Silvia Anselmi

Effects of the culture medium pH and ion uptake in in vitro vegetative organogenesis in thin cell layers of tobacco

Abstract Thin cell layers (TCL) of Nicotiana tabacum L. cv. Samsun were cultured in vitro to evaluate the effect of the pH of the culture medium and ionic uptake on vegetative organogenesis. The chromatographic analysis showed important variations during culture in the concentrations of the ions in the tissues of the explants grown at different pH levels. After 25 days of culture, shoots with regular development were obtained especially from the explants grown on the media with an initial pH (pHi) of 4.0 and 5.0. At pHi 7.0, the shoots were often grouped into tufts, lacking apical dominance and vitreous in appearance, probably due to a high uptake of ammonium in the first 48 h of culture and a low level of calcium in the first 24 h of culture. Regardless of the origin, (i.e. subepidermal chlorenchyma cells or wound callus generated by the outermost parenchyma layers) vegetative buds differed according to the pHi level. Direct superficial origin was observed only at pHi 4.0 and 5.0, whereas indirect cicatritial origin was observed at all pH levels.

Remote sensing and field analysis of urban green in Rome

Remote sensing is an important tool for the spatial description of urban green, it is often used in landscape ecology to detect habitat fragmentation and the alterations caused by man on the territory; furthermore the use of remote sensing is important for the detection of vegetation functional conditions. In this study some vegetation indices have been analysed and a land use map has been created using Landsat TM images of the city of Rome and of some of its outskirts. Remote sensing data have been integrated with field data (leaf area index and leaf fluorescence measurements) carried out on holm oak and coniferous woods. The values of the functional vegetation indices indicate a physiological alteration for the communities inside the city; the fluorescence data have confirmed this result. From a structural point of view, the NDVI map highlights the presence of some green corridors. The good correlation between the values of NDVI and LAI has allowed us to estimate LAI for the entire area analysed. This research has furnished quantitative data on structural and functional characteristics of the study area. The upscaling approach has shown a good performance of analysing and monitoring vegetation subjected to a different anthropogenic impact.

Relationships between leaf area index (LAI) and vegetation indices to analyze and monitor Mediterranean ecosystems

The analysis of LAI is of great importance to evaluate the structural characteristics of a plant community. Vegetation types remote sensed analysis is a useful tool for the investigation of structural and functional characteristics of ecosystems. The integration of data acquired at these two different spatial scales contributes to the management of the land use and in particular of protected areas for the conservation of biodiversity. Field measuraments (LAI) and remote sensed data (Landsat 5 TM) were performed in the Circeo National Park and in the Presidential Estate of Castelporziano (located along the coast of Lazio, Italy, and characterised by Mediterranean climate). In this study the relationships between LAI and vegetation indices (NDVI, PVI, SAVI, GVI) were analysed; the NDVI showed the best correlation with the LAI. Using NDVT/LAI low power we estimated the LAI for the entire study areas on a multitemporal basis and plotted different LAI maps. The results obtained permitted to define a useful approach to analyse the canopy conditions of Mediterranean ecosystems on a multitemporal scale and also to highlight the effects of biotic and abiotic causes on vegetative growth as phytophagous attac and climatic stress due to local annual variability and to potential climatic change.