scholarly journals Drought and Ozone Stress Effects on Competition among Selected Prairie Grass Species and Giant Foxtail

1999 ◽  
Vol 9 (2) ◽  
pp. 227-234 ◽  
Author(s):  
Gregory A. Endress ◽  
Anton G. Endress ◽  
Louis R. Iverson
Keyword(s):  
Leaf Area ◽  
Water Availability ◽  
Relative Yield ◽  
Leaf Number ◽  
Grass Species ◽  
Big Bluestem ◽  
Weed Species ◽  
Replacement Series ◽  
Giant Foxtail ◽  
The Impact

Differential responses of species to environmental stress may interfere with restoration of prairie ecosystems or change community structure. The impact of increasing atmospheric ozone (O3) concentrations and/or low water on the growth of Andropogon gerardii Vitm. (big bluestem) and Sorghastrum nutans (L.) Nash (indian grass), two common warm-season native grasses, and Setaria faberi Herrm. (giant foxtail), a vigorous annual weed species, were studied in replacement series. Giant foxtail grew better than either big bluestem or indian grass under all tested conditions. The leaf areas of all three species were primarily controlled by water availability. Big bluestem and indian grass accumulated biomass equally well under high water availability, but with low water, indian grass accumulated more biomass than did bluestem. Three-way analysis of variance showed biomass, leaf area, and leaf number differed among species; low water was significant in all cases except for indian grass leaf area; and the O3 effect was significant only in the case of foxtail biomass. The interaction of O3 concentration and low water was significant only for indian grass biomass and leaf number; the interaction of species combination and low water was significant only for big bluestem leaf area and biomass. Relative yield calculations indicated that under conditions of elevated O3 and low water, big bluestem was the least competitive, while indian grass was most competitive. Intraspecific competition was common, each species apparently utilizing the environment in different ways. The results also suggest that giant foxtail at a low relative density may be used as a nurse species in prairie restorations as growth of big bluestem and indian grass were improved when in mixtures with foxtail.

Interference among Bean (Phaseolus vulgaris), Barnyardgrass (Echinochloa crus-galli), and Black Nightshade (Solanum nigrum)

Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 336-342 ◽  
Author(s):  
Steven A. Fennimore ◽  
L. W. Mitich ◽  
Steven R. Radosevich
Keyword(s):  
Phaseolus Vulgaris ◽  
Leaf Area ◽  
Central Valley ◽  
Dry Weight ◽  
Field Studies ◽  
Solanum Nigrum ◽  
Weed Species ◽  
Replacement Series ◽  
Black Nightshade ◽  
The Impact

The interference between dry bean (Phaseolus vulgarisL. var. Red Kidney), black nightshade (Solanum nigrum♯3SOLNI), and barnyardgrass (Echinochloa crus-galli♯ ECHCR) was examined in replacement series experiments. A modified replacement series experiment also was performed to examine the effects of no interference, and intraspecific and interspecific interference on the height, leaf area, and dry weight of bean, black nightshade, and barnyardgrass. In both types of competition experiments, bean germinated earlier than either weed species and caused significant reductions in weed height, leaf area, and dry weight. The impact of bean upon itself was always greater than the effect of either weed species. In laboratory studies, barnyardgrass and black nightshade seeds were subjected to eight concentrations of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine). Black nightshade was 100 times more tolerant to trifluralin than barnyardgrass. Field studies, conducted at several locations in the Central Valley of California in which trifluralin-treated plots were compared with nontreated plots, demonstrated that trifluralin favors trifluralin-tolerant weeds (black nightshade), but trifluralin-sensitive weeds (barnyardgrass) have not been eliminated despite 20 yr of trifluralin use.

The Impact of Noah-MP Physical Parameterizations on Modeling Water Availability during Droughts in the Texas-Gulf Region

2021 ◽  
Author(s):  
Wen-Ying Wu ◽  
Zong-Liang Yang ◽  
Michael Barlage
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Water Availability ◽  
Water Storage ◽  
Rooting Depth ◽  
Surface Model ◽  
Terrestrial Water Storage ◽  
Area Index ◽  
Terrestrial Water ◽  
The Impact

AbstractTexas is subject to severe droughts, including the record-breaking one in 2011. To investigate the critical hydrometeorological processes during drought, we use a land surface model, Noah-MP, to simulate water availability and investigate the causes of the record drought. We conduct a series of experiments with runoff schemes, vegetation phenology, and plant rooting depth. Observation-based terrestrial water storage, evapotranspiration, runoff, and leaf area index are used to compare with results from the model. Overall, the results suggest that using different parameterizations can influence the modeled water availability, especially during drought. The drought-induced vegetation responses not only interact with water availability but also affect the ground temperature. Our evaluation shows that Noah-MP with a groundwater scheme produces a better temporal relationship in terrestrial water storage compared with observations. Leaf area index from dynamic vegetation is better simulated in wet years than dry years. Reduction of positive biases in runoff and reduction of negative biases in evapotranspiration are found in simulations with groundwater, dynamic vegetation, and deeper rooting zone depth. Multi-parameterization experiments show the uncertainties of drought monitoring and provide a mechanistic understanding of disparities in dry anomalies.

scholarly journals Interference interactions in experimental pine–hardwood stands

1993 ◽  
Vol 23 (10) ◽  
pp. 2032-2043 ◽  
Author(s):  
Todd S. Fredericksen ◽  
Shepard M. Zedaker ◽  
David W. Smith ◽  
John R. Seiler ◽  
Richard E. Kreh
Keyword(s):  
Leaf Area ◽  
Loblolly Pine ◽  
Black Locust ◽  
Light Availability ◽  
Relative Yield ◽  
Growth And Yield ◽  
Red Maple ◽  
Replacement Series ◽  
Herbaceous Vegetation ◽  
Hardwood Species

A replacement series field experiment was established in 1989 in the Piedmont physiographic province of Virginia with loblolly pine (Pinustaeda L.), red maple (Acerrubrum L.), and black locust (Robiniapseudoacacia L.) to quantify the effects of interference and elucidate its mechanisms. Stands were planted with and without herbaceous vegetation. After three growing seasons, interference among pine, hardwood species, and herbaceous vegetation significantly affected growth and yield. While herbaceous vegetation significantly affected all stands, it reduced the yield of hardwood species more than of loblolly pine. Loblolly pine appeared to ameliorate the effect of herbaceous vegetation on hardwoods in some stands. Based on relative yield totals, interference relationships between pine and hardwood species were neutral in all replacement series except for the loblolly pine–black locust series with herbaceous vegetation, where a mutualistic relationship was evident on poorer sites of the study. Pine appeared to compete effectively with hardwoods through efficient use of soil moisture and nitrogen, although pines had lower root/shoot ratios. Pine also had the greatest amount of leaf area of all species. Black locust reduced light availability to pine in some stands, but may have provided some nutritional benefits. Black locust and red maple appeared to increase allocation to roots in herbaceous vegetation, especially in pure stands. Root/shoot ratio, water-use efficiency, and leaf area were the measured variables most closely correlated with tree yield.

Competition and growth of six cowpea (Vigna unguiculata) genotypes, sunflower (Helianthus annuus), and common purslane (Portulaca oleracea)

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 954-960 ◽  
Author(s):  
Guangyao Wang ◽  
Milton E. McGiffen ◽  
Jeff D. Ehlers
Keyword(s):  
Growth Rate ◽  
Field Experiments ◽  
Growth Habit ◽  
Growth Parameters ◽  
Weight Ratio ◽  
Relative Yield ◽  
Isotonic Regression ◽  
Weed Species ◽  
Replacement Series ◽  
Common Purslane

Varietal growth habit could play a key role in the competitiveness of crop plants with weeds. The relative competitiveness of two erect, two semierect, and two prostrate cowpea genotypes with a tall-growing (common sunflower) or a low-growing (common purslane) species was evaluated in 12 replacement-series experiments conducted in 2003 and 2004. Growth analysis of the six cowpea genotypes and two weed species were also conducted to investigate the relationship of competitiveness and growth. Cowpea genotype and competitor biomass were used to calculate relative yield total (RYT) and aggressivity indices (AI). RYT and AI means of six cowpea genotypes were compared using ANOVA, and an isotonic regression was used to confirm the relative competitive superiority of the cowpea growth types. All cowpea genotypes had similar RYTs when grown with sunflower or common purslane, indicating that cowpea used the same resources as sunflower or purslane. When grown with sunflower, erect and semierect genotypes had higher AI than prostrate genotypes. When grown with purslane, erect and prostrate genotypes had higher AI than semierect genotypes. The results were confirmed by isotonic regression tests on the respective AI order. Correlation and regression between AI and growth parameters showed that the relative growth rate (RGR), leaf area ratio (LAR), and height growth rate (HGR) explained 92% of the variation of AI when cowpeas were grown with sunflower and that leaf weight ratio (LWR) and biomass explained 82% of the variation of AI when cowpeas were grown with purslane. These experiments indicate that cowpea genotypes differ in their ability to compete with purslane or sunflower. Erect genotypes were the most competitive, suggesting that an erect growth habit may be more effective in suppressing weeds than a semierect or prostrate growth habit. These results are consistent with field experiments on the competitiveness of erect, semierect, and prostrate cowpea genotypes.

Cured Dairy Compost Influence on Weed Competition and on ‘Snowden' Potato Yield

2013 ◽  
Vol 27 (2) ◽  
pp. 378-388 ◽  
Author(s):  
Alexander J. Lindsey ◽  
Karen A. Renner ◽  
Wesley J. Everman
Keyword(s):  
Specific Gravity ◽  
Potato Yield ◽  
Yield Reduction ◽  
Weed Competition ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Hairy Nightshade ◽  
Giant Foxtail ◽  
The Impact ◽  
Tuber Specific Gravity

Potatoes are an important global food crop typically produced in high-input systems in temperate zones. Growers that have access to compost may use it to improve soil health and increase tuber yields, but compost may also increase weed competition by increasing early-season water availability and weed growth. A field study at the Michigan State University Montcalm Research farm in 2010 and 2011 investigated the impact of compost on weed competition in potato. Potatoes were grown in field plots with 0, 4,000, or 8,000 kg carbon (C) ha−1of compost under weed-free conditions, and in competition with common lambsquarters, giant foxtail, and hairy nightshade. Compost did not increase biomass or seed production of any weed species. Giant foxtail and hairy nightshade at 5.3 plants per meter of row reduced potato yield by 20%; common lambsquarters reduced yield by 45%. The yield reduction by giant foxtail and hairy nightshade was due to a decrease in tuber bulking, whereas yield reductions from common lambsquarters were a result of lower tuber set and bulking. Potato yield increased 5 to 15% in compost compared to non-compost treatments; tuber specific gravity decreased by 0.3% in composted treatments. Across weed densities, elevated soil potassium levels in the 8,000 kg C ha−1composted treatment may have increased potato yield and decreased tuber specific gravity.

Effects of Water on Recovery of Weed Seedlings Following Burial

Weed Science ◽  
2016 ◽  
Vol 64 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Charles L. Mohler ◽  
Javaid Iqbal ◽  
Jianying Shen ◽  
Antonio DiTommaso
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Burial Depth ◽  
Management Problem ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Giant Foxtail ◽  
Organic Weed Management ◽  
The Impact ◽  
Better Than

Recovery of common agricultural weeds after burial by soil was studied in four greenhouse and three field experiments. Species studied included velvetleaf, Powell amaranth, common lambsquarters, barnyardgrass, and giant foxtail. Seedlings were bent over before burial to simulate the effect of the impact of soil thrown by a cultivator. Altogether, more than 35,000 seedlings were marked and observed for recovery. No seedlings recovered from 4 cm of burial. Recovery from complete burial under 2 cm of soil ranged from 0 to 24% depending on the experiment, species, and watering treatment, but recovery greater than 5% was rare. Large-seeded species tended to recover from complete burial under 2 cm of soil better than small-seeded species. The study did not reveal a difference in recovery of grasses relative to broadleaf weeds. Overall, seedlings tended to recover best when water was applied daily after burial, worst when water was applied once on the day of burial, and to an intermediate extent when no water was applied. However, difference in recovery between the no-water and watering-once treatments were usually small. Also, many experiment by species combinations showed no significant differences among watering treatments. When even a small portion of the seedling was left exposed, recovery generally exceeded 50%. Organic weed management systems commonly use burial of weed seedlings with tine weeders and soil thrown by sweeps and hilling disks to control weeds in crop rows. Recovery from burial could pose a substantial weed management problem in some circumstances, particularly for large-seeded weed species. Maximizing burial depth is important for limiting recovery. Recovery from burial can be minimized by withholding irrigation for several days after hilling-up operations.

Light and growth rate effects on crop and weed responses to nitrogen

Weed Science ◽  
2004 ◽  
Vol 52 (4) ◽  
pp. 578-583 ◽  
Author(s):  
Matthew M. Harbur ◽  
Micheal D. K. Owen
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Weed Management ◽  
Dry Weight ◽  
Weed Species ◽  
Potential Growth ◽  
Common Waterhemp ◽  
Wild Mustard ◽  
Giant Foxtail ◽  
Woolly Cupgrass

The nitrogen (N) response of competing plants may be affected by photosynthetically active radiation (PAR) availability and maximum potential growth rate, which determine N requirements. The responses of two crop (corn and soybean) and six weed species (common lambsquarters, common waterhemp, giant foxtail, velvetleaf, wild mustard, and woolly cupgrass) in low and high (150 and 450 μmol m−2s−1) PAR levels to daily fertilization with either low or high (0.2 or 7.5 mM) NH4NO3levels were studied. Leaf area of all species responded positively to N by 8 d after emergence (DAE) when grown in high PAR; in low PAR, most species did not respond until 11 DAE. Dry weight and leaf area of all species at 18 DAE were greater with high than with low N. These responses to high N were also greater in high than in low PAR for all species. Dry weights with high N were up to 100% greater in low PAR and up to 700% greater in high PAR than dry weights with low N. These responses suggest that low PAR reduced the benefit of N to the plants. The regression of relative growth rate (RGR) with high N to RGR with low N had a slope that was less than unity (β = 0.79), indicating that species with a higher RGR with high N experienced greater decreases in RGR with low N. Similarly, the sensitivity (change in RGR) of plants grown with high and low N was positively related to RGR with high N. RGR differences among crop and weed species may be related to differences in N requirement that could be exploited for weed management. RGR and seed size were negatively correlated, which may explain previous observations that small-seeded weeds were more sensitive to environmental stress.

Effects of mycorrhizae, phosphorus availability, and plant density on yield relationships among competing tallgrass prairie grasses

1994 ◽  
Vol 72 (2) ◽  
pp. 168-176 ◽  
Author(s):  
B. A. D. Hetrick ◽  
D. C. Hartnett ◽  
G. W. T. Wilson ◽  
D. J. Gibson
Keyword(s):  
Interspecific Competition ◽  
Tallgrass Prairie ◽  
Plant Density ◽  
Relative Yield ◽  
Phosphorus Availability ◽  
Andropogon Gerardii ◽  
Big Bluestem ◽  
Replacement Series ◽  
Competitive Release ◽  
Elymus Canadensis

A replacement series experiment was used to investigate the effects of mycorrhizae, phosphorus availability, and plant density on competitive relationships between three tallgrass prairie species of varying mycorrhizal dependencies. Under mycorrhizal conditions, the obligately mycorrhizal dependent warm-season grass Andropogon gerardii (big bluestem) was a better competitor in mixture with the nonmycorrhiza-dependent cool-season grass Koeleria pyramidata (Junegrass). In the absence of mycorrhizae, however, competitive effects of big bluestem were greatly reduced and Junegrass experienced competitive release. Relative yield totals increased when mycorrhizae were suppressed, suggesting greater intensity of interspecific competition in the presence of mycorrhizae. Thus, the competitive dominance of big bluestem in tallgrass prairie is strongly related to its mycorrhizal status. Elymus canadensis (Canada wild rye) outcompeted big bluestem both with and without mycorrhizae. Relative yield totals of this species mixture were also lower under mycorrhizal conditions, indicating that mycorrhizae increase the intensity of interspecific competition between them. Relative yields of wild rye competing with big bluestem increased in the absence of mycorrhizae, suggesting that it also experiences competitive release when big blue-stem are not mycorrhizal. The outcomes of competition were generally similar among the three total plant density treatments and between P-fertilized and nonfertilized treatments. However, interactions between mycorrhizal effects and plant density confirm that outcomes of interspecific competitive interactions may be density dependent in some cases. Key words: arbuscular mycorrhizae, de Wit replacement series, Andropogon gerardii, Elymus canadensis, Koeleria pyramidata.

Above and below-ground competition between Kura clover (Trifolium ambiguum) and meadow bromegrass (Bromus biebersteinii): A greenhouse study

2009 ◽  
Vol 89 (1) ◽  
pp. 21-27 ◽  
Author(s):  
J. A. Walker ◽  
J. R. King
Keyword(s):  
Leaf Area ◽  
Dry Weight ◽  
Root Competition ◽  
Leaf Number ◽  
Grass Species ◽  
Kura Clover ◽  
Greenhouse Study ◽  
Shoot Competition ◽  
Below Ground ◽  
Meadow Bromegrass

Kura clover (Trifolium ambiguum) is a perennial legume that shows potential for use in pasture mixtures in western Canada. Previous studies have shown that early growth of kura clover is reduced when grown in mixtures with grass species. A greenhouse study examined the relative importance of above- and below-ground competition on growth and development of kura clover when grown with a grass species. Kura clover plants were grown in pots with meadow bromegrass (Bromus biebersteinii) and barriers were put in place to remove all competition, shoot competition, root competition, or to allow full competition. After 12 wk, plants were harvested. Height, leaf area, leaf number, leaf dry weight, and root/crown dry weight were measured. Kura clover leaf number and leaf area were greatest when roots did not interact with meadow bromegrass roots. Vegetative biomass of kura clover doubled when there was no root competition. Shoot competition did not alter leaf number, leaf area, or leaf biomass. Successful establishment of kura clover is dependent on the reduction of root competition during the seedling phase. Measures taken to minimize the below-ground interaction should positively affect the yield potential of both species. Key words: Kura clover, meadow bromegrass, shoot competition, root competition

Sign in / Sign up

Export Citation Format

Share Document