Sheath formation inOscillatoria agardhii Gomont

Sheath formation was observed in laboratory culturedO. agardhii. The sheath serves as a protective cover against bacteria. Some comments on sheath formation by this alga are given.

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Zusammenfassung Scheidenbildung beiOscillatoria agardhii Gomont Im Kulturmaterial vonOscillatoria agardhii Gomont wurde die Bildung von Scheiden beobachtet. Diese dienen als Schutz gegen Bakterien. Es werden weitere überlegungen über die Scheidenbildung bei dieser Alge angestellt.

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Résumé Formation de gaines chezOscillatoria agardhii Gomont La formation d’une gaine chezOscillatoria agardhii Gomont fut observée dans une culture. Ces gaines protègent les algues contre les bactéries. Des considérations ultérieures sont faites sur le phénomène des gaines chez cette algue.

     

Zinc availability in relation to selected soil properties in a crude oil polluted eutric tropofluvent

The study investigated zinc availability in relation to selected soil properties in a crude-oil-polluted Eutric Tropofluvent in Egbema, Southeastern Nigeria. For this purpose, three treatments have been applied: unpolluted soil, polluted without vegetation and polluted with vegetation with five replicates arranged in a randomized complete block design. Guided by transect sampling technique, soil sampling was carried out in June 2008. Soil samples were collected from the three different land units using soil auger at a depth of 0–20 cm. Standard laboratory procedures were adopted in analysing the soils. Soil generated data were subjected to analysis of variance and correlation analysis. Results showed highly significant variation (p = 0.01) in bulk density, porosity, silt: clay ratio, pH, effective cation exchange capacity, percent base saturation, total nitrogen, organic matter, available phosphorus, calcium: magnesium ratio and zinc. It was found that zinc was higher in crude oil polluted soils than in non-polluted soil and it was below critical limits. Zinc availability in relation to selected soil properties in the crude oil polluted soils indicated that clay and organic matter did not affect zinc availability, while pH and effective cation exchange capacity did. A study on zinc dynamics in crude-oil-polluted soils will certainly provide further information on the management of crude-oil-polluted soils since it is one of the key micronutrient for crop productivity.