In semiarid environments, soil water repellency can contribute to reseeding failure by reducing soil moisture availability. Nonionic soil surfactants (wetting agents) have been shown to be effective in enhancing infiltration and improving root-zone water reserves in waterrepellent soils. However, the application of soil surfactants in wildland ecosystems can be logistically and economically prohibitive. In this study, we evaluated a potential solution for applying soil surfactants using seed coating technology. Through this technology, the seed is used as a carrier for the soil surfactant. After planting, water transfers the surfactant from the seed into the soil where it ameliorates the water repellency within the seed's microsite. The objectives of this research were 1) to establish the efficacy of a surfactant seed coating (SSC) in ameliorating soil water repellency, and 2) to determine the influence of SSC on seedling emergence and plant survival. To accomplish the first objective, detailed soil column experiments were conducted in the laboratory on water-repellent soil obtained from a burned pinyon-juniper (Pinus-Juniperus spp.) woodland. The second objective was met through greenhouse testing of SSC applied to crested wheatgrass and bluebunch wheatgrass seed, using the same soil as used in the first objective. Results indicate that SSC increased soil water infiltration, percolation, and retention. This technology had no influence on seedling emergence for crested wheatgrass, but SSC improved bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] Á. Lö ve) emergence threefold. Plant survival was dramatically improved by the SSC. Only 0.75% of the seedlings that grew from noncoated seed survived to the end of the study, whereas 37% of the plants survived in the SSC treatment. Overall, these results indicate that it may be plausible for SSC to improve postfire restoration efforts by restoring soil hydrologic function and increasing seedling emergence and early seedling development. Resumen En las zonas semiáridas, la repelencia del agua del suelo puede contribuir a las fallas de las resiembras reduciendo la disponibilidad de la humedad del suelo. Los surfactantes no iónicos del suelo (agentes de adherencia) han demostrado ser eficaces en ayudar la infiltración y mejorar las reservas de agua de la zona de la raíz en suelos impermeables. Sin embargo, el uso de surfactantes en suelos de ecosistemas de pastizales puede ser logísticamente y económicamente prohibitivo. En este estudio evaluamos una solución viable para aplicar los surfactantes del suelo usando tecnología para cubrir la semilla. Con esta tecnología la semilla se utiliza como portador para el surfactante del suelo. Después de ser plantada, el agua transfiere el surfactante de la semilla en el suelo donde mejora la repelencia del agua dentro del micro-sitio de la semilla. Los objetivos de esta investigación fueron 1) establecer la eficiencia de una cubierta en la semilla del surfactante (SSC) en el mejoramiento de repelencia del agua del suelo, y 2) det...
Ultrathin sections of leaves from American elms (Ulmus americana L.), sycamores (Platanus spp.), and two red oak species (Quercus spp.) that exhibited leaf scorch were examined by transmission electron microscopy. Rod-shaped, ripple-walled bacteria resembling the Pierce's disease organism were found consistently in tracheary elements of the primary and secondary veins of diseased plants. Smaller, ripple-walled, densely stained, irregular-shaped bodies (SDB) were found also in a matrix that lined the inner walls or filled the lumina of the tracheary elements. In leaf scorch affected American elms the bacteria were 0.3–0.4 μrn × 0.9–2.4 μm, with rounded ends. Fimbriae-like structures radiated from a few organisms. Bacteria were frequently embedded in a matrix. Pit cavities and the ends of tracheary elements were often filled with the bacteria–matrix complex. Rod-shaped bacteria were not as numerous in the diseased sycamore and oak as in diseased elm; however, SDB's were more numerous. Bacteria in sycamore (1.0–1.8 μm) and oak (1.0–2.0 μm) were slightly shorter than those in elm, many had numerous fimbriae-like hairs, and some were tapered at one end. Indirect fluorescent antibody staining showed a serological relationship between bacteria extracted from elm and oak and the Pierce's disease bacterium.
Recent studies have drawn attention to the role of mucilage in shaping rhizosphere hydraulic properties and regulating root water uptake. During drying, mucilage keeps the rhizosphere wet and conductive, but on drying it turns hydrophobic, limiting root water uptake. In this study, we introduce the concept of rhizoligands, defined as additives that (i) rewet the rhizosphere and (ii) reduce mucilage swelling, thereby reducing the rhizosphere conductivity. We tested whether selected surfactants behaved as rhizoligands. We used neutron radiography to monitor water redistribution in the rhizosphere of lupine (Lupinus albus L. cv. Feodora) and maize (Zea mays L.) irrigated with water and rhizoligands. In a parallel experiment, we tested the effect of rhizoligands on the transpiration rate of lupine and maize subjected to repeated drying and wetting cycles. We also measured the effect of rhizoligands on the maximum swelling of mucilage and the saturated hydraulic conductivity of soil mixed with various mucilage concentrations. Rhizoligand treatment quickly and uniformly rewetted the rhizosphere of maize and lupine. Interestingly, rhizoligands also reduced transpiration during drying-wetting cycles. Our hypothesis is that the reduction in transpiration was triggered by the interaction between rhizoligand and mucilage exuded by roots. This hypothesis is supported by the fact that rhizoligand reduced the maximum swelling of mucilage, increased its viscosity, and decreased the hydraulic conductivity of soil-mucilage mixtures. The reduced conductivity of the rhizosphere induced a moderate stress to the plants, reducing transpiration. Rhizoligands increase the rhizosphere wetting kinetics and decrease the maximum swelling of mucilage. As a consequence, root rehydration following irrigation is faster, a larger volume of water is available to the plant, and this water is used more slowly. This slower water consumption would allow the plant to stay turgid during a prolonged drying period. We propose that by managing the hydraulic properties of the rhizosphere, we can improve plants' adaptation to drought.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.