Low-pressure Storage of Hibiscus Cuttings. Effect on Stomatal Opening and Rooting

Cuttings of Hibiscus rosa-sinensis L. cv. Moesiana were storedat 15 or 760 mmHg (2 or 101.3 kPa) for 3, 5, 8 or 11 weeks.No ethylene production could be detected regardless of treatment.No chlorophyll degradation, proline accumulation or respiratoryincrease were seen during storage. Stomata were open under lowpressure and closed under normal pressure. The open stomatacaused water loss from cuttings after removal from storage becausethey were unable to respond normally to low humidity. Rootingability decreased as storage time increased, but satisfactoryresults were obtained up to a storage period of five weeks. Adventitious rooting, cuttings, ethylene production, Hibiscus rosa-sinensis L., hypobaric storage, low-pressure storage, senescence, stomatal resistance     

Bathymetric barriers promoting genetic structure in the deepwater demersal fish tusk (Brosme brosme)

Population structuring in the North Atlantic deepwater demersal fish tusk ( Brosme brosme ) was studied with microsatellite DNA analyses. Screening eight samples from across the range of the species for seven loci revealed low but significant genetic heterogeneity ( F _ST = 0.0014). Spatial genetic variability was only weakly related to geographical (Euclidean) distance between study sites or separation of study sites along the path of major ocean currents. Instead, we found a significant effect of habitat, indicated by significant differentiation between relatively closely spaced sites: Rockall, which is surrounded by very deep water (>1000 m), and the Mid-Atlantic Ridge, which is separated from the European slope by a deep ocean basin, were differentiated from relatively homogeneous sites across the Nordic Seas. Limited adult migration across bathymetric barriers in combination with limited intersite exchange of pelagic eggs and larvae due to site-specific circulatory retention or poor survival during drift phases across deep basins may be reducing gene flow. We regard these limitations to gene flow as the most likely mechanisms for the observed population structure in this demersal species. The results underscore the importance of habitat boundaries in marine species.