Tiziana Lombardi

Germination requirements in a population of Typha latifolia

Abstract The physio-ecological requirements of germination and early achene growth of a population of Typha latifolia L. were studied. The effects of constant (10, 20 and 30°C) or alternating ( 10 20° , 20 30° and 10 30° C ) temperatures, photoperiod ( 12 12 , 8 16 , 6 18 , 4 20 , 2 22 and 0 24 h day/night), after-ripening time and culture medium salinity (NaCl) on germination were assessed. Results showed that germination required light and alternating temperatures (optimal results at 20 30° C with 12 12 h photo-thermoperiod). In these conditions the germination trend showed no appreciable variation during the first year of achene after-ripening. The presence of more than 0.1 M NaCl in the culture medium caused a significant reduction in the percentage of seeds germinating, and inhibited further seedling growth. Typha latifolia can, therefore, be considered a helio-thermophilic and glycophilic species, at least during early growth stages.

Diachronic analysis (1954–2010) of transformations of the dune habitat in a stretch of the Northern Tyrrhenian Coast (Italy)

The aim of this work is the diachronic analysis, over the past 60 years, of the vegetation changes in dune environments of a stretch of Tuscan coast. Aerial photos of the years 1954 and 2010 were compared using photointerpretation and GIS software, and phytosociological surveys in the field were carried out. In addition to the spatial dynamics of the identified phytocoenoses, we have analyzed the different degrees of anthropogenic alteration of the examined area by the development of a synthetic index already used in neighboring contexts. The results showed with respect to the past, a deep morphological transformation of the dune system, and a consequent high spatial contraction and fragmentation of psammophilous plant communities. Today, indexed values of anthropogenic alteration, although particularly high especially when compared historically, are mitigated by the marginal and punctiform permanence, in few of those dune areas spared from urban infrastructure, of the main psammophilous plant associations typical of Tyrrhenian coasts.

Morphology and germination of yellow and brown caryopses of Aegilops geniculata Roth (Gramineae) population from Italy

Abstract The germination percentage of Aegilops geniculata Roth caryopses was studied on four Italian populations (Pisa, Manfredonia, Catania and Simbirizzi). Observation of the germination trend was carried out at constant temperatures of 10°, 20° and 30°C, from maturation up to 60 days after harvesting. Spike, spikelet and caryopsis phenotypic characteristics were also studied. The populations of Pisa, Manfredonia and Simbirizzi presented two different types of caryopses: yellow caryopses - larger, heavier and composing roughly 60% of total—and brown caryopses—smaller and lighter in weight. The Catania population formed an exception in that brown caryopses were virtually absent (5%). This Sicilian accession also showed the largest spikelet size. Yellow caryopses germinated more rapidly than the dark ones, which were shown to be endowed with longer relative dormancy, above all at 10° and 30° C. Such a phenomenon allows the two types of caryopses to have a different germination ecology, thus providing A. ...

Comparative salt tolerance of two wild Hordeum species (H. maritimum with. and H. murinum L.) from the coast of Tuscany (Italy)

ABSTRACT The differences in salt tolerance between Hordeum maritimum and H. murinum were studied. Seeds were collected at horn maturity from wild populations growing respectively near the Orbetello Lagoon and S. Piero a Grado (Tuscany, Italy) and were used in germination and growth tests at increasing salinity (NaCl) levels. H. maritimum was confirmed to be a true halophyte as compared to H. murinum, which exhibited germination behavior typical of many wild glycophytes. The higher salt sensitivity of H. murinum compared to H. maritimum was also shown by its shoot length values, which decreased only in H. murinum, albeit in 100 mM NaCl treatment. The higher degree of salt tolerance of H. maritimum is further demonstrated by the Na : K ratio. H. maritimum can accumulate a greater amount of sodium than potassium in both roots and shoots, even in the absence of salt treatment. However, in NaCl solutions H. maritimum showed a higher Na : K ratio for shoots — an index of better uptake and translocation of sodium to leaves — as has been demonstrated for many halophyte includers. These results thus help to enhance knowledge on wild relatives of barley, whose potential contribution to genetic improvement in salinity tolerance has previously not been thoroughly explored.

Foredune psammophilous communities and coastal erosion in a stretch of the Ligurian sea (Tuscany, Italy)

Italy sandy coasts are characterised by a great diversity of habitats and, at the same time, many of these coastal stretches are in erosive condition. Therefore, it is important to understand, in areas where marine erosion is particularly strong, which are the most vulnerable and most threatened habitats. The paper sets out data from the survey of foredune habitats (annual vegetation of drift lines, embryonic dunes, mediterranean white dunes, sensu Directive 92/43/EEC) in the San Rossore Estate sandy coast (Northern Tuscany, Italy) strongly subjected to erosion. The surveys, in addition to updating the information collected, aim to point out the arrangement of these habitats in relation to coastal retrogradation and foredune erosion, in order to identify appropriate management tools for mitigating disturbance factors. The surveys, conducted in the field and by photo-interpretation, revealed the presence of foredune plant communities hardly referable, from the phytosociological point of view, to known associations of neighboring coasts. The Cakile maritima plant communities of annual vegetation of drift lines, the Elymus farctus/Othantus maritimus phytocoenosis of embryonic dune and the Ammophila arenaria/Euphorbia paralias communities of white dunes, are markedly altered in their floristic composition; the coverage and distribution of the different plant communities are in a highly differentiated manner according to erosion gradients. The understanding of dynamics of alteration of psammophilous plant communities in relation to coastal erosion may suggest potential aid in the management actions aimed at containing the transformations or and/or useful for the restoration of the same habitats.

Seasonal changes in the germination responses of Hordeum maritimum and H. murinum seeds in relation to salinity, temperature and after‐ripening time

Abstract The effects of temperature and salinity (NaCl) on germination of Hordeum maritimum With, (halophyte) and H. murinum L. (glycophyte) seeds were investigated. Dehulled caryopses were used for monthly germination trials, starting from November (120 days of after‐ripening in darkness at 20±1°C). Trials were continued for one year. Differences in germination response between the two species were observed, confirming that H. Maritimum is better adapted to high salinity levels and to variations in external temperature than H. murinum. H. maritimum showed a germination control mechanism related to after‐ripening time and based on seed dormancy break/resumption. At higher temperature (30°C), thermodormancy was also recorded. No germination strategies were observed in H. murinum that is relatively insensitive to the combined effects of temperature and salinity. Thus, in virtually all treatments, H. murinum exhibited a higher germination rate compared with H. maritimum, as early as 72 h after imbibition, su...