Growing at the arid edge: Anatomical variations in leaves are more extensive than in stems of five Mediterranean species across contrasting moisture regimes.

Premise: Increasing aridity in the Mediterranean region affects ecosystems and plant life. Various anatomical changes in plants help them cope with dry conditions. This study focused on anatomical differences in leaves and xylem of five co-occurring Mediterranean plant species namely Quercus calliprinos, Pistacia palaestina, Pistacia lentiscus, Rhamnus lycioides, and Phillyrea latifolia in wet and dry sites.

Leaf membrane leakage and xylem hydraulic failure define the point of no return in drought-induced tree mortality in Cupressus sempervirens.

Measurements of resistance to embolism suggest that Cupressus sempervirens has a stem xylem that resists embolism at very negative water potentials, with 50% embolism (P) at water potentials of approximately -10 MPa. However, field observations in a semi-arid region suggest tree mortality occurs before 10% embolism. To explore the interplay between embolism and plant mortality, we conducted a controlled drought experiment involving two types of CS seedlings: a local seed source (S-type) and a drought-resistant clone propagated from a semi-arid forest (C-type).

Rapid leaf xylem acclimation diminishes the chances of embolism in grapevines.

Under most conditions tight stomatal regulation in grapevines (Vitis vinifera) avoids xylem embolism. The current study evaluated grapevine responses to challenging scenarios that might lead to leaf embolism and consequential leaf damage. We hypothesized that embolism would occur if the vines experienced low xylem water potential (Ψx) shortly after bud break or later in the season under a combination of extreme drought and heat.

Assessment of the Nutritional and Medicinal Potential of Tubers from Hairy Stork's-Bill ( L 'Hér), a Wild Plant Species Inhabiting Arid Southeast Mediterranean Regions.

Emerging needs for diversifying human diet and to explore novel therapeutic procedures have led to increasing attempts to retrieve traditional nourishments and recruit beneficial wild plant species. Species of the genus (Geraniaceae) harbor medicinal indications and substances known from folklore and scientific research. Hairy stork's bill ( L'Hér), is a small hemicryptophyte that inhabits arid southeast Mediterranean regions.

Root Development of Bell Pepper ( L.) as Affected by Water Salinity and Sink Strength.

Fruits are the dominant sinks for assimilates. At optimal conditions, assimilates supply can meet the demand of fruits and those of the vegetative organs; however, extreme circumstances such as strong sink strength or an environmental stress may disturb this fine balance. While most studies focus on aboveground parameters, information regarding root growth dynamics under variable sink strength are scarce.

Differential drought resistance strategies of co-existing woodland species enduring the long rainless Eastern Mediterranean summer.

In anticipation of a drier climate and to project future changes in forest dynamics, it is imperative to understand species-specific differences in drought resistance. The objectives of this study were to form a comprehensive understanding of the drought resistance strategies adopted by Eastern Mediterranean woodland species, and to elaborate specific ecophysiological traits that can explain the observed variation in survival among these species. We examined leaf water potential (𝛹), gas exchange and stem hydraulics during 2-3 years in mature individuals of the key woody species Phillyrea latifolia L.

Tree growth and water-use in hyper-arid Acacia occurs during the hottest and driest season.

Drought-induced tree mortality has been recently increasing and is expected to increase further under warming climate. Conversely, tree species that survive under arid conditions might provide vital information on successful drought resistance strategies. Although Acacia (Vachellia) species dominate many of the globe's deserts, little is known about their growth dynamics and water-use in situ.

Reductions in root hydraulic conductivity in response to clay soil and treated waste water are related to PIPs down-regulation in Citrus.

Citrus hydraulic physiology and PIP transcript levels were characterized in heavy (clay) and light (sandy loam) soils with and without treated waste water (TWW) irrigation after a summer irrigation season and at the end of a winter rainy season recovery period. Consistent reductions in clay soils compared to sandy loam were found for fresh water (FW) and TWW irrigation, respectively, in root water uptake, as well as in hydraulic conductivity of whole plant (K plant), stem (K stem) and root (K root). Transcript levels of most PIPs down-regulated following TWW irrigation in both soils, but relative gene expression of three PIPs was significantly higher in summer for sandy soil and FW than for clay soil and TWW; their mRNA levels was significantly correlated to K root.

Indirect Evidence for Genetic Differentiation in Vulnerability to Embolism in Pinus halepensis.

Climate change is increasing mean temperatures and in the eastern Mediterranean is expected to decrease annual precipitation. The resulting increase in aridity may be too rapid for adaptation of tree species unless their gene pool already possesses variation in drought resistance. Vulnerability to embolism, estimated by the pressure inducing 50% loss of xylem hydraulic conductivity (P 50), is strongly associated with drought stress resistance in trees.

Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil.

Lower leaf gas-exchange and higher photorespiration of treated wastewater irrigated Citrus trees is modulated by soil type and climate.

Water quality, soil and climate can interact to limit photosynthesis and to increase photooxidative damage in sensitive plants. This research compared diffusive and non-diffusive limitations to photosynthesis as well as photorespiration of leaves of grapefruit trees in heavy clay and sandy soils having a previous history of treated wastewater (TWW) irrigation for >10 years, with different water qualities [fresh water (FW) vs TWW and sodium amended treated wastewater (TWW + Na)] in two arid climates (summer vs winter) and in orchard and lysimeter experiments. TWW irrigation increased salts (Na(+) and Cl(-) ), membrane leakage, proline and soluble sugar content, and decreased osmotic potentials in leaves of all experiments.

Simulating nectarine tree transpiration and dynamic water storage from responses of leaf conductance to light and sap flow to stem water potential and vapor pressure deficit.

For isohydric trees mid-day water uptake is stable and depends on soil water status, reflected in pre-dawn leaf water potential (Ψpd) and mid-day stem water potential (Ψmd), tree hydraulic conductance and a more-or-less constant leaf water potential (Ψl) for much of the day, maintained by the stomata. Stabilization of Ψl can be represented by a linear relationship between canopy resistance (Rc) and vapor pressure deficit (D), and the slope (BD) is proportional to the steady-state water uptake. By analyzing sap flow (SF), meteorological and Ψmd measurements during a series of wetting and drying (D/W) cycles in a nectarine orchard, we found that for the range of Ψmd relevant for irrigated orchards the slope of the relationship of Rc to D, BD is a linear function of Ψmd.

Inactive xylem can explain differences in calibration factors for thermal dissipation probe sap flow measurements.

Thermal dissipation probes (TDPs) were calibrated in three diffuse porous fruit trees and one ornamental species in the field by comparison with heat pulse probes (nectarine and persimmon), in a greenhouse on lysimeters (apple and persimmon) and in the laboratory by pushing water through cut branches (apple, Peltophorum and nectarine). Two operational methods were used: continuous (constant thermal dissipation, CTD) and discontinuous, or transient, heating (transient thermal dissipation, TTD). Correction for the radial distribution of sap flux density was with an analytical function derived from a linear decrease in flux density with depth, as measured with a multi-depth 'Tmax' heat pulse system.

The importance of iron supply during repetitive harvesting of Aster tripolium.

Aster tripolium L. is a salt marsh halophyte that has recently gained interest as a cash crop vegetable. Leaf yield and quality were investigated in plants grown with salinity in experiments with Perlite in pots and in plots on dune sand.

Differential ecophysiological response of a major Mediterranean pine species across a climatic gradient.

The rate of migration and in situ genetic variation in forest trees may not be sufficient to compete with the current rapid rate of climate change. Ecophysiological adjustments of key traits, however, could complement these processes and allow sustained survival and growth across a wide range of climatic conditions. This was tested in Pinus halepensis Miller by examining seven physiological and phenological parameters in five provenances growing in three common garden plots along a climatic transect from meso-Mediterranean (MM) to thermo-Mediterranean (TM) and semi-arid (SA) climates.

Estimating sap flux densities in date palm trees using the heat dissipation method and weighing lysimeters.

In a world of diminishing water reservoirs and a rising demand for food, the practice and development of water stress indicators and sensors are in rapid progress. The heat dissipation method, originally established by Granier, is herein applied and modified to enable sap flow measurements in date palm trees in the southern Arava desert of Israel. A long and tough sensor was constructed to withstand insertion into the date palm's hard exterior stem.

Hydraulic adjustments underlying drought resistance of Pinus halepensis.

Drought-induced tree mortality has increased over the last decades in forests around the globe. Our objective was to investigate under controlled conditions the hydraulic adjustments underlying the observed ability of Pinus halepensis to survive seasonal drought under semi-arid conditions. One hundred 18-month saplings were exposed in the greenhouse to 10 different drought treatments, simulating combinations of intensities (fraction of water supply relative to control) and durations (period with no water supply) for 30 weeks.

LeFRK2 is required for phloem and xylem differentiation and the transport of both sugar and water.

It has been suggested that LeFRK2, the major fructose-phosphorylating enzyme in tomato plants, may be required for stem xylem development. Yet, we do not know if this enzyme affects the development of individual vessels, whether it affects water conductance, or whether it affects phloem development and sugar transport. Here, we show that suppression of LeFRK2 results in a significant reduction in the size of vascular cells and slows fiber maturation.

Fertilization and blending alternatives for irrigation with desalinated water.

In arid-zone agriculture where available irrigation water is saline, desalination is becoming an attractive method for increasing yields and reducing negative environmental consequences. However, irrigation with desalinated water can be problematic if essential nutrients, including Ca, Mg, and S, removed during reverse osmosis, are not reintroduced. We evaluated two strategies for supplying these nutrients - direct fertilization and blending of desalinated with saline groundwater -experimentally in a greenhouse and in a model for a case study regarding pepper (Capsicum annuum L.

Isotope effects in the evaporation of water: a status report of the Craig-Gordon model.

The Craig-Gordon model (C-G model) [H. Craig, L.I.

Hydraulic resistance components of mature apple trees on rootstocks of different vigours.

Dwarfing of fruit trees is often achieved through the use of dwarfing rootstocks. Dwarf trees are characterized by sustained reductions in vegetative growth during the lifetime of the tree. The dwarfing mechanism is not well understood, but it has been hypothesized that hydraulic properties of the rootstock and the graft union are involved.

Low air humidity increases leaf-specific hydraulic conductance of Arabidopsis thaliana (L.) Heynh (Brassicaceae).

The typical isohydric plant response to low relative humidity involves stomatal closure, followed by long-term responses like adjustment of shoot-to-root ratios. Little information is available on the early responses of the root system to exposure of shoots to low humidity, nor is it clear to what extent responses of Arabidopsis thaliana conform to the isohydric model. In this study, A.

[Transpiration of banana plant measured by Granier method].

Banana plant is the highest herbaceous plant in the world. Because of the height, it's inconvenient to measure the transpiration (Tr) of banana plant in direct way. Some indirect methods such as soil water balance method or FAO 56 Crop Coefficient are commonly used to measure or calculate the Tr, but the obtained results are easily influenced by soil texture and water content, climatic condition, and agronomic practice.

Air method measurements of apple vessel length distributions with improved apparatus and theory.

Studies showing that rootstock dwarfing potential is related to plant hydraulic conductance led to the hypothesis that xylem properties are also related. Vessel length distribution and other properties of apple wood from a series of varieties were measured using the 'air method' in order to test this hypothesis. Apparatus was built to measure and monitor conductivity to air of fresh wood segments of different lengths.