The Function of Phytochrome in Nature

Smith, Harry; Morgan, D. C.

doi:10.1007/978-3-642-68918-5_19

Cited by 31 publications

(32 citation statements)

References 98 publications

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“…This makes plausible the proposal that the growing internodes play an important role in the perception of canopy density in stands formed by plants of similar size. Furthermore, though the distribution of phytochrome in the stem is unknown (13,27), our spectral measurements show that the above contention could be maintained even if the photoreceptor is not located at the outer surface of the organ. Strong support for the hypothesis postulating a role for the stem in the detection of neighborhood density comes from the experiments involving manipulations of the light conditions of the axis.…”

Section: Resultsmentioning

confidence: 72%

Photomodulation of Axis Extension in Sparse Canopies

Ballaré

Scopel²,

Sánchez³

1989

Plant Physiol.

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A fiber optic probe inserted into plant tissues was used to investigate the effects of canopy density on the light environment in different organs. The red:far-red ratio inside the stem of Datura ferox L. seedlings and the estimated phytochrome photoequilibrium were strongly reduced by the presence of neighbors forming canopies too sparse to cause any mutual shading at the level of the leaves. In such canopies, changes in plant density had limte effects on the light regime inside the leaves of the succulent Aeonium haworthfi (S.D.) Webb et Berth., particularly when the lamina was kept nearly normal to the direct rays of the sun. In field experiments using D. ferox and Sinapis alba L. seedlings, the elongation of the intemodes responded to various types of localized light-quality treatments that simulated different plant densities in sparse canopies. The responses were quantitatively similar to those elicited by changes in plant density. The evidence supports the hypothesis that, in stands formed by plants of similar size, the red:far-red ratio of the light that impinges laterally on the stems is among the earliest environmental cues that allow plants to detect local canopy density and adjust axis extension accordingly.Stem elongation is markedly affected by the presence of neighboring plants, and changes in light quality are currently viewed as an important factor in the perception of canopy density (2,5,14,20). It has recently been shown (1, 2) that in stands formed by individuals ofsimilar size, relatively small density increments in the LAI2 range of 0 to 1 stimulate stem elongation without involving a significant reduction in PAR interception per plant. In these conditions, elongation rate is well correlated with the R:FR ratio of the light parallel to the ground collected by an integrating-cylinder probe standing vertically in the canopy (1,2 3, 6, 16, 21, and stem; 4, 7, 8, 10, 13, 16, 21). In an open canopy, leaves and stems are, to some degree, exposed to direct sunlight and to the light scattered by neighbors but, because of the complicated optics of plant tissues (9, 30), the effects of canopy density on the light conditions within the organs are difficult to predict. Rich et al. (23) found that the amount of light inside internodes of intact seedlings increases markedly when the source of light is moved from above to the side. Thus, the light scattered by adjacent plants might make a greater contribution to the light regime inside the stem than that expected from its low relative contribution to global radiation. If this were the case, a shift in the spectral composition of the light impinging laterally on the axis might affect phytochrome status in the stem, which would be the major site of density perception in sparse canopies. The experiments reported here were carried out to test this hypothesis.In the first part of this paper, we address the influence of canopy density on the light environment of stems and leaves, as evaluated with a fiber optic probe inserted into the plant tissues. In...

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Section: Resultsmentioning

confidence: 72%

Photomodulation of Axis Extension in Sparse Canopies

Ballaré

Scopel²,

Sánchez³

1989

Plant Physiol.

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“…For all species, stems were shorter under BR and FL lights when compared with the BFr and RFr mixtures. Growth and development are enhanced at certain red to far-red ratios, but can be inhibited at the upper limit (Smith and Morgan, 1983). Devlin et al (1998) have reported that, when Phytochromes A through E are monitored, internode elongation in Arabidopsis is more influenced by the level of phyE, such that its deficiency is typical in shade avoidance responses to a low red to far-red ratio.…”

Section: Resultsmentioning

confidence: 98%

Influence of mixed LED radiation on the growth of annual plants

2006

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We investigated the effect of mixed radiation from light-emitting diodes (LEDs) on the growth and flowering of ageratum, marigold, and salvia bedding plants. Blue, red, and far-red lights were applied under controlled environmental conditions for 28 d. Both the combination of blue-plus-red radiation as well as fluorescent lighting treatment (control) caused increases in dry weights, but shoot lengths were shortest when plants were exposed to blue plus red light compared with either red or blue plus far-red treatments. The number of floral buds as well as the occurrence of flower opening for ageratum and salvia plants was also enhanced under the blue plus red mixture. Likewise, carbohydrate accumulation was stimulated by that combination compared with the other radiation treatments.Keywords: chlorophyll, light-emitting diodes, mixture radiation, morphogenesis, starch Environmental conditions, such as relative humidity, temperature, light intensity, and light quality, commonly influence the growth and development of plants. Among these various factors, light quality affects stem elongation, lateral branching, leaf extension and pigmentation, and photosynthetic activity (Moe and Heins, 1990;Heo et al., 2003;Jayakumar et al., 2004). Desirable morphological characteristics can be obtained when horticultural plants are grown under less light and low temperatures, thereby reducing heat energy costs with only a minimal delay in their blooming (Merritt and Kohl, 1991 ).The objectives of this study were (1) to produce ageratum, marigold, and salvia bedding plants with compact growth, good branching, and a large number of flowers when treated with different mixtures of radiation sources, and (2) to evaluate the starch and sugar contents, as well as the optimum chlorophyll fluorescence, that would cause minimal or no delays in blooming when those plants were grown under various combinations of radiation provided by lightemitting diodes (LEDs). MATERIALS AND METHODS Plant Materials and Growth ConditionsBedding plants of ageratum (Ageratum houstonianum Mill. cv. Blue Field), marigold (Tagetes erecta L. cv. Orange Boy), and salvia (Salvia splendens E Sello ex Ruem & Schult. cv. Red Vista) with two to four true leaves were used for our experimental materials. On Day 14 after sowing, all plants with two true leaves were transplanted to a plug tray (50 x 50 mm) filled with a soil mixture (BM1 ; Berger Horticulture, Canada) of 75 to 85% Canadian sphagnum peat moss, 15 to 20% perlite, and 4 to 10% vermiculite. Two types of liquid fertilizers, 20:10:20 and 14:0:14 (Plant Prod; Plant Products, Canada), were alternately applied at a rate of 100 ppm during the experimental period. We used an LED system (GF-320s; Good Feeling, Korea) comprising LED sticks, a panel, and a main controller to maintain a photosynthetic *Corresponding author; fax +82-43-272-5369 e-mail paekky@chungbuk.ac.kr photon flux (PPF) of 90 _+ 10 ~mol m -2 5 -1 over a 16-h photoperiod, as measured on an empty culture shelf. All plants were reared for 28 d in a growth c...

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“…Dentre os tipos de dormência existentes, destacam-se os físicos, caracterizados pela impermeabilidade do tegumento, e os fisiológicos, devidos ao balanço hormonal ou à concentração de pigmento, como fitocromo vermelho ou vermelho extremo. O comprimento de onda de vermelho (660 nm) ou vermelho extremo (730 nm) possibilita a reversão do fitocromo, que é o principal receptor de luz, influenciando na germinação de sementes fotoblásticas (Smith & Morgan 1983).…”

Section: Methods To Overcome Dormancy In Tree Tomato (Solanum Betaceuunclassified

Métodos para superação de dormência em sementes de tomateiro arbóreo (Solanum betaceum)

Neto

Fabiane

Radaelli

et al. 2015

Pesqui. Agropecu. Trop.

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RESUMO O tomateiro arbóreo (Solanum betaceum) é espécie pouco conhecida, porém, apresenta frutos com enorme potencialidade de mercado, uma vez que podem ser consumidos tanto in natura como na forma industrializada. Contudo, um dos entraves para essa potencialidade se tornar realidade é a produção de mudas. A propagação dessa espécie ocorre por meio de sementes, mas, normalmente, a germinação requer tempo, principalmente sob condições de estresse. Objetivou-se verificar se existe dormência em sementes de tomate arbóreo e a técnica adequada para obter germinação rápida e uniforme. O delineamento foi o inteiramente casualizado, em esquema fatorial 5 x 2 (métodos para superação de dormência x luz), com 4 repetições de 50 ou 60 sementes, de acordo com o ciclo produtivo. Os métodos avaliados foram estratificação, hidrocondicionamento, condicionamento osmótico com GA3 e controle, com e sem luz. Também foram avaliados a germinação e o índice de velocidade de germinação, bem como o início e tempo médio de germinação. A utilização de GA3 na concentração de 100 mg L-1 ou 300 mg L-1 é recomendada para a germinação de sementes de tomate arbóreo.

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The Function of Phytochrome in Nature

Cited by 31 publications

References 98 publications

Photomodulation of Axis Extension in Sparse Canopies

Photomodulation of Axis Extension in Sparse Canopies

Influence of mixed LED radiation on the growth of annual plants

Métodos para superação de dormência em sementes de tomateiro arbóreo (Solanum betaceum)

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