Impact of Soil pH on Cogongrass (Imperata cylindrica) and Bahiagrass (Paspalum notatum) Competition

2018 ◽  
Vol 32 (3) ◽  
pp. 336-341 ◽  
Author(s):  
Candice M. Prince ◽  
Gregory E. MacDonald ◽  
Jason A. Ferrell ◽  
Brent A. Sellers ◽  
Jingjing Wang
Keyword(s):  
Soil Ph ◽  
Competitive Ability ◽  
Relative Yield ◽  
Imperata Cylindrica ◽  
Management Tool ◽  
Paspalum Notatum ◽  
Replacement Series ◽  
Cultural Management ◽  
Disturbed Areas ◽  
Poor Soil

AbstractCogongrass is commonly found in disturbed areas in Florida, where it is increasingly becoming a problem in bahiagrass pastures. Soil pH has been suggested as a possible mechanism for this invasion; to evaluate this, replacement series competition studies were conducted under greenhouse conditions at two soil pH levels: pH 4.5, or pH 6.8. Cogongrass ramets and bahiagrass seedlings were planted at proportions of 0:40, 1:20, 2:10, 4:1, and 8:0, respectively. Aboveground biomass was measured after 8 weeks and used to calculate relative yield, relative crowding coefficients, and aggressivity values. At soil pH 4.5, the relative competitiveness of cogongrass and bahiagrass was similar, with both species contributing equally to relative yield. At soil pH 6.8, bahiagrass seedlings showed greater competitive ability than cogongrass ramets. Relative crowding coefficient and aggressivity values supported this, with bahiagrass showing increased competitiveness under higher soil pH. This indicates that decreases in soil pH, often associated with poor soil fertility, is likely a contributing factor for cogongrass invasion into bahiagrass pastures. Soil amendments to raise pH may provide a cultural management tool for cogongrass infestations in pastures.

The Influence of Increasing Carbon Dioxide and Temperature on Competitive Interactions Between a C3 Crop, Rice (Oryza sativa) and a C4 Weed (Echinochloa glabrescens)

1996 ◽  
Vol 23 (6) ◽  
pp. 795 ◽  
Author(s):  
AMP Alberto ◽  
LH Ziska ◽  
CR Cervancia ◽  
PA Manalo
Keyword(s):  
Elevated Co2 ◽  
Growth Temperature ◽  
Competitive Ability ◽  
Relative Yield ◽  
Co2 Concentration ◽  
The Philippines ◽  
Replacement Series ◽  
Lower Growth ◽  
C4 Species ◽  
Lower Growth Temperature

Many of the most troublesome weeds in agricultural systems are C4 plants. As atmospheric CO2 increases it is conceivable that competitive ability of these weeds could be reduced relative to C3 crops such as rice. At the International Rice Research Institute (IRRI) in the Philippines, rice (IR72) and one of its associated C4 weeds, Echinochloa glabrescens, were grown from seeding to maturity using replacement series mixtures (100:0, 75:25, 50:50, 25:75, and 0:100, % rice:%weed) at two different CO2 concentrations (393 and 594 μL L-1) in naturally sunlit glasshouses. Since increasing CO2 may also result in elevated growth temperatures, the response of rice to each CO2 concentration was also examined at daylnight temperatures of 27/21 and 37/29�C. At 27/21�C, increasing the CO2 concentration resulted in a significant increase in above ground biomass (+47%) and seed yield (+55%) of rice when averaged over all mixtures. For E. glabrescens, the C4 species, no significant effect of CO2 concentration on biomass or yield was observed. When grown in mixture, the proportion of rice biomass increased significantly relative to that of the C4 weed at all mixtures at elevated CO2. Evaluation of changes in competitiveness (by calculation of plant relative yield (PRY) and replacement series diagrams) of the two species demonstrated that, at elevated CO2, the competitiveness of rice was increased relative to that of E. glabrescens. However, at the higher growth temperature (37/29�C), growth and reproductive stimulation of rice by elevated CO2 was reduced compared to the lower growth temperature. This resulted in a reduction in the proportion of rice:weed biomass present in all mixtures relative to 27/21�C and a greater reduction in PRY in rice relative to E. glabrescens. Data from this experiment suggest that competitiveness could be enhanced in a C3 crop (rice) relative to a C4 weed (E. glabrescens) with elevated CO2 alone, but that simultaneous increases in CO2 and temperature could still favour a C4 species.

Impact of Soil pH on Bahiagrass Competition with Giant Smutgrass (Sporobolus indicusvar.pyramidalis) and Small Smutgrass (Sporobolus indicusvar.indicus)

Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 109-116 ◽  
Author(s):  
Neha Rana ◽  
Brent A. Sellers ◽  
Jason A. Ferrell ◽  
Gregory E. MacDonald ◽  
Maria L. Silveira ◽  
...  
Keyword(s):  
United States ◽  
Soil Ph ◽  
Competitive Ability ◽  
Biomass Accumulation ◽  
The United States ◽  
Replacement Series ◽  
Native Soil ◽  
Differential Responses

Smutgrass is an invasive, well-rooted perennial that has long been recognized as an aggressive weed throughout Florida and in the subtropical regions of the United States. Small smutgrass and giant smutgrass are the two predominant smutgrass varieties found in Florida. The native soil pH of Florida flatwoods is 4.5 to 5.0 which is lower than the level of soil pH recommended for optimum bahiagrass growth. Therefore, replacement series experiments were conducted in a greenhouse in 2010 and 2011 to compare the competitive ability of bahiagrass with each of the two varieties of smutgrass at three levels of soil pH (4.5, 5.5, and 6.5), two densities; 4 (low) and 8 (high) plants pot−1, and at five planting ratios of 100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100. Relative competitive ability and aggressivity of giant smutgrass was greater than bahiagrass across all pH levels and densities, whereas relative competitive ability and aggressivity of bahiagrass was greater than small smutgrass in all pH levels and densities, except at pH 6.5. At pH 5.5, biomass accumulation of giant smutgrass was at least 73% higher than bahiagrass, whereas small smutgrass biomass was at least 46% lower than bahiagrass at equal planting ratios of both low and high densities. Differential responses were observed on bahiagrass competitive ability with small and giant smutgrass. Amending soil pH is not a likely option to increase the growth and competitive ability of bahiagrass over giant smutgrass. However, for small smutgrass, it is likely to increase the aggressivity of bahiagrass in bahiagrass–small smutgrass mixture, unless the soil pH is raised above 5.5.

scholarly journals Influence of different barley varieties on competition and yield performance in barley-oats mixtures at two levels of nitrogen fertilization

1991 ◽  
Vol 63 (4) ◽  
pp. 341-351
Author(s):  
Kari Jokinen
Keyword(s):  
Competitive Ability ◽  
Relative Yield ◽  
Grain Protein Content ◽  
Pure Stand ◽  
Replacement Series ◽  
Yield Performance ◽  
Relative Significance ◽  
Barley Cultivars ◽  
Relative Yield Total ◽  
Stand Yield

Competition between barley and oats, and yield performance of mixtures were evaluated in a two component replacement series field experiment at two levels of nitrogen applications (80 kgN/ha and 120 kgN/ha). Three barley cultivars (Aapo, Agneta ja Ida) and one oats cultivar (Veli) were used. The competitive relationship was independent of the pure stand yield of the cultivar. Ida and Agneta were more competitive than oats irrespective of nitrogen dose. Ida was the most dominant variety which was very likely due to the early development of the seedlings. Oats was slightly more competitive than the shortest cultivar Aapo at high nitrogen, although barley seedlings emerged before oats. Thus the competitive ability of a cultivar was not determined by one character of the plant only. The competition in mixtures had a greater effect on number of generative shoots and number of grains per head than on grain weight. The results revealed that the yield per plant in mixtures may be even the same as in monoculture, but the relative significance of different yield components may vary. The grain and protein yield of mixtures did not differ significantly from the yield of the highest yielding component grown alone. However, the ratio of actual and expected yield and the relative yield total were in most cases higher than one, indicating that some yield advantage may have been achieved. The genotypic composition of the stand had the greatest influence on the grain protein content of oats.

scholarly journals The effect of site on competition and yield advantages of mixtures of barley and oats

1991 ◽  
Vol 63 (4) ◽  
pp. 353-359
Author(s):  
Kari Jokinen
Keyword(s):  
Field Experiment ◽  
Grain Yield ◽  
Protein Content ◽  
Competitive Ability ◽  
Relative Yield ◽  
Early Growth ◽  
Average Yield ◽  
Replacement Series ◽  
Relative Yield Total ◽  
Genotypic Structure

Competition between six-row barley cv. Agneta and oats cv. Veli, and yield advantages of the mixtures were evaluated in a replacement series field experiment. The experiment was situated in a sloping area. Although barley was lower yielding (grain yield) than oats when the components were grown in monoculture, barley was dominant in all mixtures irrespective of the site. The competitive ability of barley decreased from the less productive site (top) to the more productive site (bottom). The improved competitive ability of oats was likely due to the faster early growth of oats. The grain yield of the mixture was about 4°70 (p >0.05) greater than the yield of the highest yielding component (oats) grown in monoculture on the more productive sites. The grain yield of the mixture was greater than the average yield of the pure stands and also the relative yield total exceeded one irrespective of the site. The grain weight of the species was independent of the genotypic structure of the stands. The protein content of oats was the highest, being greater in mixtures than in monocultures. The protein yield and the protein content of the mixture was between the values for pure stands.

scholarly journals Yield and competition in barley variety mixtures

1991 ◽  
Vol 63 (4) ◽  
pp. 287-305 ◽  
Author(s):  
Kari Jokinen
Keyword(s):  
Competitive Ability ◽  
Field Experiments ◽  
Spring Barley ◽  
Relative Yield ◽  
Growing Season ◽  
Morphological Characters ◽  
Replacement Series ◽  
Available Nitrogen ◽  
Relative Yield Total ◽  
Variety Mixtures

Competition between spring barley varieties and yield performance of two-, three and four-variety mixtures were studied in two replacement series field experiments. In the first experiment, repeated in three successive years (1983 —85) the components were the six-row varieties Agneta, Arra, Hja-673 and Porno. In the second experiment (1984), including two nitrogen doses (50 and 100 kgN/ha), both six-row (Agneta, Pomo) and two-row (Ida, Kustaa) varieties were used. Arra in the first and Agneta in the second experiment were the most competitive varieties. The results suggested that the fast growth of Arra at the beginning promoted its competitive ability. Increase in available nitrogen usually strengthened the competitiveness of Agneta. The observed competitive differences between varieties were not related to the earliness of a variety, neither to the morphological characters (two- and six-row varieties) nor to the grain yield of a variety grown alone. The competitive ability was not always a stable character, the dominant suppression relationship varying from one environment to another (e.g. growing season, nitrogen dose). The observed overyielding was not statistically significant. The ratio of actual to expected yield and the relative yield total of several mixtures exceeded slightly one. As a conclusion, the yield advantage of mixtures was marginal. As a rule, the mixtures were not more stable than monocultures as determined by the coefficient of variation. However, the yield of some mixtures varied less than the yield of the most stable monoculture.

scholarly journals Competitiveness of alexandergrass or Bengal dayflower with soybean

2010 ◽  
Vol 28 (3) ◽  
pp. 515-522 ◽  
Author(s):  
A.C.R. Dias ◽  
S.J.P. Carvalho ◽  
L.W. Marcolini ◽  
M.S.C. Melo ◽  
P.J. Christoffoleti
Keyword(s):  
Competitive Ability ◽  
Dry Mass ◽  
Total Density ◽  
Weed Species ◽  
Replacement Series ◽  
Commelina Benghalensis ◽  
Randomized Design ◽  
Full Flowering ◽  
Completely Randomized Design ◽  
Soybean Plants

Weeds compete with field crops mainly for water, light and nutrients, and the degree of competition is affected by the weed density and the intrinsic competitive ability of each plant species in coexistence. The objective of this research was to compare the competitiveness of alexandergrass (Brachiaria plantaginea) or Bengal dayflower (Commelina benghalensis) in coexistence with soybean, cv. M-Soy 8045. A factorial experiment (2 x 5) with two weed species and five competition proportions was carried out in a completely randomized design with four replicates. Proportions were based on a replacement series competition design, always maintaining the total density of four plants per 10 L plastic pots, which corresponded to 60 plants m ². The weed-crop proportions were: 0:4; 1:3; 2:2; 3:1; 4:0; that corresponded to the proportion of 100, 75, 50, 25 and 0% of soybean plants and the opposite for weeds, B. plantaginea or C. benghalensis plants. Leaf area, shoot dry mass of the weeds and soybean and number of soybean trifoliate leaves were evaluated when the soybean reached the phenologic stage of full flowering. B. plantaginea was a better competitor than soybean plants. Otherwise, C. benghalensis revealed a similar competitive ability that of the soybean. In both cases, there were evidences that intraspecific competition was more important.

scholarly journals Initial growth and competitive ability of yellow nutsedge and irrigated rice

2013 ◽  
Vol 31 (4) ◽  
pp. 813-821 ◽  
Author(s):  
N.R. Westendorff ◽  
D. Agostinetto ◽  
A.R. Ulguim ◽  
A.C. Langaro ◽  
L. Thürmer
Keyword(s):  
Leaf Area ◽  
Competitive Ability ◽  
Growth Cycle ◽  
Rice Crop ◽  
Initial Growth ◽  
Rice Cultivars ◽  
Replacement Series ◽  
Irrigated Rice ◽  
Yellow Nutsedge ◽  
Dry Biomass

Weeds cause significant reduction in the irrigated rice crop yield. Cyperus esculentus (yellow nutsedge) is adapted to irrigate environment. Information on the competitive ability of the weed to the culture, and their environmental adaptation, are scarce. In this study, we sought to determine the initial growth and competitive ability of yellow nutsedge and irrigated rice, as a function of cultivar growth cycle. Initial growth and competition studies were conducted in a randomized complete design in a greenhouse in the agricultural year 2010/11. For the initial growth study, the treatments consisted of a factorial combination of a biotype of yellow nutsedge and two rice cultivars in the function of the vegetative cycle (BRS Querência: early cycle - IRGA 424: intermediate cycle) and six evaluation times (10, 20, 30, 40, 50, and 60 days after emergence). Were evaluated: plant height, leaf area, aboveground dry biomass and root dry biomass. In the competitive ability study in the replacement series, the cultivar BRS Querência (early cycle) and yellow nutsedge were utilized and tested in different proportions of competition (100:0, 75:25, 50:50, 25:75, and 0:100). Were evaluated leaf area and aboveground dry biomass. In general, rice cultivars have an adaptive value equivalent to yellow nutsedge. IRGA 424 cultivar has less height than weed, becoming the weed control more important in this cultivar. For rice crop, intraspecific competition is more important, whereas for the weed, interspecific competition is the most pronounced.

Imazapic Effects on Competition Dynamics Between Native Perennial Grasses and Downy Brome (Bromus tectorum)

2015 ◽  
Vol 8 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Shayla A. Burnett ◽  
Brian A. Mealor
Keyword(s):  
Native Species ◽  
Relative Yield ◽  
Perennial Grasses ◽  
Downy Brome ◽  
Replacement Series ◽  
Application Timing ◽  
Ecosystem Disturbance ◽  
Series Design ◽  
Species Establishment ◽  
Negative Impacts

AbstractDowny brome inhibits revegetation efforts following ecosystem disturbance. Imazapic is a commonly used herbicide for downy brome management, but more information is needed regarding effective application timing for restoration efforts. We wished to determine (1) if native species establishment exhibited a tradeoff between downy brome competition and injury from herbicide and (2) if this differed between pre- and postemergent applications of imazapic. We used a standard replacement series design and overlaid herbicide treatments. Nine weeks after planting, aboveground biomass was harvested and relative yield (RY) indices calculated. Both imazapic applications reduced downy brome biomass by 91% or more (P < 0.05). Imazapic caused drastic reductions in native biomass but less than what was caused by downy brome competition (P < 0.05). Natives were less injured by a pre- than postemergent application (P < 0.05). In situations where downy brome may impact restoration efforts, pre-emergent applications of imazapic at 70 g ai ha−1 (0.06 lb ai ac−1) may reduce downy brome with less negative impacts on newly-seeded native grasses than post-emergent applications. Ensuring sufficient proportions of native species seeds on restoration sites may reduce downy brome.

scholarly journals Plant size, nutrient composition and biomass productivity of oats and faba bean in intercropping, and the effect of controlling Rhopalosiphum padi (Hom., Aphididae) on these properties

1990 ◽  
Vol 62 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Juha Helenius
Keyword(s):  
Faba Bean ◽  
Field Experiments ◽  
Rhopalosiphum Padi ◽  
Relative Yield ◽  
Biomass Productivity ◽  
Plant Size ◽  
Damage Function ◽  
Point Of View ◽  
Daily Maximum ◽  
Replacement Series

Effects of mixed intercropping on plant size, content of mineral nutrients and biomass yields were examined in three field experiments in Southern Finland in 1983—1985. The stand types were monocrops and replacement series of mixtures with 2/3 and 1/3 or 1/3 and 2/3 of oats (Avena sativa) and faba bean (Vicia faba), respectively. In one of the experiments control of R. padi, by means of deltamethrin sprayings, was an additional experimental factor having two levels. The height of stems or the above ground biomass of oats either were not affected or were increased by crop diversification. Bean plants remained smaller in the mixtures than in the monocrop. In plant size, there was a significant interaction between stand type and the effect of aphicide spraying: Oat benefitted most from being grown in the mixture containing most bean, and there was an indication (not statistically significant) that in these mixtures bean had proportionately higher weight loss. This result was interpreted as giving some support to the hypothesis of interspecific compensation between oats and bean against aphid damage to oats. In oats, the content of N, P, K, Ca, and Mg all decreased from the stage of inflorescence emergence to the stage of the onset of milk development. Mixed cropping increased the content in oats of all these nutrients except Ca. At the same time, contents of P and K in bean were decreased. The changes in growth form and composition in oats induced by intercropping are discussed from the point of view of host plant relationship and damage function of the aphid pest. In terms of relative yield total (RYT), there was no overyielding in the dry matter, and in one case only was there overyielding in the nitrogen. During the period of population growth of R. padi, the daily maximum temperatures within the canopy were higher in the mixtures than in the monocrop of oats.

scholarly journals Competitiveness of ALS inhibitors resistant and susceptible biotypes of Greater Beggarticks (Bidens subalternans)

2011 ◽  
Vol 29 (2) ◽  
pp. 457-464 ◽  
Author(s):  
F.P. Lamego ◽  
R.A. Vidal ◽  
N.R. Burgos
Keyword(s):  
Competitive Ability ◽  
Germination Rate ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Replacement Series ◽  
Relative Growth Rates ◽  
Temperature Conditions ◽  
Als Inhibitors ◽  
The University ◽  
Continuous Use

The continuous use of ALS-inhibiting herbicides has led to the evolution of herbicide-resistant weeds worldwide. Greater beggarticks is one of the most troublesome weeds found in the soybean production system in Brazil. Recently, a greater beggarticks biotype that is resistant (R) to ALS inhibitors due to Trp574Leu mutation in the ALS gene was identified. Also, the adaptive traits between susceptible (S) and R to ALS inhibitors biotypes of greater beggarticks were compared. Specifically, we aimed to: (1) evaluate and compare the relative growth rates (RGR) between the biotypes; (2) analyze the seed germination characteristics of R and S biotypes under different temperature conditions; and (3) evaluate their competitive ability in a replacement series study. The experiments were conducted at the University of Arkansas, USA, in 2007 and at Universidade Federal do Rio Grande do Sul (Federal University of Rio Grande do Sul), Brazil, in 2008. Plant proportions for replacement series studies were respectively 100:0, 75:25, 50:50, 25:75 and 0:100, with a total population of 150 plants m-2. There was no difference in RGR between R and S biotypes. The R-biotype germination rate was lower than that of the S biotype. However, at low temperature conditions (15 ºC), the reverse was observed. In general, there is no difference in the competitive ability between R and S greater beggarticks biotypes.

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