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Valdemaras Žiliukas Vida Žiliukienė Rimantas Repečka 《Central European Journal of Biology》2012,7(5):858-866
The aim of this study was to assess juvenile fish communities in terms of species composition, fish diversity and density in the littoral zone of the Kaunas reservoir before (in 1989–1990, period I) and after (in 1999–2000, period II, and in 2006–2007, period III) launching the Kruonis hydroelectric pumped plant (Kruonis HPP). During the whole research period, 20 fish species were caught. According to the frequency of occurrence, the three-spined stickleback Gasterosteus aculeatus, European perch Perca fluviatilis and roach Rutilus rutilus were regarded as constant species in all investigated periods. Significant differences were established in juvenile fish community density between period I and periods II and III, whereas species richness (S) and species diversity indices (H′, J′) did not change significantly. The density of the shoreline community in period III was more than two times lower than in period I, probably due to higher fluctuations in water level of the reservoir, resulting from the Kruonis HPP operation. 相似文献
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Several synthetic plant growth regulators (PGRs), including prohexadione-calcium (ProCa), paclobutrazol (PBZ), and chlormequat
chloride (CCC), known for their ability to inhibit gibberellin (GA) biosynthesis, were investigated for their influence on
Populus tremula L. (aspen) shoots grown in vitro. Changes in plant growth induced by these inhibitors were compared to the effects of exogenous
gibberellins (GA3 and GA4/7). All PGRs were added to the nutrient medium at concentrations of either 1 or 5 μM. Stem segments with and without apical
buds were excised from in vitro-grown shoot culture, and these explants were incubated either in test tubes or Petri dishes.
In the presence of 5 μM ProCa, shoot growth and rooting were inhibited when grown in test tubes, while shoots grown in Petri
dishes exhibited strongly enhanced shoot and root growth. PBZ suppressed shoot development both in test tubes and Petri dishes,
although 1 μM PBZ promoted adventitious root formation when shoots were grown in test tubes. Five micromolars CCC suppressed
shoot and root development in test tubes, but promoted shoot growth in Petri dishes. 相似文献