Mineral Nutrient Concentrations Research Articles

Gamma-aminobutyric acid (GABA) improves salinity stress tolerance in soybean seedlings by modulating their mineral nutrition, osmolyte contents, and ascorbate-glutathione cycle

BackgroundIn plants, GABA plays a critical role in regulating salinity stress tolerance. However, the response of soybean seedlings (Glycine max L.) to exogenous gamma-aminobutyric acid (GABA) under saline stress conditions has not been fully elucidated.ResultsThis study investigated the effects of exogenous GABA (2 mM) on plant biomass and the physiological mechanism through which soybean plants are affected by saline stress conditions (0, 40, and 80 mM of NaCl and Na2SO4 at a 1:1 molar ratio). We noticed that increased salinity stress negatively impacted the growth and metabolism of soybean seedlings, compared to control. The root-stem-leaf biomass (27- and 33%, 20- and 58%, and 25- and 59% under 40- and 80 mM stress, respectively]) and the concentration of chlorophyll a and chlorophyll b significantly decreased. Moreover, the carotenoid content increased significantly (by 35%) following treatment with 40 mM stress. The results exhibited significant increase in the concentration of hydrogen peroxide (H2O2), malondialdehyde (MDA), dehydroascorbic acid (DHA) oxidized glutathione (GSSG), Na+, and Cl− under 40- and 80 mM stress levels, respectively. However, the concentration of mineral nutrients, soluble proteins, and soluble sugars reduced significantly under both salinity stress levels. In contrast, the proline and glycine betaine concentrations increased compared with those in the control group. Moreover, the enzymatic activities of ascorbate peroxidase, monodehydroascorbate reductase, glutathione reductase, and glutathione peroxidase decreased significantly, while those of superoxide dismutase, catalase, peroxidase, and dehydroascorbate reductase increased following saline stress, indicating the overall sensitivity of the ascorbate-glutathione cycle (AsA-GSH). However, exogenous GABA decreased Na+, Cl−, H2O2, and MDA concentration but enhanced photosynthetic pigments, mineral nutrients (K+, K+/Na+ ratio, Zn2+, Fe2+, Mg2+, and Ca2+); osmolytes (proline, glycine betaine, soluble sugar, and soluble protein); enzymatic antioxidant activities; and AsA-GSH pools, thus reducing salinity-associated stress damage and resulting in improved growth and biomass. The positive impact of exogenously applied GABA on soybean plants could be attributed to its ability to improve their physiological stress response mechanisms and reduce harmful substances.ConclusionApplying GABA to soybean plants could be an effective strategy for mitigating salinity stress. In the future, molecular studies may contribute to a better understanding of the mechanisms by which GABA regulates salt tolerance in soybeans.

Zinc Oxide Nanoparticles and Zinc Sulfate Alleviate Boron Toxicity in Cotton (Gossypium hirsutum L.).

Boron toxicity significantly hinders the growth and development of cotton plants, therefore affecting the yield and quality of this important cash crop worldwide. Limited studies have explored the efficacy of ZnSO4 (zinc sulfate) and ZnO nanoparticles (NPs) in alleviating boron toxicity. Nanoparticles have emerged as a novel strategy to reduce abiotic stress directly. The precise mechanism underlying the alleviation of boron toxicity by ZnO NPs in cotton remains unclear. In this study, ZnO NPs demonstrated superior potential for alleviating boron toxicity compared to ZnSO4 in hydroponically cultivated cotton seedlings. Under boron stress, plants supplemented with ZnO NPs exhibited significant increases in total fresh weight (75.97%), root fresh weight (39.64%), and leaf fresh weight (69.91%). ZnO NPs positively affected photosynthetic parameters and SPAD values. ZnO NPs substantially reduced H2O2 (hydrogen peroxide) by 27.87% and 32.26%, MDA (malondialdehyde) by 27.01% and 34.26%, and O2- (superoxide anion) by 41.64% and 48.70% after 24 and 72 h, respectively. The application of ZnO NPs increased the antioxidant activities of SOD (superoxide dismutase) by 82.09% and 76.52%, CAT (catalase) by 16.79% and 16.33%, and POD (peroxidase) by 23.77% and 21.66% after 24 and 72 h, respectively. ZnO NP and ZnSO4 application demonstrated remarkable efficiency in improving plant biomass, mineral nutrient content, and reducing boron levels in cotton seedlings under boron toxicity. A transcriptome analysis and corresponding verification revealed a significant up-regulation of genes encoding antioxidant enzymes, photosynthesis pathway, and ABC transporter genes with the application of ZnO NPs. These findings provide valuable insights for the mechanism of boron stress tolerance in cotton and provide a theoretical basis for applying ZnO NPs and ZnSO4 to reduce boron toxicity in cotton production.

Liposomes as selenium nanocarriers for foliar application to wheat plants: A biofortification strategy

In the present work, liposomes have been used as nanocarriers in the biofortification of wheat plants with selenium (Se) through foliar application. Liposomal formulations were prepared using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and Phospholipon®90H (P90H) (average size <100 nm), loaded with different concentrations of inorganic Se (selenite and selenate) and applied twice to the plants in the stage of vegetative growth. Liposomes enhanced Se uptake by wheat plants compared to direct application. The highest Se enrichment was achieved using the phospholipid DPPC and a concentration of 1000 μmol·L−1 of Se without affecting the biomass, chlorophylls, carotenoids, and the concentration of mineral nutrients of the plants. The chemical speciation of Se in the plants was further investigated by X-ray absorption spectroscopy (XAS). The results from XAS spectra revealed that most of the inorganic Se was transformed to organic Se and that the use of liposomes influenced the proportion of C-Se-C over C-Se-Se-C species.

Global change impacts on mineral nutritional quality of cereal grains: Coordinated datasets and analyses to advance a systems-based understanding

ContextGlobal nutritional health outcomes are directly reliant on agroecosystem nutrient outputs. Appropriately, there is concern surrounding the impacts of a changing climate not only on crop yields, but also on crop nutritional quality (e.g., mineral nutrient concentrations). Quantifying the impacts of elevated CO2 concentrations, elevated temperature, drought stress, edaphic factors, and agronomic management on crop yields and mineral nutrition is critical, yet a systems-level understanding of these interactive factors is poorly developed, limiting our ability to effectively target solutions. Empirical data for climate impacts on crop nutritional quality remain scarce, with much of the research emerging from valuable, but geographically limited, Free-air CO2 Enrichment (FACE) experiments, several of which suggest that human nutrition will be adversely impacted by e[CO2]. Specific concerns center on observed declines in grain protein, iron, and zinc concentrations due to already wide-spread human nutritional deficiencies in these nutrients. ObjectivesAs global change experiments expand to pursue questions regarding interactive climate impacts on crop yields and nutritional quality, it is imperative to interrogate the measurements, data standardization, and metadata needed for unifying synthesis. The data reported for shifts in crop nutritional quality are often incomplete, precluding the generalizability and comparability of results. MethodsWe frame this review around six inter-reliant methods, tools, and practices to support maximally useful experimental datasets to inform questions of global change impacts on crop nutrition and aid in detecting genotypic differences in mineral nutrient density. The bulk of the data and discussion centers on wheat (Triticum aestivum L.) due to the central role this crop plays in human nutrition and sustained biofortification efforts. ResultsTo permit experimental comparability and synthesis, datasets should (1) clearly delineate analytical methods and standards and (2) link mean nutrient concentrations with the covariate of yield. (3) Multi-year, multi-location data is required to identify genotypes with significant deviations in nutrient concentrations, with (4) data normalized for yield within appropriate analytical frameworks. (5) Inclusion of data on soil properties, weather, and abiotic and biotic stresses as well as (6) agronomic practices and nutrient management is essential for understanding global change impacts on nutritional outcomes. ConclusionsCoordinated, multi-dimensional data will permit the syntheses and meta-analyses needed to identify and quantify climate impacts on nutrition. ImplicationsThis work is essential to effectively target nutritional solutions, to develop modeling tools to support nutritional planning, and to identify areas where agronomic management and breeding can minimize climate impacts on nutritional outcomes.

Unravelling the impact of soil types on zinc, iron, and selenium concentrations in grains and straw of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines

The concentration of mineral nutrients in plants is associated with bioavailabilities of soil mineral nutrients, which are regulated by various soil physio-chemical properties. A pot experiment was conducted to investigate the effects of soil type on grain and straw zinc (Zn), iron (Fe) and selenium (Se) concentrations of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines. A set of 42 treatments in a factorial combination with 21 genotypes and two soil types collected from Ngabu and Chitedze Research Stations in Malawi was laid in a randomised complete block design (RCBD) in three replicates. Pre-experiment soil Zn and Fe were extracted using DTPA extraction method followed by analysis with inductively coupled plasma-mass spectrometry (ICP-MS). Aqua-regia hotplate acid digestion was used to extract soil Se and analysis was done using ICPM-MS. Grain and straw samples were digested using nitric acid digestion (HNO3) and analysed using ICP-MS. Soil analysis results showed that the two soils had the same textural class (Sandy clay loam), but different mineral concentrations, pH levels and percentage organic matter. Analysis of variance revealed a ~two-fold higher Zn concentration in grains grown in low pH, high Zn soils (Chitedze soils) compared to grains grown in high pH, low Zn soils (Ngabu soils). Variation in grain Zn concentration was associated with the genotypes (p = 0002), soil type (p = &amp;lt;0.0001), and their interaction (p = 0.035). Grain Fe was 1.3-fold higher in low pH than in high pH soils, and it was influenced by genotypes (p = &amp;lt; 0.0001) and soil type (p = &amp;lt;0.0001). Grain Se was highly associated with soil type (p = &amp;lt;0.0001), and it was 30-fold higher in high pH than in low pH soils. Straw Zn was generally higher in plants grown in Chitedze soils than Ngabu soils, whilst straw Se was higher in plants grown in Ngabu soils than Chitedze soils. The findings demonstrate the significance of soil physio-chemical properties for mineral accumulation and distribution to plant parts, thus informing future breeding programs on important considerations on crop genetic biofortification with the three mineral elements.

Sap Yield and Sugar Content of Boxelder and Norway Maple Trees in Northern Utah

Maple syrup is a well-known natural sweetener made from the sap harvested from maple trees (Acer sp.). The North American scientific literature regarding maple syrup has predominantly originated in the Northeastern United States and Canada. However, the range of this Holarctic genus extends across the continent and all species produce sap with the potential for syrup production. This study focuses on two maple species commonly found in Northern Utah, namely the native boxelder (Acer negundo) and the introduced Norway maple (Acer platanoides). Thirty trees of each species were tapped in Cache Valley, UT, USA, on 19 Feb 2022, and measured for daily sap yield and sugar content until the season ended 37 days later on 27 Mar 2022. The same trees were re-tapped on 1 Mar 2023 and taps were removed 41 days later on 10 Apr 2023. Average 2022 sap yields were 22.1 L for boxelder and 7.5 L for Norway maple per tree. In 2023, average sap yields were 26.4 L for boxelder and 9.3 L for Norway maple per tree. Boxelder trees produced an average sap yield more than double that of Norway maple in both years. Sugar content was similar for both species ranging from 2.2% to 2.8%. Air temperatures were analyzed using data from Utah AgWeather System weather stations nearest to the trees, and air temperature had a significant impact on sap yield. It was found that an average daily air temperature of 0.5 °C and a daily air temperature difference of ∼10 °C with a minimum air temperature close to −5 °C and a maximum air temperature of ∼6 °C was the optimal condition for production. An analysis of the mineral nutrient concentrations in the sap and soil showed no correlation. These findings indicate that there is potential for using Utah’s maple species for syrup production.

The deterioration of starch physiochemical and minerals in high-quality indica rice under low-temperature stress during grain filling.

Low temperatures during the grain-filling phase have a detrimental effect on both the yield and quality of rice grains. However, the specific repercussions of low temperatures during this critical growth stage on grain quality and mineral nutrient composition in high-quality hybrid indica rice varieties have remained largely unexplored. The present study address this knowledge gap by subjecting eight high-quality indica rice varieties to two distinct temperature regimes: low temperature (19°C/15°C, day/night) and control temperature (28°C/22°C) during their grain-filling phase, and a comprehensive analysis of various quality traits, with a particular focus on mineral nutrients and their interrelationships were explored. Exposure of rice plants to low temperatures during early grain filling significantly impacts the physicochemical and nutritional properties. Specifically, low temperature increases the chalkiness rate and chalkiness degree, while decreases starch and amylopectin content, with varying effects on amylose, protein, and gelatinization temperature among rice varieties. Furthermore, crucial parameters like gelatinization enthalpy (ΔH), gelatinization temperature range (R), and peak height index (PHI) all significantly declined in response to low temperature. These detrimental effects extend to rice flour pasting properties, resulting in reduced breakdown, peak, trough, and final viscosities, along with increased setback. Notably, low temperature also had a significant impact on the mineral nutrient contents of brown rice, although the extent of this impact varied among different elements and rice varieties. A positive correlation is observed between brown rice mineral nutrient content and factors such as chalkiness, gelatinization temperature, peak viscosity, and breakdown, while a negative correlation is established with amylose content and setback. Moreover, positive correlations emerge among the mineral nutrient contents themselves, and these relationships are further accentuated in the context of low-temperature conditions. Therefore, enhancing mineral nutrient content and increasing rice plant resistance to chilling stress should be the focus of breeding efforts to improve rice quality.

Efficient In Vitro Platform for Multiplication, Acclimatization, and Deliver of High-NaCl-Tolerant Clones of the Halophyte Arthrocaulon macrostachyum

Halophytes are species able to grow and complete their life cycle under NaCl concentrations above 0.2 M. In a context of growing population and uncertain agricultural food sustainability, there is an interest on halophytes as potential source of food and fodder. However, scarce research has addressed in vitro propagation of halophytes as a tool for study, conservation, and propagation of elite germplasm. In this study, an efficient method for micropropagation of the succulent and salt accumulator halophyte Arthrocaulon macrostachyum has been established for the first time, using shoot tips from in vitro-germinated plant material. During shoot multiplication stage, superior genotypes were selected from explants grown in high strength and NaCl content medium and subsequently rooted and acclimatized to ex vitro conditions. A comprehensive characterization including determination of oxidative stress, photosynthesis performance, and mineral nutrient contents was done. This research gains insight into the physiological and biochemical characterization of halophytes during micropropagation and provides a solid platform for the production of elite A. macrostachyum germplasm for ulterior uses.

Selenium biofortification impacts nutritional composition and storage proteins in wheat grains

Selenium (Se) biofortification of staple crops can be used as a valuable pathway to prevent Se deficiency in human diet. In this study, a pot experiment was performed under semi-controlled conditions to investigate the response of indigenous wheat cultivars to different Se concentrations (0 to 100 mg L-1) and to also assess the effects of Se foliar application on the storage proteins in wheat grains. A linear increase in Se concentrations in the grains of various wheat cultivars was observed (up to 158 μg kg-1) in response to Se application rates. It was observed that Gandum-1, Fakhar-e-Bhakkar-17, Ujala-16 and Anaj-17 were the most responsive wheat cultivars to Se application rates and accumulated the highest Se concentrations in grains. Though Se foliar treatments did not significantly affect the wheat yield, a highly significant correlation was observed between the Se application rates and the concentration of mineral nutrients (iron, zinc, calcium and potassium). Moreover, the exogenous Se supply considerably enhanced the concentrations of different storage proteins viz. albumin, globulin, prolamin and glutelin in wheat grains. The target hazard quotient of all Se application rates was found less than the toxic levels. In conclusion, wheat cultivars differ in their ability to accumulate Se concentrations in grains and biofortifying the most responsive wheat cultivars could be used as an efficient agronomic strategy to overcome widespread Se deficiency in human population.

Characteristics of turion development in two aquatic carnivorous plants: Hormonal profiles, gas exchange and mineral nutrient content.

Turions are vegetative, dormant, and storage overwintering organs formed in perennial aquatic plants in response to unfavorable ecological conditions and originate by extreme condensation of apical shoot segments. The contents of cytokinins, auxins, and abscisic acid were estimated in shoot apices of summer growing, rootless aquatic carnivorous plants, Aldrovanda vesiculosa and Utricularia australis, and in developing turions at three stages and full maturity to reveal hormonal patterns responsible for turion development. The hormones were analyzed in miniature turion samples using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry. Photosynthetic measurements in young leaves also confirmed relatively high photosynthetic rates at later turion stages. The content of active cytokinin forms was almost stable in A. vesiculosa during turion development but markedly decreased in U. australis. In both species, auxin content culminated in the middle of turion development and then decreased again. The content of abscisic acid as the main inhibitory hormone was very low in growing plants in both species but rose greatly at first developmental stages and stayed very high in mature turions. The hormonal data indicate a great strength of developing turions within sink-source relationships and confirm the central role of abscisic acid in regulating the turion development.

Effect of Partial Root-Zone Irrigation on Plant Growth, Root Morphological Traits and Leaf Elemental Stoichiometry of Tomato under Elevated CO2

The increasing CO2 concentration ([CO2]) in the atmosphere decreases mineral nutrients concentration in crops, whereas it increases water use efficiency (WUE). Partial root-zone irrigation (PRI) could not only increase WUE but also improve plant nutrient status. Yet the effect of PRI combined with elevated CO2 concentration (e[CO2]) on the element stoichiometry of tomato leaves remains unknown. This study sought to investigate the responses of leaf mineral nutrients status and element stoichiometric ratios in tomatoes to PRI combined with e[CO2]. Tomato plants (cv. Ailsa Craig) were grown in pots in climate-controlled growth chambers with ambient [CO2] (a[CO2], 400ppm) and elevated [CO2] (e[CO2], 800ppm), respectively. Three irrigation regimes, i.e., full irrigation (FI), deficit irrigation (DI) and PRI, were applied to tomato plants at the flowering stage. The results showed that plants grown under DI and PRI had a similar biomass, enhanced root growth including greater root to shoot ratio, root length, surface area, volume and specific length, and an improved WUE in comparison with FI under e[CO2]. Additionally, under e[CO2], PRI showed an increase in leaf [C](+1.5%) and [N] (+9.3%), no decrease in leaf [K], [Ca], [Mg], [S] and [15N], but a decrease in leaf C/N (−6.6%) as compared with FI. Conclusively, PRI had the ability to improve leaf N concentration, maintain most leaf mineral nutrient concentrations, and optimize or maintain leaf element stoichiometric ratios under e[CO2]. Therefore, PRI would be a practicable mode of irrigation for optimizing WUE and nutrient status in tomato leaves in a future freshwater-limited and higher-CO2 environment.

Accurate monitoring of micronutrients in tilled potato soils of eastern Canada: Application of an eXplainable inspired-adaptive boosting framework coupled with SelectKbest

Plant growth is significantly dependent upon the combination and concentration of mineral nutrients in the soil, where the adequate supply of these nutrients is a severe issue in fulfilling the fundamental cellular process requirements. This study collected 22 physicochemical properties of tilled potato soils from eight stations in two Atlantic Canadian provinces (Prince Edward Island and New Brunswick). Along with the experimental investigation, an explainable dual pre-processing inspired-intelligent paradigm comprised of the SelectKbest feature selection (FS), modified bat algorithm (MBA), adaptive boosting (AdaBoost), and Shapley Additive Explanations (SHAP) explainer was designed to monitor the micronutrients, including copper (Cu) and zinc (Zn). The significant data predictors were filtered using the SelectKbest FS to monitor Cu and Zn. The MBA was coupled with AdaBoost for tuning the hyperparameters to ensure accurate predictions. To validate the outcomes of the MBA-AdaBoost, four advanced machine learning approaches, including categorical boosting (CatBoost) coupled with MBA (MBA-CatBoost), classical AadaBoost, ridge kernel regression (KRR), and multivariate adaptive regression splines (MARS), were examined to compare the accuracies. The robustness of the developed framework and the performance of comparative models were examined through several statistical metrics. Results revealed that the MBA-CatBoost performed the best in predicting the Cu (R = 0.9425, U1 = 0.1020, and U22 = 0.2036) and Zn in the soil (R = 0.9454, U1 = 0.0942, and U2 = 0.1858) when compared with other models. Furthermore, the SHAP explainer interpreted the block-box main model during the training phase by introducing the CEC and Fe as significant predictors to monitor the soil Cu and Zn, respectively. These findings demonstrate a clear and robust relationship between the presented modeling approach and the accurate prediction of soil micronutrient concentrations. Accurate predictions of micronutrients using these advanced techniques can be used to tailor site-specific micromovement management in agriculture fields to reduce production costs, increase farm profitability, and lower environmental contamination.

Foliar non-structural carbohydrates and resprouting ability of woody species in a tropical dry forest

Diverse disturbances contribute to biomass loss in tropical dry forests (TDF), of which slash-and-burn agriculture (SBA) may be the most severe; it is practiced by large populations of residents. Plant species capable of resprouting in response to such disturbances often possess above-ground structures that survive and mobilize resources for resprouting, in addition to below-ground structures. In Brazilian TDF, woody species regenerating from stem pieces that persist after SBA events are common. In this study, we evaluated the foliar concentrations of non-structural carbohydrates (NSC) and mineral nutrients during the first six months after an SBA event in all species that resprouted within the experimental area. Almost all the species resprouted exclusively from the stems. The measured nutrient concentrations did not change drastically after an SBA event. Two patterns were observed with respect to NSC concentrations among the species. Half of the studied species exhibited high concentrations of NSC before the SBA event, which gradually decreased three and six months after the disturbance. In contrast, the remaining species maintained consistent NSC concentrations throughout the study period. The cost of building new leaf tissue was similar for all species before the SBA event. However, after disturbance, the species invested different amounts of carbon into the new leaves. Those species that decreased NSC leaf concentration after SBA showed the highest regrowth intensity through the number of new tillers. Our results suggest that the intense translocation of NSC from the leaves before SBA may support the increased activity of the buds present in the remaining stem piece.

The use of hydromulching increases yield and quality of drought-stressed artichokes (Cynara cardunculus subsp. scolymus L. (Heigi)) by improving soil properties and plant hormone homeostasis

There exist many research papers which pointed out the positive effects of using the mulching technique in stressful conditions, showing crop productivity and physicochemical quality improvement of the product. We hypothesized that a novel organic liquid mulching formulations (hydromulching) can be used in sustainable agricultural production under drought stress through both their direct influence on physicochemical and biological soil properties as well as by their effect on plant hormonal balance leading to the improvement of crop yield and quality. Artichoke plants were grown on bare soil (BS) or mulched with traditional polyethylene (PE) or with three different types of ecological hydromulching treatments obtained from recycled additives, namely: substrate used for mushroom cultivation (MS), rice hulls (RH) and wheat straw (WS); and were subjected to optimal (100% ETc) and reduced (70% ETc) irrigation regimes. Under water limitation, soil organic matter and carbon and mineral soil concentrations increased in the hydromulched soils (by 60% on average). Mulched treatments produced the highest crop yield (by 40% on average) attributed to increased artichoke head fresh weight, giving rise to the improvement of the important physical quality parameters in artichoke: color, firmness, and size. Furthermore, hydromulched treatments induced higher content of mineral nutrients in artichoke heads, while sugar concentrations were superior in non-mulched soil due to a major exposure to water stress. This may be related to the diminished carbohydrate metabolism activity under drought stress, including notable changes in the hormonal balance. The crosstalk of growth-promoting hormones (cytokinins) with the stress-related hormone factors (ethylene precursor 1-aminocyclopropane-1-carboxylic acid) has been shown to regulate adaptive responses such as sugar osmoregulation in artichoke heads under drought stress. Altogether, these results demonstrate that hydromulching is a sustainable alternative to plastic films to cope with drought stress by improving yield and physical quality characteristics of artichoke heads and maintaining their chemical and nutritional quality over bare soil.

Influence of Soil and Nutrient Management Practices on Crop Productivity and Quality in High Tunnel Organic Leafy Green Production

Despite the growing interest in high tunnel organic vegetable production, limited information is available regarding optimizing nutrient management for organic leafy greens. This 3-year study examined the impacts of cowpea cover crop as well as different organic fertilizers and composts on yield, leaf mineral nutrient content, and phytochemical properties of organic leafy greens produced in high tunnels under Florida sandy soil conditions. The experiment was arranged in a split-split-plot design with three replications. The whole plots consisted of a cowpea (Vigna unguiculata ‘Iron &amp; Clay’) cover crop and a weedy fallow control, with fertilization treatments in the subplots, including preplant application of granular fertilizer vs. weekly injection of liquid fish fertilizer at the same seasonal rates of nitrogen (112 kg/ha), phosphorus (9.8 kg/ha), and potassium (74.4 kg/ha). The sub-subplots included yard waste-based compost (22.4 Mt/ha), cow manure-based compost (22.4 Mt/ha), vermicompost (5.6 Mt/ha), and no compost control. Cowpea was broadcasted (112 kg/ha) in early July or mid-August and terminated 51 to 53 days after seeding. Pac choi (Brassica rapa var. chinensis ‘Mei Qing Choi’) was transplanted in mid-Sep. or mid-Oct. and harvested after 33 to 36 days. Baby spinach (Spinacia oleracea ‘Corvair’) or baby leaf lettuce (Lactuca sativa ‘Outredgeous’) was direct seeded subsequently as a catch crop. Each experimental unit remained in the same location across the 3 years of the study. Cover cropping had little influence on yields, leaf mineral nutrients, ascorbic acid content, total phenolics, and total antioxidant capacity of pac choi and baby spinach/lettuce. Compared with preplant application of the granular organic fertilizer, weekly liquid organic fertigation improved pac choi marketable yield and dry weight by 16.8% and 5.4% on average, respectively, and enhanced leaf nitrogen and phosphorus contents on a dry weight basis. Relative to the no compost control, yard waste compost consistently improved marketable yields of pac choi by 11.6% on average and led to higher yields of the baby spinach/lettuce catch crop in years 1 and 3, suggesting that compost applications may enhance seasonal nutrient availability to better meet crop demand. However, compost application exhibited inconsistent effects on crop mineral nutrient and phytochemical contents across the years, which could be attributed to the different nutrient compositions of the composts applied in each season, as well as the legacy effects from the previous season. Furthermore, the compost benefits may be influenced by the fertilization program as indicated by their interaction effects observed in this study.

Effect of halophyte-based management in physiological and biochemical responses of tomato plants under moderately saline greenhouse conditions

Salinity, both in irrigation water and in soils, is one of the major abiotic constraints for agriculture activity worldwide. Phytodesalinization is a low-cost plant-based bioremediation strategy that can effectively amend salt-affected soils by cultivating salt tolerant plants. However, very few studies have evaluated the use of halophyte plants in crop management systems. In this work, we apply two different tomato crop management strategies involving the halophyte Arthrocaulon macrostachyum L. in a moderately saline soil: intercropping (mixed cultivation) and sequential cropping (cultivation of tomato where halophytes were previously grown). We investigated the effect of the different crop managements in some physiological and biochemical variables in tomato plants, including mineral nutrients content, photosynthesis, chlorophyll and flavonol contents, antioxidant metabolism and fruit production and quality. At soil level, both intercropping and sequential cropping decreased chloride content, sodium adsorption ratio and electrical conductivity, leading to reduced soil salinity. In tomato plants, halophyte-dependent management improved nutrient homeostasis and triggered a mild oxidative stress, whereas photosynthesis performance was enhanced by intercropping. In tomato fruits, the sequential cropping led to a 27% production increase and a slight decrease in the soluble sugar contents. We suggest the use of A. macrostachyum, and hence of halophyte plants, as an environmentally friendly phytoremediation strategy to improve plant performance while improving crop production, leading to a more sustainable agriculture and enhancing biodiversity.

Mineral contents and antioxidant activities of Karakılçık durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.) genotypes

The importance of antioxidants and minerals in food has increased with the growing awareness of consumers in recent years. Türkiye is rich in genetic diversity for wheat as it is located at the intersection of three floristic regions and is part of the Fertile Crescent. In this study, the antioxidant activity of Karakılçık durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.) populations from 12 different regions of Türkiye was determined using the DPPH method. In addition, the contents of mineral nutrients (Ca, Cu, Fe, Mg, Mn, Zn) were determined in an ICP-OES device with milled wheat. Karakılçık genotypes were sowed in a field using an augmented trial design consisting of five rows and six blocks, with each block containing five control varieties. The result of the study was that the landrace Karakılçık genotypes exhibited antioxidant activity varying between 14.7-40.2 μmol TE g-1. The Ca contents of landrace Karakılçık genotypes varied between 13.0-249.9 ppm, Cu contents 0.6-22.7 ppm, Fe contents 28.7-93.9 ppm, Mg contents 583.7-1194.0 ppm, Mn contents 31.4-87.7 ppm, and Zn contents 22.3-68.5 ppm. The results of the study reveal that Karakılçık landrace genotypes have large differences in antioxidant and mineral content, that these differences have the potential to be used in wheat breeding programs, and that wheat flour obtained from Karakılçık landrace genotypes is important.

Exploring the Impact of Potassium on Growth, Photosynthetic Performance, and Nutritional Status of Lemon Trees (cv. Adamopoulou) Grafted onto Sour Orange and Volkamer Lemon Rootstocks

(1) Background: This study investigates the effects of potassium (K) and rootstock on the growth, photosynthetic activity, and mineral nutrition of lemon trees; (2) Methods: Lemon trees (cv. Adamopoulou) grafted onto sour orange (Citrus aurantium) (SO) or Volkamer lemon (Citrus volkameriana) (VL) rootstock were cultivated hydroponically under 0.00, 0.75, 1.50, 3.00, and 6.00 mM K. Plant growth and nutrition parameters, as well as leaf photosynthetic rate, stomatal conductance, transpiration rate, intracellular CO2, chlorophyll, and carotenoid concentration were assessed; (3) Results: Under K deficiency (0 mM K), plants exhibited chlorotic and necrotic symptoms, more pronounced in older leaves. Potassium deficiency adversely affected various physiological processes in lemon leaves, including a decrease in photosynthesis rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, water use efficiency, CO2 utilization efficiency, chlorophyll a/b ratio, and carotenoid concentrations (some effects were rootstock-dependent). Low photosynthetic rates under K deficiency were due to both stomatal- and non-stomatal limitations. Elevated K in the nutrient solution consistently reduced the total plant uptake of P, Ca, Mg, B, Mn, and Zn, resulting in nutrient imbalances, as evidenced by the significant decrease in P, Ca, Mg, and Zn concentrations found in scion tissues (especially at the 6 mM K treatment). Rootstock-dependent responses were also observed in scion leaf and stem growth and in mineral nutrient concentrations, uptake, and distribution across plant parts; (4) Conclusions: Our study reveals interesting aspects on how to optimize K fertilization in lemon trees in the context of sustainable agriculture by considering nutrient interactions and rootstock-dependent effects. Understanding these complex interactions and improving K fertilization practices is expected to improve lemon tree performance, yield, and fruit quality.

Unraveling the mechanisms behind salt stress alleviation and enhanced fruit storability in pomegranate through triacontanol treatment

Salt stress is a significant factor that leads to various detrimental effects on pomegranate trees. This study was undertaken with the primary objective of developing a treatment strategy aimed at mitigating the adverse impacts of salinity in fields, and its negative reflections on the post-harvest quality of pomegranate fruit. At the commencement of the study, we utilized response surface methodology (RSM) to assess a range of triacontanol (TRA) concentrations along with different spray frequencies. Our investigation revealed that applying 10 and 20 µM TRA three times proved to be the most effective treatments. Accordingly, the effect of these concentrations was studied in depth. The treatment with TRA at concentrations of 10 and 20 µM demonstrated significant positive effects. TRA effectively mitigated the harmful impacts of salinity, preserved the plant's nutrient and antioxidant content, and led to an increase in productivity. Moreover, TRA treatments had a notable effect on enhancing post-harvest storability of fruits during storage at 5 ̊C and 90 % RH for 12 weeks. TRA treatments resulted in higher concentrations of mineral nutrients (N, P, K, and Ca), porphyrin concentration, relative water contents, activities of CAT, POD, and SOD, glycine betaine, proline, amino acids, total phenolics, and total carbohydrates, additionally, TRA treatments led to increased fruit weight and fruit yield compared to the control group. Moreover, TRA treatments attained lower hydrogen peroxide, membrane permeability, malondialdehyde, Na, and Cl compared with control. Indeed, the positive effects of TRA treatments extended to fruit storability. TRA treatments resulted in a notable decrease in the percentage of decay, weight loss, and softness. Furthermore, TRA treatments demonstrated efficacy in preserving TSS, husk color, ascorbic acid, and anthocyanin content in the arils. These combined benefits highlight the potential of using TRA as a practical and effective method to alleviate salt stress and enhance pomegranate fruit storability.

Shoot Yield and Mineral Nutrient Concentrations of Six Microgreens in the Brassicaceae Family Affected by Fertigation Rate

Microgreens have become an important specialty crop valued by their varying texture, vibrant colors, and nutrient-dense features. As the number of species and cultivars rapidly increases for microgreen production, fertigation requirements in relation to shoot production and nutrient compositions remain unclear. This study aimed to investigate the shoot yield, visual quality, and mineral nutrient concentrations of six microgreens in the Brassicaceae family including the ‘Waltham’ broccoli, ‘Red Acre’ cabbage, Daikon radish, ‘Red Russian’ kale, pea, and Rambo radish in two experiments in December 2020 and January 2021. Each microgreen was fertigated with 120 mL of fertilizer solution daily for five consecutive days with a rate of 0, 70, 140, 210, or 280 mg·L−1 N from a general-purpose fertilizer. Broccoli, Daikon radish, and kale similarly produced the highest fresh shoot weights of 916.5 to 984 g·m−2 in December 2020, while pea produced the highest fresh shoot weight of 2471 g·m−2 in January 2021 among cultivars. The fertigation rates of 140, 210, and 280 mg·L−1 N resulted in similar fresh and dry shoot weights of selected microgreens, suggesting 140 mg·L−1 N should be sufficient for microgreen fertilization. Mineral nutrients in microgreens varied among cultivars: pea microgreens had the highest nitrogen (N) concentrations of 70.6 to 75.2 mg·g−1 in December 2020 and 72.1 to 75.4 mg·g−1 in January 2021; and cabbage microgreens were rich in calcium (Ca) in both experiments. The kale, pea, and Rambo radish microgreens contained the highest concentrations of iron (Fe) and manganese (Mn) in December 2020. The fertigation rate affected macronutrient concentrations but did not affect micronutrient concentrations including Fe, Mn, or zinc (Zn).