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1.

Goat production is an important agricultural activity in Jordan. The country is one of the poorest countries in the world in terms of water scarcity. Provision of sufficient quantity of good quality drinking water is important for goats to maintain feed intake and production. This study aimed to evaluate the seasonal availability and quality of goats’ drinking water sources, accessibility, and utilization in different zones in the Karak Governorate in southern Jordan. Data collection methods comprised interviews with purposively selected farmers and quality assessment of water sources. The provision of drinking water was considered as one of the major constraints for goat production, particularly during the dry season (DS). Long travel distances to the water sources, waiting time at watering points, and high fuel and labor costs were the key reasons associated with the problem. All the values of water quality (WQ) parameters were within acceptable limits of the guidelines for livestock drinking WQ with exception of iron, which showed slightly elevated concentration in one borehole source in the DS. These findings show that water shortage is an important problem leading to consequences for goat keepers. To alleviate the water shortage constraint and in view of the depleted groundwater sources, alternative water sources at reasonable distance have to be tapped and monitored for water quality and more efficient use of rainwater harvesting systems in the study area is recommended.

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2.
Abstract

An instrument for measurement of soil dielectric constant ε r , electrical conductivity EC a, and soil temperature was tested on soils under potato crop to investigate contents of soil volumetric water θ and nutrients for eventual use in a field crop model.

To approximate the dependence of θ on ε r , a logarithmic equation was chosen. Satisfactory results were obtained on stone-free areas, with the mean relative variance between θ-values determined by dielectric constant and converted from a gravimetric method remaining within the limits of measuring error. However, variances were higher for stony soils, with ε r -values at the same θ being considerably higher. To reconcile data from stony and stone-free soils, a formula was composed.

Salinity, calculated by a semi-empirical model based on Hilhorst's theory using measured values of EC a, ε r , and soil temperature, correlated well with contents of K and Mg in the soil. A lower correlation resulted for P, and was practically absent for Ca. Inequality of these regression equations at different measuring sites demonstrates the necessity of considering soil pH when assessing plant nutrients in the soil.  相似文献   
3.
Stock‐based and ecosystem‐based indicators are used to provide a new diagnosis of the fishing impact and environmental status of European seas. In the seven European marine ecosystems covering the Baltic and the North‐east Atlantic, (i) trends in landings since 1950 were examined; (ii) syntheses of the status and trends in fish stocks were consolidated at the ecosystem level; and (iii) trends in ecosystem indicators based on landings and surveys were analysed. We show that yields began to decrease everywhere (except in the Baltic) from the mid‐1970s, as a result of the over‐exploitation of some major stocks. Fishermen adapted by increasing fishing effort and exploiting a wider part of the ecosystems. This was insufficient to compensate for the decrease in abundance of many stocks, and total landings have halved over the last 30 years. The highest fishing impact took place in the late 1990s, with a clear decrease in stock‐based and ecosystem indicators. In particular, trophic‐based indicators exhibited a continuous decreasing trend in almost all ecosystems. Over the past decade, a decrease in fishing pressure has been observed, the mean fishing mortality rate of assessed stocks being almost halved in all the considered ecosystems, but no clear recovery in the biomass and ecosystem indicators is yet apparent. In addition, the mean recruitment index was shown to decrease by around 50% in all ecosystems (except the Baltic). We conclude that building this kind of diagnosis is a key step on the path to implementing an ecosystem approach to fisheries management.  相似文献   
4.
Clubroot, caused by Plasmodiophora brassicae, has become a serious threat to canola (Brassica napus) production in western Canada. Experiments were conducted to evaluate the effect of rate of metam sodium fumigant (dithiocarbamate; sodium N-methyldithiocarbamate; trade name Vapam) and application methods including watering, soil surface covering, and soil incorporation on clubroot of canola. At higher rates (0.4–1.6 mL?1 L soil) metam sodium increased canola seedling emergence and plant health, and reduced root hair infection, gall weight and clubroot severity under greenhouse conditions. Metam sodium application improved subsequent plant growth and reduced clubroot severity, but land preparation and volume of water applied did not affect efficacy. The incorporation of metam sodium into the soil and plastic covering after application improved fumigant efficacy. The study showed that soil fumigation with metam sodium can reduce clubroot severity and improve plant health in the subsequent canola crop.  相似文献   
5.
Orange rust of sugarcane caused by Puccinia kuehnii was first reported in Florida in 2007. Since then, several sugarcane cultivars that were resistant during the initial epidemics became susceptible within a few years. These shifts in resistance were attributed to the evolution of the pathogen and appearance of new races. To study the variation in virulence of P. kuehnii, healthy leaf pieces of sugarcane cultivars susceptible to orange rust were brush inoculated with isolates of P. kuehnii collected from susceptible cultivars in the field. After inoculation, leaf pieces were placed in an incubator and disease severity based on the number of rust uredinia was determined 2 weeks postinoculation. Isolates of P. kuehnii collected from sugarcane cultivar CP 89-2143, which only showed severe symptoms of orange rust starting in 2011–2012, produced 300%–500% more uredinia on CP 89-2143 than the isolates collected from cultivar CL 85-1040 that has been susceptible since 2007. Sugarcane cultivar CL 85-1040 exhibited high and equivalent numbers of uredinia regardless of the inoculated isolate of the pathogen. These data support the occurrence of pathogenic specialization within P. kuehnii and the existence of at least two races of this pathogen in Florida. Analysis of amplified fragment-length polymorphism among isolates of P. kuehnii from cultivars CP 89-2143 and CL 85-1040 differing in resistance to orange rust revealed genetic variation among rust uredinia. However, this variation was not associated with a specific sugarcane cultivar, suggesting that pathogenic variation was not linked to major, but rather to small genetic changes within the genome of P. kuehnii.  相似文献   
6.
An astronomical digital camera is equipped with a fish-eye lens and exchangeable filters to study the fine angular structure of radiation field in forests in the red and near infrared (NIR) spectral bands. A few examples of the angular distribution of downward radiances in conifer and broadleaf forests are given. The results of field measurements are compared with the spectral flux measurements by a field radiometer and with the calculations of radiance by a combined geometric-optical/radiative transfer (RT) model. The test measurements demonstrated that the hemispheric-view imaging radiometer is a good tool to validate canopy RT models.  相似文献   
7.
An estimate of the required amount of LAI-2000 or digital hemispheric image measurements to ensure the desired accuracy of the leaf area index value derived from optical analyser measurements by inversion of gap fraction data is given. The estimate is based on a theoretical model of the second order statistics of gap occurrence in forest canopies. The main attention is paid to gap fractions averaged over the angular rings similar to the LAI-2000 instrument. Nilson's (1999) forest gap fraction model is first extended to simulate the bidirectional gap fraction and next the approximate equations for the standard deviation of gap fraction, correlation matrix of gap readings in different LAI-2000 angular rings, standard deviation of the LAI value as determined by the inversion of gap fraction data are derived. The results of simulation are compared with those obtained by LAI-2000 instrument and digital hemispheric photographs in three mature forests from Järvselja, Estonia. The comparison shows an acceptable agreement between the simulated and measured second order statistical characteristics. The distance from the observation height to the crowns and crown dimensions appear to be important in determining the magnitude of variance. When the LAI-2000 instrument is used together with a view-cap, the angular size of the view-cap has an effect on the second order statistics and on the value of apparent clumping index. A computer program has been written to calculate the second-order gap statistics.  相似文献   
8.
Three all-female strains of large rainbow trout imported to Estonia (Danish, Finnish and Donaldson strain) were evaluated in a communal rearing experiment in tanks. The fish had been reared on different fish farms before the experiment started and they had an initial weight of 400–500 g. There were no significant genetic differences between the investigated strains on the basis of three allozyme loci. The total weight gain of the strains during the trial was similar but differences were revealed between seasons. The growth rate of the Finnish trout was high during the first autumn but decreased during the second summer of the trial, probably due to infestation by eye fluke Diplostomum sp. The strains differed in the percentage of immature fish and in the level of gonad development at the age of 2.5–3 years. The Donaldson strain had the highest number of immature fish of the studied strains. Mature females of the Finnish strain had the smallest gonads but also the lowest percentage of immature fish. The level of maturation was the main factor determining the quality – slaughter yield and flesh color.  相似文献   
9.
As part of a conservation initiative, captive-bred individuals of the endangered European mink Mustela lutreola were released to a Baltic island ‘sanctuary’, Hiiumaa Island (Estonia), and their survival was monitored over eight years. Altogether, 54 released mink were equipped with radio-collars between 2000 and 2003 and their survival and causes of death were studied as a function of sex, age, housing conditions before release and number of generations in captivity. Mortality was greatest (∼ 50%) during 1-1.5 months following release. The survival of males was significantly higher than that of females (25% decline in 21 days, and 10 days, for males and females, respectively). Releasing pregnant females appeared to be an unsuccessful strategy. There was no evidence that the number of generations for which the lineage of the released individuals had been bred in captivity had any effect on survival. The main cause of death was other carnivores and raptors, although this broad categorization may conceal a diversity of fatal scenarios.We recommend for the future that the European mink being prepared for release should be maintained in large naturalistic enclosures beforehand, that a preponderance of females should be released, and that the indications that younger animals make better candidates for release should be investigated.  相似文献   
10.
Journal of Soils and Sediments - The objective of our work was to develop a software for the optimization of the processes of treatment and formulation of dredged sediments for utilization in civil...  相似文献   
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