The effect of sodium hypochlorite and gibberellic acid on seed dormancy and germination of wild oats (Avena fatua)

Abstract

The seed coverings, including the pericarp and testa of the caryopsis and the hull, arc the main barriers to the exchange of gases and the penetration of exogenous gibberellic acid (GA3) for germination of wild oats (Avena fatua L.). Dormancy was induced in seeds by immersing them in water for 15 minor longer. Dormancy induction was greater in those seeds immersed for up to 1 h in 6% sodium hypochlorite (NaOCl) and then 1 h in water than in those seeds immersed only in water for 1 h. The addition of GA3, to seeds subjected to NaOCl treatment for 15 min or less did not break dormancy, indicating a slow rate of entry, or the exclusion, of GA3, by the seeds. In the presence of GA3, germination increased with increasing exposure to NaOCl. Maximum germination was obtained by immersing dry seeds in NaOCl for 2 h, in water for 1 h, and then incubating the seeds in GA3. Gibberellic acid was not required for complete germination of imbibed, dehulled seeds immersed in NaOCl for 1 h then in water for 1 h, but it was necessary to use 10−4 M GA3 for complete germination of intact seeds that were treated with NaOCl or 2 h then with water for 1 h. Imbibed, dormant seeds that were dehulled and pierced required 10−7 M GA3, to give complete germination in this study. Piercing of the seed coverings enhances GA3, penetration and thus increases the availability of GA3, for germination. NaOCl treatment to the seeds mimics the effects of piercing. NaOCl may also have caused loss of germination inhibitors or rendered these inhibitors susceptible to oxidation. However, prolonged NaOCl treatment resulted in either poor germination or seed disintegration.

Effect of pre-sowing treatment on seed germination and seedling vigour in endive and chicory

“…GA 3 increased seed germination (32%) at the first two days, thus confirming its role as a stimulatory agent. 30 min pre-sowing with NaHClO 3 decreased seed germination (up to 34%), contrasting with the stimulatory effects reported by others (Hsiao 1979;Ho et al 1995;Nadeem et al 2000); this may be related to the type of seed (plant species) and/or concentration/time depended. These stimulatory treatments may help germinating seedlings early, providing them higher competitive ability (Zhang, Maun 1990) and hence reducing chances of their mortality.…”

The Effect of Sodium Hypochlorite, Gibberellic Acid and Light on Seed Dormancy and Germination of Stinkweed and Wild Mustard

“…(Hsiao 1979b) and subsequently increased germination of these species. Our results showed that NaOCI enhanced the penetration of GA3 into the seeds and consequently the requirement of GA, for germination of wild oats (Hsiao 1979a) and cow cockle (Hsiao 1979b) decreased. In cow cockle (Hsiao 1979b) NaOCI treatment alone had a beneficial lDlzs"C used by Best and Mclntyre (1975) effect on germination.…”

“…(Hsiao 1979a), wild buckwheat (Polygonum convolvulus L.) and cow cockle (Saponaria vaccariaL.) (Hsiao 1979b) and subsequently increased germination of these species.…”

Germinação de sementes e crescimento de plântulas de brassica chinensis L. var. parachinensis (bailey) sinskaja (couve-da-malásia)

“…A ação escarificante da solução de hipoclorito de sódio em sementes, verificada em várias espécies (McCollum & Linn, 1955;Frank & Larson, 1970;Emal & Conard, 1973;French & Sherman, 1976;Hsiao, 1979;Hsiao et al, 1981;Drew & Brocklehurst, 1984), não se mostrou drástica nas sementes da espécie estudada. A redução na germinabilidade foi de aproximadamente 12% em relação ao controle, com atraso de um dia, enquanto em sementes de alface cv.…”

“…A aplicação de hipoclorito de sódio pode ainda evitar a termodormência em sementes, o que é extremamente importante para hortaliças cultivadas em regiões mais quentes (Drew & Brocklehurst, 1984). Por outro lado, a ação prolongada do hipoclorito de sódio ou sua utilização em altas concentrações pode induzir a dormência de sementes de algumas espécies (McCollum & Linn, 1955;Hsiao, 1979;Hsiao et al, 1981).…”