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1.
Maria Antonia Machado Barbosa Kacilda Naomi Kuki Pedro Santos Peno Bengala Emilly dos Santos Pereira Angélica Fátima de Barros Sebastián Giraldo Montoya Leonardo Duarte Pimentel 《Journal of Agronomy and Crop Science》2020,206(2):263-276
Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season. 相似文献
2.
E C?té 《Veterinary Clinics of North America: Small Animal Practice》2001,31(6):1129-45, v
Severe heart disease may cause hypotension and hypoperfusion, and ultimately circulation may cease altogether. These two clinical syndromes are cardiogenic shock and cardiac arrest, respectively. This review summarizes the causes and clinical features of each, and describes the treatment options available to clinicians managing patients in cardiogenic shock. 相似文献
3.
The Chilean Intermediate Depression to the north of Santiago has experienced a physiognomical transformation from a Prosopis chilensis woodland to an Acacia caven savanna. Today P. chilensis trees are scarce and belong mostly to the larger size classes. By contrast A. caven seems to reproduce frequently and its populations consist of individuals of all size classes. In this paper we document these changes and report the results of tests aimed at determining the causes of these physiognomical changes. We found that livestock, leporids, introduced Mediterranean forbs and agriculture account for differences in seed dispersal and survival of A. caven and P. chilensis, which can explain the documented changes in the Chilean landscape. 相似文献
4.
Muscle biopsies were taken from the middle gluteal muscle of 28 Standardbred trotters, 3-4 years of age. The 13 horses in Group T were trained consistently from 18 months of age, whereas the 15 horses in Group UT were not exposed to any systematic training before 3 years of age. Group T horses had a lower percentage of Type IIB fibres (31%) than did Group UT horses (39%). Citrate synthase (CS) activity, representing oxidative capacity, was higher in Group T (72 mmol kg-1 min-1) than in Group UT (47 mmol kg-1 min-1). Biopsies were taken from 4 horses in each group when they were foals and then annually until 3-4 years of age. Results from this study indicate that regular training of Standardbreds from 18 months of age resulted in increased CS activity and a decrease in the percentage of Type IIB fibres. This study shows that training, not growth, is the main factor that induces a high oxidative capacity and a high Type IIA/IIB fibre ratio in muscle of Standardbred trotters. 相似文献
5.
6.
R J Slappendel I van der Gaag J J van Nes T S van den Ingh R P Happé 《The Veterinary quarterly》1991,13(1):30-40
A newly recognised disease, which we have given the provisional name of familial stomatocytosis-hypertrophic gastritis (FSHG), is described in two families of dogs of the Drentse partrijshond breed. The affected dogs consisted of 3 females and 5 males, 3 to 19 (mean 9.5) months of age at admission. The main clinical problems were diarrhoea, icterus, and ataxia and paresis of the pelvic limbs. Laboratory evaluation revealed abnormal red cell shape (stomatocytosis), increased osmotic fragility, haemolytic anaemia, and increased liver enzymes and serum bilirubin. Gastroscopic and histopathologic examination of the gastric mucosa revealed hypertrophic gastritis resembling Ménétrier's disease in man. Histologic findings in the liver were suggestive of progressive liver disease. Cysts were found in the kidneys of the five oldest patients. Electroneurography in 2 dogs revealed polyneuropathy. In the parents of 2 patients (sister and brother), there were no clinical or laboratory abnormalities. An autosomal recessive hereditary defect of lipid metabolism is suspected. 相似文献
7.
Total creatine kinase (CK) and CK-MM isoforms were determined in plasma and longissimus dorsi muscle extracts from normal pigs. Based on their total CK activity, the pigs were divided into two groups. Pigs of group 1 (n=16) had a mean plasma total CK of 298±16 U/L and the distribution of the CK-MM isoforms was 65.7±2.5% CK-MM3, 18.9±1.6% CK-MM2 and 15.3±1.5% CK-MM. In group 2 (n=18; 826±75 U/L total CK) four isoforms were observed: 3.1±0.9% CK-MM, 67.9±3.0% CK-MM3, 21.5±2.3% CK-MM2 and 7.5±1.3% CK-MM1. The differences between the two groups of pigs were significant (p<0.001) for CK-MM1 and the presence of CK-MM. Four CK-MM isoforms were also detected in longissimus dorsi muscle homogenates: 45.6±8.1% CK-MM, 32.6±11.7% CK-MM3, 16.6±2.3% CK-MM2 and 5.1±2.8% CK-MM1. The release of CK-MM isoforms from muscle into plasma seems to be unrelated to the concentration of these isoforms in striated muscle. 相似文献
8.
Comparative infectivity for axenic and specific-pathogen-free chickens of O2 Escherichia coli strains with or without virulence factors 总被引:1,自引:0,他引:1
Adhesion to epithelial respiratory cells, iron acquisition, and production of K1 polysaccharide capsules have been proposed as potential virulence factors of avian Escherichia coli. These factors were studied by inoculating groups of axenic or specific-pathogen-free (SPF) chickens intratracheally with O2 E. coli strains after previous challenge with a wild strain of infectious bronchitis virus (IBV). In all experiments, the association between IBV and an E. coli strain endowed with the three virulence factors previously mentioned resulted in the most severe pathological effects, as measured by mortality, weight gains, lesions, and reisolation of E. coli from internal organs. An E. coli strain devoid of virulence factors was able only to induce mild pathological effects restricted to the respiratory tract when combined with IBV. Both E. coli strains were more invasive in axenic chickens than in SPF chickens. These results confirm the probable involvement of the three factors studied in the pathogenic properties of avian E. coli. This model can be used to assess the role of virulence factors, by comparing pairs of positive and negative isogenic strains. 相似文献
9.
Protective activities of heat-inactivated (60 degrees C for 30 min) merthiolate preserved Bordetella bronchiseptica and B. pertussis bacterins were compared in intraperitoneally immunized mice challenged intracerebrally (i.p./i.c.) or intraperitoneally (i.p./i.p.). In the i.p./i.c. assay (Kendrick test), a B. pertussis bacterin protected mice against challenge with B. pertussis 18-323, as well as against phase I cytotoxic and non-cytotoxic strains of B. bronchiseptica. A B. bronchiseptica bacterin, prepared from a phase I cytotoxic strain, gave protection against two phase I B. bronchiseptica strains, irrespective of their cytotoxin-production. A non-cytotoxic phase I strain of B. bronchiseptica elicited protection against the homologous strain only. Neither cytotoxic nor non-cytotoxic B. bronchiseptica strains protected mice challenged with B. pertussis 18-323. Vaccines prepared from phase III strains of B. bronchiseptica were not protective at all against any of the challenge strains. No such differences in the protective activities of the bacterins could be detected by the i.p./i.p. method. They seem to cross-protect equally well. The results indicate that the Kendrick test may be useful in testing potency of different B. bronchiseptica bacterins. 相似文献
10.
Effect of birthweight, total protein, serum IgG and packed cell volume on risk of neonatal diarrhea in calves on two California dairies. 总被引:3,自引:0,他引:3 下载免费PDF全文
J Paré M C Thurmond I A Gardner J P Picanso 《Canadian journal of veterinary research》1993,57(4):241-246
The objective of the study was to determine if there was a relationship between hematological, immunological and physiological variables of newborn calves and risk of diarrhea during the neonatal period. Four hundred and seventeen heifer calves from two dairies (A and B) in the San Joaquin Valley of California were enrolled at birth and scored daily, to 28 days of age, for evidence and severity of diarrhea (0 to 3). Calves were weighted at birth and blood sampled at two to five days of age to determine packed cell volume (PCV), total protein (TP) and IgG serum concentration. The Cox proportional hazards model was used to determine if age at onset of the first diarrhea episode and length of the first episode were associated with the hypothesized variables (PCV, TP, IgG and birthweight). The IgG concentration was not associated with the age at onset of diarrhea (p = 0.6052, Dairy A; p = 0.4393, Dairy B) but a high IgG concentration was associated with a decreased length of episode (p = 0.0325, Dairy A; p = 0.0912, Dairy B), particularly for calves born in the winter on dairy A (p = 0.0211). For calves born in the winter, those with either a high or a low birthweight had diarrhea at a younger age (p = 0.0102, Dairy A; p = 0.0020, Dairy B). Associations were also found for PCV and TP with both the age at onset and length of the first episode of diarrhea. Results suggest that parameters measurable at, or shortly after birth may have important prognostic value in evaluating risk of calf diarrhea. 相似文献