Nutrient Losses by Runoff and Sediment from the Taluses of Orchard Terraces

The nutrient fluxes of nitrate, ammonium, phosphorus and potassium in runoff and sediments were evaluated over a two-year period (1999–2000) on the taluses of terraces, in a zone of intense subtropical orchard cultivation (SE Spain). The erosion plots were located on a terrace of 214% (65°) slope, at 180 m in altitude and with 16 m² (4 × 4 m) in area. Shrubby covers were tested for effectiveness in controlling the nutrient fluxes caused by runoff and sediments. Covers of Thymusserpylloides Bory sbsp. Gadorensis and Salvia officinalis L. reduced the NO₃ ^- runoff losses by 53 and 48%, with respect to the bare soil without natural vegetation, the NH_-4 ⁺ 61 and 56%; the PO₄ ^-3 65 and 56%; and K⁺ 58 and 46%, respectively. A greater proportion of NO₃ ^-, NH_-4 ⁺ and K⁺ were transported in runoff than in sediments. Thyme and sage with respect to the control reduced NO₃ ^- loss in sediments by 74 and 65%, NH_-4 ⁺ by 71 and 62%, P by 72 and 67%, and K by 69 and 61%, respectively. The total loss (runoff and sediments) in the bare-soil plot for NPK was 260, 39 and 888 mg m^-2 yr^-1, in the sage plot 119, 15 and 460 mg m^-2 yr^-1, and in the thyme plot 105, 12 and 360 mg m^-2 yr^-1, respectively. The results show the importance of the plant covers in soil conservation and in the recycling of nutrients on terrace slopes. This has far-reaching implications in the sense that the control of pollution from erosion is vital in reducing the eutrophication of both surface waters and groundwater located in lowlands.     

Zacatecas (Mexico) Companies Extract Hg from Surface Soil Contaminated by Ancient Mining Industries

In Zacatecas, Mexico, four plants are operating to extract Ag, Au, and Hg using CaS₂O₃ solution from surface soil containing tailings from the amalgamation method used during 1550–1900. The metal ions extracted are cemented by scrap Cu wires. Hg is separated by evaporation from the cemented amalgam and Ag and Au are obtained from the residue. A part of the soil to be leached was separated and leached as in the industrial process. Only 121 ppm of Hg was freed from 168 ppm of extractable Hg. About a half of the remaining Hg in the soil evaporated during 18 months. This confirms that the Hg in the soil is metallic. Pb and As are also freed in the same process. It is estimated that 13 000–34 000 t of Hg had been discarded in the extraction of Ag.     

Mixed culture optimization for marigold flower ensilage via experimental design and response surface methodology

Endogenous microorganisms isolated from the marigold flower (Tagetes erecta) were studied to understand the events taking place during its ensilage. Studies of the cellulase enzymatic activity and the ensilage process were undertaken. In both studies, the use of approximate second-order models and multiple lineal regression, within the context of an experimental mixture design using the response surface methodology as optimization strategy, determined that the microorganisms Flavobacterium IIb, Acinetobacter anitratus, and Rhizopus nigricans are the most significant in marigold flower ensilage and exhibit high cellulase activity. A mixed culture comprised of 9.8% Flavobacterium IIb, 41% A. anitratus, and 49.2% R. nigricans used during ensilage resulted in an increased yield of total xanthophylls extracted of 24.94 g/kg of dry weight compared with 12.92 for the uninoculated control ensilage.     

Race 1 fusarium wilt tolerance on banana plants selected by fusaric acid

Summary The selection of tolerant variants to race 1 fusarium wilt of banana was carried out through the effects of fusaric acid onin vitro banana multiple bud clumps (MBCs). The MBCs of Maçã cultivar (Musa sp., AAB, Silk), which is susceptible to the race 1 fusarium wilt, were used. And, Nanicão cultivar (AAA, Cavendish subgroup) was used in the tolerant tests as control of a disease tolerant variety. Firstly, to aim at determining an appropriate concentration of the toxin for the tolerant selection, the MBCs were cultured on the Modified Murashige & Skoog medium supplemented with 0.05 to 1.6 mM fusaric acid. The growth on both cultivars was completely inhibited on the medium containing 0.1 mM fusaric acid.Tolerant variants of Maçã were, then, selected with 0.1 mM fusaric acid after chemical mutagen treatment. The results showed an increased tolerance of the selected Maçã plants to the race 1 fungus in greenhouse tests. In vitro selection by fusaric acid is a very useful method for obtaining fusarium disease tolerance, although the tolerance mechanism of the selected plants may be different from that of existing tolerant cultivars.     

Anti-Mullerian hormone and its relationship to ovulation response and fertility in timed AI Bos indicus heifers

This study evaluated the association between plasma anti-Mullerian hormone (AMH) concentration and fertility in Nelore (Bos indicus) heifers submitted to timed artificial insemination (TAI). At the onset of the synchronization protocol, heifers (n = 289) received a subcutaneous P4 ear implant (3 mg) and 2 mg of oestradiol benzoate. Eight days later, the P4 implant was removed and 0.5 mg of oestradiol cypionate, prostaglandin (0.265 mg, i.m.) and equine chorionic gonadotropin (300 UI, i.m.) was administered, and TAI was performed 48 hr after ear implant removal. Ovarian ultrasound evaluations were performed to measure number of ovarian follicles, dominant follicle size and ovulation response. Pregnancy diagnosis was performed by ultrasound 30 days after AI. Heifers with greater circulating AMH had more antral follicles, a smaller dominant follicle near timed ovulation and lower ovulation response to the timed AI protocol compared to heifers with lower circulating AMH. Although AMH and pregnancy outcome had a quadratic-shaped pattern, AMH was not significantly associated with fertility. In conclusion, heifers with lower AMH had larger follicles towards the end of the synchronization protocol and greater ovulation responses, whereas greater circulating AMH was unrelated to conception success.     

Cryogenic preservation of spermatozoa from Prochilodus scrofa and Salminus maxillosus

This paper reports an initial trial to cryopreserve semen from two freshwater South American fishes, the curimbatá (Prochilodus scrofa) and the dourado (Salminus maxillosus). Motility and duration of motility were observed in curimbatá and dourado fresh sperm. Semen mixed with extender (0.8% NaCl) was frozen using vials (1 ml) with subsequent storage in liquid nitrogen. Samples were thawed in 1% NaHCO₃ or in 0.8% NaCl solutions. Post-thawing motility and duration of motility were verified. A simple extender consisting of 0.8% NaCl plus 10% DMSO was able to initiate motility in fresh spermatozoa. The percentage of motile cells and duration of motility were similar in both thawing solutions, but lower than in fresh sperm.     

Heritability for body weight at harvest size in the Pacific white shrimp, Penaeus (Litopenaeus) vannamei, from a multi-environment experiment using univariate and multivariate animal models

To estimate family BLUP breeding values and the heritability of body weight at harvest size (BW) in the Pacific white shrimp, Penaeus (Litopenaeus) vannamei, an experiment was conduced using information from two farm units of a Mexican hatchery and two shrimp population densities at each location. Data consisted of 12,658 shrimps that were siblings from 48 sires and 77 dams with a nested dam-sire structure. Shrimps were individually weighed at an average age of 130 days post-hatching. BW phenotypic mean (S.D.) was 18.2 (2.4) g, with values ranging from 8.4 to 30.0 g. Data were analyzed using univariate and multivariate models that considered BW within location by density pond environment as a different trait and included or not a common full-sib effect (c). The multivariate animal model included fixed effects of days from hatching and sex. For univariate models that included c effects, BW heritability (S.E.) estimates ranged from 0.24 (0.14) to 0.35 (0.18) across environments (heritability was zero in one environment). For multivariate models (excluding the environment with zero heritability) the heritabilities increased and ranged from 0.37 (0.06) to 0.45 (0.09). Standard errors of heritabilities and c effects were both drastically reduced in the multivariate analysis. Pairwise genetic correlations between environments were from 0.80 (0.08) to 0.86 (0.04). These differences may be indicative of genotype-environment interaction for BW at 130 days post-hatching. Statistical problems found to separate c from additive genetic effects both in univariate models were reduced using multivariate models. Correlation between family raw phenotypic means and family BV means from the multivariate analysis was 0.93 indicating a rather low risk of miss selecting superior families if BLUP solutions were neglected using replicated environment data. It is also concluded that use of incorrect statistical models or unreplicated data may lead to biased or inaccurate estimates of genetic parameters in shrimp breeding programs.     

Tree-cavity occurrence, cavity occupation and reproductive performance of secondary cavity-nesting birds in oak forests: The role of traditional management practices

Secondary cavity-nesting birds (SCN), which cannot create their own breeding cavities, are expected to be influenced by habitat alteration caused by forest management practices, but the mechanisms underlying the distribution pattern of SCN subjected to different management systems are poorly known. To improve our knowledge on these mechanisms, we examine cavity abundance, cavity occupation and reproductive performance of SCN in Pyrenean oak (Quercus pyrenaica) forests subjected to two management systems: (i) dense “young forests”, maintained at such stage by clear-cuttings and burns, and (ii) “old forest”, subjected to extensive traditional grazing and scarce firewood extraction by selective cutting. Young forests had considerably lower density of cavities (1.29 ± 0.71 vs 15.09 ± 2.00 cavities ha⁻¹), SCN species (0.18 ± 0.11 vs 0.61 ± 0.07 species ha⁻¹) and nests (0.40 ± 0.27 vs 2.67 ± 0.25 nests of all SCN ha⁻¹) than old forests, indicating that a low availability of cavities may limit SCN assemblages in young oak forests. However, reproductive parameters of great (Parus major) and blue (Cyanistes caeruleus) tits associated with the availability of food (laying date, clutch size, nestling number and weight, adult weight) did not differ between both forest types, suggesting that food supply was not reduced in young forests, at least for tits during the breeding season. Large diameter (up to 170 cm dbh) decayed trees were the most likely to hold cavities, but birds preferred smaller living cavity-trees for nesting (90% of nests in 21-65 cm dbh trees). The preservation of cavity-trees within traditionally managed old oak forests is crucial in providing nesting opportunities to SCN. Besides, the protection of these traditionally managed forests would also benefit to other forest organisms that depend on old and open oak forests.     

Meiotic behavior as a selection tool in the breeding of <Emphasis Type="Italic">Brachiaria humidicola</Emphasis> (Poaceae)

Brachiaria humidicola is a tropical grass that grows in seasonally swampy grasslands in Africa. In Brazil, two apomictic cultivars (2n = 54) of this species are widely used as pastures in poorly drained soils. The recent discovery of a sexual polyploid accession (2n = 36) in the germplasm collection at the Embrapa Beef Cattle Research Center allowed intraspecific hybridization with the objective of broadening the genetic variability and selection of superior genotypes in this species. Hybridization, however, depends on accessions with the same ploidy level. Cytological analyses of 55 accessions revealed that 19 apomictic accessions also presented 2n = 36 chromosomes. Chromosome pairing in hexavalent association at diakinesis and metaphase I suggested that the basic chromosome number for this species is x = 6. Cytological analysis revealed abnormalities in variable frequencies in the meiosis of these hexaploid (2n = 6x = 36) accessions. The most common were those related to irregular chromosome segregation which led to unbalanced gamete formation, but chromosome stickiness was also recorded. These results clearly demonstrate the value of cytogenetics in the choice of genitors and for superior hybrids to be obtained in the breeding of this species. For that both the ploidy level and the frequency of abnormalities need to be considered, besides other favorable agronomic characteristics.