Nitrate Reductase Independent Stimulation of Seed Germination in Sisymbrium officinale L. (Hedge Mustard) by Light and Nitrate
1989; Oxford University Press; Volume: 63; Issue: 1 Linguagem: Inglês
10.1093/oxfordjournals.aob.a087715
ISSN1095-8290
AutoresHenk W. M. Hilhorst, C. M. Karssen,
Tópico(s)Allelopathy and phytotoxic interactions
ResumoAfter a 72 h preincubation in darkness at 15 °C seed germination of Sisymbrium officinale L. (hedge mustard) at 24 °C was stimulated by a combination of red light and nitrate. In the presence of nitrate the seeds escaped from the inhibiting effect of far-red irradiation with an escape time of approx. 8 h. After red light, the exposure of seeds to nitrate could be delayed for 3 h without affecting maximal germination. Prolonged delay resulted in a decrease of the germination response. The possibility that nitrate reduction was involved in the stimulation of germination was studied by pre-incubating seeds for 72 h in nitrate and subsequently transferring them to water and irradiating with red light. During the first 8 h period after the red irradiation in which induction of germination occurred, total nitrate levels (endogenous + leachate) remained constant, indicating an absence of nitrate reductase activity. During the next 8 h visible germination started and total nitrate levels declined, suggesting induction of nitrate reduction. It is concluded that nitrate reduction docs not play a role in the induction of germination. The conclusion was supported by the lack of inhibition of seed germination by sodium chlorate and sodium tungstate in spite of an inhibition of nitrate reduction of 80 and 100%, respectively. The contrasts between our results and hypotheses concerning the mechanism of action of nitrate in seed germination are discussed
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