Germination-Regulating Mechanisms in Some Desert Seeds Viii. Artemisia Monosperma1

Koller, D.; Sachs, M.; Negbi, M.

doi:10.1093/oxfordjournals.pcp.a079027

Cited by 78 publications

(60 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…5 and 6B). Consequently, it is unlikely that critical preirradiation events, such as phytochrome hydration (10), phytochrome synthesis (18), or changes in the levels of components which inhibit (2), or promote (4,12), the expression of Pfr are sufficient to explain the reduced R sensitivity of NaCl-stressed seeds.…”

Section: Resultsmentioning

confidence: 99%

Interactions between Mild NaCl Stress and Red Light during Lettuce (Lactuca sativa L. cv Grand Rapids) Seed Germination

Scorer¹,

Epel²,

Waisel³

1985

Plant Physiol.

View full text Add to dashboard Cite

The sensitivity of lettuce (Lactuca sativa L. cv Grand Rapids) seeds to red light was reduced by NaCQ concentrations which had no effect upon the germination of continuously illuminated seeds. The germination capacity of the seeds was fully restored by increased red light exposures. Indirect evidence indicates that NaCI does not affect the photoconversion of red-absorbing form of phytochrome to the far-red absorbing form of phytochrome. Instead, the increased red light requirements are attributable to increases in the threshold levels of the far-red absorbing form of phytochrome necessary to induce germination and to changes in the slopes of the fluence-response curves. Results also show that the sensitivity of the seeds to NaCI decreased as the time between red light irradiation and the imposition of NaCl stress increased.Reductions in the germination percentage and delays in the onset of germination are well-documented effects of salinity stress. However, salinity stress seldom acts alone, and its effects on seed germination may be modified by interactions with other environmental parameters, such as temperature (14) and light (8). As the effects of NaCl on germination control mechanisms remain largely undefined, the present study investigates phytochrome-dependent germination in NaCl-stressed seeds. In particular, this study attempts to establish the level at which NaCl stress affects the phytochrome system in lettuce (Lactuca sativa L.) seeds and describes some of the effects of NaCl upon phytochrome-initiated pregermination events. Figure 1 shows the effects of a range of NaCl concentrations on the germination of continuously illuminated lettuce seeds. In water, germination was essentially complete within 24 h. At a concentration of50 mm, NaCl had little effect upon germination, and, after 24 h, the percentage germination was similar to that of the water controls. Higher NaCl concentrations increased the time required for germination, and, in 100 mm NaCl, maximum germination levels were attained 48 h after the start ofimbibition. Above 100 mM NaCl, the delay in the onset of germination was accompanied by reductions in the final germination percentage which decreased as the NaCl concentration increased. At NaCl concentrations of 200 mM and above, no germination was observed within 72 h of the start of imbibition. MATERIALS AND METHODS RESULTSAlthough the seeds become sensitive to saturating light irradiations shortly after the start of imbibition, maximal sensitivity to R develops more slowly (7, 1 1). Figure 2 shows the germination response of seeds exposed to a suboptimal R dose at varying times after the start of imbibition; the seeds were imbibed and germinated in water and 100 mM NaCl. In water, the germination percentage in response to 40-s R progressively increased as the length of the preirradiation period increased; reaching a maximum about 6 h after the start of imbibition. In 100 mM NaCl, maximal sensitivity to 85-s R was attained about 4 h after the start of imbibition. Longer preirradia...

show abstract

Section: Resultsmentioning

confidence: 99%

Interactions between Mild NaCl Stress and Red Light during Lettuce (Lactuca sativa L. cv Grand Rapids) Seed Germination

Scorer¹,

Epel²,

Waisel³

1985

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…These plants were grown in the Phytotron at Gif-sur-Yvette (France) under conditions defined previously (6 10,20,30, and 35°C before irradiation are shown in Figure 1. In absence of a prior dark incubation, the irradiation induced at most 10% germination.…”

Section: Methodsmentioning

confidence: 99%

Effect of Temperature, Oxygen, and Gibberellic Acid on the Development of Photosensitivity in Oldenlandia corymbosa L. Seeds during Their Incubation in Darkness

Corbineau¹,

Côme²

1985

Plant Physiol.

View full text Add to dashboard Cite

Two successive phases can be distinguished in the development of the responsiveness to light in Oldenlandia corymbosa L. seeds during their incubation in darkness. During phase I, the responsiveness to light increases with time if there is sufficient 02, and the higher the temperature, the faster the increase. This phase is stimulated by gibberellic acid. During the following phase (II), seeds remain responsive to light at 10 or 20°C, but lose their responsiveness at higher temperature (-30°C). This second phase depends on 2: loss of responsiveness is accelerated at lower 02 concentration. Phase II is only slightly affected by gibberellic acid. The results are discussed in terms of variation of phytochrome and of a reaction along the transduction chain initiated by phototransformation of this pigment, which is finally expressed in germination.The main characteristics of germination of Oldenlandia corymbosa L. seeds (tropical Rubiaceae) have been described in previous studies (2,6,7,9 Phytochrome is involved in the photosensitivity of 0. corymbosa seeds, but long exposures to white or red light are necessary to ensure germination (9, 10). Moreover, the action of light depends on temperature conditions of the preceding dark incubation (9, 10). The absolute requirement for light is lost in the presence of GA3 at sufficiently high concentrations (above 0.1 mM) (8).The purpose of the present study is to determine the effect of temperature, 02, and GA3 on the development of the responsiveness to light in these seeds during incubation in the dark. MATERIALS AND METHODSThe present study was carried out with O2-insensitive seeds, harvested from plants selected to produce only this type of seed (2). These plants were grown in the Phytotron at Gif-sur-Yvette (France) under conditions defined previously (6). Each germination experiment consisted of three replicates (Petri dishes), each containing 100 to 200 seeds placed on filter paper over a layer of cotton wool imbibed with deionized H20, or with GA3 (Fluka Chemical Co.) solutions at different concentrations. The results were expressed as mean values ± SE. Each experiment was repeated 2 to 3 times with different batches of seeds. Since the results of the repeated experiments were qualitatively the same, but differed somewhat quantitatively, only representative experiments are reported. Treatments in different 02-rich atmospheres were applied using the device perfected by Come and Tissaoui (4). White light (13 ± 0.5 Wm2) was provided by two 16-W Mazdafluor fluorescent tubes (warm white).Experimental procedure was as follows. Seeds were first incubated in darkness for various times, on water or on GA3, in air or in various 02 concentrations and at different temperatures. Then, they were irradiated for 4 h at 35C in air. After irradiation, they were transferred in darkness, in air, at 37°C, and germination percentages were determined 7 d later. A seed was considered to have germinated when its radicle had pierced the seed coat. RESULTSInfluence of Temperature Before ...

show abstract

“…1993), Chamaecytisus palmensis (Townsend & Radcliffe 1990;Douglas et al 1996), Colutea sp. (Roller & Negli 1955;Ceresuela & Pereira 1993), Dorycnium hirsutum and D.…”

Section: Introductionmentioning

confidence: 99%

Chemical composition of some Iberian Mediterranean leguminous shrubs potentially useful for forage in seasonally dry areas

González‐Andrés

Ceresuela

1998

New Zealand Journal of Agricultural Research

View full text Add to dashboard Cite

The chemical composition of herbage produced by legume shrubs was determined to appraise their potential value for forage. Six species were assessed for seasonal variation in the proportion of leaves, and ash content, neutral detergent fibre (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and crude protein (CP) concentrations. Hippocrepis balearica, Medicago citrina, Medicago strasseri, and Medicago arborea showed an average ADF content <25% and an average crude protein content >18%. The chemical composition of Medicago strasseri was very close to that of Medicago arborea throughout the year. In winter and summer, Medicago citrina showed lower ADF and ADL content than Medicago arborea. Therefore, Medicago citrina could be useful as a summer or a winter forage. Hippocrepis balearica showed higher crude protein content in summer and lower ADF content in winter than Medicago arborea, but significantly higher ADL contents (9.7% to 12.5% versus 7.1% to 9.4%). Therefore, Hippocrepis balearica could be a good option as a winter and summer forage, although further studies are necessary to elucidate the possible detrimental effect of lignin in forage digestibility. Coronilla juncea and Cytisus arboreus showed an average ADF content >30% and an average crude protein content <15%. Coronilla juncea showed good chemical composition in winter (28.7% ADF, 9.0% ADL, and 12.6% crude protein) making this species potentially useful as a winter forage.

show abstract

Germination-Regulating Mechanisms in Some Desert Seeds Viii. Artemisia Monosperma1

Cited by 78 publications

References 0 publications

Interactions between Mild NaCl Stress and Red Light during Lettuce (Lactuca sativa L. cv Grand Rapids) Seed Germination

Interactions between Mild NaCl Stress and Red Light during Lettuce (Lactuca sativa L. cv Grand Rapids) Seed Germination

Effect of Temperature, Oxygen, and Gibberellic Acid on the Development of Photosensitivity in Oldenlandia corymbosa L. Seeds during Their Incubation in Darkness

Chemical composition of some Iberian Mediterranean leguminous shrubs potentially useful for forage in seasonally dry areas

Contact Info

Product

Resources

About