Life-history variation in the annual arable weed Diplotaxis erucoides (Cruciferae)

1994 ◽  
Vol 72 (1) ◽  
pp. 10-19 ◽  
Author(s):  
F. X. Sans ◽  
R. M. Masalles
Keyword(s):  
Life History ◽  
Biomass Allocation ◽  
Plant Architecture ◽  
Reproductive Effort ◽  
Plant Size ◽  
Early Spring ◽  
Life History Variation ◽  
Arable Weed ◽  
Vegetative Biomass ◽  
Diplotaxis Erucoides

Variation in life-history traits such as emergence, survival, time of flowering, and fecundity were studied in Diplotaxis erucoides, a mediterranean winter annual weed, by analyzing cohorts that emerged in autumn, early spring, and spring. The response of the plants to the environment, as reflected by plant architecture and pattern of biomass allocation, was also studied. Seedlings that germinate in autumn produced from 3 to 10 times more seeds than those that germinated in spring. The main factor affecting the number of seeds produced appears to be the life-span. Reduction of the growing period led to a decrease in both number and length of modular units, which resulted in decreased numbers of leaves, flowers, and fruits of each module. In semelparous D. erucoides plants, differences in the pattern of biomass allocation to reproduction are related to plant size. Our field data indicate that an increase of reproductive effort with size occurs in small individuals; however, a decrease occurs for vegetative biomass greater than 2 g and less than 5 g. Little variation in reproductive effort occurs when vegetative biomass is greater than 5 g. From a strategic point of view, size-dependent variation of reproductive effort in D. erucoides can be interpreted as good tactics to favour a higher proportion of resources devoted to reproduction in small individuals, thus ensuring some offspring. However, structural, developmental, and physiological constraints lead to stabilization or even a decrease in reproductive effort above a certain threshold size, when production of offspring is already ensured. Key words: phenotypic plasticity, plant architecture, biomass allocation, Diplotaxis erucoides.

Colonizing ability in the Echinochloa crus-galli complex (barnyard grass). I. Variation in life history

1981 ◽  
Vol 59 (10) ◽  
pp. 1844-1860 ◽  
Author(s):  
Spencer C. H. Barrett ◽  
Blake F. Wilson
Keyword(s):  
Life History ◽  
Seed Production ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Nutrient Stress ◽  
Reproductive Phenology ◽  
Total Biomass ◽  
Barnyard Grass ◽  
Vegetative Biomass ◽  
Colonizing Ability

A comparison of life history traits in four taxa of the Echinochloa crus-galli complex (barnyard grass) which differ in colonizing ability and weediness was made under various environmental conditions. The taxa were the alien var. crus-galli, a cosmopolitan weed; var. oryzicola, a crop-mimic restricted to rice fields; var. frumentacea, a crop domesticate; and E. muricata, a native of wetland habitats. Populations studied were from the Central Valley of California where the four taxa are sympatric but ecologically differentiated. All comparisons were made under uniform glasshouse conditions to isolate the genetic component of life history variation. Measurements of the patterns of dry weight allocation, time to flowering, reproductive effort, and seed production were made on individuals grown during different periods of the year under "stress" and "nonstress" conditions utilizing randomized multi-harvest designs.Developmental plasticity in allocation patterns and reproductive phenology occurred in all taxa in response to seasonality and nutrient stress although there were significant differences among taxa in the form of the response. Individuals germinating in August yielded less total biomass and allocated a smaller proportion to roots and a larger proportion to secondary tillers and seed than individuals germinating in April. In all taxa, except E. crus-galli var. frumentacea, a delay in flowering under long days resulted in larger vegetative biomass, lower reproductive effort, and where nutrients were limiting, inhibition of secondary tillers. Nutrient stress resulted in a delay in flowering, increased senescence rates, and a reduction in total biomass and reproductive effort. Although each taxon displayed a wide range of tactics, certain differences in life history strategy among the taxa were maintained. In all regimes E. crus-galli var. crus-galli flowered earlier, and exhibited a greater seed production and reproductive effort than var. oryzicola. In general, E. crus-galli var. frumentacea and E. muricata were intermediate in behaviour.Interpopulation variability in the life history traits of E. crus-galli var. crus-galli and E. muricata was measured in a single-harvest, completely randomized design using 10 populations of each taxon. Significant interpopulation variation was recorded within taxa in tiller height and number, aboveground vegetative biomass, time to anthesis, reproductive biomass, harvest index, seed production, and seed weight. Averaged over 10 populations, E. crus-galli var. crus-galli was taller during vegetative growth, flowered more rapidly, allocated a greater proportion of aboveground biomass to reproduction, and produced a greater number of seeds than E. muricata.Variation in life history parameters among barnyard grass taxa may explain differences in colonizing potential. In particular, the failure of E. muricata and E. crus-galli var. oryzicola to colonize open, seasonally moist sites in California where E. crus-galli var. crus-galli flourishes, may be due to their inability to reach reproductive maturity before the onset of summer drought.

Infectious diseases, reproductive effort and the cost of reproduction in birds

1994 ◽  
Vol 346 (1317) ◽  
pp. 323-331 ◽  
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Reproductive Effort ◽  
Field Experiments ◽  
Parasitic Infection ◽  
Cell Mediated Immunity ◽  
Ficedula Albicollis ◽  
Life History Variation ◽  
Subsequent Performance ◽  
Trade Offs

Reproductive effort can have profound effects on subsequent performance. Field experiments on the collared flycatcher ( Ficedula albicollis ) have demonstrated a number of trade-offs between life-history traits at different ages. The mechanism by which reproductive effort is mediated into future reproductive performance remains obscure. Anti-parasite adaptations such as cell-mediated immunity may probably also be costly. Hence the possibility exists of a trade-off between reproductive effort and the ability to resist parasitic infection. Serological tests on unmanipulated collared flycatchers show that pre-breeding nutritional status correlates positively with reproductive success and negatively with susceptibility to parasitism (viruses, bacteria and protozoan parasites). Both immune response and several indicators of infectious disease correlate negatively with reproductive success. Similar relations are found between secondary sexual characters and infection parameters. For brood-size-manipulated birds there was a significant interaction between experimentally increased reproductive effort and parasitic infection rate with regard to both current and future fecundity. It seems possible that the interaction between parasitic infection, nutrition and reproductive effort can be an important mechanism in the ultimate shaping of life-history variation in avian populations.

Allometry of Corispermum macrocarpum in response to soil nutrient, water, and population density

Botany ◽  
2010 ◽  
Vol 88 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Yingxin Huang ◽  
Xueyong Zhao ◽  
Daowei Zhou ◽  
Yayong Luo ◽  
Wei Mao
Keyword(s):  
Population Density ◽  
Biomass Allocation ◽  
Environmental Conditions ◽  
Reproductive Effort ◽  
Soil Nutrient ◽  
Nutrient Content ◽  
Plant Size ◽  
Reproductive Organs ◽  
Root Allocation ◽  
Soil Nutrient Content

The allometric effects of Corispermum macrocarpum Bunge in response to soil nutrient content, water content, and population density were compared in a greenhouse experiment. The results showed that biomass allocation was size-dependent. The plasticity of roots, leaf allocation, and reproductive effort was “true” plasticity (i.e., changing biomass allocation in response to environmental conditions regardless of plant size), and no plasticity was detected in stem allocation in response to soil nutrient variation. At a low soil nutrient content, C. macrocarpum allocated more resources to reproductive organs than to roots and leaves at equivalent plant size, but the value of root allocation was consistent because of the trade-off between the effects of plant size and soil nutrient content. In the response to soil water variation, the plasticity of root allocation and reproductive effort was true plasticity, the plasticity of stem allocation was “apparent” plasticity (i.e., changing biomass allocation in response to plant size regardless of environmental conditions), which was caused by plant size, but there was no plasticity in leaf allocation. Except for the true plasticity of root allocation, there was no plasticity in stems, leaves, and reproductive organs in response to population density.

scholarly journals Effects of fertility, weed density and crop competition on biomass partitioning in Centaurea cyanus L.

2014 ◽  
Vol 68 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Łukasz Chachulski ◽  
Sławomir Janakowski ◽  
Władysław Golinowski
Keyword(s):  
Reproductive Effort ◽  
Reproductive Investment ◽  
Plant Size ◽  
Biomass Partitioning ◽  
Winter Rye ◽  
Fertility Level ◽  
Size Dependent ◽  
Reproductive Structures ◽  
Centaurea Cyanus ◽  
Arable Weed

The influence of environmental factors on biomass partitioning of annual arable weed <em>Centaurea cyanus</em> was analysed. We investigated the effect of fertilisation, density and competition with the winter rye crop on the reproductive investment. Three fertiliser treatments and three density levels were applied. In <em>Centaurea cyanus</em> differences in the pattern of biomass allocation to reproduction are related to plant size. The relationship between reproductive and vegetative mass is close to linear. It is consistent with the model of linear size-dependent reproductive output. In <em>Centaurea cyanus</em> this model worked well for size differences that have been generated by interspecific competition, nutrients supply and density. Our data support the hypothesis that plastic changes in relationship between vegetative and generative biomass are environmentally-induced. Significantly different relationship between vegetative and reproductive biomass were detected among populations growing at different density and fertility levels. The fertilisation with mineral fertiliser and manure resulted in an increase of generative biomass allocated to flowerheads and a decrease of reproductive effort. Generative dry weight increased more rapidly with plant size in higher densities of population and at lower fertility levels. The experiment showed that the rate of weight allocated to reproductive structures was bigger under the pressure of competition with cereal crop. At low fertility level and high density, when the individuals were small, generative biomass increased faster with plant size. The production of seeds was not directly dependent on biomass allocated into total reproductive structures. At low level, of nutrient supply <em>C. cyanus</em> gave more offspring per gram of its biomass. We discuss the results in context of life-history theory. From the strategic point of view, size-dependent variation in reproductive effort and in efficiency of reproduction can be interpreted as good tactics to favour high reproductive investment in small individuals, thus ensuring some offspring. Such a strategy is due to developmental constraints like short vegetation, the small amount of resources available and strong competition with crop.

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