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951.
Abstract

Non-sorted solid urban wastes (SUW) are used by periurban cereal farmers in Africa. There is however limited information on how these SUW affect soil quality and cereal production and quality. In order to answer this question we identified around Ouagadougou (Burkina Faso) sites cultivated with sorghum (Sorghum bicolor (L.) Moench) that had received SUW for less than 5 years, for more than 5 years and less than 10 years and for more than 10 years. We sampled soils at 0–15 and 15–30 cm depth and we analysed pH, total carbon (C), nitrogen (N) and inorganic phosphate (P) content and P and heavy metals availability. We also measured at some of these sites sorghum production and nutrient and metal contents in sorghum grain and straw. Our results show that the 0–15 cm horizon of the soils that had received SUW for less than 5 years had lower pH, available P and heavy metals contents and produced lower yields than those that had been amended with SUW for more than 10 years. Maximum grain yield was observed in the sites that had been amended for more than 5 years but less than 10 years. There were no clear effects of SUW application time on the heavy metal contents of sorghum grain and straw. The increases in nutrient and heavy metals content observed in the 15–30 cm horizon of soils that had been amended for more than 10 years point out to the risks of element transfer to deeper horizons. Our results suggest that a complete sorting of organic matter from SUW and its further composting as presently recommended, is not necessary. Simply removing dangerous items from the SUW such as plastics, glass and batteries, would be sufficient. Adding this sorted substrate for 5 to 10 years to cereal fields would be sufficient to reach optimal yields, thereafter this substrate should be added to other surfaces.  相似文献   
952.
953.
954.
? A study was conducted on a full scale in-vessel agitated bed process to determine the influence of two common amendments on nitrogen management. Sawdust and mulch were tested for their ability as amendments to conserve nitrogen and thus lower the amount of ammonia volatilization. Neither of the amendments showed a major advantage in conserving nitrogen, although the mulch amended mix had a slight advantage, most likely due to the more readily available nature of the carbon which would lead to greater nitrogen assimilation.  相似文献   
955.
Venereal infection of bulls with bovine herpesvirus type 1.2 (BHV-1.2) may result in acute balanoposthitis followed by the establishment of latent infection, presumably in dorsal root nerve ganglia. We herein report the characterization of the acute and latent infection of young bulls with a Brazilian BHV-1.2 isolate and the investigation of neural and non-neural sites in which viral DNA persists during latent infection, i.e. 110 days after inoculation and 50 days after experimental reactivation. Intrapreputial inoculation of BHV-1.2 isolate SV-56/90 (10(6.5)pfu per animal) resulted in severe balanoposthitis, characterized by redness of the penis and preputial mucosa, coalescent vesicles and fibrinous exsudate in all four infected bulls. Virus shedding was detected in preputial secretions and semen up to days 14 and 13 pi, respectively. Dexamethasone administration at day 60 pi led to reactivation of the infection in all animals, resulting in virus shedding in preputial secretions and/or in semen. At day 50 post-reactivation (pr), the animals were euthanized and regional tissues were collected for PCR and virus isolation. Viral DNA was consistently detected in the dorsal root ganglia of nerves genito-femoral (4/4) and obturator (4/4); frequently in the pudendal (3/4), sciatic (3/4) and rectal caudal nerve ganglia (2/3). In addition, viral DNA was detected in the pelvic sympathetic plexus of one bull and in regional lymph nodes (deep inguinal (2/4); sacral (1/4); medial iliac (1/4)) of two bulls. No infectious virus could be recovered from homogenates of DNA positive tissues, indicating the absence of actively replicating virus. These results demonstrate that BHV-1.2 DNA may persist in several sacral nerve ganglia and in regional lymph nodes as well during latent infection, i.e. 50 days after experimental reactivation. These findings may help in understanding the pathogenesis of acute and latent genital infection by BHV-1.2.  相似文献   
956.
Mortality events in cork and holm oaks have occurred in the Mediterranean basin since the beginning of the XX century, but severity of decline increased during the 1980s. By that time, the exotic soil borne pathogen Phytophthora cinnamomi was often recovered from declining stands and since then it has been considered the main factor associated with decline. This work analyses data concerning P. cinnamomi surveys in cork and holm oaks trees, pathogenicity tests carried out in controlled experiments, studies about the influence of site characteristics in tree decline and approaches to control the disease. Results of field surveys showed that the pathogen is widespread and pathogenicity tests suggested that host susceptibility to the pathogen is moderate when seedlings are in appropriate watering conditions, particularly cork oaks. Occurrence of decline is also associated with soil characteristics that interfere with root expansion and water retention. We assessed the relative importance of each factor involved in decline and revised the role of P. cinnamomi in cork and holm oak decline.  相似文献   
957.
Woodpecker species have significantly expanded their ranges in the last decades of the twentieth century in Mediterranean Europe, which seems to be closely related to forest maturation following large-scale decline in traditional uses. Here we assess the explicit role of forest landscape connectivity in the colonization of the Great Spotted Woodpecker (Dendrocopos major) and the Black Woodpecker (Dryocopus martius) in Catalonia (NE Spain). For this purpose we combined data on breeding bird atlas (10 × 10 km; 1980–2000) and forest inventories (c. 1 × 1 km, 2000). Forest connectivity was measured through graph theory and habitat availability metrics (inter- and intra-patch connectivity) according to species median natal dispersal distances. The best regressions from a set of alternative models were selected based on AICc. Results showed that connectivity between areas of mature forests [diameter at breast height (dbh) ≥ 35 cm] affected Black Woodpecker colonization events. The probability of colonization of the Great Spotted Woodpecker was greater at localities near the sources of colonization in 1980 and with a high connectivity with other less developed forest patches (dbh < 35 cm). The spatial grain at which landscape connectivity was measured influenced the model performance according to the species dispersal abilities, with the species with the lower mobility (D. major) responding better to the forest connectivity patterns at finer spatial scales. Overall, it seems that both species could expand further in European Mediterranean forests in upcoming years but at slower rates if landscape connectivity according to species requirements does not continue to increase. Hence, a proactive and adaptive management should be carried out in order to preserve these species while considering the related major impacts of global change in Mediterranean Europe.  相似文献   
958.
The shea tree, Vitellaria paradoxa, is one of the most economically and culturally important indigenous tree species in the Sudano-Sahelian region. Its seeds contain a vegetable fat, internationally known as shea butter, which is widely used in edible, cosmetic and pharmaceutical sectors. Based on samples from 456 trees distributed in 17 locations across the species natural range from Senegal to Uganda, the fatty acid and tocopherol variation, and its relationship with geographic and climatic variables, was assessed in order to address the pattern and the origin of this variation across the natural range. Significant differences between Western and Eastern regions for oleic, stearic acid, saturated–unsaturated acid ratio and γ-tocopherol were identified that it is postulated maybe a result of genetic drift due to the evolutionary history of shea tree populations. Within regions the difference among stands was significant for most constituents; however the major part of the variation was observed among trees within stand (53–90 %). Relationships with climatic variables were not verified, weakening evidence for clinal variation hypotheses suggested by previous studies.  相似文献   
959.
The character of flat versus round fruit shape is controlled by a single gene (S/s) on chromosome 6 in peach [Prunus persica (L.) Batsch], with the flat fruit phenotype produced by the S/s heterozygous genotype. We used 16 simple sequence repeat (SSR) markers at the S/s region and physically mapped them in the peach sequence. Seven were mapped in the new F1 population from a cross between the two flat fruit cultivars 'UFO-3' and ‘Sweet Cap’ that segregated for the S/s gene. Fourteen of the SSRs were mapped in the Prunus reference map (T×E), of which seven had already been mapped and seven were added within this work. Our results confirmed the position of S/s on the distal part of chromosome 6. Thirteen of the initial 16 markers were also studied in a collection of flat (66) and round (39) cultivars, where some of the alleles were associated to the character and one of them, the 131 bp allele of marker UDP98-412, predicted in 98.4 % of the cases the flat shape. This allele was highly predictive of the flat fruit character in an additional collection of 100 cultivars, and is an useful tool for marker-assisted selection of flat peaches and nectarines, a trait that is becoming of increasing interest in breeding programs as consumption of these fruits is growing in the European market.  相似文献   
960.
This work addresses to the genetic analysis and selection in populations where the whole genotypic value is transmitted through generations, using grapevine yield data as a case study. Several models were applied to different types of data sets. The individual and mean year yield and the balanced and unbalanced data resulting from various experimental designs (completely randomized, randomized complete block and row–column) were used. The aims of present work were to study: (1) the applicability of a generalised measure of broad-sense heritability to evaluate the success of the genotypic selection and compare it with the classical approach; and (2) the effect of different models on the accuracy and precision of the genotypic variance component and on the generalised broad-sense heritability estimates. The results showed that the computation of a measure of generalised broad-sense heritability is very feasible and useful for evaluating the efficiency of genotypic selection. In this study, 88 % of the fitted models did not comply with the standards for applying the classical concept of heritability. The differences between both the classical and generalised broad-sense heritability estimates increased with the complexity of the model. Higher broad-sense heritability estimates were consistently obtained with the mean years. The most accurate and precise estimates of the genetic parameters were obtained with the spatial models. Finally, the genotypic variance component of yield and the generalised broad-sense heritability were consistently significant for all grapevine varieties.  相似文献   
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