Hormonal Control of Germination under Saline Conditions of Three Halophytic Taxa in the Genus Suaeda

Abstract

The interaction between hormones and salinity on seed germination of three halophytic taxa in the genus Suaeda: S, maritima (L.) Dum. var. flexilis Focke and var. macrocarpa Moq., and S. depressa (Pursh) Wats, was studied. Exogenous applications of kinetin and gibberellic acid (GA3) were applied in order to determine if either of these growth-promoting hormones would promote germination in the two dormant taxa, Suaeda depressa and S. maritima var. flexilis and to see if osmotically induced dormancy by NaCl could be alleviated. Our results indicate that gibberellic acid is capable of breaking dormancy in these species with dormant seeds, but kinetin proved to be ineffective. A seed dormancy that was induced by osmotic stress could also be alleviated by treatments with gibberellic acid. Endogenous concentrations of both cytokinins and gibberellins were measured in seeds exposed to osmotic stress (0.85 M NaCl), and we found a reduction in cytokinin activity in these three taxa. Gibberellinlike activity was reduced in S, depressa when seeds were soaked in 0.85 Af NaCl.

Germination, α-, β-Amylase and Total Dehydrogenase Activities of Amaranthus Caudatus Seeds Under Water Stress in the Presence of Ethephon or Gibberellin A3

“…The involvement of endogenous gibberellins in A. caudatus seed germination was shown in experiments using an inhibitor of gibberellin biosynthesis (Kępczyński, 1986a). In halophyte species, saline stress inhibited seed germination and reduced gibberellin production (Boucaud and Ungar, 1976). As in other work on inhibition of seed germination (by NaCl) (Białecka and Kępczyński, 2009), in the present study ethephon was more effective than GA 3 in reversing inhibition (by PEG) of A. caudatus seed germination.…”

EFFECT OF GROWTH REGULATORS ON THE IN VITRO GERMINATION AND TUBE GROWTH OF MAIZE (ZEA MA YS L.) POLLEN FROM PLANTS RAISED UNDER SODIUM CHLORIDE SALINITY

“…GA, mediated stimulation of tube growth may be attributed to its effect on the synthesis of nucleic acids, a amylase and invertase (Mann, 1975). Several reports on the decrease in endogenous cytokinin in plants under saline conditions are available (Itai et at., 1968;Mizrahi et al, 1970Mizrahi et al, , 1972Boucaud & Ungar, 1976). The present study indirectly suggests that pollen responds to substrate salinity in a similar way.…”

Alterations of Endogenous Hormonal Levels in Plants under Drought and Salinity

“…Similarly, under salinity some reports have demonstrated that the endogenous levels and transport of CKs were also reduced in several plant species [77]. Studies with the halophytes Suaea depressa and S. maritima suggested that CKs applications may emphasize the symptoms associated with salt stress [78]. It should be pointed out that this response could be the result of the action of CKs on stimulating stomatal opening, thus facilitating transpiration and therefore magnifying the effect of salinity.…”