Germination Of Buried Seeds Research Articles

Fire has little to no effect on the enhancement of germination, but buried seeds may survive in a Neotropical wetland

Contrasting responses of seed germination to fire have been reported in different vegetation worldwide. In Brazil, the Pantanal harbors one of the world's most extensive floodplains, marked by flooding periods alternating with a dry fire-prone season. The present study aimed to understand the role of fire on regeneration from seed in the Pantanal wetland, using two pioneer species displaying physically dormant seeds as study models: Sesbania virgata (Cav.) Pers. and Guazuma ulmifolia Lam. Seeds were subjected to (1) heat shocks and (2) experimental burns, besides the controls. In Experiment 1, heat shocks of 65, 85, 105, 125, and 145°C (all treatments ± 5°C), were applied for 5 minutes of exposure. In Experiment 2, seeds and corky fruits were placed upon the soil surface, and seeds were buried at 2 cm belowground, then subjected to experimental burns. Germination trials were conducted under optimal conditions and recorded the proportions of germinated, hard, and dead seeds. Increasing temperature of heat shocks had an increasingly negative effect on seed water content and germination of both species as well as increasing the proportion of dead seeds. A slight enhancement in germination of buried seeds (18%) was found in the experimental burns for S. virgata seeds. Moreover, buried seeds remained hard (dormant) up to 80 and 40% for S. virgata and G. ulmifolia, respectively. Inside the corky fruits, seed germination was not promoted, and there was a decrease in the proportion of hard seeds after burning, while direct exposure to fire killed nearly all seeds placed upon the soil surface. Fire has little to no effect on the enhancement of seed germination, but seeds mainly survive when buried belowground. Our study provides crucial information to understand seed tolerance to increased fire occurrence in disturbed tropical wetlands.

Dynamics of the processes leading to the acquisition of sensitivity to very low fluence of photons inDatura feroxseeds

AbstractSoil tillage operations stimulate germination of buried seeds in cultivated lands, allowing them to perceive light as a germination-promoting factor. The time of burial and the effect of changing environmental factors affect the physiological state of the seeds, which may lead to an extreme light-sensitivity and very low fluence response (VLFR) through phytochrome A. This paper describes the influence of the progressive process of dormancy breakage, which is accompanied by the acquisition of extreme light-sensitivity, on processes associated with endosperm weakening and embryo growth potential in the VLFR-mediated promotion ofDatura feroxseed germination. Our results show that endosperm weakening is mainly limited by β-mannosidase enzyme activity after far-red light stimulation, which is highly dependent on the dormancy level of the seeds. In addition, stimulation of the embryo growth potential by far-red irradiation did not require an extreme light-sensitivity to very low fluence of photons to reach its maximum response, and it was not completely correlated with expansin gene expression in the embryo. Our work indicates that responses of endosperm weakening and embryo growth potential to far-red irradiation, dependent on dormancy level, have different requirements for stimulation by the signalling network initiated by phytochrome A during the course of the very low fluence response inDatura feroxseeds.

Effect of deicers on germination of buried seeds in topsoil of old field

This article presents that deicers such as calcium chloride (CaCl2) and EFDs (Eco-Friendly Deicers) composed with organic acids affect germination of seeds buried in old-field soil. CaCl2, one of a commonly used deicer in the world, have shown an inhibitory effect on the germination of the buried seeds. Species richness, species diversity, and total biomass of the plant community after germinating were greatly decreased with increase of CaCl2 concentration. The germination of buried seeds was inhibited seriously by CaCl2, but the degree of its varied significantly with plant species. EFD1 manufactured from organic chemicals showed the higher inhibition on germination than CaCl2. However, EFD2 composed with organic acids of food waste didn’t have an inhibitory effect on the species richness after germination and rather enhanced the germination and initial growth of the seedlings. The positive effect was evaluated that EFD2 caused to supply nutrition on germination or growth of buried seeds. The deicers may change dynamically the plant community of the roadside because the response of germination and growth by deicers differ from plant species.

Soil seed banks in young, closed-canopy forests of the Olympic Peninsula, Washington: potential contributions to understory reinitiation

During early stand development, coniferous forests of the coastal Pacific Northwest commonly pass through a period of dense shade and intense competition during which the abundance and diversity of understory plants decline dramatically. In young, managed forests, silvicultural thinning has been proposed to enhance the structural and floristic diversity of the understory. Although germination of buried seeds is likely to be stimulated by thinning, we know little about the composition of the soil seed bank in these forests. We used the greenhouse emergence method to assess the potential contribution of the seed bank to understory reinitiation in 40- to 60-year-old, closed-canopy forests on the Olympic Peninsula, Washington. Seed banks were well developed (610-7009 germinants/m2), containing 46 native and exotic species representing a diversity of life forms. However, many common forest understory species were absent; only 11 species were typical understory plants and these comprised <10% of all germinants. In contrast, 30% of all species and 50% of all germinants were exotic, ruderal forbs. Wind-dispersed annuals and perennials dominated litter samples, whereas ruderal forbs and graminoids with limited dispersal dominated soil samples. Our results suggest that silvicultural thinning will enhance the establishment of ruderal, exotic species but will contribute little to the regeneration from buried seed of the vast majority of forest understory plants.Key words: canopy closure, forest understory, seed germination, soil seed bank, succession, understory reinitiation.

Seed bank composition of a northeastern U. S. tussock swamp

A seedling and sporeling emergence assay was conducted on 50 soil cores taken from withinCarex stricta tussocks (intra-tussock) and from paired, adjacentinter-tussock areas in the Hawkins Conservation Area, South Hadley, Massachusetts, USA, to test the hypothesis that local heterogeneity in water levels alters seed bank composition and subsequent seedling emergence patterns. Soil cores were sliced into 2.5-cm-thick sections and split into flooded and drawn-down treatments. Germination of buried seeds and spores was assessed in these treatments under greenhouse conditions for 6 months. Eighteen species emerged from both treatments combined: 17 frominter-tussock samples and 12 fromintra-tussock samples. Pooled across sample depths and watering treatments, more species of grasses, forbs (exclusive ofImpatiens capensis), and woody plants germinated fromintra-tussock samples, while more pteridophytes germinated from theinter-tussock samples. Emergence of pteridophytes, grasses, and forbs was associated significantly with sample depth. More pteridophytes germinated from samples close to the swamp surface, while grasses and forbs were most abundant in samples 10–20 cm below the surface. In the drawn-down treatment, pteridophyte and forb seedlings were more plentiful frominter-tussock samples. In contrast, more forb seedlings emerged fromintra-tussock samples in the flooded treatment. This variation in forb emergence seems to reflect differences in species composition within and between tussocks. Twenty-two species occurred in the standing vegetation of the study area, but only nine of these also occurred in the seed bank. The composition of standing vegetation atop and between tussocks did not differ significantly. Grasses, which dominated the seed bank, were absent from standing vegetation. Grasses clearly represent a persistent population of seeds in the seed bank, while forbs are more transient within the seed bank. The depth-stratified species composition of the seed bank also suggests patterns of temporal succession in the aboveground vegetation of this New England tussock swamp.

Colonization Dynamics of Herbs and Shrubs in a Disturbed Northern Hardwood Forest

Modes of recruitment of herbs and shrubs, and the extent to which availability of propagules affected distribution of the various species after disturbance were examined in a field experiment of canopy removal at the Hubbad Brook Experimental Forest, New Hampshire, U.S.A. The most common shrubs after canopy removal were Rubus idaeus and Viburnum alnifolium; the most common herbs were Aster acuminatus, Dennstaedtia punctilobula and Dryopteris spinolusa. All of the first-year recruitment or Rubus occurred through germination of buried seeds (...)

Induction of extreme light sensitivity in buried weed seeds and its role in the perception of soil cultivations

Abstract. Light, probably acting through the photo‐receptor phytochrome, promotes germination of weed seeds when the soil is disturbed by tillage operations. A short period of burial is shown to induce an enormous ∼10000‐fold increase in light sensitivity in the seeds of the arable weed Datura ferox which is interpreted as a natural transition to the ‘very‐low‐fluence’ mode of phytochrome action. Field experiments indicated that germination of buried seeds may be triggered by millisecond‐exposures to sunlight and suggested a key role for the process of sensitization in the mechanisms whereby light requiring seeds detect the occurrence of soil cultivation events in arable lands.

Dormancy and survival in buried seeds of proso millet (Panicum miliaceum)

Survival, dormancy, and germination of buried seeds of 30 populations of proso millet (Panicum miliaceum L.) were investigated. The effects of duration and depth of burial and type of soil were considered. The 30 populations belong to three agronomic groups: crop, croplike weed, and black-seeded weed. Black seeds exhibited much greater overwinter survival and dormancy than did seeds of the other two groups. Crop seeds had almost no survival through the winter. Only one croplike weed population exhibited appreciable (13–40%) survival after one winter in the soil. A combination of endogenous and enforced dormancy in black seeds effected an adaptive germination pattern of little (1%) germination at both the surface and 20 cm deep and much greater (40%) germination at 5 cm deep. Surviving crop and croplike weed seeds germinated irrespective of position in or on the soil. In a longer term experiment with only three populations both the croplike weed and black-seeded populations survived best in a well-drained soil. For the black-seeded population greater germination in the well-drained soil depleted that seed bank earlier than those in the medium-drained or poorly drained soils. The crop and croplike weed populations produced only transient seed banks in all three soil types, whereas some black seeds survived for 4 years.

Biology and Control of Tall Ironweed (Vernonia altissima)

Tall ironweed (Vernonia altissimaNutt.) is a perennial with underground, axillary vegetative buds from which new shoots are produced. In a 2-yr study, tall ironweed plants averaged 6115 seeds/plant. Germination of buried seeds increased with increased time of burial. Foliar herbicide applications were evaluated for control of tall ironweed plants in the pre- to early-bud stages of growth. The triethylamine salt or ethylene glycol butyl ether ester of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was the most effective, providing 93 to 90% control of top growth and regrowth of tall ironweed. The butoxyethanol and propylene glycol butyl ether esters of 2,4-D [(2,4-dichlorophenoxy) acetic acid] alone and in combination with the amine salt of triclopyr also provided excellent control.

Ecology of germination of weed seeds : I. Role of temperature and depth of burial in soil.

Merremia gangetia Linn. (Cuf) is one of the most important weeds invading cultivated lands of India. Temperature, both high (45° C) and low (15° C) exhibit a definite role in development of the weed, particularly during germination. Higher tempeeratures (45° C) during dry storage appeared to be the main factor in laboratory experiments as well as in nature. Low temperature induced secondary dormancy and its removal by incubation at 35° C helps to explain the ecological mechanism through which the weed endures winter conditions. Germination of buried seeds confirm that the atmospheric conditions were found to be more effective in upper layers of soil. Ecological adaptations of this weed via germination requirements are assessed in the paper.