Crop spatial uniformity, yield and weed suppression

Lu, Ping; Jiang, Baiwen; Weiner, Jacob

doi:10.1016/bs.agron.2019.12.003

Cited by 17 publications

(27 citation statements)

References 121 publications

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“…By sowing in circular clumps within the experimental trays, the plasticity of plant growth may have allowed the roots of the native grasses to rapidly forage the surrounding un-vegetated areas of high (soil) resource levels. Similar mechanisms were suggested by Fargione et al (2003), Török et al (2010), andLu et al (2020). The resulting growth rate advantage of the native grasses led to stronger asymmetric (aboveground) competition (Freckleton and Watkinson 2001;Weiner et al 2001), and thus enhanced suppression of S. gigantea.…”

Section: Sowing Patterns and Invasibilitysupporting

confidence: 58%

Competitive trait hierarchies of native communities and invasive propagule pressure consistently predict invasion success during grassland establishment

2021

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Invasive non-native plants challenge ecosystems restoration, and understanding the factors that determine the establishment of invasive plants is crucial to improve restoration outcomes. However, the drivers of invasibility of plant communities are not sufficiently clear, and combined effects are not understood. Therefore, we investigated the contribution of the main drivers of invasion success during early phases of restoration, i.e., biotic resistance, invasive propagule pressure, and environmental fluctuations. We compared the contribution of these drivers in a series of mesocosms experiments using designed grasslands as a model system, and Solidago gigantea as invasive model species. Two grassland communities were designed according to competitive trait hierarchies with different sowing patterns, reflecting variation in biotic resistance. We then manipulated invader propagule pressure and applied different scenarios of environmental fluctuation, i.e., flood, heat, and N fertilization. Invasive biomass was considered as proxy for invasion success, while native biomass represented restoration success. There were consistent effects of biotic resistance to S. gigantea invasion via competitive trait hierarchies in the three experiments. Communities dominated by species with high-competition traits were more resistant regardless of environmental fluctuation. Clumped seeding of the native community reduced invasibility, whereas high non-native propagule density increased invasion. The effects of environmental fluctuation were less consistent and context-dependent, thus playing a secondary role when compared to biotic drivers of invasion. Restoration initiatives on grasslands impacted by invasive plants should consider biotic resistance of the restored community as a key driver and the importance of controlling further arrivals of invasive species during community assembly.

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Section: Sowing Patterns and Invasibilitysupporting

confidence: 58%

Competitive trait hierarchies of native communities and invasive propagule pressure consistently predict invasion success during grassland establishment

2021

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Section: Discussionmentioning

confidence: 99%

“…Lower individual competitiveness can increase weed invasion and may lead to a greater yield loss in modern cultivars over old cultivars [20,21]. Increasing sowing density is one approach to suppressing weed growth by maximizing the size advantage of the crop at the early growth stage [8,23,24]. We compared weed suppression in two old and two modern cultivars and tested two interdependent hypotheses: (1) weed growth is lower at higher crop sowing density, and the old cultivars have a greater ability to suppress weeds than the modern cultivars at low crop density; (2) grain yield increases with crop sowing density in the presence of weeds, and the new cultivars have higher yields than old cultivars when grown at high density.…”

Section: Discussionmentioning

confidence: 99%

“…Some researchers have argued that many crop seedlings (such as cereal crops) are larger than weed seedlings, and because of this larger seed size they can obtain a disproportionate competitive advantage over weeds in the early growth stage, a phenomenon called "size-asymmetric competition" [22]. However, weeds can avoid suppression by crops because weeds often have higher growth rates early in the growing season when competition between crops and weeds is not intense [23][24][25]. In theory, increasing crop density can increase the strength of competitive size-asymmetry, and thus benefit the crops at the cost of weeds [8,24].…”

Section: Introductionmentioning

confidence: 99%

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Differences in Weed Suppression between Two Modern and Two Old Wheat Cultivars at Different Sowing Densities

Weiner

et al. 2021

Agronomy

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Crop losses to weeds can be exacerbated in modern agricultural systems because modern crop cultivars have high population yields but low individual competitiveness. High density cropping systems offer the possibility of effectively suppressing weeds by increasing the initial size-asymmetric advantage of crops over the weeds. We tested this hypothesis in an outdoor mesocosm experiment with two old (Cultivar Heshangtou (HST) and Jinbaoyin (JBY)) and two modern (Xihan2 (XH2) and Xihan3 (XH3)) cultivars of spring wheat (Triticum aestivum L.), grown in a uniform pattern at four sowing densities under high weed pressure. Two annuals (Brassica napus and Linum usitatissimum) were used as model weeds sown at the same density in all treatments. Weed growth decreased and wheat yield increased with increasing crop density for all the cultivars, although yield levelled off at the highest densities. The old cultivars suppressed weeds better than the new cultivars at low density, reflecting the decline in individual competitiveness in modern cultivars. At high crop density, however, the modern XH3 suppressed the weeds as well as the old cultivars, supporting the hypothesis that traits that promote weed suppression are different at low vs. high density. Increasing crop density can be an effective way to suppress weed growth in many agricultural systems, and there is great potential for developing genotypes that can do this and produce high yields much better than the cultivars currently available.

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“…When densities are very high, density‐induced mortality of suppressed seedlings can occur. Under such conditions, the resources available are used less efficiently for the plant community as a whole, since some of the acquired resources are lost again upon mortality (Lu, Jiang, & Weiner, 2020; Weiner et al, 2010). Since size‐inequalities and mortality are partly counteracted by SAS responses, the community productivity might still benefit from the expression of some degree of SAS responses by the suppressed individuals (Aphalo et al, 1999).…”

Section: Shade Avoidance From a Plant Community Perspectivementioning

confidence: 99%

Light signalling shapes plant–plant interactions in dense canopies

Huber

Nieuwendijk

Pantazopoulou

et al. 2020

Plant Cell & Environment

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Plants growing at high densities interact via a multitude of pathways. Here, we provide an overview of mechanisms and functional consequences of plant architectural responses initiated by light cues that occur in dense vegetation. We will review the current state of knowledge about shade avoidance, as well as its possible applications. On an individual level, plants perceive neighbour‐associated changes in light quality and quantity mainly with phytochromes for red and far‐red light and cryptochromes and phototropins for blue light. Downstream of these photoreceptors, elaborate signalling and integration takes place with the PHYTOCHROME INTERACTING FACTORS, several hormones and other regulators. This signalling leads to the shade avoidance responses, consisting of hyponasty, stem and petiole elongation, apical dominance and life cycle adjustments. Architectural changes of the individual plant have consequences for the plant community, affecting canopy structure, species composition and population fitness. In this context, we highlight the ecological, evolutionary and agricultural importance of shade avoidance.

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Crop spatial uniformity, yield and weed suppression

Cited by 17 publications

References 121 publications

Competitive trait hierarchies of native communities and invasive propagule pressure consistently predict invasion success during grassland establishment

Competitive trait hierarchies of native communities and invasive propagule pressure consistently predict invasion success during grassland establishment

Differences in Weed Suppression between Two Modern and Two Old Wheat Cultivars at Different Sowing Densities

Light signalling shapes plant–plant interactions in dense canopies

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