Salinity Tolerance of Rice (Oryza sativa L.) with Reference to Endogenous and Exogenous Abscisic Acid     

J. S. BOHRA  H. DÖRFFLING  K. DÖRFFLING 《Journal of Agronomy and Crop Science》1995,174(2):79-86

Experiments conducted m a phytotron on three rice varieties of different salinity tolerance revealed an increase in the content of endogenous abscisic acid (ABA) with increasing NaCl salinity in IR20 (semi salt-tolerant), but in Pokkali (salt-tolerant) and IR28 (salt-sensitive) the increase in ABA content was marginal. Under sahnity stress, in general, 5 weekly sprayings of ABA (10^-4 mol L^-1) decreased Na and K concentrations in the shoot to the extent of 29.5 % and 3.3 %, respectively. However, ABA application significantly improved the K/Na ratio as well as the chlorophyll fluorescence decrease ratio (Rfd, indicator for potential photosynthetic activity), the number of green leaves per plant and the shoot dry weight. The response of IR20 and IR28 to ABA application was significantly better than that of Pokkali. Increasing salinity caused marked nutrient imbalances, decreased Rfd values and shoot dry weight. The results are discussed in relation to possible mechanism of salinity tolerance.  相似文献   

The long term benefits of manuring grassland with animal wastes     

R.S. Shiel 《Soil Use and Management》1995,11(3):148-149

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Seasonal mixing and catastrophic degassing in tropical lakes, cameroon, west Africa     

Kling GW 《Science (New York, N.Y.)》1987,237(4818):1022-1024

Lethal gas releases from Lakes Nyos and Monoun in Cameroon seem to be more lacustrine than volcanic in origin. Both of these events occurred in August and were only 2 years apart. Data show that the period of deepest mixing and lake turnover also occurs during late summer in this region of tropical Africa. In addition, recent trends of decreases in both air temperatures and effective insolation relative to long-term means suggest that weakening of stratification, coupled with a predictable seasonal interval of reduced stability in August, may be responsible for the timing of these events.  相似文献   

Hopes and Fears at NSF     

W J 《Science (New York, N.Y.)》1987,237(4818):970

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Electromagnetic stabilization of weakly conducting fluids     

Ivory CF  Gobie WA  Beckwith JB  Hergenrother R  Malec M 《Science (New York, N.Y.)》1987,238(4823):58-61

Classical hydromagnetic theory predicts that the flow of dilute aqueous electrolyte in a slit can be stabilized by application of a strong, transverse magnetic field. However, recent experiments indicate that stabilization can be achieved with the use of a much weaker field in the presence of a small lateral current. A revised theory describes how the magnetic and electric fields interact to eliminate natural convection.  相似文献   

Induced resistance and interspecific competition between spider mites and a vascular wilt fungus     

Karban R  Adamchak R  Schnathorst WC 《Science (New York, N.Y.)》1987,235(4789):678-680

The fungal pathogen Verticillium dabliae was less likely to cause symptoms of verticillium wilt on cotton seedlings that had been previously exposed to spider mites than on unexposed cotton seedlings. Conversely, populations of the spider mite Tetranychus urticae grew less rapidly on seedlings that had been inoculated with V. dabliae than on uninoculated controls. Changes caused by pathogen or herbivore attack reduced the suitability of the host plant to a diversity of organisms. This result suggests that highly unrelated organisms that share a host plant may interact strongly.  相似文献   

Response of egg weight to the inclusion of various fats in layer diets     

R. H. Scragg  N. B. Logan  N. Geddes 《British poultry science》1987,28(1):15-21

1. Brown egg layers were fed diets differing in oil content, oil source and linoleic acid concentration and the effect on performance from 22 to 69 weeks of age was studied.

2. The birds responded with an increasing mean egg weight up to a linoleic acid intake of 2.75 g/bird d.

3. Increasing the intake of readily absorbable oil without increasing linoleic acid concentration did not increase mean egg weight.  相似文献   

Carbohydrates in cat diets: digestion and utilization     

Hilton JW 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(3):129

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Causal Inferences: An Epidemiologist's Viewpoint     

Martin SW 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(3):105-106

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Infestation in the dog by the paralysis tick Ixodes holocyclus 3. Respiratory effects     

J. E. ILKIW  D. M. TURNER 《Australian veterinary journal》1987,64(5):142-144

To assess respiratory function in dogs with tick paralysis, respiratory measurements were recorded on 14 dogs experimentally infested with Ixodes holocyclus. There was a progressive fall in respiratory rate with no change in tidal volume, which resulted in a significant fall in minute respiratory volume in the latter stages of the disease. The fall in respiratory rate was possibly central in origin and was accompanied by an increased alveolar-arterial oxygen tension difference, probably caused by pulmonary congestion and oedema. The "grunting" respiration seen in tick paralysis was due to closure of the vocal cords during expiration and could represent an attempt to re-expand collapsed parts of the lung.  相似文献