Showing papers on "Germination published in 1972"

Volatile metabolites controlling germination in buried weed seeds.

Abstract: Velvetleaf (Abutilon theophrasti Medic), morning glory (Ipomoea purpurea [L.] Roth), and wild mustard (Brassica kaber [D.C.] L. C. Wheeler) seeds exhibited decreased germination with increased planting depth in soil. Flushing the soil for 2 minutes each day with air overcame the inhibition. A sealed in vitro system was used to sample the volatile components produced by weed seeds. Inhibition of seed germination was accompanied by decreased O2 levels and production of volatile metabolites identified as acetaldehyde, ethanol, and acetone. The effectiveness of these compounds in reducing germination was dependent on O2 levels.

Allelopathic Mechanisms of Arctostaphylos glandulosa var. zacaensis

Abstract: Arctostaphylos glandulosa var. zacaensis is a strong dominant of chaparral vegetation on Zaca Ridge in the San Rafael Mountains, California. It occurs in pure stands, sometimes openly spaced with the canopies covering 50 to 75% of the soil surface, or it may form completely closed cover. A barren soil surface, without seed- lings of any species in spite of sufficient light and soil moisture, char- acterizes the stands. Fire or artificial removal of shrubs results in growth of herbs and shrub seedlings until shrub dominance is again established. Detrimental biochemical interference (allelopathy) between Arcto- staphylos and associated plants is involved in this phenomenon. Aqueous leachate from Arctostaphylos foliar branches and from leaf litter is toxic to the growth of annual grasses. The allelopathic constituents leachable from Arctostaphylos plant organs have been identified as arbutin, hydro- quinone, and gallic, protocatechuic, tannic, vanillic, chlorogenic and p-hydroxybenzoic acids. Toxins such as p-hydroxybenzoic, p-coumaric, ferulic, syringic and o-coumaric acids are found in the soils beneath Arctostaphylos shrubs. These toxins can inhibit the germination and suppress the radicle growth of herbaceous plants at concentrations below 400 ppm; e.g., hydroquinone significantly inhibits radicle growth of Avena fatua and Bromus rigidus at a concentration of 50 ppm. Chem- ical constituents present in leaf litter appear to be more leachable after subjection to temperatures up to 160 C-resulting in increases of toxic- ity to herb growth-but are denatured at temperatures above 180 C, with complete loss of toxicity at temperatures above 200 C. Allelopathy

Germination and Seedling Development of Common Milkweed and Other Species

Abstract: Common milkweed (Asclepias syriaca L.) seed did not survive storage in water for 1, 2, and 12 months at 40, 30, and 5 C, respectively; but under dry storage seed viability was destroyed only at 40 C for 5 months. Stratifying common milkweed seed in water at 5 C was more effective in breaking dormancy than at 22 C. Mechanical scarification also caused a significant increase in germination. Exogenous 6-furfurylamino purine (kinetin) and gibberellic acid-3 (GA) increased germination while indole-3-acetic acid (IAA) had no effect. The optimum germination temperature scheme for common milkweed was an alternating 20 to 30 C, the maximum between 35 and 40 C, and the minimum between 15 and 20 C. Common milkweed seedlings were more susceptible to moisture stress than kochia [Kochia scoparia (L.) Schrad.] but less susceptible than hemp dogbane (Apocynum cannabinum L.) and sunflower (Helianthus annuus L.). In a greenhouse study common milkweed was less drought tolerant than eight other weed species. Common milkweed seedlings tolerated wider pH ranges than honeyvine milkweed [Ampelamus albidus (Nutt.) Britt.], kochia, and sunflower. Common milkweed seedlings were less tolerant to salt solutions than four other species. Common milkweed emerged from 6-cm depths in Sharpsburg silty clay loam (sicl) at 20 or 30 C but only from the 3-cm depth at an alternating 20 to 30 C. Results from root box studies showed that common and honeyvine milkweed produced less shoot and root weight than kochia and sunflower and had a lower growth rate index of roots than sunflower. Common milkweed seedlings resprouted 21 days after planting when clipped at ground level. As days from planting to clipping increased, sprouting activity increased.

Growth regulation by ethylene in fern gametophytes. iii. inhibition of spore germination

Abstract: Spores of Onoclea sensibilis were investigated for inhibition of germination by ethylene. A curve of germination against ethylene concentration indicated a "threshold" type of response, but percentage of spore germination was not influenced either by the density of the inoculum or by the presence of 1 % sucrose in the culture medium. Ethylene totally inhibited dark germination, but in white light reversal of inhibition was possible in about 50% of the germinating spores. Time-course studies revealed that in imbibed spores ethylene inhibited germination in the first 3 + 1 hr of illumination. Dose-response curves of light intensity vs. germination indicated that the response to light differed in the presence and absence of ethylene. Recovery from inhibition was possible once ethylene was allowed to escape, and the rate of recovery was accelerated by light. THE INHIBITORY EFFECT of ethylene on cell division in ferns was first reported in dark-grown, filamentous (1-D) gametophytes of the sensitive fern Onoclea sensibilis L. (Miller, Sweet, and Miller, 1970). The ethylene inhibition of cell division was examined in greater detail in lightgrown, multicellular, prothallial (2-D) gametophytes, and ethylene was found to inhibit the rate of increase of cell number by about one-half (Edwards and Miller, 1970, 1972). The multicellular prothallia of fern gametophytes consist of cells in different stages of growth and division, but germinating unicellular spores are a synchronously dividing population of cells. Germination of spores of 0. sensibilis involves an initial asymmetrical cell division which partitions the spore into a small rhizoidal initial and a much larger protonemal cell. The effects of ethylene on this process were examined briefly (Miller et al., 1970) and have now been much more extensively investigated. By determining the effects of ethylene on synchronously dividing spores we hoped to characterize better the inhibition of cell division by ethylene. MATERIALS AND METHODS-Germination of spores of 0. sensibilis was initiated by sowing the spores on Knop's solution, placing them in a temperature-controlled growth chamber, and irradiating with white fluorescent light for 24 hr 1 Received for publication 13 September 1971. This paper represents a portion of a thesis submitted as partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biology, Syracuse University. We wish to thank Mrs. Else Cooperrider and Dr. Pauline M. Miller for their development of the staining technique used to determine spore germination. The work was supported by grant GB-13118 from the National Science Foundation. 2 Present address: Department of Biology, The University of Tennessee at Chattanooga 37401. (Miller and Miller, 1961 ). The procedures were similar to those previously described (Miller et al., 1970; Edwards and Miller, 1972). Fertile fronds of 0. sensibilis were collected in 1968 near Syracuse, New York. Spores from a single frond were utilized throughout the study; they were sterilized, and from 300-500 were incubated on the surface of 10 ml Knop's solution either in aluminumcapped, 25 x 100 mm, specimen tubes or screwcapped, 25 x 100 mm, specimen tubes (Miller et al., 1970). All experiments were performed in duplicate. The culture medium was adjusted to pH 5.2 and was sterilized by autoclaving for 10 min at 15 lb. Early experiments included 1 % sucrose in the medium, but after observing that sucrose did not affect the percentage of spore germination, the inclusion of sucrose was abandoned. During autoclaving and subsequent culturing of unsealed control cultures, tubes were covered with solid aluminum caps. The loose-fitting aluminum caps allowed gaseous exchange, whereas the silicone-rubber-lined screw caps provided an air-tight seal. Screw caps were sterilized by exposure for 10 min to UV light in a sterile transfer chamber. Experimental cultures were sealed immediately following inoculation, and 1 iul/liter of ethylene was injected with a hypodermic syringe. In all experiments 1 1Al/liter of ethylene was used except in specific cultures for the dose-response curve. After injection with ethylene, cultures were placed in darkness or varying light intensities in a temperature-controlled (25 ? 1 C) growth chamber for 24 hr. Controls included unsealed cultures with aluminum caps and cultures sealed with screw caps but without injected ethylene in both darkness and light. Darkness was maintained by wrapping in black corduroy. Continuous illumination was provided during a 24-hr period, which usually followed immediately after inoculation. Different

Influence of birds, stones and soil on the establishment of pasture juniper, juniperus communis, and red cedar, j. virginiana in new england pastures'

Abstract: In New England the pasture juniper, Juniperus communis var. depressa Pursh, usually occurs in pastures adjacent to stones, whereas the red cedar, J. virginiana var. crebra Fern. & Grisc., occurs either at stoneside or in interstonal areas. In non-stony pastures red cedar is often dominant and pasture juniper absent. Accordingly, attempts were made to determine the effects of the stoneside position. During their fall migrational flights, robins, Turdus migratorius Linnaeus, feed heavily on the berries of both pasture juniper and red cedar, and are effective disseminators of the seed. During feeding periods the robins come to rest on exposed field stones and the seed in their droppings becomes concentrated on the stones. The seeds are subsequently washed and planted into frost-heave cracks adjacent to the stones. The burial of pasture juniper seed assures their retention in a moist condition during the long, double stratification period required for their germination. Red cedar seed requires only a single cold stratification period, however, and this may be encountered even when seeds are planted on soil surfaces. Seedlings developing in the stoneside frost-heave crack are protected from trampling or grazing, and they receive extra moisture from their stone micro-watershed. Yet, all items in the system are not favorable. Seedling junipers make their best growth in compacted soils, like those away from stoneside, and although birds are effec- tive disseminators of their seed, the passage of seed through the birds gut inhibits germination.. Nevertheless the fortuitous planting of seed on exposed stones introduces pasture juniper and red cedar to a micro-habitat that more than compensates for reduced germination and slower growth.

Dormancy: a Factor Affecting Seed Survival in the Soil

Abstract: It is unfortunate that the term dormancy, when applied to seeds, has been used in at least two distinct ways. Sometimes any seed which is not in the process of germinating — e.g. a dry seed in storage — is said to be dormant. However, more commonly — and more usefully — the term is used in a more restricted sense to indicate that the seed, although viable, will not germinate under conditions normally considered to be adequate for germination, viz. when provided with a suitable temperature, adequate water and oxygen. In this chapter the term dormancy will be used in the more restricted sense. Before discussing its relationship with viability, however, it is necessary to distinguish between various types of dormancy.

Germination of heat- and alkali-altered spores of Clostridium perfringens type A by lysozyme and an initiation protein.

Abstract: The normal system functioning in the utilization of metabolizable germinants by both heat-sensitive and heat-resistant spores of Clostridium perfringens was inactivated by heat or by treatment of the spores with alkali to remove a soluble coat protein layer. Altered spores were incapable of germination (less than 1%) and outgrowth (less than 0.0005%) in complex media without the addition of either lysozyme or an initiation protein produced by C. perfringens. The addition of either of these agents permitted, in the case of alkali-treated spores, both 90 to 95% germination and outgrowth, as measured by colony formation. In the case of heat-damaged spores, only 50% germination and 2% outgrowth resulted from addition of the initiation protein, whereas lysozyme permitted 85% germination and 8% outgrowth. Alteration of the spores by heat or alkali apparently inactivated the normal lytic system responsible for cortical degradation during germination. Kinetics of production of the initiation protein and conditions affecting both its activity and that of lysozyme on altered spores are described.

Influence of germination date on survival and seed production in a natural population of Leavenworthia stylosa.

Abstract: The influence of germination date in 1970 on survival and seed production was studied in a population of the winter annual Leavenworthia stylosa in the field. The lowest percentage of survival was in plants from July-germinating seeds, while the highest percentage was in plants from seeds that germinated in midto late September and early October. Plants from July-germinating seeds produced more fruits and seeds per plant than plants from seeds that germinated in September or October. However, since a much higher percentage of plants from seeds that germinated in September and October survived, the number of seeds produced per 100 seeds germinated was highest in these plants. The fewest seeds produced per 100 seeds germinated were in plants from seeds that germinated after 4 October.

Effects of Environment Before Harvesting on Viability

Abstract: It is well known that the germination and viability of seeds of cultivated plants can vary greatly from year to year, dramatically affecting the value of the seed for sowing. To reduce the risks of crop failure that can result from sowing poor seed, most countries now have laws prohibiting the sale of seed lots unless they have a germination greater than a statutory minimum percentage, which varies according to the species. Germination tests, carried out according to the widely used International Rules (Anon., 1959) reveal only the percentage of the seeds that are viable under near-ideal conditions and there is usually a considerable discrepancy between the results of germination tests in the laboratory and the emergence of the seeds in the field, the discrepancy usually being greater the lower the per cent germination (for examples see Perry, 1967 and Austin, 1963).

Abscisic Acid: correlations with abscission and with development in the cotton fruit.

Abstract: Abscisic acid was measured in developing cotton fruit (Gossypium hirsutum) by means of gas-liquid chromatography. High levels of abscisic acid occurred in correlation with abortion and abscission of young fruit, with low germination of immature seed, and with senescence and dehiscence of mature fruit. Declining or low levels of abscisic acid occurred in correlation with the period of most rapid fruit growth and with high germination of immature and mature seed. Young fruit of cultivar Acala 4-42 contained about twice as much abscisic acid as young fruit of cultivar Acala SJ-1, and this difference is correlated with a higher rate of young fruit abscission in Acala 4-42. Young fruit abscising late in the fruiting season contained about twice as much abscisic acid as young fruit abscising early in the fruiting season.

Yellow Nutsedge Tuber Germination and Seedling Development

Abstract: Upon germination, one or more rhizomes grew from the apical end of each yellow nutsedge (Cyperus esculentus L.) tuber. Each rhizome developed a basal bulb upon exposure to light. No significant differences in germination percentages existed between four lots of tubers which differed about five- fold in weight. The weight of plant material produced corre- lated significantly with the fresh weight of the tuber from which it emanated. When tubers germinated three successive times, over 60% of the tuber dry weight, carbohydrate, oil, starch, and protein were consumed during the first germina- tion; but less than 10% of these constituents were uitlized during each of the next two germinations. Plants weighed significantly more after 43 and 91 days of growth with tubers attached throughout the period than when tubers were de-

The effect of environmental parameters on the germination, growth, and development of suaeda depressa (pursh) wats

Abstract: A study was made to determine the effect of environmental parameters on the germination, growth, and development of Suaeda depressa (Pursh) Wats. Germination tests showed that seeds germinated in solutions containing up to 4 % NaCl with no toxic effects indicated after treatment with distilled water. The rate of germination and the percentage germination decreased with increased salinity. The effect of environmental parameters on growth was measured by shoot height, side shoot development, leaf length, and dry weight. Growth was greatest in 1 % NaCl solutions with adequate available nitrogen. With increased salinity and low available nitrogen levels plant growth decreased. A 10-hr photoperiod stimulated immediate floral induction. Although flowering and completion of the life cycle occurred in solutions containing up to 4 % NaCl, increased salinity decreased the rate of floral induction and the dry weight of flowers and fruit produced. This study indicates that environmental parameters such as salinity, available nitrogen, and photoperiod can create a variety of growth forms, causing taxonomic confusion. SUAEDA DEPRESSA, an annual leafy succulent, is distributed west of the Mississippi River from southern Canada to Mexico. In this area, S. depressa is narrowly restricted to wet saline soils with poor drainage (Ungar and Capilupo, 1969). The restriction of certain species to saline environments was reported by Miller and Egler (1950) and Adams (1963). Coupland (1950) and Ungar (1964, 1965) concluded that distribution and zonation in saline soils was controlled by competition among species and individual tolerances to salinity. Laboratory studies by Binet (1963) indicated that S. vulgaris Moq. could grow under nonsaline conditions but made its best growth in 1.0 % NaCl nutrient solutions. The distribution of halophytes such as S. depressa is apparently controlled by soil salinity, with other edaphic and climatic factors playing a secondary role (Ungar and Capilupo, 1969). Gates, Stoddart, and Cook (1956) indicated that changes in the chemical factors of soils in saline areas were inconsistent with the distribution and zonation of the vegetation. Studies by Ungar (1968) and Ungar, Hogan, and McClelland (1969) showed that even though S. depressa most commonly occurred in heavy clay soils, the soil texture varied greatly and apparently had little influence on its distribution. Suaeda depressa has ' Received for publication 17 January 1972. 2 Present address: Department of Biological Sciences, University of Arizona, Tucson 85721. We wish to thank Dr. J. W. O'Leary and Dr. L. A. Larson for critically reading this manuscript. This research was partly supported by National Science Foundation research grant GB-6009. been found growing in soils ranging from 0.374.44 % in salinity, in which NaCl made up 93 % of the total salts (Ungar, 1968). Macroclimatic factors vary greatly along S. depressa's northsouth distributional axis and appear to have little significance in determining its distribution (Gleason and Cronquist, 1963). The purpose of this study was to observe the effects of different environmental conditions on the germination and growth of S. depressa. Specific attention was placed on height, branching, and leaf length and how they correlated with saline environments. METHODS AND MATERIALS-The seeds of Suaeda depressa were collected on October 3, 1964 at Cloud County, Kansas, and stored at 5 C until the initiation of the study in April 1970. There was no loss in viability over the storage period. Germination stludies-The seeds were germinated on two sheets of Whatman #2 filter paper in 100 mm x 15 mm petri dishes. All germination studies were initiated in the dark in 6 ml of distilled water with NaCl as noted. The results are based on 10 replicates of 25 seeds each for each test solution. Emergence and radicle growth to 0.5 cm in length were used as germination criteria. A temperature regime of 15 + 1 C for 14 hr and 5 + 1 C for 10 hr was used. This temperature regime was used to approximate the 11 C mean under natural conditions for April when seeds germinate in nature. All germination

Promotion of Seed Germination by Nitrates and Cyanides

Abstract: MANY viable seeds fail to germinate in darkness after imbibing water, but do so to varying degrees in solutions of several compounds. Well known promoters of germination are nitrate, nitrite and various sulphydryl and gibberellin salts1. Hydroxylammonium salts, although often cited as inhibitory1, are known to promote germination at low concentrations2. The essential action of none of these is understood and the use of nitrates in seed testing remains empirical. In seeking underlying causes for the promotive effects of nitrates we examined the germination responses to other nitrogenous salts as well as compounds affecting respiration. Cyanides were found to promote germination of many kinds of seeds in extension of the observations of Roberts3.

The effects of elevated temperatures on spore swelling and germination in Aspergillus niger.

Abstract: Exogenous carbon and nitrogen sources were necessary for complete swelling (spherical growth) and germ-tube formation from Aspergillus niger spores. The rate of spherical growth was low at 30°, max...

Physiology of Oil Seeds: IV. Role of Endogenous Ethylene and Inhibitory Regulators during Natural and Induced Afterripening of Dormant Virginia-type Peanut Seeds.

Abstract: To further elucidate the regulation of dormancy release, we followed the natural afterripening of Virginia-type peanut (Arachis hypogaea L.) seeds from about the 5th to 40th week after harvest. Seeds were kept at low temperature (3 ± 2 C) until just prior to testing for germination, ethylene production, and internal ethylene concentration. Germination tended to fluctuate but did not increase significantly during the first 30 weeks; internal ethylene concentrations and ethylene production remained comparatively low during this time. When the seeds were placed at room temperature during the 30th to 40th weeks after harvest, there was a large increase in germination, 49% and 47% for apical and basal seeds, respectively. The data confirm our previous suggestion that production rates of 2.0 to 3.0 nanoliters per gram fresh weight per hour are necessary to provide internal ethylene concentrations at activation levels which cause a substantial increase of germination. Activation levels internally must be more than 0.4 microliter per liter and 0.9 microliter per liter for some apical and basal seeds, respectively, since dormant-imbibed seeds containing these concentrations did not germinate. Abscisic acid inhibited germination and ethylene production of afterripened seeds. Kinetin reversed the effects of ABA and this was correlated with its ability to stimulate ethylene production by the seeds. Ethylene also reversed the effects of abscisic acid. Carbon dioxide did not compete with ethylene action in this system. The data indicate that ethylene and an inhibitor, possibly abscisic acid, interact to control dormant peanut seed germination. The inability of CO2 to inhibit competitively the action of ethylene on dormancy release, as it does other ethylene effects, suggests that the primary site of action of ethylene in peanut seeds is different from the site for other plant responses to ethylene.

Pollen germination and tube growth: dependent on carbon dioxide and independent of ethylene.

Abstract: The influence of ethylene and CO2 on pollen germination and tube growth was investigated employing ventilated culture systems. Ethylene had no effect on pollen germinability or tube growth. Germinating pollen did not produce a detectable amount of ethylene (less than 0.1 nl/g·hr). Supplementing the cultures with CO2 caused a marked increase in germination and tube growth. The half-maximal response for germination was less than 0.5%. CO2 levels ranging from 1.08 to 2.22% were found in the internal cavity of lily styles. CO2 derived from stylar metabolism may, therefore, modulate pollen tube growth thus integrating the events leading to fertilization.

Spectral transmission curves of some types of leaf canopies with a note on seed germination

Abstract: SUMMARY Measurements show that dense leaf canopies transmit very little radiation in the wavelengths 400–700 nm and many times as much radiation in the longer wavelengths. It is shown that germination of seeds requiring either light or darkness can be inhibited under a dense canopy but the ecological importance of this phenomenon is not proved.

Germination and seedling response of atlantic and gulf coasts populations of uniola paniculata

Abstract: A B S T R A C T Germination response following various periods of cold treatment and seedling response to temperature, daylength, and salinity were studied for several Atlantic and Gulf coasts populations of Uniola paniculata L. Results indicated that Atlantic coast Florida populations did not require cold treatment prior to germination at 95-65 F, but that populations from Virginia and North Carolina did. Gulf coast populations exhibited a germination response intermediate between those just mentioned. Seedling studies revealed that alternating diurnal thermoperiods with daytime temperatures of 80 F and above produced good vegetative growth in all populations with little preference for either short- or long-day conditions. Gulf coast populations produced the most biomass under -all treatment conditions. Seedlings from a North Carolina and a Florida population indicated no difference in substrate salt tolerance. Salt tolerance was reduced in the higher temperature thermoperiod for both populations. Seedlings from these two populations produced more biomass in a salt spray treatment than in substrate salinity treatments. THE PERENNIAL DUNE grass Uniola paniculata L.

Hormonal regulation of germination and early seedling development in Acer pseudoplatanus (L.)

Abstract: Dormancy of intact sycamore (Acer pseudoplatanus) seeds was broken by chilling (5°C) for several weeks in moist conditions. Treatment of unchilled seeds with kinetin induced some germination, but gibberellin was ineffective. This stimulation by kinetin was not suppressed by the added presence of abscisic acid during incubation.

Interactions of light and a temperature shift on seed germination.

Abstract: Germination of Rumex obtusifolius L. seeds is potentiated to an observable degree in 2 minutes by a single shift in temperature from 20 to 35 C. Half-maximal potentiation requires less than 32 minutes at the higher temperature. Similar sensitivities to shifts in temperature were observed for seeds of Barbarea vulgaris, R.Br. B. verna (Mill.) Asch., and Lepidium virginicum L. A shift in temperature interacts strongly with change in form of phytochrome induced by light on germination of the four kinds of seeds. The potentiated effects for R. obtusifolius are only moderately affected by 40 μm cycloheximide. Both the temperature shift and light actions are apparently independent of processes of synthesis necessary for growth.

Effect of plant age on inhibition of Botrytis cinerea spores by bacteria on beetroot leaves

Abstract: Inhibition of germination of Botrytis cinerea spores by bacteria occurred in water drops placed on mature (9-week-old or over) beetroot plants but not on younger plants (6-week-old). Numbers of bacteria were higher in water drops on mature plants and species composition changed in relation to plant age. Of 9 isolates of bacteria tested in vitro a pale yellow Pseudomonas group III/IV species caused the most inhibition of germination of B. cinerea spores. Numbers of Pseudomonas group III/IV isolated both from water droplets on leaves and unwetted leaves increased in relation to plant age. On older leaves indirect evidence indicated that the bacterium may have colonized internal parts. Levels of amino acids in droplets increased as plants aged. Of 16 different amino acids the lowest concentrations were recorded on youngest (6-week-old) plants. On 10-, 13- and 16-week-old plants levels of individual amino acids were not so clearly related to plant age. Certain amino acids inhibited, others stimulated growth of Pseudomonas group III/IV in vitro , but on leaves numbers of bacteria could not be correlated with natural levels of specific amino acids.