The aim of this work was to investigate the feasibility of using a water restriction technique with osmotic solutes to control sunflower (Helianthus annuus L.) seed germination in blotter tests. The effects of water potential (-0.8 MPa - Megapascal, -1.0 MPa, -1.2 MPa and -1.4 MPa) of substrates osmotically modified with sodium chloride or mannitol were evaluated for seed germination, radicle length and mycoflora present in the samples. The effects of levels of osmotic potentials ranging from -0.35 MPa to -1.4 MPa were also investigated on mycelial growth of the fungi Alternaria alternata and Alternaria zinniae on PDA medium. All osmotic potentials were able to inhibit or to retard seed germination to the extent that seed examination in stereomicroscope became easier without affecting seed mycoflora associated with the seeds. Mycelial growth of A. alternata was stimulated by all osmotic solutes tested, while mycelial growth of A. zinniae was stimulated by mannitol and reduced by all NaCl osmotic potential levels used.
Helianthus annuus; sodium chloride; mannitol
