Soil water thresholds for photoinduction of redroot pigweed germination

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 414-418 ◽  
Author(s):  
Robert S. Gallagher ◽  
John Cardina
Keyword(s):  
Seed Germination ◽  
Soil Water ◽  
Light Stimulus ◽  
Seedling Emergence ◽  
Red Light ◽  
Soil Disturbance ◽  
Redroot Pigweed ◽  
Seed Population ◽  
Potential Gradients ◽  
Water Contents

Perception of light by phytochrome is a mechanism that triggers weed seed germination in response to soil disturbance. Photoconversion of phytochrome from the red light absorbing form to the active far-red absorbing form depends on hydration of phytochrome. This research was conducted to determine the soil water threshold for the photoinduction of germination by the brief exposure of light that occurs during soil disturbance, and to determine how this threshold is affected by the fluence of the light stimulus and fluence sensitivity of the seed population. Redroot pigweed seedling emergence and germination response to red light (R) was studied for a range of water potentials. Water potential gradients were established by incubating seeds in soils wetted to various water contents, or in polyethylene glycol 8000 (PEG) solutions. After imposing the light treatments, seeds were returned to a fully hydrated state. Seedling emergence in response to R increased as the volumetric water content (θv) of soils increased. At volumetric water contents of 4.0%, R-induced seedling emergence was inhibited 50% compared to photoinduced seedling emergence at the highest soil water contents tested. Attenuation of photoinduction was more pronounced at low vs. high R fluences in freshly imbibed seeds, but was unaffected in seeds that exhibited enhanced fluence sensitivity. In ecosystems where seasonal soil moisture extremes are prevalent, the photoinduction of seed germination may be limited in dry microsites such as surface crusts or under extreme drought conditions.

Water constraints on the photoinduction of weed seed germination during tillage

2000 ◽  
Vol 27 (5) ◽  
pp. 463 ◽  
Author(s):  
Javier F. Botto ◽  
Ana L. Scopel ◽  
Rodolfo A. Sánchez
Keyword(s):  
Seed Germination ◽  
Soil Water ◽  
Seedling Emergence ◽  
Red Light ◽  
Soil Water Potential ◽  
Laboratory Data ◽  
Soil Disturbance ◽  
Light Signal ◽  
Weed Species ◽  
Night Time

Germination of light-requiring seeds may be induced by very brief exposure to sunlight during soil disturbance through the very-low fluence (VLF) mode of phytochrome action. We studied the effect of soil water availability after cultivation on the photoinduction of seed germination in two important weed species, Datura ferox andChenopodium album. In daily-irrigated plots, seedling density was 1- to 4-fold greater in plots cultivated during daytime than in those tilled at night. In contrast, when plots were not irrigated soon after tillage and rainfall was excluded, no significant differences were observed between seed germination in daytime vs night-time cultivated plots, although seedling emergence in night-time cultivated plots was higher than in non-cultivated controls. The average critical value of soil water potential required for the expression of VLF-induced germination was higher than –0.5 MPa (at 3-cm depth during the 6 d following cultivation). Dark germination was less sensitive to decreasing soil moisture than light-induced seed germination. The promotive effect of the light signal perceived by the seeds during daytime cultivation is maintained for several days (ca 6) in drying soil, even though laboratory data suggest that the far-red-light absorbing form of the phytochrome inducing the VLF photoresponse is unstable, disappearing in less than 24 h. These results reveal the complexity of interactions between the light signal and other environmental factors that control seed germination under natural conditions.

Stimulation of Common Cocklebur (Xanthium pensylvanicum) and Redroot Pigweed (Amaranthus retroflexus) Seed Germination by Injections of Ethylene into Soil

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 510-514 ◽  
Author(s):  
G. H. Egley
Keyword(s):  
Seed Germination ◽  
Laboratory Tests ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Plastic Bags ◽  
Viable Seeds ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Stimulation Of

The effects of ethylene upon germination of common cocklebur (Xanthium pensylvanicumWallr.) and redroot pigweed (Amaranthus retroflexusL.) seeds were studied. In laboratory tests with seeds in sealed flasks in the dark, 10 μl/L ethylene increased germination of redroot pigweed seeds from 7% to 52% at 30 C, and increased germination of large and small common cocklebur seeds from 30% and 0% to 100% and 90% respectively, at 25 C. At least 12 h of exposure to ethylene was necessary for appreciable stimulation of germination. In growth chamber studies with known numbers of seeds in pots of soil, ethylene at 11 kg/ha was injected into the soil, and the pots were enclosed in plastic bags for 24 h. One such injection at 2 weeks after planting, and successive injections at 2, 3, and 4 weeks, significantly increased redroot pigweed seedling emergence, and significantly decreased the numbers of dormant, viable seeds remaining in the soil. When pots were not enclosed, injections did not significantly effect redroot pigweed seeds, but significantly increased common cocklebur seedling emergence and decreased the number of viable common cocklebur seeds remaining in the soil.

Increased weed emergence and seed bank depletion by soil disturbance in a no-tillage system

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 234-241 ◽  
Author(s):  
Dawit Mulugeta ◽  
David E. Stoltenberg
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Soil Disturbance ◽  
No Tillage ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Tillage System ◽  
Level Of Aggregation ◽  
Viable Seeds

The influence of secondary soil disturbance on the emergence pattern and seed bank depletion of an annual weed community in a long-term, no-tillage corn cropping system was determined in 1992 and 1993. As a component of this research, the seed bank was characterized prior to implementation of soil disturbance treatments. The seed bank was initially composed of common lambsquarters, redroot pigweed, and giant foxtail, with approximately 55, 36, and 8% of the total viable seeds, respectively. The remaining 1% was comprised of five other species in 1992 and eight in 1993. The spatial distribution of viable seeds of each species, except common lambsquarters and redroot pigweed, was described by a negative binomial distribution. Three dispersion indices indicated that seeds of individual and total weed species were aggregated and that the level of aggregation of viable seeds of a species was associated with seed density; at lower seed densities, the level of aggregation was greater. Soil disturbance increased common lambsquarters emergence 6-fold in 1992 relative to nondisturbed soil, but did not influence emergence in 1993. Rainfall was about 50% less in 1993. In contrast, soil disturbance increased giant foxtail and redroot pigweed emergence approximately 6- and 3-fold in 1992 and 1993, respectively. Seedling emergence associated with soil disturbance, relative to nondisturbed soil, increased seed bank depletion of common lambsquarters 16-fold in 1992, and giant foxtail and redroot pigweed and average of 6- and 3-fold in 1992 and 1993, respectively. These results indicated that soil disturbance increased seedling emergence and seed bank depletion of the predominant species in the weed community of a long-term, no-tillage system, but that this response was dependent on rainfall for common lambsquarters.

Seed stratification and germination strategy in the Mediterranean pines Pinus brutia and P. halepensis

1995 ◽  
Vol 5 (3) ◽  
pp. 151-160 ◽  
Author(s):  
Antonis Skordilis ◽  
Costas A. Thanos
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Red Light ◽  
Pinus Brutia ◽  
Temperature Range ◽  
Promotive Effect ◽  
Germination Behaviour ◽  
Mediterranean Pine ◽  
Of Greece

AbstractThe ecophysiology of germination in Pinus brutia and P. halepensis was studied in seeds collected from different areas of Greece. In regard to the temperature range of germination, both P. halepensis and the southern provenance (Lasithi, Crete) of the East Mediterranean pine, P. brutia, follow a typical Mediterranean pattern. In the latter species, dramatic differences in the degree of dormancy were noted among the three provenances investigated; in all seed lots however, 20°C was clearly the optimal temperature for germination. Stratification resulted in a considerable promotion of P. brutia seed germination. Nevertheless, the inductive effect of stratification was shown to differ among the three provenances used, escalating from a simple increase of germination rate (in the southern seed lot from Lasithi, Crete) through a broadening of the temperature range of germination (in the intermediate lot from Thasos Island) to, finally, a dramatic release from a particularly deep dormancy (in the northern lot from Soufli). These deeply dormant seeds of the latter provenance displayed an absolute stratification requirement; prolonged illumination or seed coat scarification could not substitute for the promotive effect of prechilling. A considerable interaction between far-red light and stratification was revealed in the dormant seeds of P. brutia (Soufli provenance); far-red pulses during stratification could either cancel or diminish the germination promotion induced by low temperatures. The differences observed in the germination behaviour among the various P. brutia provenances may be attributed to a variable ecophysiological strategy in regard to the temporal pattern of seedling emergence and establishment. According to the variants of this strategy, seed germination is timed to occur during either spring (in regions with relatively cold and moist climates), or autumn and early winter (in southern, mild and dry areas) or both (in intermediate conditions).

scholarly journals Evaluation of Mugwort (Artemisia vulgaris L.) Aqueous Extract as a Potential Bioherbicide to Control Amaranthus retroflexus L. in Maize

Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 642
Author(s):  
Euro Pannacci ◽  
Marco Masi ◽  
Michela Farneselli ◽  
Francesco Tei
Keyword(s):  
Seed Germination ◽  
Bioactive Compounds ◽  
Aqueous Extract ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Herbicidal Activity ◽  
Artemisia Vulgaris ◽  
Hypocotyl Length ◽  
Allelopathic Activity ◽  
Redroot Pigweed

The allelopathic plant extracts can be applied as soil or foliar bioherbicides and are capable of suppressing germination and growth of several weeds, some of which are herbicide resistant. This study evaluated the allelopathic activity of the aqueous extract of aerial biomass of mugwort (Artemisia vulgaris L.) on seed germination and seedling growth of redroot pigweed (Amaranthus retroflexus L.) and maize (Zea mays L.), in order to be applied as a potential bioherbicide. The aqueous extract of mugwort was qualitatively examined for the presence of bioactive compounds and it was applied in a Petri dish and pot bioassays quantifying its effects on redroot pigweed and maize by non-linear regression analyses according the log-logistic model. The aqueous extract of mugwort showed the presence of several bioactive compounds with allelopathic activity, such as polysaccharides, organic acids, flavonoids and terpenoids. The aqueous extract of mugwort, at the concentrations from 7.5% to 10% w/v, were found to be the optimal concentration range since it is able to inhibit seed germination, seedling emergence and plant growth of redroot pigweed, without affecting seed germination and seedling emergence of maize, or rather, stimulating its radicle, mesocotyl and plant’s growth. EC90 values for the seed germination, radicle and hypocotyl length of redroot pigweed were in the order: 6.1% and 8.1%, 3.2% and 6.2%, 3.8% and 5.7% w/v of aqueous extract in the two repeated bioassays, respectively. Due to potential herbicidal activity against weeds and biostimulant action on the crops, this extract could be the ideal solution in an integrated weed management program, in order to suppress weeds, increasing competitive ability of crops.

The effect of light during and after soil cultivation with different tillage implements on weed seedling emergence

Weed Science ◽  
1998 ◽  
Vol 46 (3) ◽  
pp. 351-357 ◽  
Author(s):  
Javier F. Botto ◽  
Ana L. Scopel ◽  
Carlos L. Ballaré ◽  
Rodolfo A. Sánchez
Keyword(s):  
Seed Germination ◽  
Light Stimulus ◽  
Seedling Emergence ◽  
Soil Cultivation ◽  
Primary Tillage ◽  
Microenvironmental Factors ◽  
Chisel Plow ◽  
Effect Of Light ◽  
Moldboard Plow

The purpose of this study was to investigate the role of sunlight perceived by weed seeds during and after soil cultivation with moldboard and chisel plows on induction of seed germination. Daytime cultivation with a moldboard plow increased weed seedling emergence by as much as 200% above the levels recorded following nighttime cultivation; however, the magnitude of this promotion varied depending on season and field history, and occasionally it was nil. In contrast, when a chisel plow was used in primary tillage, no differences in seedling emergence were observed between daytime and nighttime cultivation. The absolute germination level in plots cultivated with a chisel plow was at least 200% greater than in plots cultivated with a moldboard plow. This observation suggests that microenvironmental factors other than light played an important role in promoting seed germination in chisel-plowed plots. Covering moldboard-plowed plots with opaque plastic immediately after cultivation did not reduce weed seedling emergence compared to plots that were either covered with transparent film or left uncovered. Our results suggest that only the light stimulus perceived by the seeds during soil cultivation is effective in triggering germination.

ECOPHYSIOLOGY OF SEED GERMINATION IN ENDEMIC LABIATES OF CRETE

1995 ◽  
Vol 43 (3) ◽  
pp. 227-237 ◽  
Author(s):  
Costas A. Thanos ◽  
Maria A. Doussi
Keyword(s):  
Seed Germination ◽  
Slow Rate ◽  
Narrow Range ◽  
Seedling Emergence ◽  
Red Light ◽  
Significant Inhibition ◽  
Light Conditions ◽  
Salvia Fruticosa ◽  
Intermediate Response ◽  
Alpine Distribution

Ecophysiological aspects of seed germination were investigated in four aromatic labiate plants of Crete Origanum dictamnus (dittany), Sideritis syriaca L. ssp. syriaca (Cretan mountain tea), Salvia pomifera L. ssp. pomifera (gall-bearing sage), and Salvia fruticosa (three-lobed sage). Experiments were performed both at constant temperatures and darkness as well as under temperature and light conditions simulating those prevailing in nature during the main germination periods (i.e., start and middle of the rainy season, November and February-March, respectively). In three out of the four species, no particular dormancy was revealed and germination occurred rather promptly, although in a rather narrow range of cool temperatures and at a relatively slow rate; both characteristics determine and/or support an early, autumn seed germination and seedling establishment. In the fourth plant, Sideritis syriaca, germination was manifested at relatively warm temperatures and at a considerably faster rate, in accordance with its alpine distribution favoring spring seedling emergence and establishment. All four species tested showed an intermediate response towards light, as a result of their intermediate levels of active phytochrome maintained in darkness. Therefore seed germination was partially manifested in darkness but it was significantly enhanced (particularly at suboptimal temperatures) by white or red light; on the other hand, illumination with far-red light (simulating light conditions under a canopy) resulted in significant inhibition compared to dark controls.

scholarly journals Cranberry Germination and Emergence Response to Environmental Factors and Seeding Depth

HortScience ◽  
2021 ◽  
pp. 1-8
Author(s):  
Thierry E. Besançon
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Red Light ◽  
Soil Surface ◽  
Average Maximum ◽  
Fruit Productivity ◽  
Diurnal Temperatures ◽  
Residual Herbicide ◽  
Over Time

Cranberry (Vaccinium macrocarpon Ait.) cultivars are clonally propagated. Germination of cranberry seeds produces off-type varieties that are generally characterized by lower fruit productivity and higher vegetative vigor. Over time, the productivity of cranberry beds decreases as off-type frequency increases over time. Improved knowledge of cranberry germination biology would facilitate the use of targeted agronomic practices to reduce the emergence and growth of less productive off-types. The influences of light, temperature regime, pH, and water potential on cranberry seed germination were assessed in a growth chamber, whereas the effect of seeding depth on seedling emergence was evaluated in a greenhouse. Seeds stratified for 6 months at 3 °C were used for these experiments. Cranberry germination was influenced by light quality, with maximum germination reaching 95% after 15 minutes of exposure to red light but decreasing to 89% under far-red light. However, light was not required for inducing germination. Cranberry seeds germinated over a range of alternating diurnal/nocturnal temperatures between 5 and 30 °C, with an average maximum germination of 97% occurring for diurnal temperatures of 20 to 25 °C. The length of emerged seedlings was reduced by an average of 75% for pH 6 to 8 compared with pH 3 to 5. Seedlings that emerged at pH greater than 5 showed increasing chlorotic and necrotic injuries and were not considered viable at pH 7 or 8. Germination at 15 °C was reduced when seeds were subjected to water stress as low as −0.2 MPa, and no germination occurred below −0.4 MPa. Seeds incubated at 25 °C were more tolerant to water stress, with at least 70% maximum germination for osmotic potential (ψS) −0.6 MPa or greater. The average seedling emergence was 91% for seeds left on the soil surface or buried at a maximum depth of 1 cm; however, it was null at a burying depth of 4 cm. These results indicate that germination of cranberry seeds in cultivated beds in the northeastern United States likely occurs during the summer months, when temperatures are optimal and the moisture requirement is supported by irrigation. However, timely application of residual herbicide or sanding (a traditional cranberry agronomic practice) of open areas in cranberry beds could help prevent seed germination and reduce minimizing the onset of off-type varieties.

Very low fluence and low fluence response in the induction and inhibition of seed germination in Celosia argentea

1996 ◽  
Vol 6 (2) ◽  
pp. 43-48 ◽  
Author(s):  
Sanjay Dixit ◽  
Dilip Amritphale
Keyword(s):  
Seed Germination ◽  
Gradual Increase ◽  
Red Light ◽  
Response Mode ◽  
Light Irradiation ◽  
Considerable Proportion ◽  
Germination Inhibition ◽  
Absolute Requirement ◽  
Seed Population ◽  
Celosia Argentea

AbstractSeeds of Celosia argentea L. displayed an absolute requirement for light for germination. Germination could be induced by far-red light as well as red light, and therefore, the effect of red light was not completely reversible by far-red light. A considerable proportion of the seed population was sensitive to red light within the range 0.01–0.1 μmol m−2, which suggested that phytochrome was operating in the very low fluence response mode. Seeds showed a gradual increase in germination in response to red light with an increasing duration of previous dark imbibition. Interruption of the dark imbibition period with very low fluence (10−4−10–1 μmol m−2) or low fluence (1–103 μmol m−2) red light prevented germination subsequent to a terminal, saturating red light irradiation. Increasing responsiveness to red light with increase in imbibition temperature and inhibition of development of photosensitivity by cycloheximide suggested that phytochrome synthesis occurred during the dark imbibition period. An absolute requirement for light for seed germination, inhibition of seed germination on interrupting the dark imbibition period with very low fluence or low fluence red light, and the recovery from photoinhibition of seeds in darkness are consistent with the hypothesis that PhyA is the principal phytochrome involved in the photoregulation of seed germination in C. argentea.

Effect of inter-row cultivation on soil carbon dioxide emission in a peach plantation

2010 ◽  
Vol 59 (1) ◽  
pp. 157-164 ◽  
Author(s):  
E. Tóth ◽  
Cs. Farkas
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Carbon Dioxide Emission ◽  
Nutrient Content ◽  
Soil Disturbance ◽  
Biological Properties ◽  
Soil Tillage ◽  
Favourable Effect ◽  
Volumetric Soil Water Content

Soil biological properties and CO2emission were compared in undisturbed grass and regularly disked rows of a peach plantation. Higher nutrient content and biological activity were found in the undisturbed, grass-covered rows. Significantly higher CO2fluxes were measured in this treatment at almost all the measurement times, in all the soil water content ranges, except the one in which the volumetric soil water content was higher than 45%. The obtained results indicated that in addition to the favourable effect of soil tillage on soil aeration, regular soil disturbance reduces soil microbial activity and soil CO2emission.

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