scholarly journals Seeding year alfalfa population development as influenced by weed competition and density of establishment

1980 ◽  
Vol 52 (4) ◽  
pp. 403-422
Author(s):  
Seppo Pulli
Keyword(s):  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Plant Competition ◽  
Maximum Yield ◽  
Michigan State University ◽  
Total Biomass ◽  
State University ◽  
Seeding Rate ◽  
Yield Level

The research in intraspecific competition within an alfalfa stand and interspecific competition between alfalfa and weeds was begun on the Michigan State University farm in East Lansing in 1972. Alfalfa seeding densities of 50, 400 and 800 seeds/m2 were used to determine intraspecific competition. Interspecific competition between alfalfa and weeds occurred mainly in noncontrolled alfalfa stands at various levels of seeding densities. Plant competition was evaluated with importance values and with relative crowding coefficients. Both measurements were found to be suitable for this kind of study. Importance values primarily indicated the quantity relationships of different species. Relative crowding coefficients mainly characterized the competitive ability of a species in a mixed stand. The importance of alfalfa exceeded the importance of weeds in noncontrolled and herbicide controlled stands at the seeding rates of 14 and 7 kg/ha respectively. Relative crowding coefficients show the competitive ability of alfalfa with regard to weeds. In the case of intraspecific competition there was no change in the crowding coefficient of alfalfa in respect of weeds when the seeding rate of alfalfa was increased beyond 9 kg/ha. The crowding coefficient of weeds presented equal values under all treatments thereby indicating the variability and plasticity of weeds. The maximum yield level was obtained in all treatments with the alfalfa seeding rate of 9 kg/ha. The total biomass production per unit area was equal in the noncontrolled system at all seeding densities and in the herbicide controlled system at seeding rates of 9 kg/ha or more.

scholarly journals RELATIVE COMPETITIVENESS BETWEEN MAIZE HYBRIDS AND WILD POINSETTIA

2021 ◽  
Vol 34 (2) ◽  
pp. 298-309
Author(s):  
LEANDRO GALON ◽  
RICARDO LUIS GABIATTI ◽  
FELIPE JOSÉ MENIN BASSO ◽  
ANDRÉ LUIZ RADÜNZ ◽  
FRANCISCO WILSON REICHERT JÚNIOR ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Leaf Area ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Dry Mass ◽  
Plant Population ◽  
Grain Production ◽  
Replacement Series ◽  
Maize Hybrids ◽  
Chlorophyll Index

ABSTRACT Maize is one of the main cereals cultivated worldwide and wild poinsettia is among the weeds that cause damage in grain production. The objective of this study was to evaluate the relative competitive ability of maize hybrids in the presence of a wild poinsettia biotype through experiments in replacement series. In preliminary experiments, it was determined the plant population in which the dry mass becomes constant. For the maize hybrids ‘Agroeste’, ‘Morgan’, ‘Nidera’, and ‘Velox’, as well as the wild poinsettia, the population was 20 individuals vase-1. Subsequently, experiments were carried out in replacement series in different combinations of species that varied the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of the species' competitiveness was carried out using diagrams applied to the replacement experiments and by the relative competitiveness indexes. The height (PH), chlorophyll index (CI), leaf area (LA), and the shoot dry mass (DM) of the plants were evaluated 50 days after emergence. There was competition between the maize hybrids and the wild poinsettia; both were negatively affected, regardless of the proportion of plants, causing reductions in the species' PH, CI, LA, and DM. The competition between maize and wild poinsettia occurs for the same resources in the environment, and interspecific competition caused greater damage to maize and wild poinsettia than intraspecific competition. In general, it was observed that only the hybrids ‘Nidera’ and ‘Velox’ were more competitive than the wild poinsettia.

scholarly journals Potential use of Helianthus tuberosus to suppress the invasive alien plant Ageratina adenophora under different shade levels

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shicai Shen ◽  
Gaofeng Xu ◽  
Diyu Li ◽  
Shaosong Yang ◽  
Guimei Jin ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Mixed Culture ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Relative Yield ◽  
Branch Length ◽  
Helianthus Tuberosus ◽  
Alien Plant ◽  
Invasive Alien Plant ◽  
Ageratina Adenophora

Abstract Background An ecological approach for managing biological invasions in agroecosystems is the selection of alternative crop species to manage the infestation of invasive alien plants through competition. In the current study, plant growth, photosynthesis, and competitive ability of the crop Helianthus tuberosus L. (Jerusalem artichoke) and the invasive alien plant Ageratina adenophora (Spreng.) R. M. King and H. Rob were compared under varying shade levels by utilizing a de Wit replacement series method. We hypothesized that H. tuberosus had higher competitive ability than A. adenophora even under shaded conditions. Results The results showed the main stem, leafstalk length, leaf area, underground biomass, and aboveground biomass of A. adenophora were significantly lower compared to H. tuberosus in monoculture although A. adenophora had a greater number of branches that were longer on average. Under full sunlight, the total shoot length (stem + branch length), main stem length and branch length of A. adenophora were significantly suppressed (P < 0.05) by increasing proportions of H. tuberosus, and the same morphological variables of H. tuberosus were significantly higher with decreasing proportions of H. tuberosus. With increasing shade rates and plant ratios, the plant height, branch, leaf, and biomass of both plants were significantly suppressed, but to a greater degree in the case of A. adenophora. The net photosynthetic rate (Pn) of H. tuberosus and A. adenophora increased gradually from July to September, then decreased in October. The Pn of H. tuberosus was consistently higher than that of A. adenophora. Although the Pn for both species was significantly reduced with increasing shade rates and plant ratios, A. adenophora experienced greater inhibition than H. tuberosus. The relative yield (RY) of A. adenophora was significantly less than 1.0 (P < 0.05) in mixed culture under all shade levels, indicating that the intraspecific competition was less than interspecific competition. The RY of H. tuberosus was significantly less than 1.0 under 40–60% shade and greater than 1.0 (P < 0.05) under 0–20% shade in mixed culture, respectively, showing that intraspecific competition was higher than interspecific competition under low shade, but the converse was true under high shade. The relative yield total (RYT) of A. adenophora and H. tuberosus was less than 1.0 in mixed culture, indicating that there was competition between the two plants. The fact that the competitive balance (CB) index of H. tuberosus was greater than zero demonstrated a higher competitive ability than A. adenophora even at the highest shade level (60%). Conclusions Our results suggest that H. tuberosus is a promising replacement control candidate for managing infestations of A. adenophora, and could be widely used in various habitats where A. adenophora invades.

Competitive Ability of Wild Oats (Avena fatua) and Barley (Hordeum vulgare)

Weed Science ◽  
1991 ◽  
Vol 39 (4) ◽  
pp. 558-563 ◽  
Author(s):  
Claudio M. Dunan ◽  
Robert L. Zimdahl
Keyword(s):  
Growth Rate ◽  
Interspecific Competition ◽  
Leaf Area ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Area Ratio ◽  
Leaf Area Ratio ◽  
Field Conditions ◽  
Shoot Biomass ◽  
Wild Oats

Replacement series and growth analysis experiments under greenhouse and field conditions quantified and explained the competitive ability of wild oats and barley. Barley was a stronger competitor than wild oats under greenhouse and field conditions. The reciprocal yield approach showed that barley's intraspecific competition was 7.3 times greater than its interspecific competition with wild oats when calculated on a dry weight per plant basis. When leaf area per plant was the yield variable, barley's intraspecific competition was only 2.4 times greater than its interspecific competition. The difference was explained by wild oats' higher leaf area ratio. Barley had a greater leaf area, root and shoot biomass, absolute growth rate, and shoot-root ratio than wild oats, but wild oats' leaf area ratio was always higher. No differences were detected in relative growth rate and net assimilation rate.

scholarly journals AM Fungi Endow Greater Plant Biomass and Soil Nutrients under Interspecific Competition Rather Than Nutrient Releases for Litter

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1704
Author(s):  
Bangli Wu ◽  
Yun Guo ◽  
Minhong He ◽  
Xu Han ◽  
Lipeng Zang ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Litter Decomposition ◽  
Soil Nutrients ◽  
Intraspecific Competition ◽  
Plant Biomass ◽  
Nitrogen Concentration ◽  
Plant Competition ◽  
Nutrient Release ◽  
Am Fungi ◽  
Am Fungus

Plant competition affects belowground ecological processes, such as litter decomposition and nutrient release. Arbuscular mycorrhizal (AM) fungi play an essential role in plant growth and litter decomposition potentially. However, how plant competition affects the nutrient release of litter through AM fungi remains unclear especially for juvenile plants. In this study, a competitive potting experiment was conducted using juvenile seedlings of Broussonetia papyrifera and Carpinus pubescens from a karst habitat, including the intraspecific and interspecific competition treatments. The seedlings were inoculated by AM fungus or not inoculated, and the litter mixtures of B. papyrifera and C. pubescens were added into the soil or not added. The results were as follows: Litter addition significantly increased the root mycorrhizal colonization of two species in intraspecific competition. AM fungus significantly increased the biomass of B. papyrifera seedings and nitrogen release and decreased nitrogen concentration and N/P ratio of litter and further improved the total nitrogen and N/P ratio of soil under litter. The interspecific competition interacting with AM fungus was beneficial to the biomass accumulation of B. papyrifera and improvement of soil nutrients under litter. However, intraspecific competition significantly promoted nutrient releases via AM fungus. In conclusion, we suggest that AM fungi endow greater plant biomass and soil nutrients through interspecific competition, while intraspecific competition prefers to release the nutrients of litter.

Competition between Barnyardgrass (Echinochloa crus-galli) and Redroot Pigweed (Amaranthus retroflexus)

Weed Science ◽  
1984 ◽  
Vol 32 (2) ◽  
pp. 218-222 ◽  
Author(s):  
Gamini D. Siriwardana ◽  
Robert L. Zimdahl
Keyword(s):  
Soil Moisture ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Field Capacity ◽  
Amaranthus Retroflexus ◽  
Planting Depth ◽  
Seed Burial ◽  
Redroot Pigweed

Growth and competition of barnyardgrass [Echinochloa crus-galli(L.) Beauv. ♯ ECHCG] and redroot pigweed (Amaranthus retroflexusL. ♯ AMARE) were studied at different seed proportions, seed burial depths, and soil moisture levels. After 7 days, emergence from 1-, 2-, 4-, and 8-cm depths was 96, 90, 83, and 27% for barnyardgrass and 84, 73, 62, and 0% for redroot pigweed, respectively. Barnyardgrass was more competitive than redroot pigweed. Intraspecific competition of barnyardgrass was greater than interspecific competition from redroot pigweed. Increasing planting depth from 1 to 4 cm and increasing soil moisture from 30 to 50% (low) to 100% (high) of field capacity reduced the competitive ability of redroot pigweed.

scholarly journals Competitive Ability of Canola Hybrids Resistant and Susceptible to Herbicides

2019 ◽  
Vol 37 ◽  
Author(s):  
M.R. DURIGON ◽  
F. MARIANI ◽  
J. CECHIN ◽  
A.S. CAMERA ◽  
L. VARGAS ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Leaf Area ◽  
Intraspecific Competition ◽  
Aerial Part ◽  
Dry Matter ◽  
Competitive Ability ◽  
Crop Growth ◽  
Randomized Design ◽  
Completely Randomized Design

ABSTRACT: This work aimed to compare the competitive ability of canola hybrids susceptible (conventional) or resistant to triazine or imidazolinone group herbicides, with turnip. The experiments were conducted in greenhouse, in a completely randomized design, with four replicates. The hybrids Hyola 571CL (resistant to imidazolinone), Hyola 555TT (resistant to triazine), and Hyola 61 (conventional) were used. The treatments consisted of ratios (100:0; 75:25; 50:50; 25:75; 0:100%) of canola and turnip plants. The evaluation was performed 44 days after emergence, determining the leaf área (AF), dry matter of aerial part (MSPA), and stature (EST) of the plants. The competitiveness analysis was performed through diagrams and interpretation of the competitiveness indexes. For the canola hybrids, the competition occurred by the same mean resources. There was damage to the crop growth in competition with the turnip. The turnip was not benefited only when in competition with Hyola 571CL hybrid, for the EST variable, and with the conventional canola, for the variable AF. There was significance for the competitiveness indexes, demonstrating that turnip is more competitive then the crop. Greater AF, MSPA, and EST occurred for canola plants in the smallest proportions of turnip and, for turnip plants, in the largest proportions of canola. The ability to compete with turnip is similar among hybrids, with injury to the crop and benefit to the weed, when competing. Interspecific competition is more damaging to canola hybrids; and intraspecific competition is more damaging to turnip.

scholarly journals Interacting Flooding and Competition Negatively Affect Growth of Riparian Species Dominating a Reservoir Shoreline

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1471
Author(s):  
Yu-Han Chen ◽  
Xin-Sheng Sun ◽  
Yuan Cui ◽  
Na Zhuo ◽  
Guan-Wen Wei ◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Chlorophyll Content ◽  
Intraspecific Competition ◽  
Total Biomass ◽  
Plant Interactions ◽  
Polygonum Hydropiper ◽  
Riparian Species ◽  
Xanthium Sibiricum ◽  
Topographic Positions ◽  
Photosynthetic Capacities

Plant–plant interactions change in response to environmental conditions, and riparian species are commonly influenced by flooding. This study tested whether flooding affects the intraspecific and interspecific competition of two riparian species and whether such effects depend on the topographic positions where plants have established. Seeds of the riparian species Polygonum hydropiper were collected from both low and high positions within the shoreline of the Three Gorges Reservoir. Groups of P. hydropiper seedlings from each position were either grown alone (i.e., without competition), with another group of P. hydropiper seedlings (i.e., intraspecific competition), or with a group of seedlings of the companion species Xanthium sibiricum (i.e., interspecific competition). Each group comprised six replicates. In total, 288 plants of P. hydropiper and 84 plants of X. sibiricum were selected for the experiment. Seedlings were subjected to control and flooding treatments for 60 days. Irrespective of competition type (i.e., intra- or interspecific), both flooding and competition negatively affected the growth and/or photosynthetic capacities of P. hydropiper. Flooding only interacted with competition to explain total biomass. Flooding reduced total biomass in a larger proportion in the absence of competition, and, to a lesser extent, with intraspecific competition, compared to interspecific competition. However, such interaction effects were independent of the positions where the seeds that originated from the plants were collected from. Interspecific competition significantly decreased the chlorophyll content and photosynthetic efficiency of plants, while intraspecific competition did not. In general, plants from lower positions had higher total chlorophyll content than plants from higher positions. These results suggest that flooding may regulate the population dynamics of P. hydropiper by altering its competitive interactions.

Ultrastructural Studies of Bovine Respiratory Disease Complex

1975 ◽  
Vol 33 ◽  
pp. 428-429
Author(s):  
James C.S. Kim
Keyword(s):  
Michigan State University ◽  
State University ◽  
Diagnostic Laboratory ◽  
Ultrastructural Studies ◽  
Bovine Respiratory Diseases ◽  
Etiologic Agents ◽  
Diagnostic Difficulties ◽  
The Subject ◽  
Capillary Walls ◽  
Alveolar Capillary

Bovine respiratory diseases cause serious economic loses and present diagnostic difficulties due to the variety of etiologic agents, predisposing conditions, parasites, viruses, bacteria and mycoplasma, and may be multiple or complicated. Several agents which have been isolated from the abnormal lungs are still the subject of controversy and uncertainty. These include adenoviruses, rhinoviruses, syncytial viruses, herpesviruses, picornaviruses, mycoplasma, chlamydiae and Haemophilus somnus.Previously, we have studied four typical cases of bovine pneumonia obtained from the Michigan State University Veterinary Diagnostic Laboratory to elucidate this complex syndrome by electron microscopy. More recently, additional cases examined reveal electron opaque immune deposits which were demonstrable on the alveolar capillary walls, laminae of alveolar capillaries, subenthothelium and interstitium in four out of 10 cases. In other tissue collected, unlike other previous studies, bacterial organisms have been found in association with acute suppurative bronchopneumonia.

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