The Effect of Hydration‐dehydration on Seed Germination

Abstract

Summary Seeds of tomato and oats were subject to hydration‐dehydration treatments at various times during germination. Desiccation has little harmful effect if carried out before cell division and enlargement has commenced. Some advancement of the onset of germination was apparent due probably to slight changes in the seed covering and also to the initiation of metabolic events which could withstand the dehydration, e.g. the increased protease activity was maintained in the dried seed. Dehydration can be done more than once. The effects are only truly accumulative if the prior imbibitions are of substantial duration. Physical changes associated with hydration are fairly easily reversed but some of the chemical changes beginning in oat within 8–12 hours of imbibition cannot be returned to the original dry seed condition by desiccation. Once embryo growth is apparent, embryo damage of some sort usually results.

Seed longevity of red rice ecotypes buried in soil

“…More rapid declines in longevity of seeds placed at shallow depths have been attributed to greater environmental fluctuations (Pickett, 1989;Taylorson, 1987) favoring higher percentage seed germination (Dawson & Bruns, 1975). Repeated seed desiccation by alternate hydration and dehydration probably enhanced dormancy release and stimulated germination of red rice seed placed on the soil surface or buried at a shallow depth (Berrie & Drennan, 1971;Martinez-Ghersa et al, 1997; Viable seed (%) Simpson, 1990;Vincent & Cavers, 1978). This may help to explain why seeds harvested later after anthesis, with lower seed moisture content and a lower dormancy, tended to have higher percent viable seed in the spring.…”

Effects of Different Pretreatments and Seed Coat on Dormancy and Germination of Seeds of Senna obtusifolia (L.) H.S. Irwin & Barneby (Fabaceae)

“…Kaufmann and Ross (1970) noted that germination is not possible in most species unless the water potential of the seed is greater than -1.5MPa. Berrie and Drennan (1971) reported 60-78% water uptake after 24hrs -144hrs exposure to water in tomato seeds at 24 o C. Mensah and Agbagwa (2004), observed 70% and 12% water uptake of the initial dry weight in scarified and un-scarified seeds respectively of Gmelina arborea. In Polygonum persicaria, water uptake of the intact achenes and those with tips cut off were 30% and 37% respectively, after 16hrs incubation (Mensah, 1984).The result of the water uptake in the seed coat of S. obtusifolia indicated that the seed coat/coverings of this species is hard and largely impermeable to water, possibly diffusion of gases and offering mechanical resistance/barrier to germination.…”

Effect of hydration and dehydration cycles on seed germination of Aster kantoensis (Compositae)

“…In many species, the duration of the imbibition period required for germination is not affected by interruptions in hydration (Berrie and Drennan 1971;Akalehiywot and Bewley 1980;Baskin and Baskin 1982;Dubrovsky 1996;Ren and Tao 2003). In some species, seed exposed to cycles of hydration and dehydration had a lower germination percentage because of reduced seed viability (Berrie and Drennan 1971;Ðliw½ska and Jendrzejczak 2002) or induced secondary dormancy (Downs and Cavers 2000).…”

“…Germination of seeds after such exposure have been shown to be delayed (Vincent and Cavers 1978;Baskin and Baskin 1982;Allen et al 1993;Downs and Cavers 2000;Ren and Tao 2003) or to decline (Berrie and Drennan 1971;Vincent and Cavers 1978;Downs and Cavers 2000;Ðliwi½ska and Jendrzejczak 2002). Delayed germination occurs when the hydration period of each cycle is shorter than the imbibition period required for seed germination (Akalehiywot and Bewley 1980;Bewley and Black 1982;Baskin and Baskin 1982;Obroucheva 1999;Ren and Tao 2003).…”

“…Delayed germination occurs when the hydration period of each cycle is shorter than the imbibition period required for seed germination (Akalehiywot and Bewley 1980;Bewley and Black 1982;Baskin and Baskin 1982;Obroucheva 1999;Ren and Tao 2003). In many species, the duration of the imbibition period required for germination is not affected by interruptions in hydration (Berrie and Drennan 1971;Akalehiywot and Bewley 1980;Baskin and Baskin 1982;Dubrovsky 1996;Ren and Tao 2003). In some species, seed exposed to cycles of hydration and dehydration had a lower germination percentage because of reduced seed viability (Berrie and Drennan 1971;Ðliw½ska and Jendrzejczak 2002) or induced secondary dormancy (Downs and Cavers 2000).…”