Use of osmotic solutes to control seed germination of rice and common bean in seed health blotter tests

The objective of this work was to investigate the feasibility of using a water restriction technique by using osmotic solutes as an alternative procedure to the use of 2,4 dicholorophenoxyacetic (2,4-D) or deep-freezing to control seed germination in blotter tests. The effects of water potential of substrates osmotically modified with sodium chloride, potassium 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 (MegaPascal) to −0.9 MPa were also investigated on mycelial growth of some common seed-borne fungi on PDA (Potato – Dextrose – Agar) medium. All osmotic potentials were able to inhibit or to retard seed germination of common bean and rice to the extent that seed examination under a stereomicroscope became easier. The more negative osmotic potential of the solutes used, the higher the inhibition of seed germination or radicle elongation. Mycelial growth of all investigated fungi was not affected by any osmotic potential level used.