Structural changes in a Hieracium floribundum (Compositae) population associated with the process of patch formation

1978 ◽  
Vol 56 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Standing Crop ◽  
Structural Changes ◽  
Vegetative Reproduction ◽  
Light Availability ◽  
Dry Weight ◽  
Genetic Change ◽  
Allocation Pattern ◽  
Southern Ontario ◽  
Reproductive Structures ◽  
Allocation Patterns

The contribution of yellow devil hawkweed (H. floribundum) to the total standing crop of an abandoned pasture in southern Ontario increased from approximately 8% to 70% as H. floribundum colonized the pasture by forming patches containing as many as 3400 rosettes/m2. Within the hawkweed population, there was a significant (P < 0.05) shift in the distribution of standing crop from reproductive to vegetative structures and within the vegetative structures from leaves to roots and rhizome during the process of patch formation. These shifts presumably occurred in response to changing environmental conditions (i.e., increasing light availability, reduced soil moisture levels, greater intraspecific competition). The mechanism by which the allocation pattern changed was more likely phenotypic plasticity than genetic change since H. floribundum is an apomict and vegetative reproduction accounted for most recruitment into the population.The frequency distribution of population members in dry weight classes became more negatively skewed during the process of patch formation, but the distribution did not approach log-normality as predicted in some studies. Significant (P < 0.05) differences were observed in the allocation patterns of individuals belonging to different weight classes in the population. Only the largest plants in the population allocated dry weight to reproductive structures.

Dry weight and resource allocation patterns among individuals in populations of Plantago major and P. rugelii

1982 ◽  
Vol 60 (11) ◽  
pp. 2424-2439 ◽  
Author(s):  
W. R. Hawthorn ◽  
P. B. Cavers
Keyword(s):  
Frequency Distribution ◽  
Reproductive Effort ◽  
Natural Populations ◽  
Dry Weight ◽  
Life History Trait ◽  
Plantago Major ◽  
Allocation Pattern ◽  
Plant Weight ◽  
Frequency Distributions ◽  
Allocation Patterns

The frequency distributions of log plant weight in 1st-year plants of Plantago major L. and P. rugelii Decne. were studied in greenhouse experiments, including an investigation of associated differences in allocation patterns to plant parts between individuals in various weight classes. The frequency distributions of log plant weight of both plantains were strongly negatively skewed (many large plants and few small ones) at the lowest sowing density, where little or no mortality occurred during the course of the study. At two higher sowing densities significant mortality was noted and the frequency distributions tended to "log normality" or to a significant platykurtosis. The presence of bromegrass (Bromus inermis Leyss.) reduced the weight of individual plantains and resulted in frequency distributions that were essentially "log normal." Growing the two plantains together did not alter the shapes of the frequency distributions achieved in monocultures with and without grass. A possible pattern of changes in the frequency distribution of log plant weight with the passage of time is briefly discussed. Significant differences were observed in the allocation patterns of individuals of P. major within a population to roots, caudices, leaves, supporting reproductive structures, and seeds. The allocation patterns were not normally distributed according to plant weight; thus the use of average values of allocation pattern for the population as a whole should be viewed with caution. The proportional allocation to seeds (reproductive effort) by individuals of P. major from increasingly larger weight classes generally increased at an exponential rate, and more rapidly than simultaneous decreases in root and caudex allocation. The greatest reproductive effort and the greatest number of seeds per plant of P. major were associated with the strongest negative skewness of frequency distribution of log plant weight. First-year plants of P. rugelii exhibited a different response. Very few flowered during the study. However, in a variety of treatments the allocation to root and caudex by individuals which differed in biomass by as much as two orders of magnitude was remarkably constant at about 23%. In contrast, the allocation to belowground structures was much more variable among individuals of P. major, ranging from 50% or more by the smallest individuals to less than 5% by the largest plants. This life-history trait could partly account for the greater survival over winter and longevity observed in natural populations of P. rugelii compared with those of P. major.

Cost of seed versus rhizome production in Agropyron repens

1991 ◽  
Vol 69 (12) ◽  
pp. 2678-2683 ◽  
Author(s):  
E. G. Reekie
Keyword(s):  
Seed Production ◽  
Resource Availability ◽  
Nitrogen Availability ◽  
Vegetative Reproduction ◽  
Light Availability ◽  
Trade Off ◽  
Production Allocation ◽  
Trade Offs ◽  
Allocation Patterns ◽  
Agropyron Repens

I examined growth and allocation patterns in genotypes of Agropyron repens isolated from six habitats that differed in disturbance frequency. The trade-off between seed and rhizome production and between either mode of propagation and growth of leaves, stems, and roots was determined by calculating both within- and among-genotype correlations between functions. I also examined how level of light and nitrogen availability affected these trade-offs. Large differences were found among populations in how resources were divided between infructescences and rhizomes, but there was no evidence of a direct trade-off. Regardless of environment, or level at which correlations were examined, there was never a negative correlation between seed and rhizome production. Depending on level of nitrogen and light availability, there was usually a trade-off between seed or rhizome production and growth of leaves, stems, and roots. The two modes of propagation differed in how they responded to resource availability such that their relative cost varied among environments. I suggest differences among populations in allocation to seed versus rhizome production are due to these differences in cost. When cost of seed production is high relative to rhizome production, allocation to rhizome is favored. Conversely, when cost of rhizome production is high relative to seed production, allocation to infructescences is favored. Key words: vegetative reproduction, sexual reproduction, allocation, disturbance, reproductive cost, resource availability, clonal growth.

Intraspecific Competition of Purple Nutsedge (Cyperus rotundus) Under Greenhouse Conditions

Weed Science ◽  
1977 ◽  
Vol 25 (6) ◽  
pp. 477-481 ◽  
Author(s):  
R.D. Williams ◽  
P.C. Quimby ◽  
K.E. Frick
Keyword(s):  
Intraspecific Competition ◽  
Plant Density ◽  
Vegetative Reproduction ◽  
Dry Weight ◽  
Cyperus Rotundus ◽  
Concomitant Increase ◽  
Purple Nutsedge ◽  
Reproductive Structures ◽  
Insight Into ◽  
Plant Basis

The effects of intraspecific competition on the growth and development of purple nutsedge (Cyperus rotundusL.) were studied under greenhouse conditions. Increases in plant density increased the dry weight accumulation on a per pot basis but decreased the dry weight accumulation on a per plant basis. The partitioning of dry weight, whether on a per pot or per plant basis, indicated a shift in the method of reproduction as to density. Under low density conditions more dry weight was partitioned into inflorescences than into tubers. However, under high density conditions more dry weight was partitioned into tubers rather than inflorescences. Dry weight partitioned into rhizomes did not vary as to density. Dry weight partitioned into shoots and roots decreased with the concomitant increase in dry weight partitioned into reproductive structures. This shift to vegetative reproduction under stress conditions caused by competition provides further insight into the difficulties of controlling purple nutsedge.

Effect of altitude on resource allocation in the weed Achillea millefolium (yarrow, Asteraceae) in the Australian Alps

2004 ◽  
Vol 52 (5) ◽  
pp. 639 ◽  
Author(s):  
Frances Mary Johnston ◽  
Catherine Marina Pickering
Keyword(s):  
Biomass Allocation ◽  
Dry Weight ◽  
Achillea Millefolium ◽  
Reproductive Structures ◽  
Australian Alps ◽  
Allocation Patterns ◽  
Below Ground ◽  
Total Dry Weight ◽  
Environmental Weed ◽  
Ground Structures

Increasing severity of environment associated with increasing altitude in mountain ecosystems (decreasing temperature, increasing duration of snow cover) can affect relative and absolute biomass-allocation patterns in plants. Biomass allocation was examined along a 620-m altitudinal gradient in the Australian Alps for the important environmental weed Achillea millefolium (L., Asteraceae, yarrow). Relative and absolute biomass allocation (dry weight) to reproductive (capitula, flowering stems and associated leaves), vegetative (leaves not on the flowering stem) and below-ground structures (rhizome and roots) were measured at each of nine sites by using quadrats. Increasing altitude resulted in a decrease in relative and absolute allocation of biomass to reproductive structures. For example, the dry weight of inflorescences declined as altitude increased because of a decrease in the weight of the terminal and side branches of the inflorescences, but not the total number of capitula produced. There was also a trend for increased relative allocation to below-ground structures with increasing altitude, even though altitude did not affect absolute allocation to below-ground and vegetative structures, or the total dry weight of A. millefolium. These results are consistent with those for other species growing at high altitude. The management implications for the control of A. millefolium in the Australian Alps are discussed, including in relation to predicted climatic change.

Intra-annual changes in seagrass standing crop, Green Island, Northern Queensland

1993 ◽  
Vol 44 (1) ◽  
pp. 33 ◽  
Author(s):  
JE Mellors ◽  
H Marsh ◽  
RG Coles
Keyword(s):  
Standing Crop ◽  
Climatic Factors ◽  
Standing Stock ◽  
Light Availability ◽  
Principal Component ◽  
Dry Weight ◽  
Day Length ◽  
Strong Wind ◽  
Indirect Measures ◽  
Green Island

A visual estimation technique was used to estimate the standing crop of a mixed-species seagrass meadow at Green Island, northern Queensland. This technique measured monthly changes in the standing crop of seagrass within 10 fixed quadrats along three fixed transects from May 1987 to April 1988. The mean standing crop fluctuated by a factor of two from 60 g dry weight (DW) m-2 (August 1987) to 133 g DW m-2 (December 1987). The climatic factors that correlated with mean monthly standing crop were investigated. Owing to the high degree of association between these factors, principal-components analysis was used to create new orthogonal variables to be included in an 'all- subsets regression'. The best regression model explained only 12% of the variation in seagrass standing crop. This model and the magnitude and direction of the loadings of the vectors associated with the first principal component suggested that seagrass standing crop was positively correlated with any day length and temperature and negatively correlated with number of strong-wind days. These variables were indirect measures of light availability and temperature, suggesting that fluctuations in seagrass standing stock at Green Island were influenced by changes in temperature and light availability.

scholarly journals Valorization of sugarcane bagasse by chemical pretreatment and enzyme mediated deconstruction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vihang S. Thite ◽  
Anuradha S. Nerurkar
Keyword(s):  
Cell Wall ◽  
Sugarcane Bagasse ◽  
Structural Changes ◽  
Enzymatic Saccharification ◽  
Dry Weight ◽  
Gravimetric Analysis ◽  
Chemical Pretreatment ◽  
Cell Wall Degrading Enzymes ◽  
First Time ◽  
Soluble Components

Abstract After chemical pretreatment, improved amenability of agrowaste biomass for enzymatic saccharification needs an understanding of the effect exerted by pretreatments on biomass for enzymatic deconstruction. In present studies, NaOH, NH4OH and H2SO4 pretreatments effectively changed visible morphology imparting distinct fibrous appearance to sugarcane bagasse (SCB). Filtrate analysis after NaOH, NH4OH and H2SO4 pretreatments yielded release of soluble reducing sugars (SRS) in range of ~0.17–0.44%, ~0.38–0.75% and ~2.9–8.4% respectively. Gravimetric analysis of pretreated SCB (PSCB) biomass also revealed dry weight loss in range of ~25.8–44.8%, ~11.1–16.0% and ~28.3–38.0% by the three pretreatments in the same order. Release of soluble components other than SRS, majorly reported to be soluble lignins, were observed highest for NaOH followed by H2SO4 and NH4OH pretreatments. Decrease or absence of peaks attributed to lignin and loosened fibrous appearance of biomass during FTIR and SEM studies respectively further corroborated with our observations of lignin removal. Application of commercial cellulase increased raw SCB saccharification from 1.93% to 38.84%, 25.56% and 9.61% after NaOH, H2SO4 and NH4OH pretreatments. Structural changes brought by cell wall degrading enzymes were first time shown visually confirming the cell wall disintegration under brightfield, darkfield and fluorescence microscopy. The microscopic evidence and saccharification results proved that the chemical treatment valorized the SCB by making it amenable for enzymatic saccharification.

scholarly journals Large scale laboratory cultures of Ankistrodesmus gracilis (Reisch) Korsikov (Chlorophyta) and Diaphanosoma biergei Korinek, 1981 (Cladocera)

2008 ◽  
Vol 68 (4) ◽  
pp. 875-883 ◽  
Author(s):  
LH. Sipaúba-Tavares ◽  
AML. Pereira
Keyword(s):  
Exponential Growth ◽  
Large Scale ◽  
Light Availability ◽  
Sharp Decrease ◽  
Dry Weight ◽  
Good Alternative ◽  
Production Costs ◽  
Determining Factors ◽  
Weight Protein ◽  
Low Costs

Large-scale lab culture of Ankistrodesmus gracilis and Diaphanososma birgei were evaluated by studying the biology and biochemical composition of the species and production costs. Ankistrodesmus gracilis presented exponential growth until the 6th day, with approximately 144 x 10(4) cells.mL-1, followed by a sharp decrease to 90 x 10(4) cells.mL-1 (8th day). Algae cells tended to increase again from the 11th day and reached a maximum of 135 x 10(4) cells.mL-1 on the 17th day. D. birgei culture showed exponential growth until the 9th day with 140 x 10² individuals.L-1, and increased again as from the 12th day. Algae A. gracilis and zooplankton D. birgei contain 47 to 70% dry weight protein and over 5% dry weight carbohydrates. The most expensive items in the context of variable costs were labor and electricity. Data suggested that temperature, nutrients, light availability and culture management were determining factors on productivity. Results indicate that NPK (20-5-20) may be used directly as a good alternative for mass cultivation when low costs are taken into account, promoting adequate growth and nutritional value for cultured A. gracilis and D. birgei.

Population variation in Sorghum halepense, Johnson grass, at the northern limits of its range

1984 ◽  
Vol 62 (9) ◽  
pp. 1781-1790 ◽  
Author(s):  
S. I. Warwick ◽  
B. K. Thompson ◽  
L. D. Black
Keyword(s):  
New York ◽  
Dry Weight ◽  
Population Variation ◽  
Sorghum Halepense ◽  
Johnson Grass ◽  
Allocation Patterns ◽  
Cultivated Species ◽  
Relationship Of ◽  
The Relationship ◽  
Enzyme Patterns

Thirteen populations of Sorghum halepense, Johnson grass, were sampled from fields in Ontario, Canada, and Ohio and New York, United States. Only four of these populations were reported to overwinter as rhizomes. The morphology, phenology, resource allocation patterns, and growth of seedling and mature plants of the overwintering and the non-overwintering populations were compared. Field-collected specimens from the nonoverwintering populations had wider culms and leaves and larger seeds and inflorescences. Analysis of material grown in a 5-month greenhouse trial indicated similar differences. Greenhouse plants from the nonoverwintering populations were also characterized by greater percent emergence, larger and faster growing seedlings, earlier flowering, larger culms and seeds, greater reproductive dry weight per plant, and about 1/10th the rhizome dry weight of overwintering plants. Differences between populations within a biotype were evident for both biotypes, although there was little within-population variation, except in rhizome production, where certain individuals of some nonoverwintering populations did not produce extended rhizomes. Among the five enzymes which were examined electrophoretically, only one, phosphoglucomutase (PGM), showed variable isozyme patterns. No differences in enzyme patterns were apparent between the overwintering and the nonoverwintering biotypes. The relationship of the nonoverwintering populations to the cultivated species, Sorghum bicolor and S. almum, an introgressant between S. halepense and S. bicolor, is discussed.

Lichen Products of Cladonia Stellaris and C. Rangiferina Maintained Under Artificial Conditions

1981 ◽  
Vol 13 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Dianne Fahselt
Keyword(s):  
Light Intensity ◽  
Light Availability ◽  
Usnic Acid ◽  
Dry Weight ◽  
Lichen Thallus

AbstractLichen thallus fragments were maintained in a growth cabinet under four differing conditions of light intensity. Levels of usnic acid and atranorin did not differ significantly from the control under any of the treatments. However, perlatolic acid and fumarprotocetraric acid per unit dry weight of thallus were dependent upon light availability.

Lipid and Caloric Contents of the Relict Amphipod Pontoporeia affinis in Cayuga Lake, New York

1971 ◽  
Vol 28 (5) ◽  
pp. 776-777 ◽  
Author(s):  
Roger H. Green
Keyword(s):  
New York ◽  
Lipid Content ◽  
Standing Crop ◽  
Dry Weight ◽  
Caloric Content ◽  
High Lipid Content ◽  
Northwestern Ontario ◽  
High Lipid ◽  
Cayuga Lake ◽  
Benthic Crustacean

The relict amphipod Pontoporeia affinis at 100 m depth in Cayuga Lake, New York, had a lipid content of 33.1% of dry weight, which is unusually high for a benthic crustacean. This high lipid content resulted in the unusually high caloric content of 5240 cal/g dry weight, and a mean annual standing crop of 370 cal/m2. Annual production was estimated to be 1565 cal/m2 per year. In confirmation of the high caloric value, P. affinis from an oligotrophic lake in northwestern Ontario had a caloric content of 4741 cal/g dry weight.

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