A Possible Ecological Relation Between Soil Disturbance, Light‐Flash, and Seed Germination

Sauer, Jonathan D.; Struik, Gwendolyn J.

doi:10.2307/1934942

Cited by 89 publications

(57 citation statements)

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“…A few flasks of seeds were also incubated at -10 and -12 bars, and 5.1 and 51,ul/l ethylene, to determine whether the gas can cause some germination under such severe stress. We also examined the ethylene-water potential interaction in continuous white light (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30),tE/m2. s).…”

Section: Methodsmentioning

confidence: 99%

“…Because buried seeds are extremely hard to kill, efforts are directed mainly toward identifying and manipulating the environmental factors that control their germination and emergence. Soil temperature and water status play key roles, and brief exposure to light during plowing can promote germination (25,34) but the patterns of weed emergence are poorly understood. Ethylene has received increasing attention both as an endogenous or exogenous stimulant of seed germination, and as a potential tool in weed control.…”

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confidence: 99%

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Effects of Temperature, Water Potential, and Light on Germination Responses of Redroot Pigweed Seeds to Ethylene

Schonbeck

Egley²

1980

Plant Physiol.

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The responses of redroot pigweed (Amaranthus retrojixus L.) seeds to nine ethylene concentrations between 0.5 and 50 microlters per liter were assessed at different temperatures and water potentials and in either continuous white ight or darkness. Under all experimental treatments, the probit-transformed percentages increased inearly with the log of the ethylene concentration. In dormant seeds, the slope of the response line was unaffected by either light or water potential but increased with decreasing temperature. Conversely, the sope increased with increasing temperature in a partiaBy afterripened seed lot.The ethylene response threshold for germination was little affected by temperature or light, ranging from 0.2 to 0.7 microliter per liter, but decreased to less than 0.1 microliter per liter at negative water potentials. One of the main targets in weed research is the enormous reservoir ofviable dormant weed seeds present in agricultural soils (34), which escape mechanical and chemical weed control. Because buried seeds are extremely hard to kill, efforts are directed mainly toward identifying and manipulating the environmental factors that control their germination and emergence. Soil temperature and water status play key roles, and brief exposure to light during plowing can promote germination (25, 34) but the patterns of weed emergence are poorly understood. Ethylene has received increasing attention both as an endogenous or exogenous stimulant of seed germination, and as a potential tool in weed control. MATERIALS AND METHODSRedroot' pigweed seeds were collected near the Delta Branch Experiment Station at Stoneville, Mississippi, in 1973 (seed lot A) or 1977 (seed lot C) and kept in dry storage at -20 C. Both lots showed 99%o viability in tetrazolium (2, 3,5-triphenyltetrazolium chloride) tests. Seeds of lot A showed 15-20% dark germination at 30 C whereas seeds from the more dormant lot C showed only 0-2%.For each replicate, 50 sound seeds were counted onto two 1-x 3-cm strips of blotter paper moistened with distilled H20. The blotter strips were inserted into a 250-ml Erlenmeyer flask containing a 6-cm disc of blotter paper moistened with 5 ml distilled H20. The flask was closed with a serum cap through which ethylene was injected to give a known concentration within the flask. Immediately after injection, the flasks were placed in an incubator that maintained the desired temperature to within ± 1 C.Unless otherwise specified, seeds were incubated in darkness, receiving at most a brief exposure to a green safelight.Preliminary work showed that in either seed lot germination (defined as protrusion of the radicle through the seed coat) occurred within 7 days at 15 or 20 C or at -2 to -8 bars water potential, and within 3 days at 0 bars and at 25 C or higher. Thereafter, little further germination took place. Because seedlings occasionally decayed during longer incubations at high temperatures, germination was recorded after 3 days unless experimental conditions necessitated the 7-day incubation...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Effects of Temperature, Water Potential, and Light on Germination Responses of Redroot Pigweed Seeds to Ethylene

Schonbeck

Egley²

1980

Plant Physiol.

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“…Dormant seeds, brought close to the surface by cultivation, could receive light, either directly during cultivation or later through the soil, and could therefore germinate. Experiments have tended to confirm this hypothesis (3,7,10,12). Still, there has been no attempt to measure light penetration into soil or to find out how near a seed must be to the surface to be affected.…”

Section: Introductionmentioning

confidence: 99%

Light Penetration and Light-induced Seed Germination in Soil

Woolley¹,

Stoller²

1978

Plant Physiol.

207

122

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Light penetration through a Drummer silty clay loam and a Broomfield sand was measured spectrophotometrically and biologically. The spectrophotometric measurements showed that less than 1% of the incident fight penetrated 2.2 millimeters at any wavelength between 350 and 780 nanometers for ped sizes up to 1 milimeter. Biological measurements with lightsensitive lettuce (Lactuca sativa) seeds In soil showed that an exposure to Ught equivalent to about I sunny day induced some germination of seeds which were 2 milmeters below the surface, but did not affect seeds 6 millimeters below the surface.The known light sensitivity of many seeds (11) has led to the hypothesis that light may be important in inducing the germination of weed seeds in cultivated fields. Dormant seeds, brought close to the surface by cultivation, could receive light, either directly during cultivation or later through the soil, and could therefore germinate. Experiments have tended to confirm this hypothesis (3,7,10,12). Still, there has been no attempt to measure light penetration into soil or to find out how near a seed must be to the surface to be affected. Nor has there been an attempt to consider the role of temperature in such germination, even though light sensitivity of seeds is known to be highly dependent on temperature (1-3, 6, 10, 11). We therefore measured light penetration through soil spectrophotometrically and also biologically, controlling temperature, and using light-sensitive lettuce seeds buried in the soil as our bioindicator. At temperatures below about 20 C, Grand Rapids lettuce (Lactuca sativa L.) seeds do not require light treatment for germination, and will germinate when allowed to imbibe water. At higher imbibition temperatures, some of the seeds will germinate without light, but others need a light treatment for germination. At field sand. The Drummer soil, when dry, is dark gray with a Munsell color notation of 5YR 4/1, and when moist is black (5YR 2.5/1). The two Drummer ped sizes, 0.42 to 0.50 mm and 0.84 to I mm, were separated by sifting. This soil maintains the integrity of its aggregates well through wetting and drying cycles. Dry Broomfield sand is yellowish brown (IOYR 5/4), and the moist sand is dark yellowish brown (IOYR 3/4). The sand grain size range was 0.3 to 0.5 mm.To determine light transmittance spectrophotometrically, we used a Beckman DK-2A spectroreflectometer, with soil samples in acrylic plastic cuvettes.To determine light transmittance through soils biologically, we placed light-sensitive lettuce seeds at various depths in the soils, then exposed the soils to light. Subsequent germination of the seeds indicated light penetration into the soil.In the preliminary experiment to determine the exact characteristics of our seeds and to establish the optimum temperature, time, and light regimes, we cultured seeds in Petri dishes, which were kept dark at the desired inbibition and incubation temperature for the desired time, then exposed to light and again placed in the dark at a desired tem...

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“…Germination of these buried weed seeds occurs when the soil containing the seed is disturbed (9,13,14) and causes a continuing problem for agriculturists. The germination of many buried weed seeds is dependent on exposure to light (9,13,14), specifically red light involving the phytochrome system (4,5,12).…”

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confidence: 99%