Search Results (13)

In semi-arid regions of Morocco, where the majority of water withdrawals are devoted to irrigation, optimizing irrigation practices in agriculture is a national priority in the face of recurring droughts and growing pressure on groundwater resources. However, the hydrological impacts of different drip-irrigation systems in the soil–plant–atmosphere continuum remain insufficiently understood. We monitored the stable isotope composition (δ²H, δ¹⁸O) across the two agricultural plots in Marrakech (Morocco) with surface drip and subsurface drip irrigation treatments for a complete hydrologic year (June 2022 to June 2023). Weekly to daily samples of rainfall, irrigation water, groundwater, and soil at various depths (5–50 cm) were sampled, and water from branch xylem was extracted using the cryogenic vacuum distillation method. We found that the subsurface irrigation treatment, which delivered water directly to the root zone, maintained narrow isotopic ranges in water of soils beyond 30 cm, as well as in branch xylem and leaf water. By contrast, surface irrigation treatment plots showed pronounced evaporative isotopic enrichment: summer topsoil water δ¹⁸O peaked at −1.1‰ (vs. −8.7‰ in subsurface irrigation treatment), and leaf water reached +13‰ (vs. +8‰ in subsurface). Despite this larger isotopic heterogeneity in surface irrigation site, branch xylem water δ¹⁸O remained within −6 to 2.5‰ across all soil depth, similar to subsurface irrigation treatment, which ranged between −5 and 0‰. This suggests that olive roots accessed soil water uniformly from the upper 50 cm under both irrigation treatments. Seasonal xylem isotopic enrichment in spring and midsummer mirrored shifts towards shallow, evaporatively altered soil water under surface irrigation, but not under the subsurface. The results suggest that subsurface drip irrigation can significantly improve drought resilience and water-use efficiency in the expanding olive sector of the Maghreb, while continuous isotope monitoring serves as a practical approach to enhance sustainable and adaptive water management in water-limited regions. Full article

To understand how phreatophytes correspond to groundwater dynamics in arid regions, it is important to examine the specific water use patterns in different habitats. In this study, we investigated whether and how saltcedar (Tamarix ramosissima Ledeb.) responded in its water use patterns to the changing groundwater table during the growing season in two contrasting habitats (i.e., riparian and dune sites). δ¹⁸O and δ²H values of xylem sap and four potential water sources (i.e., shallow, middle, and deep soil water, and groundwater) were measured to determine the water-use pattern. Comparisons of the water sources in different habitats indicated that the depths of water extraction by saltcedar were shallower in the riparian habitat than in the dune habitat. During the growing season, saltcedar in the diparian habitat consistently extracted soil water from a depth of 30−60 cm (volumetric water content: 18.2 ± 3.5%), which was recharged by groundwater. In contrast, the saltcedar in the dune habitat either extracted soil water from a deeper depth (below 100 cm, volumetric water content: 5.8 ± 1.2%) that was also supposed to be recharged by groundwater, or directly used groundwater. These results suggest that the primary water source for saltcedar was from deeper groundwater during the growing season and did not change with the groundwater fluctuation. Full article

Stable isotopes of water (δ²H and δ¹⁸O) are reliable tracers for the investigation of plant–soil–water interactions in forest ecosystems. However, variations in isotopic compositions may arise due to differences in analytical instruments and water extraction methods. In this study, we conducted three different experiments to identify isotopic differences caused by analytical and methodological variations. First, we analyzed soil water by using the two most commonly applied methods: isotope ratio mass spectrometry (IRMS) and cavity ring-down spectroscopy (CRDS). Second, we compared the isotopes in xylem water extracted from the stems of nine tree species using cryogenic vacuum distillation (CVD) with different heating times. Third, we compared the compositions in xylem water extracted with three different methods: mechanical squeezing using a pressure chamber (PC), an induction module (IM), and CVD. The differences in isotopic composition between IRMS and CRDS were significant but minimal. Soil properties were not significant factors contributing to differences between the two instruments. For the xylem water extraction with CVD, each of the nine tree species required heating for more than three hours. Significant differences were observed in δ²H among the three extraction methods for xylem water. Xylem water extracted by CVD showed more depleted values compared to those obtained by PC and IM. Our results highlight the importance of considering analytical and methodological variations in stable isotope analysis. Full article

This trial was carried out over two years in southern Italy. Two grapevine rootstocks, 110R and SO4, were compared to evaluate their ability to extract water from the soil and the effect on the yield and quality of the Cardinal grapevine table cultivar. Therefore, a new approach to plant water consumption based on sap flow was adopted. The earlier and faster water refilling of the xylem in Cardinal onto 110R (C/110R) appears responsible for the earlier evolution of the phenological phases than Cardinal onto SO4 (C/SO4). The maximum length of the principal shoot was reached in Cardinal/110R compared to the C/SO4, while a higher number of lateral shoots with lower internode changed the canopy architecture and light distribution in the C/SO4. The 110R used more water compared to the SO4. It was possible to quantify the real transpired flux of the plant per day: the sap flow was 12.3 L.plant⁻¹.d⁻¹ and 11.7 L.plant⁻¹.d⁻¹ in C/110R in the first and second year, respectively, while it was 14% lower in the alternative graft combination. The overall lower C/SO4 water status does not compromise the production result, with similar or higher-quality aspects compared to the alternative graft combination C/110R, which can be also attributed to the strong resilience of Cardinal to water deficit. Full article

The installation of solar facilities is increasing rapidly in the Mojave Desert USA, with the largest facility in North America (3227 ha) currently being built 30 km north of Las Vegas, NV. At the state level, Nevada (USA) has developed an energy plan to diversify its energy portfolio by 2030 with green energy representing 50% of the energy produced. Although solar is considered a clean energy, it does require significant amounts of land and as such may have negative consequences at the habitat and ecosystem levels. A multi-year study was conducted to assess the impact a photovoltaic facility in the Mojave Desert had on the growth and physiological response of two native shrubs (Ambrosia dumosa and Larrea tridentata) growing inside and outside the facility. These species were selected because they were the dominant species at the site and are representative of desert scrub communities throughout the Mojave Desert. At the time of construction, native plants and washes were left intact inside the solar facility. The solar panel arrays were separated at either 8 m or 10 m. Plants were selected for monitoring on the basis of location: at the panel drip line, below the panels, or midway between panel rows. Abiotic factors, including PAR, reference evapotranspiration, precipitation, soil water in storage, and infiltration, were monitored bi-monthly. The growth and physiological status of the plants were assessed by monitoring leaf water potential, chlorophyll index, canopy temperatures, non-structural carbohydrates in the roots and stems, leaf tissue ion concentrations, stem elongation, and seed production. Plants at the bottom edges of the panels received more precipitation due to runoff from the panels, which led to increased soil moisture in the long spacing but not the short spacing. The lower soil water in storage in the short spacing was related to greater growth and higher soil water extraction. Although the area under the panels provided shade in the summer and warmer temperatures in the winter, the incoming PAR was reduced by as much as 85%, causing plants growing under the panels to be spindly with lower canopy volume (L. tridentata, p = 0.03) and seed yield (A. dumosa, p = 0.05). Ambrosia plants remained green in color year-round (not going into winter dormancy) inside the facility and had elevated levels of starch in their roots and stems compared with plants growing at the outside control sites (p < 0.001). Larrea growing outside the facility had lower xylem water potentials compared with those inside the facility (p < 0.001), lower chlorophyll index (p < 0.001, Ambrosia as well), and lower stem elongation (p < 0.001), supporting the conclusion that both Larrea and Ambrosia performed better inside the facility. Shifts in δ¹³ C suggested greater water-use efficiency at the locations with the least amount of soil water in storage. Our results support the installation of solar facilities that minimize the impact on native plants and wash connectivity (ecovoltaics), which should translate into a reduced negative impact at the habitat and ecosystem levels. Basedon our results, energy companies that embrace ecovoltaic systems that take an engineering and biological approach should provide acceptable environments for desert fauna. However, corridors (buffers) will need to be maintained between solar facilities, and fences will need to have openings that allow for the continuous flow of animals and resources. Full article

Xanthomonas campestris pv. campestris is the causal agent of black rot in crucifers, a plant disease with significant economic impact. Xanthomonadaceae is a large family of Gram-negative bacteria that cause symptoms by blocking water flow in plants by invading the xylem. To accomplish this, the main mechanism the bacteria use to adapt to environmental changes and colonize tissues is biofilm formation. In recent years, growing interest in natural antimicrobial compounds has led to the study of different phytocomplexes derived from plants. In this work, Moringa oleifera was selected, as its leaves are rich in phenols, essential oils, and vitamins that exert antibacterial activity. X. campestris pv. campestris biofilm, one of its major virulence factors, was studied. Biofilm formation and removal were analyzed on abiotic and biotic surfaces with and without M. oleifera leaf extracts. The data from the analysis show that Moringa oleifera leaf extracts and single phenols were able to inhibit biofilm growth on abiotic surfaces, but the activity of the whole phytocomplex was significantly higher compared to that of individual phenols. The effect of Moringa oleifera extracts on cabbage leaves in vivo was also found to be very important, as scanning electron microscopy showed that treatment with the extracts led to clear unblocking of the xylem, implying many advantages for use in black rot control. Full article

In recent years, the use of wood has gained social interest, leading to a global increase in its demand. Yet, this demand is often covered by the production of woods of low natural durability against biological deterioration. The main biological agents with the potential to attack the structural integrity of wood are wood-decay fungi, saproxylic beetles, termites, and marine molluscs and crustaceans. In most circumstances, fungi are the main wood-deteriorating agents. To attack the cell wall, wood-decay fungi combine a complex enzymatic mechanism with non-enzymatic mechanisms based on low-molecular-weight compounds. In some cases, the larvae of saproxylic beetles can also digest cell wood components, causing serious deterioration to wooden structures. The impact of subterranean termites in Europe is concentrated in the Southern countries, causing important economic losses. However, alien invasive species of voracious subterranean termites are expanding their presence in Europe. Wooden elements in permanent contact with marine water can be readily deteriorated by mollusc and crustacean borers, for which current preservatives lack efficacy. The natural durability of wood is defined as the inherent resistance of wood to catastrophic action by wood-destroying organisms. Besides exposure to the climate, product design and use conditions, the natural durability of wood is key to the prediction of the service life of wooden products, which can be shortened due to the impact of global change. The major wood properties involved in natural durability are related to the composition of lignin in the cell wall, the anatomy of the xylem, nutrient availability, the amount and composition of heartwood extractives, and the presence of moisture-regulating components since wood moisture content influences the establishment of wood-degrading organisms. Full article

pH of xylem sap (pHx) was determined in three trees (Malus domestica (apple tree), Picea abies and Pinus cembra) in response to seasonal changes. Conifer trees from lowland (600 m) were compared to trees growing at the alpine timberline (1950 m a.s.l.). Xylem sap was extracted with a Scholander pressure bomb and pHx was measured with a pH microsensor. In all species, pHx changed markedly with season. In spring, pHx was acidic; during winter, the pHx was more alkaline. In apple trees, the pHx did not show a significant correlation with temperature but was rather affected by developmental stage. During flushing in spring, xylem sap acidification took place concomitant to the developmental stage “tight cluster”, when foliar development enables a significant transpiration and a consequent movement of water in the xylem. The xylem sap of the two studied conifers showed a significantly larger seasonal alkalinisation (+2.1) than found in apple trees (+1.2) and was significantly more pronounced at the timberline. Xylem sap acidification took place before bud break. pHx had a significant negative correlation with soil temperatures and corresponded to already reported pHx of angiosperms. Overall, pHx appears to be a sensitive stress marker and indicator of activity status in tree xylem. Full article

The increase in the use of herbal medicines has led to the implementation of more stern regulations in terms of quality variation and standardization. As medicinal plants are prone to quality variation acquired due to differences in geographical origin, collection, storage, and processing, it is essential to ensure the quality, efficacy, and biological activity of medicinal plants. This study aims to standardize the widely used fruit, i.e., Prunus domestica Linn., using evaluation techniques (microscopic, macroscopic, and physicochemical analyses), advanced instrumental (HPLC, HPTLC, and GC–MS for phytochemical, aflatoxins, pesticides, and heavy metals), biological, and toxicological techniques (microbial load and antioxidant activities). The results revealed a 6–8 cm fruit with smooth surface, delicious odor, and acidic taste (macroscopy), thin-walled epidermis devoid of cuticle and any kind of excrescences with the existence of xylem and phloem (microscopy), LOD (15.46 ± 2.24%), moisture content (13.27 ± 1.75%), the high extractive value of 24.71 ± 4.94% in water:methanol (1:1; v/v) and with ash values in the allowed limits (physicochemical properties), and the presence of numerous phytochemical classes such as alkaloids, flavonoids, carbohydrates, glycosides, saponins, etc. (phytochemical screening). Furthermore, no heavy metals (Pb, Hg, Cd, Ar), pesticides, ad microbial limits were detected beyond the permissible limits specified, as determined with AAS, GC–MS analysis, and microbial tests. The HPTLC was developed to characterize a complete phytochemical behavior for the components present in P. domestica fruit extract. The parameters utilized with the method used and the results observed for the prunus herein may render this method an effective tool for quality evaluation, standardization, and quality control of P. domestica fruit in research, industries, and market available food products of prunus. Full article

Rootstocks with internal hydraulic limitations can effectively restrict scion growth, influence crop load, and improve yield efficiency in apple production. The characteristics of xylem vessels in rootstock and scion play essential roles in determining the hydraulic properties of the grafted tree; however, much remains unknown for commonly available rootstocks. In this study, we extracted secondary xylem using an increment borer from living Honeycrisp scion (Malus domestica cv. ‘Honeycrisp’), and two Malling rootstocks, one Budagovsky rootstock, and five Geneva rootstocks. The size and density of xylem vessels in rootstocks and scions were analyzed in relation to trunk cross-section area (TCSA), tree–water relations, and fruit dry matter of 2019, as well as with cumulative yield efficiency during 2014–2019. Honeycrisp scion exceeded most of the rootstocks in cross-section size and density of vessel elements. Scion vigor and cumulative yield were positively correlated with TCSA and total vessel cross-section area (VCSA) of the rootstock, with G.202 being the highest, and B.9 being the lowest with small xylem vessels in high density. In the rootstocks with the highest cumulative yield efficiency, the rootstock/scion ratio in VCSA was equal to or slightly higher than 1. Lower scion vessel density in G.214 was associated with lower fruit dry matter weight, more restricted water relations, and worsened leaf chlorosis. G.935 with larger rootstock vessels led to both high yield and high yield efficiency. This suggested that higher scion vessel density and larger rootstock vessel size can be advantageous characteristics for early-stage evaluation. Full article

Vascular tissues essentially regulate water, nutrient, photo-assimilate, and phytohormone logistics throughout the plant body. Boron (B) is crucial for the development of the vascular tissue in many dicotyledonous plant taxa and B deficiency particularly affects the integrity of phloem and xylem vessels, and, therefore, functionality of long-distance transport. We hypothesize that changes in the plants’ B nutritional status evoke differential responses of the vasculature and the mesophyll. However, direct analyses of the vasculature in response to B deficiency are lacking, due to the experimental inaccessibility of this tissue. Here, we generated biochemical and physiological understanding of B deficiency response reactions in common plantain (Plantago major L.), from which pure and intact vascular bundles can be extracted. Low soil B concentrations affected quantitative distribution patterns of various phytohormones, sugars and macro-, and micronutrients in a tissue-specific manner. Vascular sucrose levels dropped, and sucrose loading into the phloem was reduced under low B supply. Phytohormones responded selectively to B deprivation. While concentrations of abscisic acid and salicylic acid decreased at low B supply, cytokinins and brassinosteroids increased in the vasculature and the mesophyll, respectively. Our results highlight the biological necessity to analyze nutrient deficiency responses in a tissue- rather organ-specific manner. Full article

Drought and topographic position are the most important factors influencing tree growth and survival in semiarid sandy regions of Northeast China. However, little is known about how trees respond to drought in combination with topographic position by modifying the depth of soil water extraction. Therefore, we identified water sources for 33-year-old Mongolian pine (Pinus sylvestris L. var. mongolica Litv.) trees growing at the top and bottom of sand dunes by comparing stable isotopes δ²H and δ¹⁸O in twig xylem water, soil water at various depths and groundwater during dry and wet periods. Needle carbon isotope composition (δ¹³C) was simultaneously measured to assess water use efficiency. Results showed that when soil moisture was low during the dry period, trees at the top used 40–300 cm soil water while trees at the bottom utilized both 40–300 cm soil water and possibly groundwater. Nevertheless, when soil moisture at 0–100 cm depth was higher during the wet period, it was the dominant water sources for trees at both the top and bottom. Moreover, needle δ¹³C in the dry period were significantly higher than those in the wet period. These findings suggested that trees at both the top and bottom adjust water uptake towards deeper water sources and improve their water use efficiency under drought condition. Additionally, during the dry period, trees at the top used shallower water sources compared with trees at the bottom, in combination with significantly higher needle δ¹³C, indicating that trees at the bottom applied a relatively more prodigal use of water by taking up deeper water (possibly groundwater) during drought conditions. Therefore, Mongolian pine trees at the top were more susceptible to suffer dieback under extreme dry years because of shallower soil water uptake and increased water restrictions. Nevertheless, a sharp decline in the groundwater level under extreme dry years had a strong negative impact on the growth and survival of Mongolian pine trees at the bottom due to their utilization of deeper water sources (possibly groundwater). Full article

In semi-arid environmental settings with sparse canopy covers, obtaining remotely sensed information on soil and vegetative growth characteristics at finer spatial and temporal scales than most satellite platforms is crucial for validating and interpreting satellite data sets. In this study, we used a ground-based NDVI system to provide continuous time series analysis of individual shrub species and soil surface characteristics in two different semi-arid environmental settings located in the Great Basin (NV, USA). The NDVI system was a dual channel SKR-1800 radiometer that simultaneously measured incident solar radiation and upward reflectance in two broadband red and near-infrared channels comparable to Landsat-5 TM band 3 and band 4, respectively. The two study sites identified as Spring Valley 1 site (SV1) and Snake Valley 1 site (SNK1) were chosen for having different species composition, soil texture and percent canopy cover. NDVI time-series of greasewood (Sarcobatus vermiculatus) from the SV1 site allowed for clear distinction between the main phenological stages of the entire growing season during the period from January to November, 2007. NDVI time series values were significantly different between sagebrush (Artemisia tridentata) and rabbitbrush (Chrysothamnus viscidiflorus) at SV1 as well as between the two bare soil types at the two sites. Greasewood NDVI from the SNK1 site produced significant correlations with chlorophyll index (r = 0.97), leaf area index (r = 0.98) and leaf xylem water potential (r = 0.93). Whereas greasewood NDVI from the SV1 site produced lower correlations (r = 0.89, r = 0.73), or non significant correlations (r = 0.32) with the same parameters, respectively. Total percent cover was estimated at 17.5% for SV1 and at 63% for SNK1. Results from this study indicated the potential capabilities of using this ground-based NDVI system to extract spatial and temporal details of soil and vegetation optical properties not possible with satellite derived NDVI. Full article