A STUDY ON THE DORMANCY OF XHAYNALDOTICUM-SARDOUM SEEDS (POACEAE)

The possible role of pentose phosphate pathway (PPP) in dormancy relea se of xHaynaldoticum sardoum Meletti et Onnis seeds was investigated. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities and the C6/C1 ratio in dormant and non dormant embryos fro m the two natural lines (Culmo Vuoto and Culmo Pieno) were consequentl y studied. Dry embryos of dormant seeds showed appreciable amounts of both dehydrogenase activities. Furthermore, gibberellic acid incubatio n of the seeds or their storage in dry conditions (after-ripening), bo th of which treatments are effective in dormancy breaking, did not pro duce any serious changes in enzyme activity pattern. Some increase in dehydrogenase activities during late imbibition did not seem correlate d with dormancy breaking, which happened earlier. Finally, the C6/C1 r atio of dormant embryos did not change after gibberellic acid treatmen t, while non dormant embryos showed an increased C6/C1 ratio. Conseque ntly the PPP did not appear to be involved in dormancy breaking of xHa ynaldoticum sardoum seeds.