Approaches to Breed for Improved Weed Suppression in Organically Grown Cereals

Hoad, SP; Bertholdsson, Nils‐Øve; Neuhoff, Daniel; Köpke, Ulrich

doi:10.1002/9781119945932.ch4

Cited by 22 publications

(21 citation statements)

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“…In several studies, heritage cultivars resulted more competitive against weeds than modern cultivars because of higher plant height, biomass accumulation, tillering and soil cover (Korres and Froud-Williams, 2002;Mason et al, 2007;Hoad et al, 2012;Ruisi et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

et al. 2017

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Sowing density can have a strong impact on crop stand development during wheat growing cycle. In organic and low-input agriculture, and therefore with minimum or nil use of chemical herbicides, increased sowing density is expected to affect not only grain yield but also weed suppression. In this study we tested, under Mediterranean conditions, six common wheat cultivars (three modern and three heritage) and two three-component mixtures (arranged by combining the three modern or the three heritage cultivars). The different crop stands were tested at sowing densities of 250 (low) and 400 (high, similar to standard sowing density used by local farmers) viable seeds m -2 for two growing seasons. We did not detect a significant effect of crop stand diversity (single cultivars vs mixtures) on grain yield and weed suppression. Differences were ascribed to type of cultivars used (heritage vs modern). Compared to high sowing density, in modern cultivars grain yield did not decrease significantly with low sowing density, whereas in heritage cultivars it increased by 15.6%, possibly also because of 21.5% lower plant lodging. Weed biomass increased with low sowing density both in heritage and modern cultivar crop stand types. However, heritage crop stands had, on average, a lower weed biomass (56%) than modern crop stands. Moreover, weed biomass in heritage crop stands at low density (6.82±1.50 g m -2 ) was lower than that of modern cultivars at the same sowing density (15.54±3.35 g m -2 ), confirming the higher suppressive potential of the former. We can conclude that lower sowing density can be advisable when using heritage crop stands as it keeps productivity while decreasing plant lodging and maintaining weeds under control.

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Section: Introductionmentioning

confidence: 99%

Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

et al. 2017

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“…the grain dry matter yield divided by the supply of available nitrogen from the soil and fertilizer (Moll et al, 1982;Bingham et al 2012) and weed competitive ability (WCA) are two characteristics that are of great importance for organic cereal production (Eisele and Köpke, 1997;Hoad et al, 2012;Arterburn et al, 2012;Costanzo and Bàrberi, 2014). In addition, early vigour of roots and shoots, as well as allelopathic activity, are important for WCA (Huel and Huel, 1996;Bertholdsson, 2005Bertholdsson, , 2011.…”

Section: Introductionmentioning

confidence: 99%

Evolutionary changes of weed competitive traits in winter wheat composite cross populations in organic and conventional farming systems

Bertholdsson

Weedon

Brumlop

et al. 2016

European Journal of Agronomy

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a b s t r a c tSeedling root and shoot growth in hydroponics and allelopathic activity using a bioassay have been studied in very diverse populations of winter wheat grown under either organic or conventional conditions for a number of generations and subjected only to natural selection. The study was conducted on seeds from generation 6 (F 6 ) and 11 (F 11 ) from three composite cross populations (CCPs) produced by the Organic Research Centre in the UK. Since the F 5 the populations were maintained under organic and conventional conditions in Germany. Two parallel populations were created from each CC, resulting in a total of six organic and six conventional CCPs. The sets of parallel populations showed similar evolutionary trends indicating that the observed changes are related to differences in management rather than chance. Seedling root length and seedling root and shoot weight in the F 11 of the organically-managed CCPs were significantly greater than in the organic F 6 CCPs. In the conventionally-managed CCPs no such differences were observed. Both organic and conventional CCPs produced for quality showed higher early root and shoot growth than those produced for yield pointing to genetic differences among population types and highlighting the importance of early vigour for NUE. There were no significant differences in the allelopathic activity of the populations and between generations. The Shannon-Weaver diversity indices were similar for the studied traits in organic and conventional CCPs and hence no major changes in diversity had occurred between F 6 to F 11 . As changes in plant height were small and weed pressure in the fields low it is concluded that the observed differences are more related to NUE, rather than intra-specific competition for light or the direct effect of increased weed pressure in the organic system.

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“…It is known that weed growth and development is directly dependent on the resources that are also essential to the crop. Therefore, cultivars that are able to intercept more light tend to mitigate the harmful effects of undesirable weeds, especially when that interception occurs during the TPIP (Hoad et al 2012). …”

Section: Introductionmentioning

confidence: 99%