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100%
Relative humidity takes not unworthy part in weather situations visibly conducive to growth of air pollution concentration. If it exceeds 70%, activation of SO₂ conversion can be observed, what in turn leads to hicher toxicity of this gas (fig. 1). It seems to be useful to make a through study of diurnal-yearly changes of relative humidity in the area of increased atmospheric pollution. Annual course of relative humidity has been calculated on the basis of an average for a ten year period (1961-1970) of mean daily values (fig. 2). The highest relative humidity occurs in the third decade of November (above 90%), and the lowest in mid June (about 60%). The threshold value of 70% remains common from the second decade of August until the beginning of April. Periods with increased humidity (f>70%) occur in cyclic (fig. 3). During the summer high humidity remains uninterruptedly not longer then two days, but in the winter it can remain most frequently for six to ten, or even for twenty six to thirty days. Values of relative humidity oscillate in range of 41 to 70% during the summer and 80 to 90% during the winter (fig. 4). Probability of relative humidity occurrence above 70% equals ca. 31% during the summer, but in the winter it can rise even to 84% (fig. 5).
The object of the study was the assessment of the usefulness of laboratory cage tests in the estimation of honey yield and the parameters characterising the springtime colony development and the colony strength. Each experiment comprised 10 colonies representing three groups of honeybees: pure-bred Buckfast (Bcf), Caucasian queen x Carniolan drone hybrids (Cau x Car) and Norwegian queen x Caucasian drone hybrids (Nor x Cau). In the course of the experiments, laboratory cage tests were carried out with the aim of checking the foraging efficiency and life span of bees. The results of those tests were compared with the honey yield and the parameters characterizing springtime colony development. In the Bcf group no significant correlations were found between the average quantity of the foraged food per one cage, per one day of the test, and the honey yield. Such correlations were present in the Cau x Car group, and those traits were negatively correlated in the Nor x Car group. Only in the Bcf group were significant correlations found between the average quantity of the foraged food per one bee per one day of the test and the honey yield. The correlation coefficient was especially high in May, which may have resulted from the fact that it was in May that the bees were acquired for use in the experiments. Only negative correlations between food foraging and the honey yield were found in the Nor x Cau group under laboratory conditions. Negative correlation between the life span and the honey yield was found in the Nor x Cau group. Similar result was achieved in the Bcf group. In the Cau x Car group those traits were positively correlated. In all groups under assessment, the correlation coefficient between the life span and the brood area was positive at the second measurement and negative at the third. Positive values of the correlation coefficients at the third measurement of the brood area as opposed to their negative values at the second measurement may have resulted from the fact that the date of the third measurement was close to the date of collecting the bees for the experiments. Positive correlation between the colony strength at the last autumn inspection and the life span was found in all the groups. Unexpected negative correlation between the life span and the colony strength occurred in the Nor x Cau group in March. In the remaining groups, correlation coefficients were positive and significant. The conformity between the results of the laboratory tests, the real honey yield and the parameters characterizing the springtime colony development and the colony strength may be considerably influenced by the genotype/breed of the bees as well as by the date of collecting the bees for the laboratory test. Detailed explanation of that issue, however, requires further studies.
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