Evolutionary ecology of seed dormancy and seed size

1996 ◽  
Vol 351 (1345) ◽  
pp. 1299-1308 ◽  
Keyword(s):  
Seed Dormancy ◽  
Clonal Growth ◽  
Evolutionary Ecology ◽  
Seed Mass ◽  
Dispersal Limitation ◽  
Lateral Spread ◽  
Adult Longevity ◽  
Establishment Success ◽  
Spatial Dispersal ◽  
Animal Dispersed Seeds

The theoretical ideas underpinning the evolution of seed dormancy and seed mass are briefly reviewed. Comparative tests of these theoretical ideas are then presented; all tests use modern comparative methods to allow accurate, meaningful comparisons across species. The comparative analyses of seed dormancy demonstrate that species that average the environment across time, by having long-lived adults or space as a result of clonal growth, typically have less dormant seeds. Amongst species with seeds unspecialized for spatial dispersal, seed mass is not related to dormancy. However, in species with wind- or animal dispersed seeds those with heavy seeds typically have less dormancy. This is consistent with heavy seeds having better establishment success and /or suffering higher levels of herbivory. The relationships between seed mass and plant height, lateral spread and adult longevity are explored using the Sheffield dataset. The complex pattern of relationships between these variables is interpreted in terms of dispersal limitation, escape from competition with clonal ramets and differences in establishment conditions. Some of the problems that are frequently encountered in the interpretation of comparative data are briefly discussed.

scholarly journals Relative importance of region, seasonality and weed management practices effects on the functional structure of weed communities in French vineyards

2021 ◽  
Author(s):  
Marie-Charlotte Bopp ◽  
Elena Kazakou ◽  
Aurelie Metay ◽  
Guillaume Fried
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Environmental Gradients ◽  
Cropping Systems ◽  
Seed Mass ◽  
Soil Disturbance ◽  
Lateral Spread ◽  
Maximum Height ◽  
Weed Communities ◽  
Mechanical Disturbance

Winegrowers have diversified their weed management practices over the last two decades changing the structure and the composition of weed communities. Complementary to taxonomic studies, trait-based approaches are promising ways for a better understanding of weed communities responses to environmental and agronomic filters. In the present study, the impacts of climate, soil characteristics, seasons and weed management practices (chemical weeding, tillage and mowing) were assessed on weed communities from 46 plots in three French wine-growing regions (Champagne, Languedoc and Rhone valley). These agro-environmental gradients structuring weed communities according to their combinations of traits were highlighted using multivariate analysis (RLQ). The impacts of these filters on Community Weighted Means (CWM) and Community Weighted Variance (CWV) of weed communities were analysed using mixed and null modelling. Our results showed that spatio-temporal and weed management practices variables explained from 13% to 48% of the total variance of CWM (specific leaf area, maximum height, seed mass, flowering onset and duration and lateral spread). Region, seasonality and management practices explained 53%, 28% and 19% of CWM marginal variance, respectively. Weed management impacted CWM and CWV through two main gradients: (i) a soil disturbance gradient with high mechanical disturbance of soil in tilled plots and low mechanical disturbance in chemically weeded plots and (ii) a vegetation cover gradient with high vegetation abundance in mowed plots compared to more bare soils in tilled and chemically weeded plots. In Languedoc, chemical weeding filtered weed communities with ruderal strategy trait values (low seed mass, small-stature) while mowed communities were more competitive (higher seed mass, higher stature and lower SLA). In Languedoc and Champagne, tillage favoured communities with high seed mass that increases the viability of buried seeds and high lateral spread values associated to the ability to resprout after tillage. This study demonstrated that trait-based approaches can be successfully applied to perennial cropping systems such as vineyards, in order to understand community assembly to better guide weed management practices.

scholarly journals Seed production and seed quality of the dune building grass Panicum racemosum Spreng

1994 ◽  
Vol 8 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Cesar Vieira Cordazzo ◽  
Anthony John Davy
Keyword(s):  
Seed Production ◽  
Clonal Growth ◽  
Seed Quality ◽  
Seed Mass ◽  
Coastal Dunes ◽  
Cultivated Plants ◽  
Strong Negative Correlation ◽  
Seed Characteristics ◽  
The Relationship

Seed production, pollination requirement, seed characteristics related to quality and the relationship between number and mass of seeds were examined for Panicum racemosum in three successional populations in southern Brazilian coastal dunes. The seed production was generally low and declined further between the frontal dunes and the backdunes, dropping from 4.05 seeds per panicle in the former to 1.8 seeds in the latter. However fertility (% fertile florets) did not differ among the three habitats. Plants cross-pollinated in a glasshouse showed an increase in seed production to 41.4 seeds compared to no seed production in self-pollinated plants. Caryopses varied in mass from 3.2 to 12.2 mg with a mean of 7.98 mg. A strong negative correlation was found between mean individual seed mass and the total number of seeds per panicle in a natural population. However, this relationship did not persist in seeds produced by cultivated plants in the glasshouse. The causes of low seed production appear to be mainly pollen self-incompatibility and additionally competition for nutrients between sexual reproduction and allocation to clonal growth. Under conditions of nutrient shortage, Panicum racemosum probably allocates resources more to clonal growth and to fewer, but well-endowed seeds. This would permit emergence from deeper burial sand, faster growth and greater survival of seedlings.

Morphology of white clover during development from seed to clonal populations in grazed pastures

2000 ◽  
Vol 135 (2) ◽  
pp. 103-111 ◽  
Author(s):  
J. L. BROCK ◽  
K. A. ALBRECHT ◽  
J. C. TILBROOK ◽  
M. J. M. HAY
Keyword(s):  
White Clover ◽  
Clonal Growth ◽  
Growth Stage ◽  
Transition Period ◽  
Clonal Plant ◽  
Clonal Plants ◽  
Plant Size ◽  
Lateral Spread ◽  
Initial Population ◽  
Clonal Population

Following germination, the ontogeny of white clover is characterized by two distinct morphological growth phases, a seminal taprooted stage followed by a clonal growth stage. Death of the seminal taproot and primary stolon initiates a process of fragmentation of the taprooted plant into a variable number of independent clonal fragments (plants) which comprise the initial population of the clonal growth stage. The objective of this study was to characterize the plant morphology of field-sown white clover populations from germination through to established clonal populations. Populations of eight white clover cultivars were assessed when sown with perennial ryegrass or tall fescue in pastures established under a common grazing regime for 16 months prior to imposition of continuous or rotational grazing treatments. One year from sowing, taprooted plants attained maximum size, with a mean plant branching order of 3·35, stolon DW of 460 mg and lateral spread of 250 mm, with some individuals having 6th order branching, 3·5 g stolon DW and 1m lateral spread. These taprooted plants were 4–5 times the size of plants in the subsequently formed clonal population. Nine months after sowing, the first individual taprooted plants fragmented into clonal plants. Twelve months from sowing, fragmentation processes were occurring at a linear rate, eliminating 6% of the original taprooted population each month. This resulted in a 12–15 month transition period when the white clover population comprised both taprooted and clonal plants. During this transition period, the initial clonal fragments produced from taprooted plants were large, and this maintained a larger mean plant size in the clonal plant proportion of the transition population than measured in the later fully clonal population. This process was also considered to act to prevent the development of the expected differences between grazing managements, as it was not until the third year when all taprooted plants had disappeared that the clonal populations developed characteristics reflecting the expected influence of grazing management. Variation due to white clover cultivar and companion grasses was minor. The substantial differences in plant size and branching structure between taprooted and clonal populations has significant implications for the evaluation of breeding lines.

scholarly journals Seed size and dormancy in Rumex obtusifolius

1999 ◽  
Vol 35 (No. 3) ◽  
pp. 103-107 ◽  
Author(s):  
A. Martínková ◽  
A. Honěk ◽  
F. Pudil
Keyword(s):  
Seed Size ◽  
Seed Dormancy ◽  
Seed Mass ◽  
Size Variation ◽  
Germination Percentage ◽  
Plant Materials ◽  
Rumex Obtusifolius ◽  
Ex Post ◽  
Germinating Seeds ◽  
Range Of Variation

We tested the hypothesis, suggested by literature data, that in Rumex obtusifolius L. the germination of matured seeds harvested from dry standing shoots and achene morphology are correlated. In these seed materials the level of germination is determined by the incidence of primary seed dormancy. The regression of the percentage of germinating seeds on achene, perianth and seed size and mass were calculated for seed materials of 30 plants. The materials in which achene morphology was investigated were selected ex post from a set of seed materials of 241 plants to cover the range of variation of germinability of individual plants which was between 0-66%. There was no relationship between any characteristic of achene quality and germination except for a positive correlation between germination percentage and achene mass calculated only for seed materials of plants which pro­ duced germinable seeds (i.e. when plants with 0% germination were excluded from the analysis). The second part of the study investigated the effects of size variation on germinability among seeds harvested from one plant and after removal from the perianth. This variation was tested using sets of 20 size-assorted groups of 50 seeds, each originating from a particular plant; materials from six plants were tested. There were significant differences in the average germination between plants. However, in the material from the same plant there was no consistent relationship between seed mass and percentage of germination. We conclude that there exists no direct relationship between achene, perianth or seed size or mass and incidence of primary seed dormancy.

scholarly journals Clonal growth forms in Arctic plants and their habitat preferences: a study from Petuniabukta, Spitsbergen

2012 ◽  
Vol 33 (4) ◽  
pp. 421-442 ◽  
Author(s):  
Jitka Klimešová ◽  
Jiří Doležal ◽  
Karel Prach ◽  
Jiří Košnar
Keyword(s):  
Plant Communities ◽  
Clonal Growth ◽  
Life History Traits ◽  
Environmental Gradients ◽  
Habitat Preferences ◽  
Clonal Plants ◽  
Lateral Spread ◽  
Arctic Regions ◽  
Entire Plant ◽  
Successional Communities

Abstract The ability to grow clonally is generally considered important for plants in Arctic regions but analyses of clonal characteristics are lacking for entire plant communities. To fill this gap, we assessed the clonal growth of 78 plant species in the Petuniabukta region, central Spitsbergen (Svalbard), and analyzed the clonal and other life-history traits in the re- gional flora and plant communities with respect to environmental gradients. We distin- guished five categories of clonal growth organs: perennial main roots produced by non- clonal plants, epigeogenous rhizomes, hypogeogenous rhizomes, bulbils, and stolons. Clonal growth differed among communities of the Petuniabukta region: non-clonal plants prevailed in open, early-successional communities, but clonal plants prevailed in wetlands. While the occurrence of plants with epigeogenous rhizomes was unrelated to stoniness or slope, the occurrence of plants with hypogeogenous rhizomes diminished with increasing stoniness of the substratum. Although the overall proportion of clonal plants in the flora of the Petuniabukta region was comparable to that of central Europe, the flora of the Petunia- bukta region had fewer types of clonal growth organs, a slower rate of lateral spread, and a different proportion of the two types of rhizomes.

scholarly journals Deforestation reduces the genetic structure of an epiphytic weed across space and time: an IBM approach

2020 ◽  
Author(s):  
Cleber Juliano Neves Chaves ◽  
Bárbara Simões Santos Leal ◽  
Davi Rodrigo Rossatto ◽  
Uta Berger ◽  
Clarisse Palma-Silva
Keyword(s):  
Genetic Structure ◽  
Clonal Growth ◽  
Spatial Genetic Structure ◽  
Dispersal Limitation ◽  
Anthropogenic Landscapes ◽  
Loss Of Resistance ◽  
Rapid Spread ◽  
Self Fertilization ◽  
Spatio Temporal ◽  
North And South America

AbstractDeforestation has allowed the massive dispersal and reproduction of some plants that are commonly referred to as weeds. The rapid spread of many weeds into newly disturbed landscapes is often boosted by clonal growth and self-fertilization strategies, which conversely increases the spatial genetic structure (SGS) of populations and reduces the genetic diversity. Here, we use empirical and modeling approaches to evaluate the spatio-temporal SGS dynamics of Tillandsia recurvata (L.) L., a common epiphytic weed with selfing reproduction and clonal growth widespread in dry forests and anthropically deforested landscapes in North and South America. We constructed an individual-based model (IBM) and adjusted the parameters according to empirical genetic data, to simulate the spreading of T. recurvata over time and across random landscapes with distinct tree densities. From empirical data, we observed a strong SGS among T. recurvata subpopulations hosted on neighbor trees and a contemporary spread from several population sources. Our model shows that the highest SGS appear in landscapes with more than 200 trees/ha and up to the 5th year of colonization of open landscapes (ca. 100 trees/ha) when SGS starts to reduce drastically. These results suggest that the deforestation commonly observed in anthropically transformed landscapes may reduce the dispersal limitation and genetic structure of T. recurvata subpopulations, creating suitable conditions for the rapid spread of T. recurvata from multiple surrounding sources. The combination of clonal growth and self-fertilization with the optimal conditions created by anthropogenic transformations may explain the spreading success of T. recurvata and other weeds into new landscapes. Our results indicate that the drastic reductions in tree densities induced by human-modifications in natural landscapes may lead to a partial loss of resistance for dispersal by wind and increased the conditions for T. recurvata to develop massive populations in anthropogenic landscapes.

Breaking Seed Dormancy in Corchorus olitorius Landraces

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
AE-D Helaly ◽  
H Al-Amier ◽  
AA Al-Aziz ◽  
LE Craker
Keyword(s):  
Seed Dormancy ◽  
Corchorus Olitorius ◽  
Breaking Seed Dormancy

Multi-environment evaluation of Spanish bunch groundnut genotypes for fresh seed dormancy

2019 ◽  
Vol 79 (3) ◽  
Author(s):  
Narendra Kumar ◽  
B. C. Ajay ◽  
A. L. Rathnakumar ◽  
T. . Radhakrishnan ◽  
M. C. Dagla1 ◽  
...  
Keyword(s):  
Seed Dormancy ◽  
Stability Index ◽  
Pooled Analysis ◽  
Genetic Stock ◽  
Breeding Lines ◽  
Fresh Seed ◽  
Differential Behavior ◽  
Environmental Interactions ◽  
Crop Maturity

The present study was carried out to evaluate eight promising Spanish bunch groundnut genotypes during four consecutive year (2014, 2015, 2016, 2017) to study genotype × environmental interactions and to identify stable sources of fresh seed dormancy in Spanish background in groundnut. Pooled analysis of variance revealed highly significant differences among the genotypes and genotype × environmental interactions for fresh seed dormancy at weekly intervals indicating that differential behavior of genotypes for fresh seed dormancy over the environmental conditions. Based on the results of intensity and duration of dormancy and germination stability index, identified four stable advanced breeding lines viz., PBS 12192, PBS 12187, PBS 12191 and PBS 12190 having high fresh seed dormancy of three week and two stable advanced breeding lines viz., PBS 12189 and PBS 12171 having high fresh seed dormancy of two week. Therefore, these genotypes can be used as novel genetic stock of fresh seed dormancy in Spanish bunch and they can be integrated into breeding programs to develop high yielding Spanish bunch cultivars with 2-3 weeks of fresh seed dormancy to avoid yield losses due to in-situ germination at the time of crop maturity.

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