Nutrient Solution Research Articles

Growth Dynamics and Nutrient Removal from Biogas Slurry Using Water Hyacinth

Aquatic macrophytes, notably the invasive water hyacinth, exhibit proficiency in nutrient removal from polluted water bodies, rendering them appealing for water remediation applications. This study investigates the potential of water hyacinth in phytoremediation, focusing on the effect of using nutrient-rich biogas slurry mixed with water in varying concentrations, i.e., 16.6, 33, 66.6, 100, and 133 mg/L for the investigation. The physiochemical properties of the liquid biogas slurry were evaluated before and after treatment with water hyacinth over eight weeks, with continuous monitoring of nutrient reduction rates. Results showcased substantial average reductions of nitrogen, phosphorus, and potassium, with a relative growth rate of 5.55%. The treatment also decreased pH, total dissolved solids, hardness, and chemical oxygen demand. The theoretical BMP of water hyacinth was determined using Buswell’s equation. Water hyacinth grown in the concentration of the biogas slurry exhibited the highest methane yield at 199 mL CH4/gm VS, along with the highest relative growth rate. This study used experimental data to create a mathematical model that describes how the relative growth of water hyacinth depends on the number of days and biogas slurry concentration (C). The model’s quality and effectiveness were evaluated using the goodness of fit (R2) and observable approaches. The polynomial model, referred to as Poly model 1, 2, is the best fit for describing the relationship between the growth percentage of water hyacinth, days, and nutrient solution concentration. In this model, C has a polynomial degree of one (normalized mean of 69.84 ± 43.54), while D has a degree of two (normalized mean of 30 ± 21.65).

Arbuscular mycorrhizal symbiosis allows to overcome phosphorus deficiency in soilless culture of Lactuca sativa: A phenotypic and transcriptomic analysis

Lettuce (Lactuca sativa L.) is an annual autogamous diploid plant belonging to Asteraceae and is among the top ten most profitable crops worldwide due to its nutritional value. Nevertheless, lettuce is an intensive crop with high input demand, especially fertilisers, both in soil-bound and soilless culture, with negative impact on the environment and production costs. In this context, arbuscular mycorrhizal symbioses could help to reduce the impact of fertilisers, improving plant nutrition, particularly regarding phosphorus, and contributing to growing healthier plants for human consumption. In our work, we compared lettuce plants (cv. Salinas) grown in soilless culture with optimal phosphorus concentration in the nutrient solution, with sub-optimal phosphorus nutrition and with plants grown with sub-optimal phosphorus concentration and inoculated with the fungus Funneliformis mosseae before transplanting.Higher levels of primary and secondary metabolites along with increased biomass were observed for mycorrhizal plants compared to lettuces grown with optimal and sub-optimal concentrations of phosphate. Gene expression profile was analysed in both roots and leaves, and transcriptomic values were associated with growth and biochemical parameters. Three-thousand and fifty-seven genes were differentially regulated by mycorrhizal symbiosis and 2,606 genes by optimal phosphate nutrition.Different genes related to photosynthesis, solute transport, metabolism of phytohormones, redox homeostasis, and transcriptional regulation resulted differentially regulated between culture conditions. Mycorrhizal plants also boosted the activation of genes involved in phenylpropanoids and carotenoids metabolism. In conclusion, growth, biochemical, and transcriptomic data show that symbiotic plants benefit both plant growth and leaf content of health promoting phytochemicals through genetic pathways that largely differed those activated in plants grown with optimal phosphorus supply.

Exploring the impact of copper excess on soybean genotypes: insights from root morphology and plant ionome

ABSTRACT Global growing demand for food production and commodity increased prices stimulate soybean cultivation in Brazil even in areas with high soil copper (Cu) concentration. This can promote root injuries and nutritional imbalances, reducing the growth and yield of Cu-sensitive soybean genotypes. The study aimed to investigate soybean genotypes potentially adapted to Cu-contaminated zones. Four soybean genotypes (NA 5909, DM 5958, M 6410, and DM 6563) and three Cu concentrations in the nutrient solution (0.03, 1.2, and 2.4 mg L−1) were evaluated. Root and shoot dry mass, root morphology, and inorganic composition of plant tissues were determined. The shoot and root dry mass was affected by Cu excess, especially in DM 5958 genotype, which decreased by up to 46%. Otherwise, the DM 6563 genotype stood out for growing satisfactorily under Cu excess and keeping significant amounts of Cu in the belowground biomass. The Cu excess promoted root thickening and shortening, and altered the ionome of soybean plants by decreasing the concentrations of K, Ca, Mg, and Fe, yet increasing P and N, which caused decreased plant growth. Finally, our outcomes indicated DM 6563 genotype exhibits promising traits for Cu phytostabilization, making it preferable for cultivation in Cu-contaminated areas.

Foliar spraying of zinc oxide nanoparticles improves water transport and nitrogen metabolism in tomato (Solanum lycopersicum L.) seedlings mitigating the negative impacts of cadmium.

The use of bio-nanotechnology in agriculture-such as the biological applications of metal oxide nanoparticles (NPs)-greatly improves crop yield and quality under different abiotic stress factors including soil metal contamination. Here, we explore the effectiveness of zinc oxide (ZnO)-NPs (0, 50 mg/L) foliar spraying to ameliorate the detrimental effects of cadmium (Cd) on the water transport and nitrogen metabolism in tomato (Solanum lycopersicum Mill. cv. Chibli F1) plants grown on a Cd-supplied (CdCl2; 0, 10, 40 μM) Hoagland nutrient solution. The results depicted that the individually studied factors (ZnO-NPs and Cd) had a significant impact on all the physiological parameters analyzed. Independently to the Cd concentration, ZnO-NPs-sprayed plants showed significantly higher dry weight (DW) in both leaves and roots compared to the non-sprayed ones, which was in consonance with higher and lower levels of Zn2+ and Cd2+ ions, respectively, in these organs. Interestingly, ZnO-NPs spraying improved water status in all Cd-treated plants as evidenced by the increase in root hydraulic conductance (L0), apoplastic water pathway percentage, and leaf and root relative water content (RWC), compared to the non-sprayed plants. This improved water balance was associated with a significant accumulation of osmoprotectant osmolytes, such as proline and soluble sugars in the plant organs, reducing electrolyte leakage (EL), and osmotic potential (ψπ). Also, ZnO-NPs spraying significantly improved NO3- and NH4+ assimilation in the leaf and root tissues of all Cd-treated plants, leading to a reduction in NH4+ toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils.

From Salinity to Nutrient-Rich Vegetables: Strategies for Quality Enhancement in Protected Cultivation

Salinity, a significant abiotic stressor, imperils vegetable growth, yield, and quality. Moreover, elevated salinity levels, driven by climate change, jeopardize vegetable nutritional quality. In particular, protected cultivation systems, responsible for 60% of the global vegetable industry’s economic value, encounter notable challenges in managing salinity due to water runoff and drainage mechanism limitations. Therefore, it is crucial to understand the intricate mechanisms that control salinity and use this knowledge to improve plant tolerance to these conditions. In this study, we explore strategies to effectively mitigate the detrimental impacts of salinity on vegetable crops cultivated within protected environments. Additionally, we investigate the benefits of controlled moderate salinity adjustments in protected cultivation to enhance their nutritional content. Moderate salinity or nutrient solution increases typically raise total soluble solids, sugar, vitamin C, phenols, lycopene, and antioxidants in most fruit vegetables. Though generally applicable to leafy vegetables, exceptions like lettuce and wild rocket may show inconsistencies, potentially reducing some quality traits. Interdisciplinary approaches are essential to developing sustainable solutions for managing salinity in protected cultivation systems, thereby ensuring the resilience of vegetable production in the face of changing environmental conditions. Given the impracticality of desalinating all areas, future research should also investigate synergies between moderate salinity stress, cultivars used, and environmental factors from physiological and molecular perspectives to enhance vegetable nutritional quality.

Low nitrate under waterlogging triggers exodermal suberization to form a barrier to radial oxygen loss in rice roots.

To acclimate to hypoxic waterlogged conditions, the roots of wetland plants form a radial oxygen loss (ROL) barrier that can promote oxygen diffusion to the root tips. We hypothesized that the low-nitrate concentrations that occur after molecular oxygen is consumed in waterlogged soils are an environmental trigger for ROL barrier formation in rice (Oryza sativa). We previously identified 128 tissue-specific up/downregulated genes during rice ROL barrier formation. The RiceXPro database showed that many of these genes were differentially regulated in response to nitrogen deficiency. Therefore, we assessed changes in the concentrations of ionic species of nitrogen under stagnant conditions, i.e. in a nutrient solution that mimics waterlogged soil conditions, and examined the effects of an increase or decrease of nitrate in the nutrient solution on ROL barrier formation and exodermal suberization. Preventing nitrate deficiency in the stagnant nutrient solution suppressed the formation of an ROL barrier. Conversely, a decrease in nitrate strongly induced ROL barrier formation, even under aerated conditions. In parallel with ROL barrier formation, suberin lamellae formed at the exodermis. Nitrate deficiency also promoted aerenchyma formation and the enlargement of root diameters. These findings suggest that the severe decline of nitrates under waterlogged conditions is an environmental cue for exodermal suberization to form an ROL barrier in rice roots.

Pengaplikasian Panel Surya dan Automatic Transfer Switch (ATS) untuk Menggerakkan Pompa Tanaman Hidroponik sebagai Sumber Energi Terbarukan

Solar panels are renewable energy which is very useful for agricultural needs to meet electricity needs, one of which is its application in agriculture, namely as a pump driver for hydroponic plants. Hydroponics is farming with an emphasis on meeting the nutritional needs of plants using water as a medium with a nutrient solution as fertilizer. In the hydroponic system the pump must be on continuously, for this reason the Automatic Transfer Switch (ATS) tool is used to substitute the electrical energy of the State Electricity Company (PLN) with the electrical energy of solar panels in the event of a power outage from the State Electricity Company (PLN) which aims to drain nutrient water. This research aims to apply solar panels to a hydroponic plant system and apply the Automatic Transfer Switch (ATS) tool as a substitute for the State Electric Company's (PLN) electrical energy and solar panels. This research was carried out on Jalan Polonia no.11 fresh water east, North Padang District, Padang City, West Sumatra in January – March 2024, with the initial stages (1) preparation, (2) solar panel assembly, (3) analysis of test results , (4) preparation of reports. The results of this research can determine the power output required by solar panels as a renewable energy source as well as the application of the Automatic Transfer Switch (ATS) in hydroponic plant cultivation.

Plant Biostimulants Enhance Tomato Resilience to Salinity Stress: Insights from Two Greek Landraces

Salinity, one of the major abiotic stresses in plants, significantly hampers germination, photosynthesis, biomass production, nutrient balance, and yield of staple crops. To mitigate the impact of such stress without compromising yield and quality, sustainable agronomic practices are required. Among these practices, seaweed extracts (SWEs) and microbial biostimulants (PGRBs) have emerged as important categories of plant biostimulants (PBs). This research aimed at elucidating the effects on growth, yield, quality, and nutrient status of two Greek tomato landraces (‘Tomataki’ and ‘Thessaloniki’) following treatments with the Ascophyllum nodosum seaweed extract ‘Algastar’ and the PGPB ‘Nitrostim’ formulation. Plants were subjected to bi-weekly applications of biostimulants and supplied with two nutrient solutions: 0.5 mM (control) and 30 mM NaCl. The results revealed that the different mode(s) of action of the two PBs impacted the tolerance of the different landraces, since ‘Tomataki’ was benefited only from the SWE application while ‘Thessaloniki’ showed significant increase in fruit numbers and average fruit weight with the application of both PBs at 0.5 and 30 mM NaCl in the root zone. In conclusion, the stress induced by salinity can be mitigated by increasing tomato tolerance through the application of PBs, a sustainable tool for productivity enhancement, which aligns well with the strategy of the European Green Deal.

Engineering a far-red fluorescent probe for rapid detection of Hg(II) ions in both cells and zebrafish

Abnormal accumulation of mercury ions (Hg2+) in organisms can lead to severe central nervous system and other diseases. Therefore, the monitoring and detection of Hg2+ are of great significance for human health and environmental safety. Herein, we designed and synthesized a novel far-red to NIR emission fluorescent probe (Rho-Hg) based on rhodamine derivative as the fluorophore and thiospirolactone as the recognition site for turn-on detecting of Hg2+ in living cells and zebrafish. The probe Rho-Hg displayed superior sensitivity (detection limit = 17.5 nM), rapid response (<1 min), colorimetric change, high selectivity, and moderate pH stability. Leveraging this probe, we realized the real-time monitoring of Hg2+ in real samples, living cells and zebrafish. By fostering zebrafish embryos and larvae in Hg2+-containing nutrient solution, we noticed that Hg2+ was ingested into the zebrafish liver when zebrafish were grown up to 3 days old, and thus we successfully monitored the accumulation and changes of Hg2+ during zebrafish growth and development. Thus, the probe Rho-Hg could be a powerful tool for sensitive and real-time monitoring of Hg2+ in living systems.

Microbial impact on basalt‐water‐hydrogen system: Insights into wettability, capillary pressure, and interfacial tension for subsurface hydrogen storage

AbstractHydrogen (H2) fuel is assessed to be a major component of sustainable energy systems in the net‐zero world. However, hydrogen storage is challenging and requires safe and environmentally friendly solutions like H2 geo‐sequestration. This study evaluates the effects of sulphate‐reducing bacteria (SRB) on H2 geological storage potential in the basalt rock. Fourier‐transform infrared spectroscopy (FTIR) findings show the presence of significant components, that is, O‐Si‐O and organic functional groups, that is, aromatics, amine salts, alkane, and cyclohexane in the basalt rock immersed in the nutrient solution without SRB. However, we found that C‐H stretching modes of organics with peaks at 1,465 cm−1 were observed. Consequently, amine salt (N‐H) (850–750 cm−1), solvent impurities (C‐H), and alkane spectrums are components of nutrient solutions and can be results of metabolic microbial activity that can influence on the surface of the basalt rock. Hence, these changes indicate the presence of microbial activity which might affect the surface chemistry of the rock leading to wettability alteration. We observed that the contact angle (θ) of brine‐H2 on the rock surface slightly changed from 500 to 4,000 psi pressure after the effect of bacteria at 50 °C. The wettability changed the surface of the rock from strong water‐wet to weak or intermediate water‐wet condition (i.e., θ &lt; 75°) at 4,000 psi and temperatures 25 and 50 °C after the bacteria effect. The affiliation of brine water reduces on the rock surface with increasing temperatures and pressures, even without microbial influence. Additionally, we investigated interfacial tension and capillary pressure on SRB bacteria treated basalt which is not yet reported in the published work. Interfacial tension (IFT) and Pc of H2 were reduced by 19% and 65%, respectively at 50 °C and 4,000 psi after the bacteria effect. Hence, the above findings could help to answer the key factors of the reservoir rock including wettability, capillary pressure, and interfacial tension to plan a field‐scale H2 geo‐sequestration strategy under the influence of biotic life. © 2024 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Antagonistic K/Mg ratios: is foliar application of MgSO4 a superior alternative to root resupply?

Abstract Backround and aims The main cause of magnesium (Mg) deficiency is its competition with potassium (K). Maize, as the world’s most widely grown crop, has a high risk of interplay with poorly balanced soils. Since foliar fertilization is applied when availability and distribution of nutrients is limited, this study aimed to determine whether Mg foliar application (FA) is to be favored over root resupply (RS) under such conditions. Methods Plants of Zea mays L. were grown hydroponically with low and sufficient Mg supply under adequate to excess [K]. These ratios were combined with FA or RS of Mg, and plants were analyzed for Mg uptake, translocation and distribution. The primary physiological functions of Mg were quantified by chlorophyll content, photosynthetic rate and starch accumulation. Results Maize showed a restriction in the uptake antagonism of Mg by K, synergism in translocation, but no effect at distribution. Whilst tissue [Mg] remained unaffected by K, the increased K/Mg ratio impaired the physiological functions of Mg. The FA significantly reduced this K/Mg ratio, but neither the decline in chlorophyll levels and photosynthesis nor starch accumulation was reduced any faster or more markedly than by RS via nutrient solution (NS). Conclusions Foliar Mg application is an effective alternative under high K/Mg ratios, but due to the restricted antagonism and the unknown suppressive mechanism of K on the physiological functions of Mg it is not superior to a RS via NS. Under field conditions when compared to soil fertilization, however, it may offer a decisive advantage.

Quantifying Nitrogen Uptake Rates of Maize Roots Using Stable Isotopes.

Nitrogen is an essential element for plant growth and development; however, application of nitrogen (N)-based fertilizers comes with a high environmental cost. This includes the energy required for production, volatilization from fields, and runoff or leaching to waterways triggering algal blooms. As such, a key goal in plant breeding programs is to develop varieties that maintain yield while requiring less fertilization. Central to this goal is understanding how roots take up nitrogen and finding traits that represent improvements in the net uptake. Maize, one of the most widely produced crops in the world, has seminal, crown, and brace root types, each under independent developmental control. Recent evidence suggests that these independent developmental patterns may result in different nutrient uptake characteristics. As such, understanding the uptake dynamics of each root type under different environmental conditions is an essential aspect for the selection of new maize varieties. A key method for tracking nitrogen uptake is the use of the 15N stable isotope, which is naturally less abundant than the main 14N isotope. This method involves replacing the 14N in nutrient solutions with 15N, exogenously providing it to the plant tissues (roots in this case), and then measuring the 15N content of the tissues after a fixed amount of time. Here, we provide a brief overview of nitrogen uptake and remobilization in maize, and discuss current techniques for measuring nutrient uptake, with a focus on methods using stable isotopes of nitrogen.

Morphological, biochemical and nutritional variations in a Mexican purslane (Portulaca oleracea L.) variety exposed to salt stress during the vegetative stage

Salt stress limits productivity of crop plants, and differential responses may be observed among genotypes. Herein we analyzed the effects of saline stress induced by the application of different concentrations of sodium chloride (0.00, 0.25, 0.50, 0.75, and 1.00 M NaCl) in a local Mexican variety of purslane (Portulaca oleracea L.) named ‘Atlapulco’ in vegetative stage. The NaCl concentrations were applied in the Hoagland nutrient solution used in irrigation for 14 days under greenhouse conditions, using perlite as a substrate. Analysis of variance and comparison of means were carried out with the data obtained. NaCl concentrations from 0.50 M reduced canopy coverage 36.8% and stem diameter by almost 21%, while all NaCl doses reduced the leaf area by 28.2%, on average, as compared to the control. Dry stem biomass and chlorophyll b were reduced by the saline gradient. Secondary stems and root length increased with 1.00 M by 23 and 29%, respectively. Proline concentration both in leaves and stems increased by 223.9 and 138%, respectively, when applying 1.00 M NaCl, compared to the control. Applying 0.75 and 1.00 M NaCl reduced N concentrations by 47 and 28.8% in leaf tissues, respectively, compared to the control. The concentrations of P and K in leaves, and K in roots also decreased with the saline treatments, while those of Ca and Mg were not affected in any of the analyzed tissues. The highest concentrations of Na in leaves were observed in doses 0.50 and 0.75 M NaCl, surpassing the control by 67.5 and 73.1%, respectively. The findings reported herein are very useful to propose programs for the recovery of saline soils in the region and design environmental policies aimed at mitigating the effects of climate change on food production.

Sulfated Nutrition Modifies Nutrient Content and Photosynthetic Pigment Concentration in Cabbage under Salt Stress.

Negative effects of salt stress may be counteracted by adequate management of sulfated nutrition. Herein, we applied 3.50, 4.25, and 5.00 mM SO42- in a nutrient solution to counteract salt stress induced by 75 and 150 mM NaCl in cabbage cv. Royal. The increase in NaCl concentration from 75 to 150 mM reduced the contents of macronutrients and micronutrients in the shoot. When increasing from 3.50 to 4.25 mM SO42-, the contents of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) in shoots were enhanced, at both concentrations of NaCl. Increasing from 3.50 to 4.25 mM SO42- enhanced iron (Fe), zinc (Zn), manganese (Mn), and sodium (Na) concentrations with 75 mM NaCl. With 150 mM NaCl, the increase from 3.50 to 4.25 mM SO42- enhanced the contents of Cu and Mn, but also those of Na. Chlorophylls a, b, and total decreased as the concentration of SO42- increased in plants treated with 150 mM NaCl. With 75 mM NaCl, carotenoid concentration had a positive relationship with SO42-. Hence, the 4.25 mM SO42- concentration increased the contents of macronutrients and micronutrients in the presence of 75 mM NaCl, while, with 150 mM NaCl, it improved the contents of macronutrients except K. The chlorophyll a/chlorophyll b ratio remained close to 3 when the plants were treated with 5.00 mM SO42-, regardless of NaCl. Similarly, this level of SO42- increased the concentration of carotenoids, which translated into reductions in the total chlorophyll/carotenoid ratios, indicating a protective effect of the photosynthetic apparatus. It is concluded that higher doses of sulfur favor the accumulation of nutrients and increase the concentration of carotenoids under salt stress.

Enhanced Nitrate Nitrogen Removal from Wastewater Using Modified Reed Straw: Adsorption Performance and Resource Utilization

This paper presents a study on the efficient removal of nitrate nitrogen from wastewater using modified reed straw (MRS) and its subsequent resource utilization. The modification of the reed straw involved the introduction of branching quaternary amine groups to enhance its adsorption capacity for nitrate nitrogen. Experimental investigations were conducted to analyze the impact of packing height, flow rate, and initial solution concentration on the dynamic adsorption performance of the MRS. The results revealed that the maximum dynamic adsorption capacity of the MRS for nitrate nitrogen reached 14.76 mg/g. Furthermore, valuable nitrate nitrogen nutrient solution was successfully recovered through subsequent desorption experiments for resource recycling. Moreover, the application of the MRS led to notable enhancements in column height, fresh weight, chlorophyll content, and nitrogen content of the treated plants, indicating its efficacy in promoting plant growth. Overall, the findings demonstrate that MRS serves as a versatile adsorbent capable of efficient nitrate nitrogen removal and subsequent resource utilization.

Study on Plugging the Multiscale Water Channeling in Low-Permeability Heterogeneous Porous Media Based on the Growth of Bacteria

Summary To promote the effect of waterflooding of a heterogeneous low-permeability reservoir in the Ordos Basin, a microbial plugging agent is developed to plug the multiscale water channeling. Based on the characteristics of the growth of bacteria, the microbial plugging agent can plug both porous media and microfractures with different scales. The microbial plugging agent is prepared by activating the native bacteria present in low-permeability reservoirs by using the fermentation nutrients. After growing in the fermentation nutrient solution for 4 days in a beaker, the growth of microbial strains begins to stabilize. After that, the main particle size of the prepared microbial plugging agent is between 40 μm and 160 μm and the median particle size (D50) is near 90 μm. The microbial plugging agent has good shear resistance, salt resistance, and stability. At the initial state, due to good injectivity, the microbial plugging agent can smoothly enter into a low-permeability core, a heterogeneous core, and a fractured core, respectively. Thus, it can grow and reproduce in the cores. Based on the characteristics of growth, it can match with the spatial scale of pore or fracture in the cores, so that it cannot only plug the porous media water channeling with different scales but also plug the microfracture water channeling with different scales. This phenomenon has been confirmed by microscopic visualization flow experiments and core flow experiments. The developed microbial plugging agent can be applied to plug the multiscale water channeling to enhance oil recovery of low-permeability heterogeneous reservoirs.

Microgreen vegetables’ production can be optimized by combining the substrate and nutrient solution in a PFAL

Microgreen vegetables are nowadays a popular crop mainly produced hydroponically in controlled environments. In soilless culture, plants are produced using inert substrates with various properties. Besides, all the macronutrients and trace elements necessary for plant growth and development are provided in the form of a nutrient solution. It is possible to achieve similar yield and product quality of microgreens by using different substrates and reducing the input of nutrients. Our aim was to test the effect of three substrates (peat, coco coir, and cannabis mat) and three nutrient solution strengths (0, 50, and 100 %; NS0, NS50, and NS100) on the growth and quality of mustard, radish, and pea grown as microgreens in a plant factory with artificial lighting. As a general rule, cannabis mat and/or NS0 led to considerably decelerated growth of all microgreens. The antioxidant content including the amount of phenolics showed opposite trends compared to the yield of each microgreen. The hydroponic substrate showed species or variety dependency, especially in the phytochemical compounds. To conclude, treatments including NS100, as well as NS50 with peat showed promising results for high yield, relatively high nutritional value, while also saving the most from the use of fertilizers during microgreen vegetable production.

Bioassay of Root Exudates, their Impact in Susceptible Species and their Degradation in Hydroponics: A Review

Plants grown in hydroponics exhibit superior characters and yield compared to those grown in soil. However, root exudates accumulated particularly in renewed nutrient solution (RNS) hinders development of crops in hydroponics. These exudates are secondary metabolites released by the roots as a result of physiological processes, exhibiting autotoxic effects in plants. They are allelochemicals encompassing various chemical groups such as phenolic compounds, terpenoids, alkaloids, benzoxazinoids or other organic acids. The quantity and type of allelochemical released by plants varies depending on multiple factors such as temperature, light, nutrient deficiency, stress, physiological status of plant, pH and environment. The combined effect of more than one allelochemical is often additive or synergistic thus elevating the impact caused by individual allelochemical. These phytotoxic exudates are known to have inhibited the growth and development of plants by diverse pathways unique to their characteristic. There are several methods developed for degradation of exudates including AC (Activated Charcoal), O3/H2O2 treatment or other. This review discusses the bioassay of secondary metabolites causing autotoxicity, mechanism, impact in horticultural and ornamental crops, factors affecting their release and methods for elimination in hydroponics.

Effect of Spraying with Marvel Nutrient and Antioxidants on the Mineral Content of Apricot leaves Labib Cultivar

This study was carried out in one of the orchards of Kerbala city/Al-Hussainiya district. Where 30 apricot trees of Labib cultivar were selected, each tree was considered as an independent experimental unit with three replications. Foliar fertilizer by Marvel Nutrient solution at a concentration (0,2) ml/L was the first factor and the second factor was antioxidants which represented by ascorbic acid and citric acid at concentrations (500,1000) mg/L. for each tree. In addition, water was sprayed as the control application. The results showed that there was a significant effect for experimental treatments on the content apricot trees leaves of the mineral elements (Nitrogen, phosphorus, potassium, zinc and iron as the nutrient solution F2 and the antioxidant factor A2, S2 were superior. The interactions between factors F2*A2, F2* S2 (nutrient solution and antioxidants) was greater in giving the highest results levels of the content apricot trees leaves of the mineral elements (NPK, Fe and Zn).

Morphological and Physiological Responses of Two Penstemon Species to Saline Water Irrigation

Penstemon, with more than 250 species native to North America, holds significant aesthetic and ecological value in Utah, supporting diverse pollinators. Despite their significance, the survival of penstemon is threatened by challenges such as habitat loss, climate change, and Utah’s naturally high soil salinity. To address these challenges and understand their adaptability, this study evaluated the salt tolerance of two penstemon species [Penstemon davidsonii (Davidson’s penstemon) and Penstemon heterophyllus (foothill penstemon)] under controlled greenhouse conditions. The aim was to develop baseline information for nursery production and landscape use that utilize reclaimed water for irrigation. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.0 dS·m−1 as control or a saline solution at an EC of 2.5, 5.0, 7.5, or 10.0 dS·m−1 for 8 weeks. Half of the plants were harvested after four irrigation events, and the remaining plants were harvested after eight irrigation events. At harvest, visual rating (0 = dead and 5 = excellent without foliage salt damage), plant width, number of shoots, leaf area, shoot dry weight, leaf greenness [Soil Plant Analysis Development (SPAD)], stomatal conductance, and canopy temperature were collected to assess the impact of salinity stress. In both species, salt damage was dependent on the salinity levels and length of exposure. After four irrigation events, both species exhibited foliage damage that increased in severity with rising EC. The most severe damage was observed in plants receiving saline solution at an EC of 10.0 dS·m−1. After eight irrigation events, P. davidsonii exposed to a saline solution with an EC of 10.0 dS·m−1 received a visual rating of 0, whereas P. heterophyllus had a visual rating of 0.4. Both species exhibited salinity-induced effects, with variations observed in the specific parameters and the degree of response. Penstemon davidsonii exhibited significant salinity stress, as indicated by reduced leaf area, shoot dry weight, SPAD reading, and stomatal conductance with increasing EC of the saline solution. In addition, in both species, at both harvests, canopy temperatures increased either linearly or quadratically by 8% to 36% as the EC levels of the saline solution increased. These results indicate that P. davidsonii was more sensitive to salinity stress than P. heterophyllus.