Direct Water Uptake Research Articles

DECIPHERING THE OILSEED BACTERIAL ENDOPHYTES AND STUDY OF THEIR ROLE AND TRIPARTITE INTERACTIONS WITH PLANTS AND PATHOGEN

Endophytes colonize interior regions of oilseeds depending on water, nutrient, space availability and microbial competition. Oilseeds are filled with oil globules making it difficult for microbes to obtain direct uptake of water and nutrient for growing into colonies. Recent research shows very less areas explored in endophytic study in oilseeds and as endophytes play a vital part in managing diseases in plants by releasing genes encoding jasmonate and salicylic acid which induces defense against pathogens and modify plant regions structurally adding to their fitness and increased productivity, their study is indispensable. This review focuses on the bacterial endophytes in oilseeds, the challenges faced in their isolation, their colonization and interactions with host and pathogens and their applications. Oilseed endophytic study is essential for understanding the benefits of oilseeds consumed as vegetable oil or used as fuel by people all over the world.

Multilayering of conventional latex-based dispersion coatings containing small amounts of silica nanospheres: Runnability on a pilot scale flexographic coater and barrier performance

The addition of functional coatings to packaging materials is a key requirement for increasing their performance and creating innovative packaging solutions. Flexography, a cost-effective printing method commonly used to print information and graphics directly onto a wide variety of packaging substrates, shows good potential for applying functional coatings. In this study, conventional clay-latex coating formulations containing approximately 1.3 wt% silica nanospheres were applied to a linerboard using a pilot scale flexographic printing web press. The performance of multilayered silica nanosphere-based coatings was compared with conventional coatings containing talc and/or wax dispersion in terms of coating grammage, runnability, and barrier performance. Coating grammage increased with an increased number of coating layers and a significant decrease in both the water vapor transmission rate (WVTR) and the direct water uptake of water (Cobb 120 wettability test) was observed for coatings containing silica nanoparticles. In general, the silica nanosphere-based coatings performed better than talc-based coatings. Talc/wax-based coatings had the highest variation in surface roughness due to an uneven distribution and variations of coating layers.

A research agenda for nonvascular photoautotrophs under climate change.

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Foliar water uptake in the needles of Pinus torreyana

The natural habitat of Pinus torreyana, the Torrey pine, is restricted to two locales in coastal Southern California that experience substantial fog and low clouds during the dry months of a Mediterranean climate. In similar semi-arid climate systems that encounter fog or low clouds, many plants can capture atmospheric moisture and are capable of direct foliar water uptake to reduce water stress. In this study, we investigated if the needles of P. torreyana are also capable of direct water uptake. In addition to water immersion, we measured the surface properties along a needle using microdroplets. The droplet contact angle is a measure of surface wettability, and the droplet absorption is a measure of localized foliar water uptake. The results showed that the entire length of the P. torreyana needle, including under the base sheath, is hydrophilic and capable of direct water uptake. The spatial gradients of the wettability and the water uptake along the needle are relatively small. Moreover, the wettability and water uptake increase from young shoots to one-year and two-year old needles. Our results also showed that the decrease in water uptake at higher contact angles can be described by a linear regression. Compared with the leaves of four shrubs in the same habitat, Heteromeles arbutifolia, Malosma laurina, Rhus integrifolia, and Eriodictyon crassifolium, the P. torreyana needles have lower contact angles and higher water uptake rates.

Identifying the pathways for foliar water uptake in beech (Fagus sylvatica L.): a major role for trichomes.

Foliar water uptake (FWU), the direct uptake of water into leaves, is a global phenomenon, having been observed in an increasing number of plant species. Despite the growing recognition of its functional relevance, our understanding of how FWU occurs and which foliar surface structures are implicated, is limited. In the present study, fluorescent and ionic tracers, as well as microcomputed tomography, were used to assess potential pathways for water entry in leaves of beech, a widely distributed tree species from European temperate regions. Although none of the tracers entered the leaf through the stomatal pores, small amounts of silver precipitation were observed in some epidermal cells, indicating moderate cuticular uptake. Trichomes, however, were shown to absorb and redistribute considerable amounts of ionic and fluorescent tracers. Moreover, microcomputed tomography indicated that 72% of empty trichomes refilled during leaf surface wetting and microscopic investigations revealed that trichomes do not have a cuticle but are covered with a pectin-rich cell wall layer. Taken together, our findings demonstrate that foliar trichomes, which exhibit strong hygroscopic properties as a result of their structural and chemical design, constitute a major FWU pathway in beech.

Use of spherical silica particles to improve the barrier performance of coated paper

Abstract The use of clay filler materials in dispersion coatings is a well-established method to provide improved barrier properties to the coated paper substrate, in particular lowering the water vapour transmission rate (WVTR) through the coating. In this paper we demonstrate the use of small spherical silica particles (∼100–220 nm) as an additive to a clay-latex coating formulation is able to provide further improvements to the barrier properties, when compared to the equivalent silica-free coatings. A significant decrease in both the water vapour transmission rate and the direct water uptake of water ( Cobb 120 {\text{Cobb}_{120}} wettability test) is observed for coatings containing as little as 1 % silica additive.

Film formation and barrier performance of latex based coating: Impact of drying temperature in a flexographic process

The post-application behaviour of aqueous dispersion barrier coatings is investigated. We have adapted a dispersion formulation initially optimised for rod coating, for application to linerboard by a flexographic press. The clay/talc/wax/poly(styrene-butadiene) latex dispersion coatings demonstrated a 60% reduction in water vapour transport rate across the barrier, and a 75% reduction in direct water uptake when the applied film was dried at 75 °C. Multi-layer coatings with a combined application rate of 7 g m−2 exhibited Cobb120 direct water uptake of 16.3 ± 3.7 g m−2 (120 s water contact duration) and a water vapour transport rate of 140 ± 12 g m−2 d−1 (23 °C, 50% RH). Investigation of the post-coating curing regime demonstrated a decrease in the prevalence of crack defects within the cured film, and corresponding improvement in barrier properties when higher drying temperatures were employed. Dynamic mechanical analysis of the cured films indicated improvements in homogeneity and a greater extent of intermolecular interactions in the coating formulations cured at elevated temperatures.

The incidence and implications of clouds for cloud forest plant water relations

Although clouds are the most recognisable and defining feature of tropical montane cloud forests, little research has focussed on how clouds affect plant functioning. We used satellite and ground-based observations to study cloud and leaf wetting patterns in contrasting tropical montane and pre-montane cloud forests. We then studied the consequences of leaf wetting for the direct uptake of water accumulated on leaf surfaces into the leaves themselves. During the dry season, the montane forest experienced higher precipitation, cloud cover and leaf wetting events of longer duration than the pre-montane forest. Leaf wetting events resulted in foliar water uptake in all species studied. The capacity for foliar water uptake differed significantly between the montane and pre-montane forest plant communities, as well as among species within a forest. Our results indicate that foliar water uptake is common in these forest plants and improves plant water status during the dry season.

Stochastic soil water dynamics of phreatophyte vegetation with dimorphic root systems

As the direct uptake of deep groundwater by vegetation may be essential in semiarid regions, we incorporated this process in stochastic root zone water balance models. The direct water uptake by vegetation via deep tap roots is simulated using one additional empirical parameter. This is considered for the case of feedback with root zone saturation and without such feedback. The model that accounts for feedback between shallow root zone saturation and groundwater uptake by deep roots takes up less water if the shallow root zone is wet. The behavior of the models demonstrates that for certain combinations of climate and groundwater depths this feedback becomes important in determining differences in total evapotranspiration (ET). This feedback mechanism also captures hydraulic redistribution processes. The range of relative contributions of groundwater to ET predicted by the models was similar to values derived in isotope studies.

Modeling the Potential Influence of Particle Deposition on the Accumulation of Organic Contaminants by Submerged Aquatic Vegetation

Submerged aquatic vegetation can act as both a mitigating factor(e.g., reducing downstream impacts of pesticides following runoff/spray drift) and mobilizing factor (e.g., remobilization of contaminants from sediments) influencing the fate and distribution of organic contaminants in the environment. Consequently, there has been wide scientific and regulatory interest in assessing the role of these plants in different contamination scenarios. Mechanistic models describing the environmental fate of contaminants in submerged aquatic vegetation are useful tools for interpreting laboratory and field measurements in addition to providing valuable information to risk assessors. In this study, we developed a fugacity-based model to investigate the influence of particle deposition to plant surfaces on the fate and distribution of two substances in small ponds. The main motivation for conducting this study was to address the fact that the potential contribution of this process is not typically considered by many types of models describing contaminant dynamics in submerged aquatic vegetation. For the hydrophobic substance included in this evaluation (lambda-cyhalothrin), model performance was greatly improved by including this process. The model was also applied in a generic context to compare the importance of particle deposition versus directwater uptake as a function of chemical properties (log Kow) and concentration of suspended solids in the water column. The generic application demonstrated that contaminant mass transfer is dominated by particle deposition for chemicals with log Kow greater than approximately 5.5--6 across a wide range of suspended solid concentrations and can be important even for low log Kow substances in some circumstances. Further empirical and modeling studies are recommended to explore this process more comprehensively.

Does the enhanced tolerance of arbuscular mycorrhizal plants to water deficit involve modulation of drought‐induced plant genes?

Does the enhanced tolerance of arbuscular mycorrhizal plants to water deficit involve modulation of drought‐induced plant genes?

Water sources and water-use efficiency in mediterranean coastal dune vegetation.

In coastal environments plants have to cope with various water sources: rainwater, water table, seawater, and mixtures. These are usually characterized by different isotopic signatures ( (18)O/ (16)O and D/H ratios). Xylem water reflects the isotopic compositions of the water sources. Additionally, water-use efficiency (WUE) can be assessed with carbon isotope discrimination (Delta) analyses. Gas exchange, Delta of leaf dry matter, and isotopic composition (delta (18)O) of xylem water were measured from June to August 2001 in herbaceous perennials of mobile dunes (Ammophila littoralis, Elymus farctus) and sclerophyllous shrubs and climbers (Arbutus unedo, Pistacia lentiscus, Phillyrea angustifolia, Qercus ilex, Juniperus oxycedrus, Smilax aspera) of consolidated dunes. Assimilation rates were rather low and did not show clear seasonal patterns, possibly due to limited precipitation and generally low values of stomatal conductance. The lowest values were shown in S. aspera. Different physiological patterns were found, on the basis of delta (18)O and Delta analyses. Values of delta (18)O of xylem water of phanerophytes were remarkably constant and matched those of the water table, indicating dependence on a reliable water source; values of Delta were relatively high, indicating low intrinsic WUE, with the exception of J. oxycedrus. Surprisingly, very high delta (18)O values were found for the xylem water from S. aspera in August. This suggests retrodiffusion of leaf water to xylem sap in the stem or direct uptake of water by leaves or stems, owing to dew or fog occurrence. Low Delta values indicated high WUE in S. aspera. Contrasting strategies were shown by the species of mobile dunes: E. farctus relied on superficial water and exhibited low WUE, accordingly to its therophyte-like vegetative cycle; on the contrary, A. littoralis used deeper water sources, showing higher WUE in relation to its long-lasting vegetative habit.

Deuterium tracing for the estimation of transpiration from trees Part 1. Field calibration

Flow rates calculated using the deuterium tracing method were compared with measurements of direct water uptake of excavated trees which had been inserted into water containers. Taking into account that the tracing method provides an estimate of the weighted mean flow rate over the period that the tracer pulse is present (the weighting factor is the relative concentration of the tracer as measured at the sampling point) agreement was obtained within the experimental error (about 10%) associated with the tracing method.

Dynamics of Polychlorinated Biphenyls in Striped Bass from the Hudson River. III. Tissue Disposition and Routes for Elimination

Striped bass were exposed to14C-polychlorinated biphenyls (PCB) in single-dose and multiple-dose experiments. Samples were analyzed to determine rate constants for PCB elimination from individual tissues, PCB concentration in tissues, the proportion of the PCB burden retained and the proportion of the cumulative dose retained by each tissue at various times after exposure. An experiment was also conducted to determine both the potential for secondary PCB uptake in dietary exposure studies and the relative tissue disposition of PCBs assimilated from dietary sources as compared to direct water uptake. PCBs were present in the tissues of striped bass within 6 h after administration of a single dose. Certain tissue compartments, such as the liver/gall bladder, accumulated PCBs over a period of 48 h even though the whole-body burden had decreased between 24 and 48 h. Except for the gills, elimination rate constants for all tissues were similar and were similar to the whole body elimination rate constant. Elimination during the first few hours following exposure to PCBs may be due to equilibrium partitioning from the gill to the environment. The multiple-dose study showed that PCB burdens in striped bass continued to increase with dosing. However, tissue-specific rate constants for PCB elimination led to an increased flux of PCB out of tissues, and an overall decline in the percent of the cumulative dose remaining in the body 48 h after administration of each dose. The most likely route for PCB elimination from striped bass was from tissues to the liver and thence to the intestine via the bile. There were no differences in the tissue disposition of PCB related to route of exposure.

Water relations and keeping-quality of cut Gerbera flowers. I. The cause of stem break

Experiments were performed to find out the cause of stem break in some Gerbera cultivars. In cut flowers fresh weight decreased sharply 3 days before stem break occurred, and this was accompanied by a decline in absorption of water by the flowers. The petal water potential (ω) decreased in these flowers whereas it remained constant in flowers without stem break. Stem break could be prevented by pretreatment of the stems with sodium hypochlorite or silver nitrate, by adding silver nitrate or dichlorophen to the vase water, and by handling the stems in such a way that water could enter into the cavity of the stem. In 1 of the 4 cultivars used, the percentage of stem break varied strongly between summer- and winter-grown flowers. It is suggested that there are 2 different pathways for water uptake: a direct one through the xylem vessels at the cut surface and an indirect one through the cavity in stem. Only the direct water uptake is strongly inhibited by growth of bacteria in the vase water. Stem break occurs when the direct water uptake is inhibited by bacterial activity and the indirect uptake is hampered.

Accumulation and distribution of selenium in mussel and shrimp tissues.

The tissue distribution of selenium in mussels and shrimp was examined and the bioaccumulation kinetics in the various tissues was elucidated with the aid of radio selenium. Mussels (Mytilus galloprovincialis) and shrimp (Lysmata seticaudata) collected near the Monaco port, were apportioned into several groups. One group of mussels and shrimp was maintained in sea water containing 0.8 ..mu..Ci/liter high specific activity Se-75. Three to four individuals were dissected and their tissues monitored for Se-75 content periodically. Another group of shrimp, maintained in flowing sea water, were fed ad libitum mussels that had previously accumulated Se-75 from sea water for several days. Shrimp were periodically dissected to follow tissue accumulation of ingested selenium. The highest concentrations of selenium were found in the exoskeleton, presumably due, in part, to the relatively large amount of isotope sorbed to its outer surface. Molts, cast by shrimp at various times throughout uptake, contained from 60 to 90% of the total Se-75 body burden. Direct uptake of water led to initially small fractions in internal tissues such as muscle and viscera compared to the relatively large fraction associated with the exoskeleton. With time percentages in internal tissues gradually increased relative to that in the exoskeleton. Whenmore » Se-75 was accumulated through the food chain an opposite trend was noted with the Se-75 fraction in exoskeleton slowly increasing and that in viscera decreasing during the course of the experiment. All tissues examined readily accumulated the isotope and, in general, did not appear to have reached a steady state concentration after 63 days. The highest Se-75 concentrations were found in the visceral mass with lesser amounts in gills, muscle and mantle, in that order.« less