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This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact

Science: general issues --- Botany & plant sciences --- plant development --- root system architecture --- lateral root --- pericycle --- branching --- morphogenesis --- plant development --- root system architecture --- lateral root --- pericycle --- branching --- morphogenesis

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Allelopathy refers to the influence of an organism on the growth or development of another. This natural phenomenon mainly takes place in the soil by a biochemical mechanism called exudation. Rye (Secale cereale L.) is commonly known for its allelopathic potential and largely used as a cover crop. For that reason, it has been chosen as plant model for this study. On the other hand, pigweed (Amaranthus retroflexus L.) causes extent losses on crop yields, such as many other weeds encountered in all types of agroecosystems.
First, the interaction between the two plants were investigated through complex culture system and neighborhoods. Biological observations show two very distinct trends of rye morphology towards the growing environment. Indeed, facing the experimental conditions, the aboveground features of rye remained relatively constant whereas the belowground characteristics largely varied.
Secondly, the biological activity of rye raw extract was tested directly on pigweed. Even though germination and survival rate were globally not influenced, the biological essays gave a glimpse on how pigweed seeds and seedlings could react to rye presence in natural conditions.
Thirdly, the allelochemical content of rye root exudates was analyzed. Two benzoxazinoids are mostly known to take part in poaceous allelopathy: DIMBOA and DIBOA. Manifestly, only DIBOA was revealed in rye’s exudates, regardless of the plant present next to it during its growth.
Lastly, the VOCs emission of rye root was also studied. A specific experimental device allowed the extraction of VOCs directly from the rye rhizosphere. Several biogenic compounds were detected but very few of them are already listed for presumed allelopathic activities. This aspect of this work opens the door towards a whole new field in the study of volatile plant metabolites.
To conclude, viewing the actual environmental context, more sustainable agronomic practices are urgently required. Allelopathy might be one the key for better weed management as long as plant interactions with their surrounding are well understood. This work contributes to a better comprehension of the war that is taking place underground.

Allelopathy --- Secale cereale --- Amaranthus retroflexus --- Benzoxazinoids --- VOC --- root system --- Sciences du vivant > Agriculture & agronomie

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Nutrient Signalling --- Root System Architecture (RSA) --- Modelling Biological Systems --- Roots --- Nutrient Uptake --- Modelling Transport Processes --- Ion Transport

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La stabilisation des pentes est cruciale pour prévenir les glissements de terrain. Parmi les méthodes de stabilisation, l'utilisation des plantes est de plus en plus courante. Les racines des plantes contribuent à la stabilisation de deux manières : elles assèchent le sol, ce qui accroît sa résistance et sa stabilité, et elles renforcent la cohésion des particules de sol, améliorant ainsi sa structure.

Ce mémoire se penche sur l'amélioration de la résistance au cisaillement des sols enracinés à différentes étapes de l'enracinement. Pour atteindre cet objectif, le travail est structuré en deux parties distinctes.

La première partie consiste en une revue de la littérature existante afin d'établir un état de l'art. Celui-ci se focalise d'abord sur les racines avec leur réseau racinaire différent et leur anatomie. Il poursuit en examinant l'un des effets majeurs des racines sur les sols, à savoir l'amélioration de la cohésion. Enfin, il s'intéresse à l'application potentielle de ces connaissances dans le domaine de la stabilité des pentes.

La deuxième partie se concentre sur une étude expérimentale réalisée sur deux types de plantes : le plantain lancéolé (Plantago lanceolata) et le trèfle (Trifolium repens). L'objectif principal est de quantifier la résistance au cisaillement générée par les racines, en termes de cohésion et d'angle de frottement. Cette étude s'étend sur plusieurs semaines de croissance des plantes et s'appuie sur des essais de cisaillement direct en condition saturée ainsi que des essais de compression triaxiale en condition consolidée drainée. En parallèle, les paramètres morphologiques du réseau racinaire, tels que la biomasse, la largeur et l'angle d'ouverture, sont également analysés afin d'évaluer l'évolution de la densité du réseau. Enfin, les résultats obtenus, qui montrent une augmentation de la cohésion et de la densité au fil du temps, sont mis en relation pour mieux comprendre les interactions entre ces variables. Slope stabilization is crucial for preventing landslides. Among the stabilization methods, the use of plants is becoming increasingly common. Plant roots contribute to stabilization in two ways: they help to dry out the soil, which increases its strength and stability, and they enhance the cohesion of soil particles, thereby improving its structure.

This thesis focuses on the enhancement of shear strength in rooted soils at various stages of root development. To achieve this objective, the work is structured into two distinct parts.

The first part involves a review of existing literature to establish a state of the art. It initially focuses on roots, their varying root networks, and their anatomy. It then examines one of the major effects of roots on soils, namely the improvement of cohesion. Finally, it explores the potential application of this knowledge in the field of slope stability.

The second part concentrates on an experimental study conducted on two types of plants: narrowleaf plantain (Plantago lanceolata) and white clover (Trifolium repens). The primary objective is to quantify the shear strength generated by the roots, in terms of cohesion and friction angle. This study spans several weeks of plant growth and relies on direct shear tests under saturated conditions as well as triaxial compression tests under consolidated drained conditions. In parallel, the morphological parameters of the root network, such as biomass, width, and opening angle, are also analyzed to assess the evolution of network density. Finally, the results, which demonstrate an increase in cohesion and density over time, are correlated to better understand the interactions between these variables.

Sol --- Racines --- Réseau racinaire --- Cisaillement --- Cisaillement direct --- Compression triaxiale --- Cohésion --- Angle de frottement --- Stabilité des pentes --- Soil --- Roots --- Root system --- Shear strengt --- Direct shear test --- Triaxial compression test --- Cohesion --- Friction angle --- Slope stability --- Ingénierie, informatique & technologie > Ingénierie civile

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This book is a collection of fundamental and applied research on the plant root response to environmental clues. In particular, the continued adaptation of both fine and coarse roots to modifications due to natural and anthropogenic causes were investigated from different viewpoints. Additionally, specific root traits were investigated as an optimal indicator of responses to the environment at the whole-plant level. Aspects such as an innovative methodological approach, the root morphology, gene expression, and primary and secondary metabolite concentrations were at the center of the investigations conducted in this collection.

Research & information: general --- Biology, life sciences --- TIFY --- Populus trichocarpa --- protein interaction network --- phytohormone treatment --- abiotic stress --- bioengineering --- Carpinus betulus --- Fagus orientalis --- tensile force --- Acer pseudoplatanus --- competition below ground --- extracellular enzymes --- Fagus sylvatica --- intraspecific and interspecific competition --- toot economic spectrum --- toot respiration --- tree root traits --- soil compaction --- N loading --- fine root --- root morphology --- ectomycorrhizal fungi --- forest gap --- forest management --- fine roots --- morphology --- lignin --- carbon --- nitrogen --- hydro-fluctuation zone --- Three Gorges Dam Reservoir --- winter submergence --- Taxodium distichum --- Salix matsudana --- organic acids --- phosphorus deficiency --- T.‘Zhongshanshan’ --- root foraging ability for phosphorus --- anchorage --- coarse root --- measurement method --- Pinus thunbergii --- root cross-sectional area --- root system architecture --- morphological attributes --- physiological analysis --- Populus euramericana --- reforestation --- n/a --- T.'Zhongshanshan'