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.

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.

scholarly journals Factors affecting Cyperus difformis seed germination and seedling emergence

2013 ◽  
Vol 31 (4) ◽  
pp. 823-832 ◽  
Author(s):  
A. Derakhshan ◽  
J. Gherekhloo
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Factors Affecting ◽  
Cyperus Difformis ◽  
Emergence Patterns

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

scholarly journals Seed germination ecology of Conyza stricta Willd. and implications for management

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244059
Author(s):  
Safdar Ali ◽  
Fakhar Din Khan ◽  
Rehmat Ullah ◽  
Rahmat Ullah Shah ◽  
Saud Alamri ◽  
...  
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Cropping Systems ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Conservation Agriculture ◽  
Weed Species ◽  
Seed Burial ◽  
Germination Ecology ◽  
Tillage Practices

Numerous cropping systems of the world are experiencing the emergence of new weed species in response to conservation agriculture. Conyza stricta Willd. is being a newly emerging weed of barley-based cropping systems in response to conservational tillage practices. Seed germination ecology of four populations (irrigated, rainfed, abandoned and ruderal habitats) was studied in laboratory and greenhouse experiments. The presence/absence of seed dormancy was inferred first, which indicated seeds were non-dormant. Seed germination was then recorded under various photoperiods, constant and alternating day/night temperatures, and pH, salinity and osmotic potential levels. Seedling emergence was observed from various seed burial depths. Seeds of all populations proved photoblastic and required 12-hour light/dark period for germination. Seeds of all populations germinated under 5–30°C constant temperature; however, peak germination was recorded under 17.22–18.11°C. Nonetheless, the highest germination was noted under 20/15°C alternating day/night temperature. Ruderal and irrigated populations better tolerated salinity and germinated under 0–500 mM salinity. Similarly, rainfed population proved more tolerant to osmotic potential than other populations. Seeds of all populations required neutral pH for the highest germination, whereas decline was noted in germination under basic and alkaline pH. Seedling emergence was retarded for seeds buried >2 cm depth and no emergence was recorded from >4 cm depth. These results add valuable information towards our understanding of seed germination ecology of C. stricta. Seed germination ability of different populations under diverse environmental conditions suspects that the species can present severe challenges in future if not managed. Deep seed burial along with effective management of the emerging seedlings seems a pragmatic option to manage the species in cultivated fields. However, immediate management strategies are needed for rest of the habitats.

Factors Affecting Buffalobur (Solanum rostratum) Seed Germination and Seedling Emergence

Weed Science ◽  
2009 ◽  
Vol 57 (5) ◽  
pp. 521-525 ◽  
Author(s):  
Shouhui Wei ◽  
Chaoxian Zhang ◽  
Xiangju Li ◽  
Hailan Cui ◽  
Hongjuan Huang ◽  
...  
Keyword(s):  
Seed Germination ◽  
Light Exposure ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Distribution Area ◽  
Burial Depth ◽  
Weed Species ◽  
Continuous Darkness ◽  
Invasive Weed

Buffalobur is a noxious and invasive weed species native to North America. The influence of environmental factors on seed germination and seedling emergence of buffalobur were evaluated in laboratory and greenhouse experiments. The germination of buffalobur seeds occurred at temperatures ranging from 12.5 to 45 C, with optimum germination attained between 25 and 35 C. Buffalobur seeds germinated equally well under both a 14-h photoperiod and continuous darkness; however, prolonged light exposure (≥ 16 h) significantly inhibited the seed germination. Buffalobur seed is rather tolerant to low water potential and high salt stress, as germination was 28 and 52% at osmotic potentials of −1.1 MPa and salinity level of 160 mM, respectively. Medium pH has no significant effect on seed germination; germination was greater than 95% over a broad pH range from 3 to 10. Seedling emergence was higher (85%) for seeds buried at a soil depth of 2 cm than for those placed on the soil surface (32%), but no seedlings emerged when burial depth reached 8 cm. Knowledge of germination biology of buffalobur obtained in this study will be useful in predicting the potential distribution area and developing effective management strategies for this species.

Environmental factors affect seed germination and seedling emergence of invasive Centaurea balsamita

2017 ◽  
Vol 68 (6) ◽  
pp. 583 ◽  
Author(s):  
Iraj Nosratti ◽  
Samira Soltanabadi ◽  
Saeid J. Honarmand ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Potassium Nitrate ◽  
Weed Species ◽  
Invasive Weed ◽  
Western Iran ◽  
Temperature Regimes ◽  
Wide Range

Centaurea balsamita is a problematic and invasive weed of agricultural fields in western Iran. This study was conducted to determine the effect of different environmental factors on germination and seedling emergence of this weed species. Results revealed that seed germination occurred over a wide range of temperatures (from 5°C to 35°C) with the highest germination at 25°C. Seed germination of C. balsamita was similar between light and dark conditions. Germination decreased with increased in water stress levels, but some seeds were capable of germinating at –1.4 MPa osmotic potential. Seed germination was sensitive to salt stress and complete inhibition occurred at 150 mM sodium chloride. Seed germination of C. balsamita occurred over a pH range of 4–10 with lowest seed germination at pH 4. Seed germination was inhibited by increasing concentrations of potassium nitrate. No seedlings emerged when seeds were buried in the soil at depths greater than 6 cm, suggesting that using a sweep cultivator in crops and deep tillage would be beneficial in managing C. balsamita. The ability of C. balsamita to germinate under a wide range of temperature regimes and high levels of osmotic potential shows that this weed is well adapted to invade other cropping regions, especially rain-fed fields in western Iran.

THE EFFECT OF SOIL WATER POTENTIAL, TEMPERATURE AND SEEDING DEPTH ON SEEDLING EMERGENCE OF WHEAT

1979 ◽  
Vol 59 (3) ◽  
pp. 259-264 ◽  
Author(s):  
R. DE JONG ◽  
K. F. BEST
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Minimum Temperature ◽  
Seedling Emergence ◽  
Potential Temperature ◽  
Soil Water Potential ◽  
Triticum Aestivum L ◽  
Planting Dates ◽  
Water Potentials ◽  
Soil Temperatures

Daily emergence counts were made on Canthatch wheat (Triticum aestivum L.) grown in five soil types, at four soil temperatures and three water potentials and planted at five different depths. Regardless of soil type, soil water potential or depth of planting, 50% emergence generally occurred within a week at 19.4 and 26.7 °C, and within 2 wk at 12.2 °C, but it took up to 6 wk at 5 °C. The heat sum required to attain 50% seedling emergence did not increase significantly with decreasing soil water potentials, but the minimum temperature for emergence dropped from 1.3 to 0.2 °C as the water potential decreased from −⅓ to −10 bar. It was suggested that the seedlings compensated for the increased water stress by lowering their minimum temperature requirements. Increasing the planting depth not only increased the heat requirement for emergence, but it also increased the variability of emergence, especially at low temperatures. Practical aspects concerning planting dates and depths were considered.

Redistribution of water following precipitation on previously dry sandy soils

Soil Research ◽  
1975 ◽  
Vol 13 (1) ◽  
pp. 13 ◽  
Author(s):  
BA Carbon
Keyword(s):  
Soil Water ◽  
Seedling Emergence ◽  
Soil Water Potential ◽  
Sandy Soils ◽  
Soil Surface ◽  
Field Capacity ◽  
Wetting Front ◽  
Applied Water ◽  
Dry Soil ◽  
The Relationship

Theoretical and experimental evidence is provided to show that the redistribution of a given amount of water some days after infiltration into a previously dry soil can be predicted, provided that the relationship between soil water potential and soil water content is known. The capillary potential at the wetting front during infiltration into the dry soil is also required. In sandy soils an increase in amount of applied water leads to a decrease in the soil moisture content at the soil surface. This change in 'field capacity' as a function of applied water is shown to strongly influence seedling emergence.

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).

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