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

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.

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

Weed Science ◽

10.1017/s0043174500059828 ◽

1984 ◽

Vol 32 (5) ◽

pp. 702-706 ◽

Cited By ~ 19

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).

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

Weed Technology ◽

10.1017/s0890037x00033534 ◽

1991 ◽

Vol 5 (1) ◽

pp. 206-210 ◽

Cited By ~ 8

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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Effect of numbers of Bradyrhizobium japonicum applied in commercial inoculants on soybean seed yield in Ontario

Canadian Journal of Microbiology ◽

10.1139/m92-097 ◽

1992 ◽

Vol 38 (6) ◽

pp. 588-593 ◽

Cited By ~ 40

Author(s):

D. J. Hume ◽

D. H. Blair

Keyword(s):

Glycine Max ◽

Seed Yield ◽

Bradyrhizobium Japonicum ◽

Field Experiments ◽

Soybean Seed ◽

Yield Response ◽

Cubic Equation ◽

Glycine Max L ◽

Seed Yields ◽

Commercial Inoculants

In the absence of Bradyrhizobium japonicum populations in the soil, yields of field-grown soybean (Glycine max (L.) Merrill) usually respond to inoculation with B. japonicum. The objective of this research was to determine the relationship between numbers of B. japonicum per seed in inoculants and soybean nodulation and yield. A total of six field experiments were conducted in 1989 and 1990 on new soybean soils. In dilution trials, Grip inoculant was applied to provide approximately 106, 105, 104, and 103B. japonicum per seed at two locations in 1989. Nodule number and mass, as well as seed yield, increased curvilinearly upward with increasing log10 most probable numbers (MPNs) of B. japonicum. The yield response curve was best fit by a cubic equation, which accounted for 97% of the variation in yield. Seed yields increased 19% (1.83 to 2.13 Mg/ha) from 105 to 106B. japonicum per seed. In field experiments involving 8 commercial inoculants in 1989 and 10 in 1990, and conducted at two locations in each year, responses to increasing log MPNs in the inoculants also were concave upwards and cubic. In the two years, 78 and 46% of the yield variation was accounted for by log MPN per seed. Increasing MPN per seed from 105 to 106 improved yields in first-time fields by an average of 24%, indicating the present minimum standard of 105B. japonicum per seed should be increased. Key words: most probable numbers, response to inoculation, nodulation, Glycine max (L.) Merrill.

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Mutual Influences of Seedling Johnsongrass (Sorghum halepense), Sicklepod (Cassia obtusifolia), and Soybean (Glycine max)

Weed Science ◽

10.1017/s0043174500056289 ◽

1990 ◽

Vol 38 (2) ◽

pp. 139-147 ◽

Cited By ~ 18

Author(s):

Barry D. Sims ◽

Lawrence R. Oliver

Keyword(s):

Glycine Max ◽

Seed Production ◽

Seed Yield ◽

Dry Matter ◽

Field Experiments ◽

Growing Season ◽

Growth And Yield ◽

Sorghum Halepense ◽

Competitive Effects ◽

Matter Production

Field experiments were conducted to evaluate competitive effects of johnsongrass and sicklepod on growth and yield of irrigated and nonirrigated soybeans. Johnsongrass reduced soybean growth early in the growing season. Sicklepod was competitive all season, but competitiveness was greatest during the soybean reproductive stage. Soybean yields were reduced 31% by sicklepod, 14% by johnsongrass, and 36% by both weeds growing together. Nonirrigated soybeans yielded less than irrigated, but percent yield reductions were similar. Johnsongrass dry matter production and seed yield were reduced more than sicklepod by soybean interference. Soybean and sicklepod interference reduced johnsongrass seed production 73 to 95%. Johnsongrass produced 245 to 1238 seeds per plant when interfering with soybeans and sicklepod. Sicklepod seeds per plant were reduced 6 to 31% by johnsongrass interference and 47 to 75% by soybeans and soybeans plus johnsongrass.

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Pennsylvania Smartweed (Polygonum pensylvanicum) Interference in Soybeans (Glycine max)

Weed Science ◽

10.1017/s0043174500064547 ◽

1978 ◽

Vol 26 (6) ◽

pp. 556-559 ◽

Cited By ~ 40

Author(s):

H. D. Coble ◽

R. L. Ritter

Keyword(s):

Glycine Max ◽

Seed Yield ◽

Soybean Seed ◽

Yield Reduction ◽

Weed Population ◽

Weed Interference ◽

Naturally Occurring ◽

Allelopathic Interaction ◽

Significant Yield ◽

Polygonum Pensylvanicum

The effects of Pennsylvania smartweed(Polygonum pensylvanicumL.) interference in soybeans [Glycine max(L.) Merr. ‘Pickett 71’] were studied in the field under a naturally occurring weed population. Soybean seed yield was reduced an average of 13% by a density of eight Pennsylvania smartweed plants per 10 m of row. Greater yield reductions of 21, 37, and 62% resulted from full-season interference by densities of 16, 32, and 240 weeds per 10 m of row, respectively. Fewer than five weeds per 10 m of row did not significantly reduce crop yield. A natural population of 240 weeds per 10 m of row did not reduce soybean yield if the period of interference was limited to 6 weeks or less after crop emergence. However, more than 6 weeks of weed interference resulted in significant yield reduction. Conversely, if the crop was kept weed-free for a period of 4 weeks or more after emergence, seed yield was not reduced. No allelopathic interaction between the two species was observed in greenhouse studies using a recirculating nutrient solution and alternate pots of soybeans and Pennsylvania smartweed.

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

Weed Science ◽

10.1017/s0043174500046117 ◽

1979 ◽

Vol 27 (6) ◽

pp. 665-674 ◽

Cited By ~ 25

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.

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Seed Yield, Seed Protein, Oil Content, and Agronomic Characteristics of Soybean (Glycine max L. Merrill) Depending on Different Seeding Systems and Cultivars in Germany

Agronomy ◽

10.3390/agronomy10071020 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1020

Author(s):

Olena Sobko ◽

Sabine Zikeli ◽

Wilhelm Claupein ◽

Sabine Gruber

Keyword(s):

Glycine Max ◽

Protein Content ◽

Seed Yield ◽

Dry Matter ◽

Oil Content ◽

Seed Protein ◽

Row Spacing ◽

System A ◽

Glycine Max L ◽

Plant Characteristics

Soybean (Glycine max L. Merrill) is one of the most important crops worldwide. In several European countries such as Germany, soybean cultivation is not traditional and as such remains to be optimized. One option to increase soybean production is to adapt and improve the seeding system. To investigate the effects of different seeding systems on seed yield, seed protein, and oil content, plant characteristics were assessed using a two-factorial (two seeding systems and four cultivars) field trial over two years (2017–2018) at two locations in southeast Germany. The seeding systems were drill (row spacing 14 cm) and precision seeding (row spacing 28 cm), and the cultivars were Viola 000, Lissabon 000, ES Mentor 00, and Orion 00. Depending on the seeding system, a seed yield of 3.8 t ha−1 dry matter (DM), 40.9% protein content (DM), and 18.8% oil content (DM) was achieved by drilling, and 3.6 t ha−1 yield (DM), 40.1% protein content (DM), and 19.1% oil content (DM) with precision seeding (average across four cultivars, two locations, and two years). No significant effects of the seeding system on all seed and plant characteristics were observed. As drilling and precision seeding did not affect the seed yield, seed protein, oil contents, and plant characteristics of soybean in this study, farmers are able to choose the seeding system which fits best into their farms and is economically most viable.

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

Weed Science ◽

10.1017/s0043174500067734 ◽

1986 ◽

Vol 34 (5) ◽

pp. 711-717 ◽

Cited By ~ 19

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.

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Giant Ragweed (Ambrosia trifida) Interference in Soybeans (Glycine max)

Weed Science ◽

10.1017/s0043174500073069 ◽

1991 ◽

Vol 39 (3) ◽

pp. 358-362 ◽

Cited By ~ 55

Author(s):

Jerry A. Baysinger ◽

Barry D. Sims

Keyword(s):

Glycine Max ◽

Seed Yield ◽

Field Experiments ◽

Yield Loss ◽

Soybean Seed ◽

Critical Duration ◽

Ambrosia Trifida ◽

Soybean Yield ◽

Giant Ragweed

Field experiments were established near Portageville, MO, to determine the effects of giant ragweed interference in soybeans. Threshold densities of giant ragweed that reduced soybean yield were less than two plants 9 m−1of soybean row. This density reduced soybean seed yield 46 and 50% in 1988 and 1989, respectively, after full-season interference. The critical duration of giant ragweed interference in soybeans was between 4 and 6 weeks after emergence (WAE) in 1988 and between 2 and 4 WAE in 1989. Full-season giant ragweed interference at densities of 220 000 and 360 000 plants ha−1in 1988 and 1989, respectively, resulted in almost complete soybean yield loss. Eight to 10 weeks after emergence of giant ragweed-free conditions were required to prevent soybean yield reductions.

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Sicklepod (Senna obtusifolia) Control in Soybean (Glycine max) with Imazaquin and Metribuzin Combinations

Weed Technology ◽

10.1017/s0890037x00045747 ◽

1996 ◽

Vol 10 (1) ◽

pp. 78-84 ◽

Cited By ~ 5

Author(s):

Robert E. Etheridge ◽

Edward C. Murdock ◽

Gregory S. Stapleton ◽

Joe E. Toler

Keyword(s):

Glycine Max ◽

Seed Yield ◽

Soil Type ◽

Soybean Seed ◽

Field Studies ◽

Weed Biomass ◽

Senna Obtusifolia ◽

Untreated Check ◽

Sequential Treatments ◽

Yield Responses

Field studies were conducted in 1993 and 1994 to evaluate sicklepod control with combinations of imazaquin + metribuzin at lower than normal use rates. Soybean was seeded in late-May to early-June each year and imazaquin and metribuzin were applied PPI alone at 0.75 and 1x and 0.5, 0.75, and 1x their registered rates, respectively, and in factorial combinations of their 0.5 and 0.75x rates. The registered (1x) rates for imazaquin and metribuzin on this soil type are 0.14 and 0.43 kg/ha, respectively. Several standard sequential treatments and flumetsulam + trifluralin PPI at 0.06 + 0.70 and 0.07 + 0.95 kg/ha were included for comparison. Sicklepod control and soybean seed yield responses differed between 1993 and 1994. In 1993, the combinations of imazaquin + metribuzin averaged 90% control 6 wk after planting (WAP) and soybean seed yield increased 75% compared to the untreated check. Imazaquin + metribuzin at their respective 0.5x rate was as effective as any treatment evaluated. In 1994, sicklepod control was generally lower with all treatments. Soybean seed yield was reduced due to sicklepod interference with soil-applied treatments alone. However, imazaquin + metribuzin at their respective 0.75x rate provided sicklepod control levels and reductions in weed biomass similar to those observed with flumetsulam + trifluralin at 0.07 + 0.95 kg/ha and the sequential treatments, and increased soybean seed yield 19% compared to the untreated check.

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