Evaluation of estimated weather data for calculating Penman-Monteith reference crop evapotranspiration

Utilizing the weather generator ClimGen, daily solar radiation (R_s) and vapor pressure deficit (VPD) were estimated from temperature data and used to calculate evapotranspiration at five locations, representing tropical, temperate, semi-arid, and arid climates. ClimGen was calibrated for each location using the most recent 2 or 5 years of complete daily weather records. Actual and estimated values were compared on a daily and weekly (7-day running average) basis. Error indices were defined to indicate excellent to poor performance of the estimation methods. Overall in all locations, the ClimGen estimates for both daily R_s and VPD were poor to acceptable. The weekly analyses showed significant improvement in performance for both R_s and VPD estimations in arid and semi-arid locations. Daily reference crop evapotranspiration values using the FAO Penman-Monteith equation (PM ET_o) were calculated using complete daily weather records. These values were compared with (1) ET_o calculated with the PM model, actual temperature data, and ClimGen estimates of daily R_s, VPD, and generated wind speed (PM_Est ET_o), and (2) ET_o calculated solely from actual daily temperature data using a calibrated version of the Hargreaves method (HG_Adj ET_o). The daily PM_Est ET_o results were poor to acceptable in all locations, but analyses for weekly periods showed improved performance to acceptable and good levels for arid and semi-arid locations. The performance of the HG_Adj ET_o method was also poor to acceptable for daily ET estimates in all locations, while weekly analyses showed improvement. A non-calibrated version of the Hargreaves method did not work for either daily or weekly periods. The PM_Est ET_o and HG_adj ET_o methods appeared suitable for weekly periods in arid and semi-arid locations provided that at least 2 years of complete weather records were available to calibrate the parameters required. There was no advantage in using 5 years of weather records for calibration.Communicated by E. Fereres     

Quantification of Aluminum-Induced Changes in Wheat Root Architecture by X-ray Microcomputed Tomography

Root architectural traits are of fundamental importance for plant performance, especially under unfavorable soil conditions. This study examined the effect of aluminum (Al) toxicity in different growing media (nutrient solutions and soil) on root architecture of two wheat (Triticum aestivum L.) cultivars with different Al tolerances. Seedlings were grown in acidic and limed soil and in two contrasting nutrient solutions. Root systems of soil-grown plants were scanned using x-ray microcomputed tomography (µCT) while that of nutrient solution–grown plants were assesses using WinRhizo, 3 and 5 days after planting (DAP), respectively. Aluminum caused significant reduction of all examined root traits (number of seminal roots, root length, length of the longest seminal root, root surface area, and root volume). Growth in acidic soil caused significant reduction in root length, length of the longest seminal root, and root surface area at 5 DAP. Soil-grown plants produced a larger root system compared to plants grown in nutrient solutions. Aluminum toxicity–induced differences of root traits were also found between different nutrient solutions. Beside the well-known reduction of root length, Al toxicity had a profound effect on other root architectural traits. X-ray µCT has revealed root architectural changes under specific conditions of acidic, Al-toxic soil. Differences obtained in Al-induced effects on root architecture between different nutrient solutions as well as between different growing systems emphasize the need for further study of root architecture, especially under specific conditions of Al toxicity in acidic soils.     

Genetic Variation in Alfalfa, Sweet Clover and Fenugreek for the Activity of Symbiosis with Rhizobium meliloti

The aim of this work was to examine variation for activity of symbiosis with Rhizobium meliloti in alfalfa, sweet clover and fenugreek. Seed specimens were obtained from the collection of the All-Union Research Institute for Plant Breeding and Rhizobium strains from the All-Union Research Institute for Agricultural Microbiology, both in Leningrad. Sterile methods of vegetative culture were employed. Statistical analysis of data on inter- and intracultivar variation allow one to suppose that in alfalfa and sweet clover, nitrogenase activity and symbiotic efficiency (ability of plants to increase biomass after inoculation) are controlled by different groups of genes. The latter symbiotic property is more strictly controlled by host genotype than the former. Fenugreek appeared to be more variable in its capacity for symbiosis than alfalfa and sweet clover. Differences between genotyyes in symbiotic activity correlate with division into subspecies and are inherited in self-fertile progeny of fenugreek plants. Differences between R. meliloti strains for the efficiency of symbiosis with heterogceic natural fenugreek population are expressed to a lesser degree than with plants of more homogenic cultivar populations.     

Mechanized thinning of walnut plantations established on ex-arable land

The study compares two product strategies—chips versus firewood—and two technological levels—manual versus mechanized—as applied to the thinning of walnut agroforestry plantations, established on ex-arable land. Such plantations are widespread all across Europe, and their establishment was subsidized under the provisions of EU Directive 2080/90, and of regional grant schemes. Field test data were used to build a simple deterministic model for estimating thinning productivity and cost under varying work and economic conditions. This model can assist prospective users when checking the profitability of an operation, or when assessing the competitiveness of alternative options. Removing nurse alder from young walnut plantations yields between 25 and 50 t of fresh biomass per hectare and is crucial to the good development of the stand. The study shows that the removal of nurse alder from walnut plantations is economically viable, and it can also offer some profits if stand and market conditions are favourable. As a rule, the average DBH of removal trees should not be smaller than 12 cm. Best results are obtained with mechanized harvesting, which does not seem to cause heavier stand and soil damage than manual harvesting. Manual harvesting is preferable only if the annual utilization of machinery is very low, and in this case it should be geared to firewood production. The manual whole-tree harvesting (WTH) method used in this study offers the lowest performance under all conditions, and should be replaced with some other manual alternative to WTH. Mechanized WTH offers a significant cost reduction over mechanized short-wood (SWS) harvesting, but this difference is still rather limited: hence, other parameters come into play when deciding what system to apply, and namely product price and mass output. In this respect, one also has to consider the cost of managing the harvesting residue, and that of fertilizing, if soil nutrient depletion is to be feared.     

Habitat models and habitat connectivity analysis for butterflies and burnet moths - The example of Zygaena carniolica and Coenonympha arcania

In this paper, habitat models were used to predict potential habitat for endangered species, which is an important question in landscape and conservation planning. Based on logistic regression, we developed habitat distribution models for the burnet moth Zygaena carniolica and the nymphalid butterfly Coenonympha arcania in Northern Bavaria, Germany. The relation between adult occurrence and habitat parameters, including the influence of landscape context, was analyzed on 118 sites. Habitat connectivity analyses were carried out on the basis of (1) habitat suitability maps generated from these models and (2) dispersal data from mark recapture studies. Our results showed that (1) the presence of the burnet depended mainly on the presence of nectar plants and of nutrient-poor dry grasslands in direct vicinity, that of the nymphalid on larger areas of extensively used dry grasslands within 100 m vicinity in combination with small patches of higher shrubs and bushes. (2) Internal as well as external validation indicated the robustness and general applicability of the models. Transferability in time and space indicated their high potential relevance for applications in nature conservation, such as predicting possible effects of land use changes. (3) Habitat connectivity analyses revealed a high degree of habitat connectivity within the study area. Thus, we could show no effects of isolation or habitat size for both species.     

Mercury in the Aquatic Environment of the Village of Caimito at the Mojana Region,North of Colombia

During May–September 1999, several aquatic environmental samples were collected from the village of Caimito, in the San Jorge River basin area, state of Sucre (Colombia), and analyzed for total mercury (T-Hg). Mean T-Hg concentration in sediments from surrounded marshes was 0.155 ± 0.016 g Hg/g. Low Hg concentrations were found in the phytoplanktivorous fish species Prochilodus magdalenae (0.087 ± 0.01 g Hg/g), while four-fold greater concentrations were found in all the carnivorous species. In average, T-Hg concentrations for fish samples did not exceed the limit consumption level (0.5 g Hg/g). However, risk assessment based on the hazard index suggested that the consumption of 0.1 kg per day of carnivorous fish could increase the risk of mercury poisoning in local population.     

Habitat selection by the pale-headed brush-finch (Atlapetes pallidiceps) in southern Ecuador: implications for conservation

The pale-headed brush-finch (Atlapetes pallidiceps) is threatened with extinction due to habitat loss, but very little is known about its ecological requirements. We used multiple logistic regression to study habitat selection of this species at landscape, territory, and nest site scales in order to make recommendations about effective management. Habitat selection by the sympatric stripe-headed brush-finch (Buarremon torquatus) was examined with the same methods in order to analyse interspecific resource partitioning and potential competition. The pale-headed brush-finch selected semi-open habitat types with intermediate scrub heights, and avoided forests. Nest sites depended on the presence of vines or bamboo. By contrast, the stripe-headed brush-finch chose dense habitat with low ground cover under tall vegetation and avoided semi-open habitat. The two species had overlapping territories but differed significantly in microhabitat use and the use of vegetation strata. We found no convincing evidence that the stripe-headed brush-finch displaces the pale-headed brush-finch from optimal habitat. The preservation of semi-open scrubland maintained by low-intensity grazing is suggested for future conservation of the pale-headed brush-finch.     

Immunomodulatory effect of glucan on specific and nonspecific immunity after vaccination in puppies

The objective of the study was to determine the immunostimulatory effect of β-(1,3/1,6)-D-glucan in puppies. The effect exerted on the efficacy of vaccination, especially against canine parvovirus and rabies infection, was studied. The application of vaccine and glucan leads to significant increases in the nonspecific immunological parameters (phagocytic ability of leukocytes, blastogenic response of lymphocytes, metabolic and chemotactic activity of polymorphonuclear cells). The level of antibodies against canine parvovirus (Ab CPV) and rabies infection reached the most statistically significant values on the 28th day after the application of vaccine and a syrup containing β-(1,3/1,6)-D-glucan (Group GV) as compared to the control group (Group V, puppies receiving only vaccine). Dogs without glucan supplementation did not produce such significant levels of antibodies. We can conclude that glucan has relevant immunostimulatory effects in dogs with altered immunity. The glucan product tested in this study (PleraSAN V, PLEURAN, Bratislava, Slovakia) could be used in the small animal clinical practice.     

Relationship between the oil and sugar content in olive oil fruits from Moraiolo and Leccino cultivars during ripening

In our previous work (Cherubini et al., 2009), sugar concentration was proposed as an accurate, reproducible index for technological ripening of olive oil fruits. During 2009 crop season, sugar and oil content of olive oil fruits from Moraiolo and Leccino cultivars were measured during ripening. The sugar content of olive oil fruits was determined both by titration and by using a portable refractometer.