Superabsorbent Polymer Seed Coating Reduces Leaching of Fungicide but Does Not Alter Their Effectiveness in Suppressing Pathogen Infestation

Superabsorbent polymers (SAPs) applied to soil have been recognized as water reservoirs that allow plants to cope with periods of drought. Their application as a seed coat makes water available directly to the seeds during their germination and early growth phase, but on the other hand, it can affect the efficiency of plant protection substances used in seed dressing. In our experiments, we evaluated the effect of seed coating with SAP on fungicide leaching and changes in their effectiveness in suppressing Fusarium culmorum infestation. Leaching of fungicide from wheat seeds coated with SAP after fungicide dressing, as measured by the inhibition test of mycelium growth under in vitro conditions, was reduced by 14.2–15.8% compared to seeds without SAP coating. Germination of maize seeds and growth of juvenile plants in artificially infected soil did not differ significantly between seeds dressed with fungicide alone and seeds treated with SAP and fungicide. In addition, plants from the seeds coated with SAP alone grew significantly better compared to untreated seeds. Real-time PCR also confirmed this trend by measuring the amount of pathogen DNA in plant tissue. Winter wheat was less tolerant to F. culmorum infection and without fungicide dressing, the seeds were unable to germinate under strong pathogen attack. In the case of milder infection, similar results were observed as in the case of maize seeds.

Project to Establish Growth & Mortality Rates of Three Carex Species in Two Planting Types at Thomas Dairy Site, Tigard, Oregon

Clean Water Services (CWS) currently increases the diversity of their wetland restoration projects using a plug planting method utilizing juvenile herbaceous plants. They have planted most of their projects using this method and plan to continue until a better one is discovered. According to the literature reviewed in this paper, juvenile plants are smaller and weaker than more mature plants and therefore have higher mortality rates. This paper is the culmination of work completed of phase 1 of this two-phase project. The objective of this project (both phases) was to design and establish a study that would test, in the field, two common wetland planting methods: installation of plugs of juvenile plants at a relatively high density and installation of containerized, more mature plants at a lower density. This study will examine three species of Carex frequently used in wetland restoration (Carex stipata, C. obnupta, and C. unilateralis) and compare the growth and mortality of mature versus juveniles of these species within Thomas Dairy Site in the Tualatin River Watershed. For phase 2, at Thomas Dairy Site, 13 randomly selected plots will each containing six subplots including a subplot planted with monocultures of each of the three plants, and two sizes (i.e., mature C. stipata, juvenile C. stipata, mature C. obnupta, juvenile C. obnupta, mature C. unilateralis, and juvenile C. unilateralis). These will be monitored for five years, during which mortality rates will be recorded once a year and total percent cover recorded three times a year. I hypothesize that the mature plants will have a higher percent cover after five years because juvenile plants are more susceptible to die over that timeframe and may have slower growth rates overall. Answering these questions will allow CWS and other wetland restoration managers to achieve greater plant coverage, reduce waste, and reduce costs.

Chloride Accumulation in Aboveground Biomass of Three Macrophytes (Phragmites Australis, Juncus Maritimus, and Typha Latifolia) Depending on Their Growth Stages and Salinity Exposure. Application for Cl- Removal and Phytodesalinization.

Anthropogenic activities can be the source of saline solid wastes that need to be treated to reduce their salt load to meet the purposes of reuse, valorization or storage. In this context, chloride remediation can be achieved using high-salt accumulating plants. However, there is very limited information on the comparative potential of different species in the same environment, and only scarce data concerning their efficiency as a function of growth stage. In order to rationalize these selection criteria, three macrophytes i.e. common reed (Phragmites australis), sea rush (Juncus maritimus) and cattail (Typha latifolia) were cultivated at two growth stages (6-months old and 1-year old) for 65 days in Cl- spiked substrates (from 0 up to 24 ‰ NaCl). The plants’ survival and potential capacity for removal of Cl- from substrates and accumulation in shoots were investigated. For the three studied species, mature and juvenile plants display a high tolerance to salinity. However, mature specimens with higher shoot biomass and Cl- contents are capable of greater chloride removal than juvenile plants. The sole exception is P. australis which displays just the same phytoremediation potential for both mature and juvenile specimens. Moreover, P. australis has the lowest potential when compared with other species, being 1.5 and 3 times lower than for J. maritimus and T. latifolia. When considering the plant growth and the shoot biomass production, chloride removal rates from the substrate point that mature J. maritimus should preferentially be used to design an operational chloride remediation system. The results highlight the relevance of considering the growth stage of plants used for Cl- removal.

Effects of the electromagnetic field of Wi-Fi systems and experimental gadget M4 on growth, development and photosynthesis of wheat

Objectives. To assess the effects of the electromagnetic field of a Wi-Fi system and the experimental gadget M4 developed by SAS “IRDT” (France) on wheat seed germination, growth and photosynthetic activity of juvenile plants. Material and methods. The test-plants were grown under controlled conditions of light, temperature and humidity for 8 days in a pot experiment modeling the following treatments: (1) the absence of electromagnetic field of Wi-Fi systems (control); (2) at a distance of 30 cm from the operating Wi-Fi router; (3) at a distance of 30 cm from operating Wi-Fi router and the experimental gadget M4. The test plant development and vitality were assessed using indices of seed germination, growth rates (shoot height, root length, number of lateral roots, shoot and root dry weights), photosynthetic pigment content in leaves and the number of chloroploplasts per a mesophyll cell in foliar tissues. Results. It was found that the electromagnetic field of Wi-Fi router initially stimulated, but then suppressed the germination of seeds, reduced the growth of shoots and roots, the content of photosynthetic pigments and chloroplastogenesis in the mesophyll tissues in leaves of wheat juvenile plants. The root length was the most sensitive morphometric parameter to the electromagnetic field of Wi-Fi router. The use of the gadget M4 completely compensated the negative impact of Wi-Fi router on the seed germination, shoots growth, and partially compensated for the suppression of root growth, chloroplastogenesis, chlorophyll a and b content in wheat leaves. Conclusion. The attenuation effect of gadget M4 against the damaging effect of electromagnetic fields of anthropogenic origin is promising and further investigations are required to observe the effects on long term, from sowing to maturity, including the next generation of seeds.

Spatial Distribution, Regeneration, Growth and Thicket Formation of Thornless Mimosa tenuiflora in a Caatinga Site of Northeast Brazil

Aims: Percentage of native thorny and thornless Mimosa tenuiflora (Willd.) Poiret trees, and their growth, height and/or diameter class distribution and clustering pattern were determined in a pure stand of this species. Study Design: A survey of the adult and juvenile plants was carried out in a 50 m x 50 m site after 10 years of tree cover regeneration. Place and Duration of Study: The study site was located at Fazenda Nupearido, Patos-PB, Brazil and data collection occurred in September 2017. Methodology: Adult plants with trunk circumference at breast height (1.3 m from the soil) > 6 cm (CBH > 6 cm) were measured for height and CBH, and located within the study area. Juvenile plants (i.e.: CBH ≤ 6 cm) were divided into 4 height classes. The position of only the thornless individuals within the study area was determined. Results: Among the 170 adult plants documented in the area, 95.3% and 4.7% were thorny and thornless, respectively. Height and diameter at breast height averaged higher for thornless than for thorny adult plants (4.13 m and 9.28 cm vs. 3.61 m and 5.90 cm). In contrast, thornless juvenile plants averaged lower for height and basal diameter than the thorny ones. The number of juvenile M. tenuiflora totaled 897 plants, including 58 thornless ones, but percentage of thornless juveniles peaked at 17.6% for 10-to-50 cm high plants. In general, thorny plants showed a clustering pattern of distribution while the thornless plans were randomly distributed. Conclusion: The density, random distribution and growth of the thornless plants suggest the possibility to form thickets of thornless plants in caatinga sites where this tree predominates. Also, these data show that in forested sites with thorny trees that generate thornless mutants, as observed in the Caatinga Biome for M. tenuiflora and other tree species, it is possible to increase the frequency and abundance of the naturally regenerating thornless plants, making easier the exploitation of forest resources, an approach that may be applied in other types of vegetation.

Differential submergence tolerance between juvenile and adult Arabidopsis plants involves the ANAC017 transcription factor

Plants need to attune stress responses to the ongoing developmental programs to maximize their efficacy. For instance, successful submergence adaptation is often associated to a delicate poise between saving resources and their expenditure to activate measures that allow stress avoidance or attenuation. We observed a significant decrease in submergence tolerance associated with aging in Arabidopsis thaliana, with a critical step between two and three weeks of post-germination development. This sensitization to flooding was concomitant with the transition from juvenility to adulthood. Transcriptomic analyses indicated that a group of genes related to ABA and oxidative stress response was more expressed in juvenile plants than in adult ones. These genes are induced by endomembrane tethered ANAC factors that were in turn activated by submergence-associated oxidative stress. A combination of molecular, biochemical and genetic analyses showed that these genes are located in genomic regions that move towards a heterochromatic state with adulthood, as marked by lysine 4 dimethylation of histone H3. We concluded that, while the mechanism of flooding stress perception and signal transduction were unaltered between juvenile and adult phases, the sensitivity that these mechanisms set into action is integrated, via epigenetic regulation, into the developmental programme of the plant.