scholarly journals Studies of the Involvement of an Endogenous Rhythm in the Photoperiodic Response of Hyoscyamus niger

1967 ◽  
Vol 42 (5) ◽  
pp. 725-730 ◽  
Author(s):  
Joseph Ching Seng Hsu ◽  
Karl C. Hamner
Keyword(s):  
Photoperiodic Response ◽  
Endogenous Rhythm ◽  
Hyoscyamus Niger

Circadian rhythms of flower induction and their significance in photoperiodic response

1969 ◽  
Vol 47 (2) ◽  
pp. 309-324 ◽  
Author(s):  
Bruce G. Cumming
Keyword(s):  
Active Form ◽  
Photoperiodic Response ◽  
Endogenous Rhythm ◽  
Flower Induction ◽  
Primary Control ◽  
Endogenous Rhythms ◽  
Free Running ◽  
System 1 ◽  
And Control ◽  
Measurement And Control

Endogenous rhythms of flower induction in Chenopodium rubrum provide at least a partial basis for time measurement and control of flower induction in daily light: dark (photoperiodic) cycles. The results support Bünning's hypothesis of the physiological clock.The following three intrinsic components can exert a primary control in both the endogenous free-running and the externally forced system.(1) GenotypeThe endogenous rhythmic flowering responses of different latitudinal ecotypes show specific characteristics that are also expressed in daily photoperiodic cycles.(2) PhytochromeChanges in the level of Pfr (the active form of phytochrome) cause shifts in endogenous phase and photoperiodic optima that are qualitatively similar. Changes in Pfr level have effects on flower induction that are similar in both the photophile phase of an endogenous rhythm and in the light period of inductive daily photoperiodic cycles—just as the effects obtained in the transduction (skotophile) phase of the endogenous rhythm are similar to those obtained in the dark period of daily photoperiodic cycles.(3) Photosynthetic Energy MetabolismThe effects on flower induction obtained by changing light intensity and (or) quality, and by applying sugars, suggest that there is a greater utilization and (or) availability of substrates (arising from carbohydrate metabolism and involved in Pfr pacemaker effects) in the photophile than in the transduction phases of prolonged darkness. This appears to reflect the sequence that would normally be imposed in daily photoperiodic cycles.A basis for the overt relationships between endogenous rhythmic and photoperiodic response could exist if there are endogenous oscillations in energy metabolites derived from photosynthesis. Such a system could have become selectively evolved as an adaptive response to natural alternations of light and darkness. Demultiplication of higher frequency oscillations may be a significant adaptive mechanism in circadian timing of flower induction.

ECOTYPIC VARIATION IN PHOTOPERIODISM OF TREES WITH SPECIAL REFERENCE TO PINUS RESINOSA AND THUJA OCCIDENTALIS

1962 ◽  
Vol 40 (6) ◽  
pp. 849-856 ◽  
Author(s):  
O. Vaartaja
Keyword(s):  
Special Reference ◽  
Growth Pattern ◽  
Tree Species ◽  
Pinus Resinosa ◽  
Photoperiodic Response ◽  
Endogenous Rhythm ◽  
Thuja Occidentalis ◽  
Ecotypic Variation ◽  
Middle Latitudes ◽  
Broad Subject

A certain daylength treatment inhibited the growth of northern seedlings of Pinus resinosa and Thuja occidentalis more than it inhibited southern seedlings of these species. These treatment – seed source interactions were small, but otherwise similar to those found earlier in 29 northern tree species. The smallness of the interaction was caused by the overruling effect of the endogenously determined growth pattern in P. resinosa, and by the lack of large photoperiodic response in T. occidentalis.The broad subject of ecotypic variation in the photoperiodism of trees is discussed. The evolution of dormancy mechanism suggests that photoperiodism should tend to be overruling in the truly northern trees, and the endogenous rhythm in trees from the middle latitudes.

Chemical structure of hyoscyamosides D and D1 - spirostanol glycosides from the seeds of Hyoscyamus niger L

Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
I Lunga ◽  
P Kintia ◽  
S Shvets ◽  
C Bassarello ◽  
S Piacente ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Hyoscyamus Niger
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