Antonino Onnis

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.

The germination characteristics of a population of Zannichellia palustris subsp pedicellata

Abstract In this study the germination characteristics of Zannichellia palustris L. subsp. pedicellata (Wahlemb. et Rosen) Hegi seeds collected from a population along the margin of the Orbetello Lagoon (Tuscany, Italy) was examined. The effect of variations in duration of seed after-ripening and environmental parameters such as light, temperature and culture medium salinity on germination was assessed. In addition, germination ability of seeds subjected to stratification (+ 4°C for 30 days) and differing in morphology was evaluated. A constant temperature of 20°C was optimal for germination, while alternating temperatures of 10/20 and 20/30°C were highly unfavourable and frequently produced no germination. Darkness inhibited germination but this was overcome by a period of stratification. At 20°C seed germination showed a sinusoidal trend linked to seasonal changes. A dimorphism in Z. palustris achenes was observed. Such achenes were also found to differ in germination response. The pronounced control over germination exerted by this species could represent one of its main survival strategies, allowing reproduction in unstable environments characterized by variations in salinity such as were observed in the area under investigation.

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. ...

Althenia Filiformis Petit: Azione Della Temperatura e Dell'Acqua di Mare Sulla Germinazione

Abstract Effects of temperature and sea water on germination behaviour of Althenia filiformis Petit seeds. - Germination capacity and energy of Althenia filiformis Petit seeds have been investigated, 90 and 180 days after ripening, to carry out a preliminary study on ecology of this species. This species, halophite and hydrophyte, is spreaded along the coast shores of middle-west mediterranean sea and atlantic shores of Morocco, Spain, Portugal and France. Seeds were soaked in the dark, at 10°, 20°, 30°C, in solutions at different salt concentration: sea water; sea water diluted in deionized water at ratios (v/v) 1: 2, 1: 4, 1: 8; sea water plus 26 gr/l NaCl; deionized water, as control. The experimental results show that germination is reduced and delayed when seeds are soaked in progressively concentrated salt solutions; in sea water plus 26 gr/l NaCl seed germination is inhibited. Seeds pretreated by soaking at 3°C for 10 days in sea water diluted (1:1) by deionized water did not show, when soaked in s...

Dormienza e alotolleranza in due specie spontanee di Hordeum (H. murinum L. e H. marinum Huds.)

Abstract Dormancy and salt-tolerance in two spontaneous species of Hordeum. — Dormancy behaviour and germination capacity in salt-solutions of Hordeum murinum L. and Hordeum marinum Huds. seeds have been studied. Seeds (caryopses) have been sown in Petri dishes on filter paper soaked with deionized water (control) or with NaCl solutions at concentrations: 3.2 - 6.5 - 13.0 - 26.0%. Germination was tested during after-ripening, 20, 40, 60, 100, 160, 260 and 365 days from harvest (fully ripe seeds). The two species of Hordeum are spontaneous and characterized by peculiar ecological features. The present results have shown that, during the first year from harvest, Hordeum murinum and H. marinum have different length and strength of dormancy (longer and stronger in H. marinum than in H. murinum). Germination capacity and energy of the two species — during after-ripening stage — when seeds are sown in salt-solutions differ strongly and seem to be correlated with dormancy. Hordeum murinum seeds, which exhibit a ...

Comportamento Alla Germinazione Delle Cariossidi Delle Linee Primaverile e Invernale del Triticum Esaploide «Denti de Cani»

Abstract The germination of spring and winter wheat lines of exaploid Triticum « Denti de Cani ». — The dormancy in the seeds of two lines of Triticum « Denti de Cani » (which is spontaneous in Sardinia), one with solid stem (CP line), a spring line, the other with hollow stem (CV line), an winter line, has been studied. Germination was carried out in the dark, in Petri dishes at the constant temperatures of 5°, 10°, 20°, 23°, 26°, 30° and 35°C, using full ripe seeds, and seeds in different stages of after-ripening up to one year of age. The increase in % germination, for increasing temperatures above 5°C, is clearly conditioned by the progress of after-ripening in the seeds. In fact it was seen that, in general for the two lines, percentages over 50% of seeds germinated at 3 days were reached: at 10° and 20° after 15 days from the full ripening; at 23°C after 30 days; at 26°C after 50 days; at 30°C after about 100 days and at 35°C only after about 4–5 months from the harvest. During the experiment at 5°C...

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.

Althenia Filiformis Petit in Puglia: Nuovi Dati Sulla Distribuzione Ed Ecologia

Abstract New data on the ecology and distribution of « Althenia filiformis » Petit in Puglia (Italy). — Althenia filiformis Petit subsp. filiformis (Potamogetonaceae), has been discovered, during some researches along the Southern Italian shores, in some salt pools of the Apulian coast, south of Manfredonia. The pools in which Althenia has been discovered are the remaining parts of pools wider in the past and now partly reclaimed. At the same time it has been ascertained that Althenia is not detectable in the Salpi lake, station where it was first found (R ABENHORST 1849–50). This fact is probably due to the partial reclamation of the lake and to its transformation into salters (Saline Margherita di Savoia).

Puccinellia festucaeformis (Host) Parl.: Germinazione e crescita iniziale in funzione della salinità del substrato

Abstract Puccinellia festucaeformis (Host) Parl.: germination and early growth on different salt substrates. Germination behaviour of Puccinellia festucaeformis seeds and early growth of seedlings at different experimental conditions was analysed. The following growth substrates were utilized: NaCl, KCl, KNO3, MgCl2, MgSO4, Na2SO4, NaNO3, CaCl2 at the decreasing concentrations of 0.50, 0.25, 0.12, 0.06M. Caryopses were allowed to imbibe and grow at alternating temperatures (10°-20°C or 20°-30°C) in the dark for 3 days. Seedling were grown for 15 days, at controlled light and temperature conditions, in the same nutrient substrates as those used for the germination experiments. The germination experiments showed a high tolerance to salts up to 0.25M solution and for the whole range of MgSO4 concentrations. High growth temperatures increased the depressive effects of salt concentrations. Seedling growth was highly reduced when salt concentration was higher than 0.12M. High salt tolerance - maximum shoot and ...

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...