Pasture weed biology and management in Brazil

The livestock production model historically practiced in Brazil has a strong extractive bias, wherein the premise is to produce livestock with absolutely no concern for the preservation or renewal of environmental resources. The absence of technical criteria for the use of pastures has generated low productivity rates, making the activity unsustainable from both economic and environmental points of view. This scenario led the several sectors linked to the production chain to develop a package of strategies to solve the problems faced by livestock farmers. This package of strategies is conventionally called postmodern or corporate farming, in which the extractive process gives way to the business logic of avoiding waste and recovering profit margins mainly through pasture perpetuation. However, there is still a technical gap in corporate cattle farming related to problems caused by pasture weeds because all the concepts applied are derived or copied from concepts generated in agriculture. Furthermore, few researchers have studied or scientific articles written on elucidating the real problem of weeds in livestock production. Thus, the goal of the present review was to present some aspects related to weed ecology, their interference, and management alternatives in pasture areas, thereby collaborating with corporate livestock farming in Brazil because solutions to weed problems are crucial to increase commitment in all sectors of the production chain.

Toward an Investigation of Diversity and Cultivation of Rye (Secale cereale ssp. cereale L.) in Germany: Methodological Insights and First Results from Early Modern Plant Material

Rye (Secale cereale ssp. cereale L.) is a secondary domesticate, considered to have originated as a weed in wheat fields and to have developed traits of domestication by evolving similar physiological and morphological characteristics to those of wheat. Although it migrated into Europe as a weed possessing domestication traits, it became one of the most significant crops grown in large parts of Europe from the medieval period onward. Within the modern borders of Germany, rye was grown using at least two divergent cultivation practices: eternal rye monoculture and three-field rotation. The straw of rye was used to produce Wellerhölzer, which are construction components in traditional half-timbered houses that have enabled a desiccated preservation of the plant remains. In order to assess the impact of cultivation practices, local environmental conditions and genetic variation on the genetic diversification of rye, we seek to integrate well-established archaeobotanical methods with aDNA sequencing of desiccated plant remains obtained from Wellerhölzer from Germany. In the current contribution, we present a proof of concept, based on the analysis of plant remains from a Wellerholz from the Old Town Hall of Göttingen. We use arable weed ecology to reconstruct cultivation practices and local environmental conditions and present a phylogenetic analysis based on targeted loci of the chloroplast and nuclear genome. Our results emphasise that the study of desiccated remains of plants from Wellerhölzer offer a unique opportunity for an integration of archaeobotanical reconstructions of cultivation practices and local environment and the sequencing of aDNA.

Weed Ecology and New Approaches for Management

The rich biodiversity of agricultural fields and their surroundings enhances natural ecosystems and has a positive impact on their productivity and resistance, e [...]

Effect of Differential Responses of Weed Infestation on Shoot Functional Traits of Wheat (Triticum aestivum L.)

Background: Shoot functional traits that help the plant to increase its competitive ability, mechanical strength and allocation of photosynthetic products and nutrients from soils in shoot formation strengthens the plant growth. To understand the complexity of weed-crop competition via plant functional traits might be a feasible option and that can provide a better understanding of weed ecology. Methods: Present study was designed to understand the performance of wheat crop under weed infestation (Avena and Phalaris combination) during each rabi season of 2014-2017 at the experimental enclosure of Panjab University, Chandigarh. This experiment was established with water and fertilizer treatments following the Latin Square Matrix (LSM) model. Result: Results indicated that under a different mixed combination of weeds, growth parameters of wheat crop such as shoot functional traits were significantly distinguishable. However, the maximum differential response in corresponding parameters was found under combination when the wheat was grown in mixed with both the weeds and when full doses of fertilizers and water were applied. This finding now confirms that these weeds have much more inclination to exploit available resources and provide a high degree of inter-specific competition to the wheat crop.

Which Traits Make Weeds More Successful in Maize Crops? Insights from a Three-Decade Monitoring in France

A major aim in invasion biology is identifying traits distinguishing alien invasive and alien non-invasive plants. Surprisingly, this approach has been, so far, poorly used to understand why some arable weeds are abundant and widespread while others are rare and narrowly distributed. In the present study, we focused on the characteristics of successful weeds occurring in maize fields, one of the most important crops worldwide. Two national weed surveys conducted in France were used to identify increasing and decreasing species based on 175 and 484 surveyed fields in the 1970s and the 2000s, respectively. Weed trait values related to regional frequency, local abundance, and specialization to maize were identified with phylogenetic generalized least-squares (PGLS). We found a positive relationship between regional frequency and local abundance, i.e., the most widespread weeds were also locally more abundant. We highlighted that weeds with the C4 photosynthetic pathway and summer emergence were more abundant, more frequent, and more specialized to maize crops. More generally, we highlighted two successful strategies: On the one hand, traits related to a general weediness syndrome with rapid resource acquisition (high SLA and Ellenberg-N) and high colonization capacity (seed longevity, fecundity, and wind dispersal); on the other hand, traits related to specific adaptation to spring cultivation (thermophilous species with summer emergence, late flowering, and C4 photosynthetic pathway). Deviations from the abundancy–frequency relationships also indicated that species of the Panicoideae sub-family, species with Triazine-resistant populations, and neophyte species were more abundant than expected by their regional frequency. To some extent, it is therefore possible to predict which species can be troublesome in maize crops and use this information in weed risk assessment tools to prevent new introductions or favor early detection and eradication. This study showed how tools developed in functional and macro-ecology can be used to improve our understanding of weed ecology and to develop more preventive management strategies.

Which Traits Make Weeds More Successful in Maize Crops? Insights from a 3-Decade Monitoring in France

Invasion ecology has a long tradition of searching for traits distinguishing alien invasive and non-invasive plants. Surprisingly, this approach has been so far poorly used to understand why some arable weeds are abundant and widespread while others are rare and narrowly distributed. In the present study, we focused on the characteristics of successful weeds occurring in maize fields, one of the most import crop worldwide. Two national weed surveys conducted in France were used to identify increasing and decreasing species based on 175 and 484 surveyed fields in the 1970s and the 2000s, respectively. Weed trait values related to regional frequency, local abundance and specialization to maize were identified with Phylogenetic Generalized Least-Squares (PGLS). We found a positive relationship between regional frequency and local abundance, i.e. the most widespread weeds were also locally more abundant. We highlighted that weeds with the C4 photosynthetic pathway and summer emergence were more abundant, more frequent and more specialized to maize crops. More generally, we highlighted two successful strategies: on the one hand, traits related to a general weediness syndrome with rapid resource acquisition (high SLA and Ellenberg-N) and high colonization capacity (seed longevity, fecundity and wind dispersal), on the other hand, traits related to specific adaptation to spring cultivation (thermophilous species with summer emergence, late flowering and C4 photosynthetic pathway). Deviations from the abundancy-frequency relationships also indicated that species of the Panicoideae sub-family, species with Triazine-resistant populations and neophyte species were more abundant than expected by their regional frequency. To some extent, it is therefore possible to predict which species can be troublesome in maize crops and use this information in weed risk assessment tools to prevent new introductions or favor early detection and eradication. This study showed how tools developed in functional and macro-ecology can be used to improve our understanding of weed ecology and to develop more preventive management strategies.

Shifting the Paradigm: An Ecological Systems Approach to Weed Management

Weeds have been historically, and are still today, the primary and most economically important pest in agriculture. Several selection pressures associated with weed management, such as an overreliance on herbicides, have promoted the rapid evolution of herbicide-resistant weeds. Integrated Weed Management (IWM) is promoted as an ecological systems approach, through the combination of biological, chemical, cultural, ecological, and mechanical control methods. The concept of a systems approach is defined as managing weeds by combining practice and knowledge with the goals of increasing yield and minimizing economic loss, minimizing risks to human health and the environment, and reducing energy requirements and off-target impacts. The reliance on herbicides in modern cropping systems has shifted the management focus from requiring intimate knowledge of biology, ecology, and ecological systems to herbicide chemistry, mixes, and rotations, application technology, and herbicide-tolerant crop traits. Here, an ecological systems approach is considered, examining new trends and technologies in relation to IWM and weed ecology. Prevention of spread, seedbank management, crop rotations, tillage, cover crops, competitive cultivars, biological weed control, and future solutions in concept-only are presented, and knowledge gaps are identified where research advancements may be possible. An ecological systems approach will provide improved stewardship of new herbicide technologies and reduce herbicide resistance evolution through diversification of selection pressures. Agroecological interactions should be studied in light of new, developing weed control technologies. The science of weed management needs to refocus on the foundations of weed biology and ecology to enable an ecological systems approach and promote agricultural sustainability.