The Effect of Light upon Plant Rhythms

Wilkins, Malcolm B.

doi:10.1101/sqb.1960.025.01.011

Cited by 40 publications

(16 citation statements)

References 21 publications

(71 reference statements)

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“…Plants do exhibit endogenous (circadian) rhythnms in various physiological phenomena (3,4,28). With respect to root physiology, the periodicitv of exudation exhibited by (letopped plants is well established (7,25).…”

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confidence: 99%

Diurnal Variation in Root Respiration

Huck¹,

Hageman²,

Hanson³

1962

Plant Physiol.

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The existence of a diurnal fluctuation in root metabolism can be deduced from several studies. While studying root respiration, Harris (13) noted a diurnal variation in the rate of CO2 production by roots of tomatoes and certain deciduous fruit trees. Cannon (5) found oxygen consumption of roots to be increased in light under conditions conducive to high transpiration. Grossenbacher (7) (16) believes may be associated with increased transpiration during the period of illumination. Went (26) observed that the accumulation of p32 in the shoots of tomato plants was more rapid during the day.These diurnal fluctuations in root activity could be a reflection of a diurnal variation in respiration rate, as suggested by the experiments of Harris (13). However, Grossenbacher (7) were propagated in a sand bed. After 4 weeks, uniformly rooted cuttings were transplanted to culture containers patterned after the root respiration apparatus described by White and Childers (27). Culture containers were 19-liter glass bottles with a 2.5 cm diameter hole drilled in the bottom. The bottles were inverted, filled with pea-sized gravel and the plant inserted through the hole. The woody stem of this species allowed the culture vessel to be completely sealed except for inlet and outlet tubes. Nutrient solution (Shive's R5C,, complete with iron and micronutrients) (21) was supplied by sub-irrigation. The containers were immersed in separate water baths which were controlled by individual thermostats to provide 15.6, 21.1, 26.7, and 32.2 C temperatures about the root systems. The shoots, however, were exposed to the normal greenhouse environment.Since the primary purpose of the Derris experiment was to study the long-term effect of root temperature on the synthesis of rotenone, the respiration studies were made just prior to harvest when the plants were 28 months old.Respiration measurements were made by periodically displacing the total volume of air from the gravel-filled bottles with nutrient solution. Aliquots of the displaced gas mixture were assayed for CO2 and 02 content by the procedure of Haldane (10). Measurements were made on duplicate plants for each of the four temperature treatments. Air samples were taken at 6-hour intervals, beginning at 6 AM for 5 days. Air volume was corrected to standard temperature and pressure.-

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confidence: 99%

Diurnal Variation in Root Respiration

Huck¹,

Hageman²,

Hanson³

1962

Plant Physiol.

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“…At 2 lux, on the other hand, the phase delay is proportional to the length of the treatnment. This suggests that the level of energy input required to drive the basic system from linmit B to limit A in 6 hours is between 2 and 8 lux (18,19). In this paper it is found that entrainment of the rhythm by light-clark cycles of period less than 24 hours is also dependent upon light intensity.…”

Section: Discussionmentioning

confidence: 64%

“…Bruce (1) has drawn attention to the generalization that if a rhythm is readily shifted and quickly entrained by light, frequency demultiplication is less likely to occur. The oscillator in Bryophyllum conforms to this generalization because of the absence of frequency demultiplication, the rapidity vith which it is entrained by lightdark cycles and the ease with which its phase is reset by a single exposure to light (18,19).…”

Section: Discussionmentioning

confidence: 78%

“…Under some circumstances the rhythm of spore discharge in Piloboluis sphaerosporus appears to retain the period of the entraining cycles for a limited time after the onset of a uniform environment (15). It is unlikely, however, that this phenomenon is due to nmodification of the free-running period of the basic rhythmic process (19,7). The alga Hydrodictyon reticulatimi is the only organism in which the persistence of a rhythm equal in period to the entraining cycles has been clearly established (11,13).…”

Section: Discussionmentioning

confidence: 99%

“…The variation in the times of occurrence of the first peaks in the curves shown in figures 5B and C and 6A and B, and the shorter periods found in figures 6A and B, are most probably due to some of the light exposures exerting a slight phase shifting effect on the basic oscillating system in the leaf cells. A light treatment of 3 or 6 hours duration shifts the phase of the rhythm when it is given between, but not at the crests of, the peaks (18,19). While repetitive exposure to 3 or 6 hours' low intensity illuminationi dces not entrain the rhythm, those exposures which occur in that part of the cycle where the phase is most sensitive to light could have a slight effect on the position of the next peak of the rhythm.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

An endogenous rhythm in the rate of carbon dioxide output of Bryophyllum. IV. Effect of intensity of illumination on entrainment of the rhythm by cycles of light & darkness

Wilkins

1962

Plant Physiol.

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A circadian rhythm of mating type reversals in Paramecium multimicronucleatum, syngen 2, and its genetic control

Barnett

1966

Journal Cellular Physiology

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Two new alleles, C ahd c, involved in mating type expression were demonstrated. A dominant allele, C(cycler), must be present for the expression of the rhythm involving a sequential alternation of the two complementary mating types (I11 and IV). Cultures can be entrained with light-dark cycles. The phase of each clone can be characterized by its I11 to IV and IV to I11 transitions in relation to the zero hour of a given light-dark cycle. Phase is a stable phenotypic trait during asexual reproduction, but following sexual reproduction it does not display Mendelian segregation. Instead phase is determined through nuclear differentiation, he., the trait is controlled by differently determined macronuclear anlagen (caryonidal inheritance) which normally segregate at the second cell division after conjugation. The phase of a clone within its genetic limits is a function of the photofractions and the light intensities used in the entraining treatment. By examining a number of clones a variety of phase angles between the mating type cycle and the entraining light-dark cycle are found. Dividing cells which are sexually unreactive and therefore do not express the rhythm can be entrained and following entrainment, phase is inherited through repeated cell replications at a rate greater than one fission a day in continuous darkness or continuous dim light. This result unique to this system indicates that the cellular processes underlying the phase and period of this circadian rhythm persist (unexpressed: sexual reactivity requires slight starvation) through repeated cell replications even when the division cycle is considerably shorter than the expressed circadian period. The rhythm has a circadian period in continuous darkness or light (tested for six days) of less than 24 hours. The reversal of mating type ceases in continuous light at higher intensities. Cells homozygous for the recessive allele, c(acyclic), do not reverse mating type but are either mating type I11 or IV, again as a consequence of nuclear differentiation. Since individual cells with the dominant allele express both mating types, differentiation for mating type can not involve the absence in the macronucleus of mating type determining factors.

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The Effect of Light upon Plant Rhythms

Cited by 40 publications

References 21 publications

Diurnal Variation in Root Respiration

Diurnal Variation in Root Respiration

An endogenous rhythm in the rate of carbon dioxide output of Bryophyllum. IV. Effect of intensity of illumination on entrainment of the rhythm by cycles of light & darkness

A circadian rhythm of mating type reversals in Paramecium multimicronucleatum, syngen 2, and its genetic control

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