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Biomedical subjects

A L Mancinelli

Publications and source records attributed to A L Mancinelli.

25 records · Page 2Linked to original sources
PubMed1968

Phytochrome and Seed Germination. IV. Action of Light Sources With Different Spectral Energy Distribution on the Germination of Tomato Seeds.

Germination of tomato seeds exposed to a single, saturating irradiation from light sources of different spectral energy distribution seems to be dependent upon the photostationary P(FR)/P(R) ratio established by the irradiation. Germination of tomato seeds exposed to prolonged irradiations from the same light sources does not seem to be controlled solely by the P(FR)/P(R) ratio induced and maintained by the irradiation.

Journal Article↗
PubMed1968

Phytochrome and seed germination. V. Changes of phytochrome content during the germination of cucumber seeds.

Cucumber seeds are light-sensitive, dark-germinating seeds. Inhibition of germination can be induced by prolonged exposure to continuous or intermittent FR. The dark germination process and the response to FR are phytochrome controlled. Phytochrome can be detected in these seeds by differential spectrophotometry in vivo. Spectrophotometrically measurable phytochrome increases during dark germination. The rate of increase is temperature dependent. Light treatments which are inhibitory for germination result in phytochrome contents lower than those of the seeds germinating in darkness. Treatments which restore germination also restore phytochrome formation.

Journal Article↗
PubMed1967

Inhibition of Flowering of Xanthium pensylvanicum Wallr. by Prolonged Irradiation with Far Red.

Interrupting each long night with a prolonged period of far red radiant energy resulted in the inhibition of floral initiation in cocklebur. Irradiations inducing different relative levels of P(FR) from 1 to 2% to 80% had about the same effect under 4-hour photoperiods. The lower levels of P(FR) induced by continuous far red irradiation were not as effective as the higher levels induced by red under 8 and 12-hours photoperiods. The critical P(FR) level required to induce inhibition of flowering seems to increase with increasing photoperiods.

Journal Article↗
PubMed1967

Phytochrome and Seed Germination. III. Action of Prolonged Far Red Irradiation on the Germination of Tomato and Cucumber Seeds.

Prolonged irradiation with continuous or intermittent far red prevents the germination of tomato and cucumber seeds. The inhibitory efficiency of intermittent far red decreases with the lengthening of the interval between successive irradiations, and with the increase of temperature. If each far red irradiation is followed by red, germination is restored. Intermittent far red is less inhibitory than intermittent red-far red when red is given immediately before each far red. This effect is more evident when the interval between successive irradiation becomes longer.

Journal Article↗
PubMed1967

Phytochrome and Seed Germination. I. Temperature Dependence and Relative P(FR) Levels in the Germination of Dark-germinating Tomato Seeds.

Germination of the dark-germinating seeds of 3 varieties of tomato is controlled by the phytochrome system. Germination is inhibited by far red radiation and repromoted by red applied after far red. At low temperatures, 17 to 20 degrees , a single, low energy far red irradiation is sufficient to inhibit germination in all 3 varieties. At higher temperatures far red is less effective in the inhibition of the germination of the tomato seeds. The phytochrome fraction present as P(FR) in the dark-germinating seeds of the Ace variety is about 40% of the total phytochrome present.

Journal Article↗