The roles of inorganic nitrogen salts in maintaining phytochrome- and gibberellin A3-mediated germination control in skotodormant lettuce seeds

✍ Scribed by A. I. Hsiao; W. A. Quick

• Publisher: Springer
• Year: 1996
• Tongue: English
• Weight: 704 KB
• Volume: 15
• Category: Article
• ISSN: 0721-7595
• DOI: 10.1007/bf00190579

✦ Synopsis

Skotodormant seeds of Lactuca sativa Grand

Rapids imbibed in darkness for 10 days (10-day DS) germinated poorly upon terminal treatment with red light (R) or gibberellin A 3 (GA3). Inorganic nitrogen salts in the imbibition solutions reduced seed skotodormancy. Ten-day DS seeds, imbibed in 25 mM salt solutions followed by terminal R, germinated 99% if imbibed in NHaNO 3, 70% if imbibed in KNO 3 or NHaC1, and 55% if imbibed in NaNO 3. Seeds imbibed in higher salt concentrations germinated fully upon terminal R treatment. Seeds imbibed in 25 mM NHaC1 or in 50 mM NHnNO 3 germinated completely upon GA 3 treatment. Osmotic effects of imbibition media accounted for only part of the effect, since seeds imbibed in 50 mM CaC12 or NaC1 germinated poorly following R or GA 3 treatment. Seeds imbibed in 500 mM polyethylene glycol (PEG) 1000 or mannitol solutions for 10 days still exhibited skotodormancy. Treatments of R or GA 3 did not stimulate germination in seeds imbibed in mannitol, but germination was complete if seeds were given 1-h acid immersion plus a water rinse before the terminal R or GA 3 treatment. Seeds imbibed in 50-500 ms PEG during 10-day DS germinated significantly better in response to terminal R. Terminal GA 3 significantly improved germination only in seeds imbibed at 500 mM PEG. Pfr appeared to function in mannitol-imbibed seed only after an acid treatment. Seed exposure to inorganic nitrogen salts during the 10-day DS maintained seed sensitivity to terminal R or GA 3 treatment. The depth of seed skotodormancy was related to the availability of inorganic nitrogen and also involved the levels of Pfr or endogenous GA 3.