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

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 Grade (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 wird 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 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

Germination requirements in a population of Typha latifolia

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°) temperatures, photoperiod (12/12,8/16,6/18 ,4/20 , 2/22 and 0/24 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°with 12/12photo-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

Germination of Briza maxima L. seeds: effects of temperature, light, salinity and seed harvesting time

Germination behaviour of Briza maxima L. seeds was studied in relation to different environmental parameters. The influence of harvesting time and after-ripening time of the seeds were also considered. Caryopses were collected at maturity at the beginning and end of June (harvest1 and harvest2) from wild populations located at the Orbetello Lagoon (Italy) and were germinated in deionized water or NaC 1 solutions at 10, 20 and 30 degrees C in the dark or under 12/12 h photoperiod. The results obtained showed that: (i) immediately after collection, germination rate was higher for harvest 2 seeds, (ii) seed germination was not significatively affected by the light; (iii) optimum temperature was at 20 degrees C, at which germination started earlier, (iv) germination percentages at 10 days of culture progressively increased during 6 months of after-ripening; (v) the presence of NaCl in the culture medium reduced the germination rates (above all of harvest1 seeds) and seedling growth, but did not induce damage (e.g. necrosis of the root tip)