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71.
Naser A. Anjum Iqbal Ahmad M��nica V��lega M��rio Pacheco Etelvina Figueira Armando C. Duarte Eduarda Pereira 《Water, air, and soil pollution》2011,222(1-4):1-15
The availability of metals to plants is a complex function of numerous environmental factors. Many of these factors are interrelated, and vary seasonally and temporally. The current study intended to understand the influence of seasonal fluctuations and the vegetation of salt marsh plants (SMPs; Halimione portulacoides, Juncus maritimus) on sediment??s mercury (Hg) and its pH and redox potential (Eh), as well as their cumulative effect on the plant??s Hg-accumulation and Hg-partitioning potential. The area selected for the study was Laranjo Basin at Ria de Aveiro lagoon (Portugal) where a known Hg gradient was existed due to chlor-alkali plant discharge. Three sampling sites (L1, L2 and L3) were selected along a transect defined by the distance from the main Hg source. Samples were also collected from the Hg-free site (R). Irrespective of the plant vegetation, Hg in sediments gradually increased with a decreasing distance towards Hg-point source. The sediment colonised by J. maritimus showed more Hg concentration compared with H. portulacoides irrespective of the season. As a whole, J. maritimus accumulated Hg more than H. portulacoides at all the sampling sites, whereas in root, stem and leaf, the concentration was ranked as: L1 > L2 > L3 in both the plant species and was differentially influenced by seasonal changes. Moreover, root of both plants exhibited highest Hg concentration compared with stem and leaf. In addition, the leaf of H. portulacoides exhibited more Hg than leaves of J. maritimus. Bioaccumulation and translocation factors and dry weight were differentially influenced by seasonal changes. Taking together the results, the physico-chemical properties of sediment especially the sediment-Eh seems to be influnced by the type of plant vegetation and seasonal changes which in turn may have influenced the chemistry of sediments; thus, it enfluences the bioavalability of Hg and the Hg-retention capacity of both salt marsh sediments (SMSs) and SMPs (bioaccumulation factor). Moreover, SMSs vegetated by J. maritimus exhibited a stronger capacity for the retention and phytostabilization of Hg belowground (in sediments and/or roots) than those dominated by H. portulacoides. Conversely, those SMSs extensively vegetated by H. portulacoides are expected to translocate more Hg to aboveground parts, acting as a potential source of this metal to the marsh ecosystem. Therefore, J. maritimus and H. portulacoides may be used repectively for phytostabilization (in rhizosediments) and phytoextraction (by accumulation in aboveground plant tissue for subsequent plant removal). 相似文献
72.
73.
Lorena V. Armando Alicia D. Carrera María A. Tomas 《Genetic Resources and Crop Evolution》2013,60(5):1737-1747
Panicum coloratum (Poaceae) is a perennial grass native to South Africa, distributed all over the world, but poorly adopted by ranchers in Argentina. Adapted to a wide range of soil and climatic conditions, it constitutes a good forage resource for zones with edaphic and climatic restrictions, where cattle rising activities are here displaced. The high polymorphism in the species has made it difficult to delineate sub specific taxonomic categories. It has been classified in botanical varieties, types and/or cultivars. In order to document the morphological variability in P. coloratum and to investigate the differences between var. makarikariense and var. coloratum, a collection was gathered in INTA Rafaela composed by fourteen accessions from different provinces of Argentina: six accessions of var. makarikariense and eight from var. coloratum. The evaluation of 152 individuals gives evidence of a wide morphological variation in the collection in traits related to forage and caryopses production; seven out of nine traits showed significant differences between var. makarikariense and var. coloratum. Based on the study of local type specimens, a morphological key to distinguish between P. coloratum varieties is provided. These results report new information about the diversity in P. coloratum in Argentina and provide valuable insights for future use of the collection as the base material of a breeding program. 相似文献
74.
Raúl López-Aguilar Andrés Orduño-Cruz Armando Lucero-Arce Bernardo Murillo-Amador Enrique Troyo-Diéguez 《Soil Science and Plant Nutrition》2013,59(3):329-336
Abstract The material balance of all the chemical species associated with the phosphate sorption reaction by two amorphous clays, silica-alumina gel and synthetic goethite was investigated adjusting the initial pH to 4.0, 5.0, 6.0, and 7.0. Phosphate sorption was found to decrease with increasing initial pH. During phosphate sorption, the equilibrium pH rose, adsorption of Cl- decreased to a state of negative adsorption, adsorption of Na+ increased markedly, silicate was released, and Al in the solution was precipitated. With increasing initial pH, the amount of apparent released OH- increased, the amount of Na+ adsorption increased, and the amount of released silicate decreased. The overall relationship of the material balance is explained in terms of the charge balance associated with phosphate sorption. 相似文献
75.
Hernández-Pérez T Carrillo-López A Guevara-Lara F Cruz-Hernández A Paredes-López O 《Plant foods for human nutrition (Dordrecht, Netherlands)》2005,60(4):195-200
Biochemical and nutritional changes were studied during the ripening process of three Opuntia morphospecies with different ripening behavior: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Esmeralda (Opuntia sp.) of early, early-intermediate, and intermediate-late ripening, respectively. In loss of fresh weight, Naranjona showed
the highest values, while in Blanca Cristalina and Esmeralda, a discrete weight loss was found. No significant differences
were found among morphospecies in soluble solids, total titratable acidity and pH during the postharvest days. Blanca Cristalina
and Esmeralda showed an increase in the content of carotenoids, while these diminished in Naranjona. The cell wall enzymes
evaluated showed particular behaviors during the ripening of each morphospecies suggesting a fine biochemical control and
not a clear relationship between fruit softening and enzyme activity. This study provides basic information on prickly pear
ripening, in order to understand this process for its control and for improving shelf life. 相似文献
76.
Julio C. Barbosa Sarah S. Barreto Alice K. Inoue-Nagata Marcelo S. Reis Ana Carolina Firmino Armando Bergamin Filho Jorge Alberto Marques Rezende 《Journal of General Plant Pathology》2009,75(6):440-443
Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil. 相似文献
77.
Antonio D. del Campo Tarcísio J. G. Fernandes Antonio J. Molina 《European Journal of Forest Research》2014,133(5):879-894
Hydrology-oriented silviculture might adapt Mediterranean forests to climatic changes, although its implementation demands a better understanding and quantification on the water fluxes. The influence of thinning intensity (high, medium, low and a control) and its effect on the mid-term (thinned plots in 1998 and 2008) on the water cycle (transpiration, soil water and interception) and growth [basal area increment (BAI)] were investigated in 55-year-old Aleppo pine trees. Thinning enhanced a lower dependence of growth on climate fluctuations. The high-intensity treatment showed significant increases in the mean annual BAI (from 4.1 to 17.3 cm2) that was maintained in the mid-term. Thinning intensity progressively increased the sap flow velocity (v s) in all cases with respect to the control. In the mid-term, an increased functionality of the inner sapwood was also observed. Mean daily tree water use ranged from 5 (control) to 18 (high intensity) l tree?1. However, when expressed on an area basis, daily transpiration ranged from 0.18 (medium) to 0.30 mm (control), meaning that in spite of the higher transpiration rates in the remaining trees, stand transpiration was reduced with thinning. Deep infiltration of water was also enhanced with thinning (about 30 % of rainfall) and did not compete with transpiration, as both presented opposite seasonal patterns. The changes in the stand water relationships after 10 years were well explained by the forest cover metric. The blue to green water ratio changed from 0.15 in the control to 0.72 in the high-intensity treatment, with the remaining treatments in the 0.34–0.48 range. 相似文献
78.
Martin G. Maquivar Carlos S. Galina Jaime R. Galindo Sandra Estrada Rafael Molina German David Mendoza 《Tropical animal health and production》2010,42(4):555-560
In order to evaluate the effect of protein supplementation on the productive and reproductive performance of heifers, 45 Bos indicus × Bos taurus heifers, 673 ± 146 days of age and weighing about 340 kg, were divided into two groups. The control group (n = 23) continued without supplementation, but the supplemented group (SG; n = 22) received concentrate at a rate of 1% BW kg per day. Animals were adapted to the concentrate over a 15-day period and
then supplemented for 30 days, after which estrus was synchronized using a progesterone implant. Back fat thickness (BFT)
was assessed by ultrasound. The SG had better average daily weight gain than the nonsupplemented group (0.63 ± 0.16 vs. 0.51 ± 0.13 kg/day,
P < 0.05) and tended to show a better percentage ovulation (P < 0.10, 77% vs. 57%, respectively). However, this tendency was not reflected in the final pregnancy rates. No differences
were observed between groups in dry matter intake and body condition scores. SG with a high BFT (>0.70 cm) showed a better
ovulation percentage than those with low BFT (<0.69 cm; P < 0.01). Additionally, the pregnancy rate of supplemented heifers with high BFT tended to be better than heifers with low
BFT in this same group (67% vs. 30%, respectively, P < 0.10). It is concluded that protein supplementation improved reproductive performance and that ultrasonography to measure
BFT may be used to estimate reproductive performance. 相似文献
79.
García A Landete-Castillejos T Molina A Albiñana B Fernández C Garde J Gallego L 《Journal of animal science》1999,77(12):3150-3155
This study examines milk production and the effect of milk production and sex of calf on body weights and gains of red deer calves and hinds of the Iberian subspecies (Cervus elaphus hispanicus). Milk production was assessed in 14 hinds by weighing calves before and after suckling and by adjusting these values to the Gamma function. Gamma estimates of total milk production up to d 105 were similar to the amounts computed directly from double weighing. Hinds showed two types of lactation curve: 1) the standard mammal lactation curve, with an asymmetrical peak at wk 2 to 4 (Type I) and 2) decreasing curves with no peak (Type II). Although there was great interindividual variability, hinds with Type I curves showed a trend to produce more milk than those with Type II. The type of curve did not seem to affect weight variables of the calf or those of the dam. Calves that gained more weight consumed greater amounts of milk (P<.05). Males were heavier than females at birth (P<.05), but males did not differ from females in their weight at 105 d, milk consumption, and gain. Gender did not affect hind weight, but dams of male calves showed a trend to be lighter (P = .063) at d 105 than dams of female calves. Our results suggest that suckling differences found in other studies between male and female calves may not involve differences in milk production, although other rearing costs seem to affect hind weight losses. They also suggest that the curve type may not depend only, as reported, on the nutrition plane. 相似文献
80.
I. Rojas‐Molina E. Gutirrez M. E. Corts‐Acevedo A. Falcn R. Bressani A. Rojas C. Ibarra J. L. Pons‐Hernndez S. H. Guzmn‐Maldonado A. Cornejo‐Villegas M. E. Rodríguez 《Cereal Chemistry》2008,85(3):409-416
This study showed the protein changes in Quality Protein Maize (QPM H‐368C) during the traditional nixtamalization process as a function of the steeping time from 0 to 15 hr. Protein content (N × 6.25), pH, protein fractionation, reactive lysine, essential amino acids, and protein digestibility were analyzed to explain the protein quality modifications in nixtamalized corn flours (NQF). The thermoalkaline process increased significantly (P ≤ 0.05) the protein content (5.57 ± 0.86%) in NQF obtained at 3, 5, 7, 9, 11, 13, and 15 hr of steeping time compared with native corn or corn without treatment (NC). The pH values of NQF were not proportional to the steeping time and significantly different (P ≤ 0.05) between them. At 5 hr critical steeping time, the total lysine and reactive lysine content decreased severely (36 and 32%, respectively) with statistical differences (P ≤ 0.05) compared with NC. On the other hand, the tryptophan content decreased significantly (P ≤ 0.05) at steeping times of 5–15 hr (38.70 ± 6.7%) compared with NC. The changes in the lysine and tryptophan content were not proportional to the steeping time. The protein recovery in the albumin and globulin fraction diminished (P ≤ 0.05) with respect to raw corn. The protein recovery for γ‐zeins, glutelin‐like proteins, glutelins, and residue increased. A significant (P ≤ 0.05) decrease was found in the essential amino acids in NQF with 3–7 hr of steeping time compared with NC. Equally important was the reduction in protein digestibility observed in NQF steeped at long steeping times (11–15 hr) with significant (P ≤ 0.05) differences compared with NC. The protein solubility distribution along the steeping step and the essential amino acids location, specifically lysine in corn kernel, could explain partially the protein quality changes observed in this research. Finally, these results contribute to reconciling discrepancies associated with the protein quality modifications in nixtamalized corn reported previously in literature. 相似文献