and reveals the high level of divergence within the country. A logarithmic model was created and used to run simulations to predict the possible results of convergence-oriented policy in Georgia. In order to make the forecast we estimated GDP per capita and average growth rates in all the Georgian regions. Use of the model allowed us to answer two main questions: (1) If the last 5 and 10 year average growth rates are maintained, how long will it take for the poorest region to converge to the wealthiest one? (2) What should be the minimum growth rate in the poorest region for the upcoming 5, 10 and 20 years in order to converge to the wealthiest capital? Results of the calculations showed that convergence between regions can only be achieved by slowing down economic growth in relatively wealthier regions and by focusing on the development of the poorest ones. The results of the study revealed that the convergence process will be faster for the regions with medium or big cities and growth centres. Therefore, creating competitive growth centres would be a reasonable regional policy objective to promote fast economic growth and future convergence without redirecting the growth process from more developed areas to lagging ones.

Abstract

Norway spruce (Picea abies [L.] Karst.) and silver fir (Abies alba Mill.) are main tree species of Central Europe that are currently highly vulnerable in times of global climate change. The research deals with the effect of climate and air pollution on radial growth of silver fir and Norway spruce in mixed age-varied (56 – 146 years) forests in the Jeseníky Protected Landscape Area, the Czech Republic. The objectives were to evaluate biodiversity, structure and production, specifically interaction of radial growth of fir and spruce to air pollution (SO2, NOX, tropospheric ozone) and climatic factors (precipitation, air temperature). Concentration of SO2 and NOX had negative effect on radial growth of fir, while radial growth of spruce was more negatively influenced by tropospheric ozone. Fir showed higher variability in radial growth and was more sensitive to climatic factors compared to spruce. On the other hand, fir was relatively adaptable tree species that regenerated very well when the pressure of stress factors subsided (air pollution load, Caucasian bark beetle, frost damage). Low temperature was a limiting factor of radial growth in the study mountainous area, especially for fir. Fir was significantly sensitive to late frost, respectively, spruce to winter desiccation and spring droughts with synergism of air pollution load. Generally, older forest stands were more negatively influenced by air pollution load and climatic extremes compared to young trees.

Abstract

This study investigated the efficacy of Tamarind Leaves (TL) and Mango Leaves (ML) with Oxytetracycline (OXY) on growth performance, haematoimmunological and disease resistance of Clarias gariepinus juveniles against Aeromonas hydrophila. Experimental diets consist of control (0%), TL2 (1%), TL3 (2%), ML4 (1%), ML5 (2%), OXY6 (30mg/kg diet), (TL+ML) 7, (TL+OXY) 8, (ML+OXY) 9 and (TL+ML+OXY) 10. The fish (3.02±0.01g) were replicated twice with 20 fish per replicate and were fed twice daily at 3% body weight of 40% crude protein for twelve weeks (8 weeks for feeding trial and 4 weeks for challenge test). Mean Weight Gain (MWG), Specific Growth Rate (SGR), Packed Cell Volume (PCV), Haemoglobin (Hb), Lymphocytes (LYM), Globulin (GLO), Amino Alanine Transferase (ALT) and Aspertate Amino Transferase (AST) contents were ascertained using standard technique. The fish were infected with A. hydrophila at 5.94 log10 CFU/ml interperitoneally and fed different diets to evaluate their Relative Percent of Survival (RPS). Data was subjected to descriptive statistics and one-way analysis of variance at P=0.05. Clarias gariepinus juveniles fed treated diets had higher growth rates than the control diet but C. gariepinus fed (TL+ML+OXY) 10 had a significantly higher MWG and SGR of 7.74±0.69 g and 0.97±0.01 g, respectively. The PCV (44.0±2.00%), Hb (14.7±2.00 g/dl), LYM (37.0±2.00), GLO (42.0 ±2.00 g/dl) were higher in the C. gariepinus fed (TL+ML+OXY) 10 than the control diet. The AST and ALT values among the treated groups were lower than the values in the control at the post-challenge test. The RPS against A. hydrophila was higher in the treated groups (100%) than in the control (0%). Fish fed tamarind and mango leaves had enhanced mean weight gain and were more resistant to A. hydrophila infection.