Increased density and spatial uniformity increase weed suppression by spring wheat

Previous research has shown that both the density and spatial pattern of wheat have an influence on crop growth and weed suppression, but it is not clear what degree of uniformity is necessary to achieve major improvements in weed suppression. Field experiments were performed over 3 yr to investigate the effects of crop density and different spatial distributions on weed suppression. The spatial pattern of spring wheat sown in five patterns and three densities in small weed-infested plots were analyzed with the use of digitized photographs of field plots to describe the locations of individual wheat plants asxandycoordinates. We used a simple quantitative measure, Morisita's index, to measure the degree of spatial uniformity. Increased crop density resulted in reduced weed biomass and increased crop biomass every year, but crop pattern had significant effects on weed and crop biomass in the first year only. Weather conditions during the second and third years were very dry, resulting in very low weed biomass production. We hypothesize that water deficiency increased the importance of belowground relative to aboveground competition by reducing biomass production, making competition more size symmetric, and reducing the effect of crop spatial pattern on weed growth. The results indicate that increased crop density in cereals can play an important role in increasing the crop's competitive advantage over weeds, and that spatial uniformity maximizes the effect of density when low resource levels or abiotic stress do not limit total biomass production.

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Weed suppression and yield of thirteen spring wheat (Triticum aestivum L.) varieties grown in an organic system

Acta Agrobotanica ◽

10.5586/aa.1721 ◽

2017 ◽

Vol 70 (3) ◽

Author(s):

Beata Feledyn-Szewczyk ◽

Krzysztof Jończyk

Keyword(s):

Triticum Aestivum ◽

Grain Yield ◽

Spring Wheat ◽

Morphological Features ◽

Weed Suppression ◽

Yield Potential ◽

Wheat Varieties ◽

Organic System ◽

Weed Infestation ◽

Competitive Abilities

The aim of this study was to determine the relationships between morphological features, canopy parameters, weed infestation, and grain yield of spring wheat varieties. The study was conducted in the period 2011–2013, on fields managed organically at the Experimental Station of The Institute of Soil Science and Plant Cultivation – State Research Institute, Osiny, Poland. Thirteen spring wheat varieties were sown in a randomized complete block design with four replications. Weed density and dry matter production were estimated as well biometric features of the wheat varieties at tillering (BBCH 22–24) and dough (BBCH 85–87) stages. The analyses of variance showed that the year had a stronger effect than varieties on the level of weed infestation. Pearson’s correlation analysis indicated that weed number was influenced by the height of wheat plants and their aboveground biomass at the tillering stage and additionally by number of tillers at the dough stage. A significant correlation (r = −0.328, siginfficant at p < 0.05) was shown between the number of weeds and wheat grain yield. Different morphological features and canopy parameters influenced the competitive abilities of the spring wheat varieties tested. A cluster analysis detected one set of varieties with the largest (‘Bombona’, ‘Brawura’, ‘Hewilla’, ‘Kandela’, ‘Katoda’, ‘Łagwa’, and ‘Żura’) and another with the smallest (‘Monsun’, ‘Ostka Smolicka’, and ‘Parabola’) competitive abilities against weeds. The main outcome of the research is information for farmers as to which varieties are highly competitive against weeds and also high yielding. Among the varieties with the highest competitiveness, Triticum aestivum ‘Żura’ was the highest yielder (3.82 t ha−1 on average), whereas ‘Bombona’ yielded only at an average level (3.03 t ha−1). The suppressive ability of spring wheat varieties against weeds and yield potential should be both taken into account in the selection of varieties suitable for an organic farming system where weed control is absent.

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Weed suppression and crop productivity by different arrangement patterns of maize

Plant Soil and Environment ◽

10.17221/606/2011-pse ◽

2012 ◽

Vol 58 (No. 3) ◽

pp. 148-153 ◽

Cited By ~ 3

Author(s):

M. Simić ◽

Ž. Dolijanović ◽

R. Maletić ◽

L. Stefanović ◽

M. Filipović

Keyword(s):

Crop Productivity ◽

Weed Suppression ◽

Weed Biomass ◽

Combined Application ◽

Spatial Uniformity ◽

Crop Density ◽

Weed Infestation ◽

Maize Plants ◽

High Yields ◽

Row Space

A field experiment was conducted in order to estimate the influence of different arrangement patterns of maize plants (Zea mays L.) in combination with low rates of herbicides on weed infestation and on production parameters of the crop. The maize was sown at 70-, 50-, and 35-cm row space with the same crop density. The weed biomass declined with smaller row spaces and was, on average, the lowest with the 35-cm row space; even though the arrangement patterns of the maize plants had no significant effect on the average values of the weed biomass. The interaction of the arrangement pattern and the herbicide rate significantly influenced weed biomass. Maize grain yield expressed the greatest variation under the effects of applied factors, but did not differ significantly between treatments with the full and the half rate of herbicides. The results indicate that it is possible to control weed infestation level if maize is grown with increased spatial uniformity and combined application of other practices such are herbicides. In such a way, maize plants are more competitive against weeds and even lower amounts of herbicides could be applied in order to achieve high yields.    

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Undersown cover crops have limited weed suppression potential when reducing tillage intensity in organically grown cereals

Organic Agriculture ◽

10.1007/s13165-019-00262-6 ◽

2019 ◽

Vol 10 (1) ◽

pp. 107-121 ◽

Cited By ~ 6

Author(s):

J. Salonen ◽

E. Ketoja

Keyword(s):

Winter Wheat ◽

Spring Wheat ◽

Cover Crops ◽

Weed Management ◽

Spring Barley ◽

Wheat Yield ◽

Weed Suppression ◽

Reduced Tillage ◽

Perennial Weeds ◽

Weed Infestation

Abstract Adoption of reduced tillage in organic cropping has been slow, partly due to concerns about increasing weed infestation. Undersown cover crops (CCs) are considered to be a feasible option for weed management but their potential for weed suppression is insufficiently investigated in low-till organic cropping. The possibilities to reduce primary tillage by introducing CCs to maintain weed infestation at a level that does not substantially jeopardize crop yield were studied in a field experiment in southern Finland during 2015–2017. Eight different CC mixtures were undersown in cereals and the response in weed occurrence was consecutively assessed in spring barley, winter wheat, and finally, as a subsequent effect, in spring wheat. Growth of CCs was too slow to prevent the flush of early emerging weeds in spring barley whereas in winter wheat, CCs succeeded in hindering the growth of weeds. However, CCs could not prevent the increase of perennial weeds in a reduced tillage system in which the early growth of spring wheat was retarded in cool 2017. Consequently, after 2 years of reduced tillage, weed biomass was about 2.6 times higher and spring wheat yield was 30% lower than in plowed plots, respectively. No major differences in weed control efficacy among CC treatments were evident. A grain yield benefit was recorded after repeated use of leguminous CCs. The need for long-term field studies remains of particular interest regarding post-harvest performance and influence of CCs on perennial weeds before the inversion tillage.

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Crop Density, Sowing Pattern, and Nitrogen Fertilization Effects on Weed Suppression and Yield In Spring Wheat

Weed Science ◽

10.1614/ws-07-065.1 ◽

2008 ◽

Vol 56 (1) ◽

pp. 97-102 ◽

Cited By ~ 58

Author(s):

Lars Kristensen ◽

Jannie Olsen ◽

Jacob Weiner

Keyword(s):

Spring Wheat ◽

Nitrogen Fertilization ◽

Weed Suppression ◽

Crop Density ◽

Fertilization Effects

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Relationship among phenotypic growth traits, yield and weed suppression in spring wheat landraces and modern cultivars

Field Crops Research ◽

10.1016/j.fcr.2007.08.004 ◽

2008 ◽

Vol 105 (1-2) ◽

pp. 107-115 ◽

Cited By ~ 63

Author(s):

K.M. Murphy ◽

J.C. Dawson ◽

S.S. Jones

Keyword(s):

Spring Wheat ◽

Growth Traits ◽

Weed Suppression ◽

Wheat Landraces

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Weed, disease and grain yield effects of cultivar mixtures in organically managed spring wheat

Canadian Journal of Plant Science ◽

10.4141/cjps06006 ◽

2007 ◽

Vol 87 (4) ◽

pp. 855-859 ◽

Cited By ~ 9

Author(s):

J. C. Pridham ◽

M. H. Entz ◽

R. C. Martin ◽

P. J. Hucl

Keyword(s):

Grain Yield ◽

Key Words ◽

Spring Wheat ◽

Yield Stability ◽

Weed Suppression ◽

Wheat Cultivars ◽

Modern Cultivar ◽

Modern Wheat ◽

Organically Managed ◽

Cultivar Mixtures

Two heritage wheat cultivars, Red Fife and Marquis, along with two modern wheat cultivars, 5602HR and AC Barrie, were assessed in organically managed monocultures and mixtures to discern if mixtures provided a benefit to grain yield and disease and weed suppression in Manitoba over 3 site-years. 5602HR was the highest yielding sole cultivar, while Marquis and AC Barrie were the lowest yielding sole cultivars. Red Fife yielded similar to the modern cultivar 5602HR in several cases. Cultivar mixtures did not provide a yield advantage but did stabilize yields of mixtures containing disease susceptible cultivars. Key words: Cultivar mixtures, heritage cultivar, yield stability

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Effects of missing-row sowing supplemented with row spacing and nitrogen on weed competition and growth and yield of wheat

Crop and Pasture Science ◽

10.1071/cp10203 ◽

2011 ◽

Vol 62 (1) ◽

pp. 48 ◽

Cited By ~ 14

Author(s):

T. K. Das ◽

N. T. Yaduraju

Keyword(s):

Weed Management ◽

Wheat Yield ◽

Weed Suppression ◽

Growth And Yield ◽

Weed Competition ◽

Row Spacing ◽

Weed Growth ◽

Spatial Uniformity ◽

Weed Infestation ◽

Ecological Weed Management

Crop husbandry practices, i.e. sowing method, row spacing, and nitrogen (N) fertilisation, influence weed competition in a crop and play a role in ecological weed management. Missing-row sowing is a novel method of sowing wheat, with one row left unsown after several rows of continuous sowing. It affects density and spatial uniformity of wheat, which may influence the wheat plants’ competitiveness and weed suppression. It may have interactions with row spacing and N, which may further improve crop–weed balance, but is rarely studied in India or elsewhere. We undertook this study to optimise the method of missing-row sowing of wheat in combination with row spacing and N application. The results revealed that leaving 20% of rows unsown significantly reduced weed populations and dry weights, and increased the competitiveness of wheat plants through greater leaf area, numbers of ear-bearing tillers, and uptake of N. Leaving 20% of rows unsown increased wheat yield by 10.9%, 17.3%, and 8.2%, respectively, during the first, second, and third year compared with conventional sowing (no missing rows). An 18.5-cm row spacing resulted in a more weed suppression than 22.5-cm row spacing, but the latter gave higher yield. Application of N at 120 kg/ha resulted in higher yield than N at 60 kg/ha, due to a significant reduction in weed growth. A practice that combines 20% of rows unsown, 22.5-cm row spacing, and 120 kg N/ha will yield more through better suppression of a moderate weed infestation.

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