Blue Light Interference in the Phytochrome-controlled Germination of the Spores of Cheilanthes farinosa

Short exposure of the spores of Cheilanthes farinosa to low intensity red light promotes their germination, which is not reversed by a subsequent exposure to far red light. Germination is, however, inhibited by blue light administered before or after red light. Inhibition of germination by blue light is annulled by exposure to a higher intensity of red light, and germination of the repromoted spores is inhibited by far red light. Mutual photoreversibility of germination is also observed in repromoted spores irradiated successively with far red and red light. Although germination appears to be basically under phytochrome control, it is postulated that the presence of a blue light-absorbing pigment interferes with phytochrome transformations in the spores.     

The effect of light on growth and development of two nitrogen fixing blue-green algae

Summary Green, blue, yellow, red and white light all support spore germination whereas vegetative growth occurs only in red, yellow or white light. This indicates a requirement of nonphotosynthetic light for spore germination and of photosynthetic light for growth and cell divisions. The green or blue light is neither inhibitory to vegetative growth nor to sporulation of red, yellow or white light grown filaments. The growth promoting effect of white light is greater than that of red or yellow light. Whereas spore germination is not affected by the intensity of white light, vegetative growth increases linearly with increase in white light intensity.     

Light intensity and wavelength influence development, reproduction and locomotor activity in the predatory flower bug Orius sauteri (Poppius) (Hemiptera: Anthocoridae)

Light wavelength and intensity are physical factors that can affect arthropod development and reproduction. The present study examined the development, reproduction and locomotor activity of the predatory flower bug, Orius sauteri (Poppius) (Hemiptera: Anthocoridae), under five light intensities (1000, 2000, 3000, 4000 and 5000 lux) and five wavelengths [red (678.5 nm), green (620.0 nm), yellow (581.7 nm), blue (478. 1 nm) and white (all wavelengths)] at constant temperature (25 °C) and RH (70 %). The duration of nymphal development was extended at lower light intensities, primarily due to effects on the first three instars. Under white, yellow and green light, O. sauteri completed development in 18.0 days, but blue light extended development by 3.2 days and red light extended it by 7.4 days. Although lower light intensities extended the preoviposition period and reduced fecundity, they improved egg fertility. Both red and blue light negatively affected preoviposition period, fecundity and egg fertility. Whereas adult female mean walking speed over a five min period was reduced at lower light intensities, longer wavelengths (yellow and red) increased it, ostensibly reflecting an avoidance response. The respiration quotient of adult O. sauteri females was also elevated under red light conditions. These findings are informative for optimizing O. sauteri mass-rearing procedures and maximizing its efficacy as a biological control agent in greenhouse cultures.     

光质、光强对入侵植物紫茎泽兰种子萌发及幼苗状态的影响

为了探讨紫茎泽兰种子需光萌发特性,对光质（不同颜色、红光/远红光）和光强对种子萌发率及幼苗状态进行了研究。研究发现：不同颜色光对发芽率影响显著,其中黄光、橙光和红光等波长在（591~750 nm）之间的光更有利于提高种子的萌发率（74.3%~83.3%）,而较短波长的光（<570 nm,紫光、蓝光和绿光）促进效果显著降低（62.3%~66.7%）（p<0.05）。光强对紫茎泽兰种子发芽和幼苗影响较光的颜色更具有规律性。黑暗条件下发芽率22%,随着光照提高,发芽率指数增加(r²=0.96),芽长指数下降(r²=0.99)、根长指数增加(r²=0.98),而鲜重呈现线性增加(r²=0.70)。适量红光（630 nm）和远红光（730 nm）照射能够打破和引起休眠,红光照射量与发芽率提高量成线性正相关（r²=0.98）,而远红光照射率与发芽率降低量呈线性正相关（r²=0.92）,说明紫茎泽兰需光萌发是一个光敏色素引起的过程。紫茎泽兰通常在裸地和人为干扰土壤上泛滥,这可能与其种子需光萌发有关。而对其生态学控制可以考虑从光强、特别是光质角度（如人工造林）控制种子萌发来实现。     

PHOTOMORPHOGENESIS IN PTERIS VITTATA: I. PHYTOCHROME-MEDIATED SPORE GERMINATION AND BLUE LIGHT INTERACTION

1. Spores of the fern Pteris vittata did not germinate under totaldark conditions, while an exposure of the spores to continuouswhite light brought about germination. The germination was mosteffectively induced by red light and somewhat by green and far-red,but not at all by blue light. The sensitivity of spores to redlight increased and leveled off about 4 days after sowing at27–28. The promoting effect of red light could be broughtabout by a single exposure of low intensity. Far-red light givenimmediately after red light almost completely reversed the redlight effect, and the photoresponse to red and far-red lightwas repeatedly reversible. The photoreversibility was lost duringan intervening darkness between red and far-red irradiations,and 50% of the initial reversibility was lost after about 6hr of darkness at 27–28. These observations suggest thatthe phytochrome system controls the germination of the fernspore.
2. When the imbibed spores were briefly exposed to a low-energyblue light immediately before or after red irradiation, theirgermination was completely inhibited. The blue light-inducedinhibition was never reversed by brief red irradiation givenimmediately after the blue light. The escape reaction of redlight-induced germination as indicated by blue light given aftervarious periods of intervening darkness was also observed, andits rate was very similar to that determined by using far-redlight. Spores exposed to blue light required 3 days' incubationin darkness at 27–28 to recover their sensitivity tored light. The recovery in darkness of this red sensitivitywas temperature-dependent. It is thus suggested that an unknownbluelight absorbing pigment may be involved in the inhibitionof phytochrome-mediated spore germination.

(Received August 21, 1967; )     

Influence of light intensity and wavelength on phototactic behaviour of larval silver perch Bidyanus bidyanus and golden perch Macquana ambigua and the effectiveness of light traps

Larval golden perch, Macquaria ambigua , and silver perch, Bidyanus bidyanus , were exposed to light gradients in wavebands centred on 400, 496, 601 and 695 nm at nominal quantum irradiance values of 0–1, 1–0 and 10 μmol m⁻² s^−l. Silver perch larvae displayed stronger phototactic behaviour than golden perch, and both species were most responsive to light in the 601 nm waveband. The intensity of phototactic responses in both species was greater at higher irradiance levels. Enhanced responsiveness to longer wavelengths reflects possible adaptations to life in turbid habitats where the underwater light field is dominated by yellow/orange wavebands.
At night, traps fitted with 12 h yellow lightsticks attracted more golden perch larvae than traps with blue, green, orange, red or no lightstick. The efficacy of yellow lightsticks may be due to yellow/orange wavebands not being attenuated under water as rapidly as blue or red wavebands. Yellow lightsticks also emit a greater intensity of light over a longer time than other colours tested, which may have increased the effectiveness of yellow traps. Light traps were ineffective during the day.     

Photoinduction of Spore Germination in a Fern, Mohria caffrorum

Irradiation of spores of the fern Mohria caffrorum Sw. witheither red light (67.4 µW cm^–2) or far-red light(63.2 µW cm^–2) for a period of 24 h induced maximumlevels of germination. Brief irradiations with blue light (127.6µW cm^–2) administered before or after photoinductioncompletely nullified the effects of red or far-red light; however,with prolonged exposure to blue light, germination levels roseto near maximum. The similar effects of red and far-red lightin promoting spore germination makes the involvement of phytochromein this process questionable. Based on energy requirements,the promotive and inhibitory phases of blue light appear toinvolve independent modes of action. Mohria caffrorum, ferns, spore germination, photoinduction, phytochrome     

Light germination ofAnthoceros miyabeanus spores

The effects of light on the spore germination of a hornwort species,Anthoceros miyabeanus Steph., were investigated. Spores of this species were photoblastic, but their sensitivities to light quality were different. Under either continuous white, red or diffused daylight, more than 80% of the spores germinated, but under blue light none or a few of them germinated. Under continuous far-red light or in total darkness, the spores did not germinate at all.Anthoceros spores required red light irradiation for a very long duration, i.e., over 12–24 hr of red light for saturated germination. However, the spore germination showed clear photo-reversibility by repeated irradiation of red and far-red light. The germination pattern clearly varied with the light quality. There were two fundamental patterns; (1) cell mass type in white or blue light: spores divide before germination, and the sporelings divide frequently and form 1–2 rhizoids soon after germination, and (2) germ tube type in red light: spores germinate without cell division, and the single-cell sporelings elongate without cell division and rhizoid formation.     

Ecophysiological effects of light quality and nitrate on seed germination in species from Western Australia

Germination occurs usually in response to multiple environmental cues. Seeds with the ecophysiological ability to simultaneously sense the previous presence of fire and appropriate levels of temperature, light and soil nitrate could restrict germination to postfire, winter and competition-free microhabitats, where the potential for seedling survival is enhanced. Germination responses of 16 species with a range of life forms, fire responses and seed weights were determined under controlled conditions of 15°C temperature, a 12 h light cycle, exposure to 1 g L^?1 nitrate solution, and six conditions of light quality (white, blue, yellow, red, far-red light and darkness). Germination in Oenothera stricta, a weedy naturalized ephemeral, and two small-seeded indigenous Asteraceae species of mulga woodlands, Leucochrysum fitzgibbonii and Craspedia sp., were enhanced by white, yellow or red light compared with germination achieved in the dark, or under far-red or blue light. In red light, KNO₃ further enhanced germination of these positively photoblastic species. The germination response of Trachyandra divaricata, a naturalized herb of sandy, seaside locations, and several native jarrah forest legumes (four Acacia species, Bossiaea aquifolium, Gompholobium marginatum and Sphaerolobium vimineum) proved to be negatively photoblastic. Of these seven negatively photoblastic herb and shrub species, exposure to KNO₃ overcame the inhibition of light only in the resprouter species, Acacia lateriticola. In the serotinous, negatively photoblastic tree species, Corymbia calophylla and Eucalyptus marginata, KNO₃ seemed to be required before the negative response to light exposure was recorded. A dose–curve experiment on two positively photoblastic and three negatively photoblastic species indicated that although KNO₃ exposure affected germination in all species, different concentrations of KNO₃ (0, 0.5, 1, 2, and 5 g L^?1) produced different levels of response. Detailed studies with additions of KNO₃ (1 g L^?1) and the growth hormone, gibberellic acid (GA₃; 50 mg L^?1), showed that increased germination percentages of the positively photoblastic species, Oenothera stricta, occurred in the light, but blocking endogenous gibberellic synthesis with paclobutrazol, or adding exogenous GA₃ or KNO₃ had no effect on the light-induced germination levels. In the negatively photoblastic species Trachyandra divaricata, additions of KNO₃ and GA₃ had no influence on the germination inhibition induced by exposure to light nor did blocking endogenous GA synthesis. The 16 species growing naturally in Western Australia, Australia show a range of germination responses to environmental conditions, but depending on their natural habitat, the ecophysiology of each species appears to be optimized for subsequent seedling survival.     

Photocontrol of spore germination in the fern Thelypteris kunthii

The light requirement for germination in spores of the fern Thelypteris kunthii (Desv.) Morton was fully satisfied by a long period of continuous red light or partially by intermittent, short periods of red light. Red light-potentiated spore germination was inhibited by brief far-red light irradiation, indicating phytochrome involvement. Repeated exposure of spores to prolonged red and short far-red irradiations, or exposure of red-potentiated spores to far-red light after an extended period in darkness, led to their escape from inhibition of germination by far-red light. Prolonged irradiation of spores with blue light before or after red light treatment partially antagonized the effect of red light.     

卷蛾分索赤眼蜂雌蜂的颜色偏好性

为了确定卷蛾分索赤眼蜂Trichogrammatoidea bactrae Nagaraja 雌蜂的颜色偏好性, 在室内通过在培养皿底部黏贴彩纸的方法测定卷蛾分索赤眼蜂雌蜂对红、 黄、 黑、 紫、 绿、 白、 蓝7种颜色的行为趋性反应。结果表明, 卷蛾分索赤眼蜂雌蜂在红、 黄、 紫、 绿和蓝5种颜色上的滞留时间都极显著地高于对照（P<0.01）, 在黑和白2种颜色上的滞留时间与对照没有显著差异（P>0.05）; 对黄色的首次选择率极显著高于对照(P< 0.01), 对红、 紫、 绿和蓝色的首次选择率均显著高于对照(P＜0.05), 对黑色和白色的首次选择率与对照没有显著差异。当雌蜂分别在黄与红、 紫、 绿和蓝两两颜色之间选择时, 雌蜂在黄色彩纸上的滞留时间显著长于其他4种颜色。当雌蜂对红、 紫、 绿、 蓝和黄色5种颜色一起选择时, 在首次选择率、 滞留次数上5种颜色间都没有明显差异(P＞0.05); 但在红色和蓝色上的滞留时间显著长于紫色(P＜0.05), 在这3种颜色上的滞留时间与在黄色和绿色上的滞留时间均无显著差异(P＞0.05)。卷蛾分索赤眼蜂雌蜂在7种颜色卵卡上分别与透明纸（对照）上的米蛾卵的选择寄生时, 在黄色卵卡上的寄生卵量极显著多于对照(P＜0.01), 黑色卵卡上的寄生卵量极显著少于对照(P＜0.01), 其他5种颜色的卵卡上的寄生卵量与对照没有显著差异(P＞0.05)。结果说明, 卷蛾分索赤眼蜂雌蜂对黄色最为偏好, 其次偏好红、 紫、 绿和蓝色, 较不喜好白色和黑色。     

An investigation of the effects of light on basidiocarp formation of Coprinus domesticus

Coprinus domesticus, grown on a synthetic agar medium, failed to produce primordia and basidiocarps unless exposed to light. Lightdark cycles are not required for maturation of basidiocarps. Short exposure to white light induced primordia, but a longer exposure was necessary for primordia to develop into basidiocarps. The length of exposure to light was related inversely to the length the stipe finally attained. Young basidiocarps were phototropic, growing towards the light. The mycelium of cultures were dark brown following exposure to white and blue light, but the mycelium was light yellow in cultures grown in darkness. The blue end of the visible spectrum at intensities ranging from 1.5–3 × 10⁴ ergs/cm²/sec induced mature basidiocarps, whereas green, red and far red failed to induce basidiocarps and primordia.Department of Biology contribution no. 90     

An unusual effect of the far-red absorbing form of phytochrome: Photoinhibition of seed germination inBromus sterilis L.

Seeds ofBromus sterilis L. germinated between 80–100% in darkness at 15° C but were inhibited by exposure to white or red light for 8 h per day. Exposure to far-red light resulted in germination similar to, or less than, that of seeds maintained in darkness. Germination is not permanently inhibited by light as seeds attain maximal germination when transferred back to darkness. Germination can be markedly delayed by exposure to a single pulse of red light following 4 h inhibition in darkness. The effect of the red light can be reversed by a single pulse of far-red light indicating that the photoreversible pigment phytochrome is involved in the response. The response ofB. sterilis seeds to light appears to be unique; the far-red-absorbing form of phytochrome (Pfr) actually inhibiting germination.Abbreviations Pr red absorbing form of phytochrome - Pfr far-red absorbing form of phytochrome     

Photocontrol of the germination of onoclea spores: I. Action spectrum

Light stimulates the germination of spores of the fern Onoclea sensibilis L. At high dosages, broad band red, far red, and blue light promote maximal germination. Maximal sensitivity to these spectral regions is attained from 6 to 48 hours of dark presoaking, and all induced rapid germination after a lag of 30 to 36 hours. Maximal germination is attained approximately 70 hours after irradiation. Dose response curves suggest log linearity. The action spectrum to cause 50% germination shows that spores are most sensitive to irradiation in the red region (620-680 nm) with an incident energy less than 1000 ergs cm⁻²; sensitivity decreases towards both shorter and longer wavelengths. Although the action spectrum is suggestive of phytochrome involvement, photoreversibility of germination between red and far red light has not been demonstrated with Onoclea spores. An absorption spectrum of the intact spores reveals the presence of chlorophylls and carotenoids. Since the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea does not inhibit germination, it is concluded that photosynthesis does not play a role in the germination process.     

Photophysiology of turion formation and germination inSpirodela polyrhiza

Standardized laboratory techniques for the vegetative growth of the duckweedSpirodela polyrhiza (Lemnaceaé), and for formation as well as germination of their turions were described. Increasing photon fluence rates of blue or red light increased the yield of turions. A specific stimulating effect of blue light was demonstrated under autotrophic but not under mixotrophic conditions. Therefore the spectral composition of light is not important in mixotrophic formation of turions whereas in autotrophic formation light sources with a higher portion of blue light are recommended. Dark-grown (etiolated) turions showed accelerated germination and higher germination percentage in comparison with light-grown turions after induction by a single red light pulse. This difference was overcome in continuous red light by speeding up the germination response of light-grown turions. Use of Petri dishes (8 cm³ nutrient solution) instead of Erlenmeyer flasks (50 cm³ nutrient solution) retarded germination response. Especially for long term experiments the use of Erlenmeyer flasks is recommended. Storage of turions for 72 h at 25 ‡C following at 5 ‡C in darkness after-ripening resulted in a decreased lag phase of the light-induced germination both after induction by a single light pulse and in continuous light. We thank Dr. Halina Gabrys, University of Crakow, Poland for critical discussion.     

SPECTRAL SENSITIVITY OF SEED GERMINATION IN ARTEMISIA MONOSPERMA

The absolute requirement for light in the germination of achenesof Artemisia monosperma is as satisfied by radiant energy inthe blue, green, yellow, red and far-red regions of the visiblespectrum, as by unfiltered white light. The same stimulationwas obtained by a short irradiation as by an uninterrupted one.Phytochrome seems to be either absent, or masked by a differentpigment which absorbs light in the entire visible spectrum andthus initiates germination. ¹ This study was supported by grant FG-Is-115 from the UnitedStates Department of Agriculture.     

Photocontrol of Hook Opening in Cuscuta gronovii Willd

Hook opening in seedlings of Cuscuta gronovii Willd. occurred only after prolonged exposures to blue, red, or far red light. Prolonged far red exposure was less effective than prolonged exposure to red or blue light. Brief far red irradiation inhibited the inductive effect of red light. The far red inhibition was in turn reversed by brief red irradiation. These effects suggest the involvement of two photosystems in the control of hook opening in Cuscuta gronovii Willd.: a phytochrome-mediated system and a separate high energy requirement.     

Dormancy in Dioscorea: Gibberellin-Induced Inhibition or Promotion in Seed Germination of D. tokoro and D. tenuipes in Relation to Light Quality

Effects of light and gibberellic acid (GA₃) application on the germination of Dioscorea tokoro Makino and Dioscorea tenuipes Franch. et Savat. were observed. For complete germination, seeds of both species required prechilling in moist condition before incubation at a higher temperature. Red light irradiation during the incubation after the prechilling promoted germination; blue, green, or far red light markedly inhibited the germination of both species.     

The influence of blue light on dark-germinating seeds of Nemophila insignis

Summary After inhibition of Nemophila insignis seeds by far-red (FR) light, a short exposure to blue (Bl) will not induce germination again but stimulation by red (R), with reversion by FR, can be observed. Germination is inhibited by long exposures to Bl (maxima at 455 and 475 nm). These radiations are absorbed either directly by phytochrome or through intermediary pigments such as flavoproteins.Abbreviations Bl blue - FR far-red - R red     

Light-controlled Leaf Expansion in Peas Grown under Different Light Conditions

Several photosystems control leaf expansion in Alaska peas (Pisum sativum). Phytochrome is known to control expansion in dark-grown peas. But plants exposed briefly to red light are insensitive to phytochrome, an insensitivity that is itself phytochrome-produced. Leaf expansion in these plants is promoted by 440 or 630 nm of light (probably mediated by protochlorophyll). Plants grown in white fluorescent light required simultaneous exposure to high intensity blue and yellow light for promotion of leaf expansion. Since these results parallel studies on light-controlled inhibition of stem elongation, shoot growth as a whole is coordinated by these photosystems. Such coordination might be a mechanism of plant competition for light.