Interference of Redroot Pigweed (Amaranthus retroflexus) and Robust Foxtail (Setaria viridisvar.robusta-albaor var.robusta-purpurea) in Soybeans (Glycine max)

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 665-674 ◽  
Author(s):  
P. L. Orwick ◽  
M. M. Schreiber
Keyword(s):  
Glycine Max ◽  
Seed Yield ◽  
Initial Density ◽  
Soybean Seed ◽  
Amaranthus Retroflexus ◽  
Row Spacing ◽  
Setaria Viridis ◽  
Redroot Pigweed ◽  
Growing Seasons ◽  
Wide Row Spacing

Redroot pigweed (Amaranthus retroflexusL.) and robust foxtail [Setaria viridis(L.) Beauv. var.robusta-albaSchreiber (RWF) orSetaria viridisvar.robusta-purpureaSchreiber (RPF)] were investigated regarding their ability to interfere with soybean [Glycine max(L.) Merr. ‘Amsoy 71′] at different weed densities and soybean row spacing throughout two growing seasons. Final weed densities for each species tended to reach a common value because of intraspecific interference regardless of the initial density. With cultivation, a narrow soybean row spacing (38 cm) resulted in less weed growth than did a wide row spacing (76 cm) but with no cultivation, the trend was reversed. Soybeans provided less interference to foxtail than to pigweed during both growing seasons. Interference from foxtail adversely affected soybean yield components and soybean seed yield more than did pigweed interference. Water-stress conditions in 1976 increased the intensity of weed interference and reduced soybean seed yield more severely than in 1975 when moisture was adequate throughout the growing season.

Comparison of Soybean (Glycine max) – Weed Interference from Large and Small Plots

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 836-839 ◽  
Author(s):  
Michael G. Patterson ◽  
Robert H. Walker ◽  
Daniel L. Colvin ◽  
Glenn Wehtje ◽  
John A. McGuire
Keyword(s):  
Glycine Max ◽  
Seed Yield ◽  
Dry Matter ◽  
Field Experiments ◽  
Soybean Seed ◽  
Regression Coefficients ◽  
Row Spacing ◽  
Soybean Field ◽  
Weed Biomass ◽  
Weed Interference

Soybean field experiments were conducted to compare weed interference data obtained from small 2.7-m2plots to that obtained from large 11-m2plots. Soybean row spacings of 15, 30, 45, and 90 cm were used. Sicklepod, common cocklebur, and soybean biomass as dry matter were harvested from small plots 10 weeks after planting and were compared to weed biomass and soybean seed yield from the large plots. Sicklepod and common cocklebur biomass in small plots increased and soybean biomass decreased as soybean row spacing increased. Soybean biomass was not affected by row spacing when weeds were not present. Sicklepod and common cocklebur biomass in large plots increased and soybean seed yield decreased as soybean row spacing increased. Soybean seed yield was not affected by row spacing when weeds were not present. Comparison of regression coefficients for paired regression lines indicates that soybean biomass from small plots may be substituted for seed yield from large plots as a measure of sicklepod or common cocklebur interference if both size plots use the same soybean row spacing and are irrigated until harvest.

Shade Development Effects on Pitted Morningglory (Ipomoea lacunosa) Interference with Soybeans (Glycine max)

Weed Science ◽  
1986 ◽  
Vol 34 (5) ◽  
pp. 711-717 ◽  
Author(s):  
Edward C. Murdock ◽  
Philip A. Banks ◽  
Joe E. Toler
Keyword(s):  
Glycine Max ◽  
Seed Yield ◽  
Inflection Point ◽  
Soybean Seed ◽  
Row Spacing ◽  
Ipomoea Lacunosa ◽  
Pitted Morningglory ◽  
Seed Yields ◽  
Uniform Population

‘Ransom’, ‘Govan’, and ‘Bragg’ soybeans [Glycine max(L.) Merr.] were seeded in 30-, 61-, and 91-cm row spacings to achieve a uniform population of 323 000 plants/ha. In 1979 and 1980, shade development within the row was similar for all row spacings, but 15 cm from the row the inflection point occurred earlier when soybeans were seeded at the 30-cm row spacing. In 1979, shading 30 cm from the row was similar with the 61- and 91-cm row spacings, but in 1980 the 61-cm row spacing provided earlier shading. Shading within the row and 15 and 30 cm from the row was similar for all cultivars in 1979, but Govan and Bragg shaded row middles earlier than Ransom at the 91-cm row spacing. In 1980, shade development in the row was similar for all cultivars, but delayed shading was observed between the rows with Ransom. In 1979, maximum soybean seed yields were produced with 2, 2, and 0 weed-free weeks at the 30-, 61-, and 91-cm row spacings, respectively. In 1980, 2 weed-free weeks prevented soybean seed yield reductions at all row spacings. In 1979, Ransom, Bragg, and Govan required 4, 2, and 0 weed-free weeks, respectively, for maximum seed yields. In 1980, all cultivars achieved maximum seed yields with 2 weed-free weeks.

Interference of Certain Broadleaf Weed Species in Soybeans (Glycine max)

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 654-657 ◽  
Author(s):  
Janet L. Shurtleff ◽  
Harold D. Coble
Keyword(s):  
Glycine Max ◽  
Leaf Area ◽  
Seed Yield ◽  
Soybean Seed ◽  
Yield Reduction ◽  
Weed Species ◽  
Soybean Yield ◽  
Common Ragweed ◽  
Common Lambsquarters ◽  
Redroot Pigweed

Field experiments were conducted in 1979, 1980, and 1981 to determine the level of interference five broadleaf weed species exert on soybean [Glycine max(L.) Merr.]. Weed species studied were common cocklebur (Xanthium pensylvanicumWallr. ♯ XANST), common ragweed (Ambrosia artemesiifoliaL. ♯ AMBEL), common lambsquarters (Chenopodium albumL. ♯ CHEAL), sicklepod (Cassia obtusifoliaL. ♯ CASOB), and redroot pigweed (Amaranthus retroflexusL. ♯ AMARE). The following soybean seed yield reductions were observed with a density of 16 weeds/10-m row: redroot pigweed 22%, common lambsquarters 15%, common ragweed 12%, and sicklepod 5%, respectively. At a density of 8 weeds/10-m row, common cocklebur reduced soybean yield 11%. No single weed growth parameter predicted soybean seed yield reduction for all weed species. Soybean height was reduced by sicklepod competition; was not affected by competition from common lambsquarters, common ragweed, or common cocklebur; and was increased in the presence of redroot pigweed at 12 weeks after planting, when measured 30 cm from the weeds. Leaf area of soybean was higher at greater distances from the weed for all weed species. The range of soybean leaf area reductions occasioned by proximity to individual weed species corresponded fairly well with differences in soybean yield reduction.

Analysis of Nonstructural Carbohydrates in Redroot Pigweed (Amaranthus retroflexus) and Robust Foxtail (Setaria viridisvar.robusta) Throughout the Growing Season

Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 374-379 ◽  
Author(s):  
P. L. Orwick ◽  
M. M. Schreiber
Keyword(s):  
Reducing Sugars ◽  
Amaranthus Retroflexus ◽  
Setaria Viridis ◽  
Nonstructural Carbohydrates ◽  
Redroot Pigweed ◽  
Growing Seasons ◽  
Total Nonstructural Carbohydrates ◽  
Nonstructural Carbohydrate ◽  
Middle Strata ◽  
Upper Third

Redroot pigweed (Amaranthus retroflexusL.) and robust foxtail [Setaria viridis(L.) Beauv. var.robusta-albaSchreiber orSetaria viridisvar.robusta-purpureaSchreiber] were investigated to measure the accumulation of nonstructural carbohydrates throughout two separate growing seasons. Pigweed tended to accumulate more total nonstructural carbohydrates (TNC) than foxtail, particularly in the roots. In both weeds, peak levels of TNC in leaves, stems, and roots occurred during early flowering. The primary nonstructural carbohydrate in the leaves of both weeds was starch. Reducing sugars were the predominant nonstructural carbohydrate in the stems. Starch accumulated more in the leaves of the upper third of the plant and reducing sugars occurred in the greatest quantity in the middle strata of the stem. Accumulation levels of TNC in the plant organs suggested that the stem was a major sink during the vegetative growth phases of both pigweed and foxtail.

The Fate of Nitrofen in Rape, Redroot Pigweed, and Green Foxtail

Weed Science ◽  
1971 ◽  
Vol 19 (5) ◽  
pp. 555-558 ◽  
Author(s):  
D. Hawton ◽  
E. H. Stobbe
Keyword(s):  
Light Intensity ◽  
Brassica Campestris ◽  
Molecular Size ◽  
Amaranthus Retroflexus ◽  
High Light ◽  
Setaria Viridis ◽  
Light Conditions ◽  
Ether Linkage ◽  
Redroot Pigweed ◽  
Green Foxtail

The fate of 2,4-dichlorophenyl p-nitrophenyl ether (nitrofen) in the foliage of rape (Brassica campestris L. ‘Echo’), redroot pigweed (Amaranthus retroflexus L.), and green foxtail (Setaria viridis (L.) Beauv.) was investigated with the aid of 14C-nitrofen. Only limited amounts of the label were translocated in these species. Plants treated with 14C-nitrofen under high light conditions produced several labelled compounds of different molecular size and chromatographic properties. The time at which these compounds were first detectable depended on light intensity. At least two of these compounds are lipid-nitrofen conjugates or nitrofen polymers and others may be formed by cleavage of nitrofen at the ether linkage.

scholarly journals Crop density and seed production of tall fescue (Festuca arundinacea Schreber). 1. Yield and plant development

1999 ◽  
Vol 79 (4) ◽  
pp. 535-541 ◽  
Author(s):  
N. A. Fairey ◽  
L. P. Lefkovitch
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Seed Yield ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Plant Density ◽  
Initial Density ◽  
Row Spacing ◽  
Initial Population ◽  
Crop Density

A field study was conducted with tall fescue (Festuca arundinacea Schreber) to determine the effect of the initial population density and spatial arrangement of plants on crop development and seed yield. Individual seedling plants were transplanted at seven densities (1.6, 3.1, 6.3, 12.5, 25, 50, and 100 plants m−2) and three row spacings (20, 40, and 80 cm), and characteristics of seed production were determined for 3 yr (1991–1993). Over the 3 yr, heading commenced at dates differing by 15 d and was delayed, as density increased, by 8, 6, and 2 d, respectively, in the first, second, and third production years. The time of seed maturity differed among years (21 July to 4 August) but was generally unaffected by density or row spacing. In the first production year, seed yield increased with density up to 25 plants m−2 for each row spacing, then remained constant to at least 50 plants m−2 with both 20- or 40-cm rows; it decreased slightly at 100 plants m−2 with 20 cm rows. In the second production year, seed yield was relatively independent of plant density except that it decreased when the initial density was less than 6 plants m−2 with a row spacing of 80 cm, and tended to be greatest with the 40-cm row spacing at 6–25 plants m−2. In the third production year, seed yield was much lower than in the previous 2 yr but the pattern of response to the density and row spacing treatments was similar to that in the second production year. The seed yield of tall fescue can be optimized for at least 3 consecutive years by establishing an initial density of 20–100 plants m−2 in rows spaced 20–60 cm apart. If the maximization of first-year seed yield is a priority, then the initial establishment should be at a density of 25–50 plants m−2 in rows spaced 20–40 cm apart. Key words: Tall fescue, Festuca arundinacea Schreber, population density, plant spacing, seed production

Effects of Insecticide, Weed-Free Period, and Row Spacing on Soybean (Glycine max) and Sicklepod (Cassia obtusifolia) Growth

Weed Science ◽  
1984 ◽  
Vol 32 (5) ◽  
pp. 702-706 ◽  
Author(s):  
Robert H. Walker ◽  
Michael G. Patterson ◽  
Ellis Hauser ◽  
David J. Isenhour ◽  
James W. Todd ◽  
...  
Keyword(s):  
Glycine Max ◽  
Seed Size ◽  
Seed Weight ◽  
Significant Interaction ◽  
Soybean Seed ◽  
Row Spacing ◽  
Fresh Weight ◽  
Cassia Obtusifolia ◽  
Insecticide Treatment ◽  
Weed Interference

Results from identical experiments conducted at Headland, AL, and Plains, GA, from 1980 through 1982 show insecticide treatment had little effect on soybean [Glycine max(L.) Merr. ‘Coker 237′] growth and morphology. Maximum insecticide applications increased soybean seed weight in two of five trials. Soybeans maintained free of sicklepod (Cassia obtusifoliaL. ♯3CASOB) for 4 weeks after emergence produced yields equal to those receiving season-long control in all trials, and 2-week control was equal to season-long maintenance in three trials. Length of weed interference-free maintenance did not affect soybean height. The number of pods per plant and seed weight were decreased when there was no control. Sicklepod shoot fresh weight and numbers decreased as the weed-free period increased from 0 weeks through the season. Row spacing had no effect on soybean height or seed size; however, the number of pods per plant was higher in 80- than in 40-cm rows. Row spacing influenced yield in only one trial where 20-cm rows outyielded 40-cm rows. A significant interaction occurred between the weed-free period and row spacing in two trials. Soybeans in 20-cm rows outyielded those in 40- and 80-cm rows when sicklepod was not controlled (i.e., 0 weeks interference-free maintenance).

Wild Oat (Avena fatua) Competition in Soybean (Glycine max)

Weed Science ◽  
1981 ◽  
Vol 29 (4) ◽  
pp. 410-414 ◽  
Author(s):  
Duane P. Rathmann ◽  
Stephen D. Miller
Keyword(s):  
Glycine Max ◽  
Seed Yield ◽  
Seed Weight ◽  
Soybean Seed ◽  
Avena Fatua ◽  
Wild Oat ◽  
Soybean Yield

The effects of various densities and durations of wild oat (Avena fatuaL.) competition in soybean [Glycine max(L.) Merr. ‘Evans’] were determined in the field during a 2-yr period. Season-long competition by densities of 1, 3,9, and 30 wild oat plants/m of row reduced soybean seed yield an average of 6, 17, 32, and 51%, respectively. An infestation of 30 wild oat plants/m of row did not reduce soybean yield if the period of competition was limited to 4 weeks after crop emergence; however, yields were reduced 29, 50, 63, 58, and 63% when wild oat competed for 5, 6, 7, and 8 weeks, or season long, respectively. Wild oat competition reduced soybean pods per plant and seeds per plant more than seeds per pod or seed weight.

Effect of Imazaquin and Chlorimuron Plus Metribuzin on Sicklepod (Cassia obtusifolia) Interference in Soybean (Glycine max)

1991 ◽  
Vol 5 (1) ◽  
pp. 206-210 ◽  
Author(s):  
David R. Shaw ◽  
Marshall B. Wixson ◽  
Clyde A. Smith
Keyword(s):  
Glycine Max ◽  
Seed Yield ◽  
Dry Matter ◽  
Soybean Seed ◽  
Cassia Obtusifolia ◽  
Soybean Yield ◽  
Herbicide Treatment ◽  
Herbicide Treatments ◽  
Herbicide Use

Three experiments evaluated sicklepod interference with soybean with and without preplant incorporated applications of chlorimuron plus metribuzin or imazaquin. Sicklepod density, weed-free period, and weedy period were examined. In the absence of herbicides, soybean seed yield was reduced with 2 sicklepod plants row m-1, whereas 8 plants row m-1were necessary to reduce yield when herbicides were used. Herbicide use also increased soybean yield at higher sicklepod densities. Chlorimuron plus metribuzin reduced sicklepod dry matter at 8 plants row m-1. To maintain soybean yield, a weed-free period of 4 wk after emergence was required, regardless of treatment. Both herbicide treatments resulted in increased soybean yield at the zero and two wk weed-free periods; however, they did not affect soybean yield when the weed-free period was 4 wk or more. Imazaquin reduced sicklepod density when plots were left weedy full-season, and further reductions were noted with chlorimuron plus metribuzin. A sicklepod weedy interval of 8 wk reduced soybean yield when untreated, but either herbicide treatment extended that interval to 16 wk.

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