seed development under the effect of exogenous application of GA.

Numerous studies have demonstrated the impact of exogenous gibberellin on fleshy fruit formation, but the effect on dry fruits is not yet well known. To test the role of gibberellin (GA) in dry fruit formation, we analysed the impact of exogenous GA on the invasive plant Sosnowsky's hogweed ( Manden.) seed development and germination.

Changes in plasmalemma K+Mg2+ -ATPase dephosphorylating activity and H+ transport in relation to seasonal growth and freezing tolerance of Festuca pratensis Huds.

Changes in plasmalemma K(+)Mg(2+)-ATPase dephosphorylating activity and H(+) transport were examined in freezing-tolerant and non-tolerant genotypes of the perennial grass species Festuca pratensis Huds. Enzyme activity and DeltamuH(+) were measured in plasmalemma fractions isolated from basal nodes and roots. Three types of experiments were undertaken: (i) a field experiment, utilizing the seasonal growth and cessation cycle of a perennial plant; (ii) a cold acclimation experiment in hydroponics; and (iii) an instant freezing test.