Root biomass serves as a critical indicator of plant eco-physiological status and crop productivity, yet its non-destructive monitoring remains challenging because of its underground location. The use of transparent nutrient film technique (NFT) systems enables direct observation of entire root systems, rendering image-based phenotyping feasible. In this study, we investigated and compared the performance of RGB and hyperspectral imaging for predicting root dry weight in hydroponically grown spinach (Spinacia oleracea L.). Using 430 root segments divided from 60 plants, three models were developed: (1) an area-based regression based on root coverage, (2) a convolutional neural network (CNN) using RGB images, and (3) a partial least squares regression (PLSR) model using hyperspectral data (450-950nm). The area-based regression exhibited limited accuracy (R² = 0.446) because of saturation at high root coverage. The CNN model improved predictive performance (R² = 0.739) but tended to overestimate sparse roots as a result of resolution constraints. The PLSR model achieved the highest accuracy (R² = 0.822, RMSE = 0.019g/segment), with significantly lower error than RGB-based approaches (P < 0.01). Variable importance in projection analysis indicated that PLSR effectively exploited spectral signatures at 450nm (background contrast) and 750nm (tissue scattering), thereby maintaining stable accuracy across the full biomass range. When validated using 104 independent plants, the PLSR model achieved high predictive accuracy. Furthermore, as a proof of concept, this model successfully visualized the spatiotemporal dynamics of root biomass accumulation over 50 days, with only a 7.70% relative error at harvest. To our knowledge, this study is among the first to demonstrate the non-destructive monitoring of biomass distribution within entire root systems under production conditions. Hyperspectral imaging combined with PLSR outperforms RGB-based approaches by capturing spectral signatures that reflect internal tissue properties of roots, thereby overcoming limitations caused by morphological occlusion. This approach provides a robust tool for precision agriculture and high-throughput phenotyping, enabling continuous assessment of root growth through simple modifications to the existing hydroponic systems.

Retraction Note: Salt stress amelioration and nutrient strengthening in spinach (Spinacia oleracea L.) via biochar amendment and zinc fortification: seed priming versus foliar application.

Optimizing Spinacia oleracea production through organic fertilizers use in the lower Gangetic plain, West Bengal

Industrial-scale application of bacteriophages on baby spinach: One-year study of Listeria control, quality and microbial community shifts.

Abstract. Rubisco is the central photosynthetic enzyme that catalyzes the fixation of CO2 to RuBP, initiating the most dominant carbon assimilation pathway on Earth that supports nearly all trophic chains in the biosphere. The CO2 fixation reaction expresses a strong kinetic isotope effect, producing biomass depleted in 13C and leaving characteristic imprints in sediments and sedimentary rocks, which are widely used to reconstruct past biological activity and environmental conditions, including ancient atmospheric CO2 levels. Despite its importance, carbon isotope fractionation of Rubisco (ϵRubisco) has been measured in only a limited number of organisms, with most studies focusing on land plants rather than on major contributors to the sedimentary record, such as cyanobacteria and coccolithophores. This scarcity reflects the complexity of existing experimental procedures and the high cost of instrumentation. Here, we present a simplified method that overcomes these limitations, eliminating the need for complex purification protocols, specialized equipment, and experimental designs that yield little CO2 fixation and high uncertainties. We use a simplified purification procedure yielding semi-purified Rubisco extracts, together with an Apollo–Picarro δ13C-DIC analyzer capable of simultaneously measuring DIC concentration and 13C isotope ratios. Using this protocol, we accurately determined ϵRubisco for the model plant Spinacia oleracea, the cyanobacterium Synechococcus sp., and provide the first determination for the coccolithophore Gephyrocapsa oceanica. The measured values span a striking range, from 13.1 ‰ to 30 ‰, highlighting both the variability of Rubisco fractionation and the versatility of our approach for studying carbon isotope discrimination across diverse biological systems. This study establishes a method that enables reliable determination of ϵRubisco across phylogenetically diverse groups, thereby supports research that provides new insights into the mechanisms of Rubisco fractionation, and improves interpretation of environmental carbon isotope records.

This study evaluated productive performance, nutrient use efficiency, and nitrogen and phosphorus mass balance in an intensive aquaponic polyculture system combining Nile tilapia (Oreochromis niloticus), channel catfish (Ictalurus punctatus), lettuce (Lactuca sativa), and spinach (Spinacia oleracea) under high biomass density (40 kg m−3). Nine treatments were established through a 3 × 3 factorial combination of fish (tilapia:catfish = 75:25, 50:50, 25:75) and plant (lettuce:spinach = 75:25, 50:50, 25:75) species ratios and evaluated over three consecutive 60-day production cycles. Nitrogen and phosphorus use efficiencies differed significantly among treatments, reaching maximum values above 50% for NUE and 47% for PUE in catfish-dominant systems with higher spinach proportions, indicating improved nutrient recovery and reduced losses. These treatments also produced greater fish biomass, whereas lettuce-dominant combinations favored plant yield. Water quality remained within acceptable ranges, although higher catfish proportions were associated with lower dissolved oxygen and increased nitrogen availability. Overall, results demonstrate that optimizing fish–plant species ratios enhances nutrient retention and sustainable productivity in intensive aquaponic systems. Future research should explore adaptive species ratio management and economic feasibility to support large-scale implementation of polyculture aquaponics.

IntroductionThe KUP/HAK/KT family is the largest group of potassium ion transporters in plants and plays a central role in K+ uptake, transport, and abiotic stress responses. However, the function of individual KUP genes in salt-tolerant crops remains under explored. In this study, BvKUP13 was isolated from the salt-tolerant beet variety AK3018.MethodsWe cloned and analyzed the sequence, subcellular localization, and expression profile of BvKUP13 under salt stress. Transgenic Arabidopsis thaliana plants overexpressing BvKUP13 were generated to evaluate its role in salt stress tolerance.ResultsBvKUP13 encodes a protein of 732 amino acids, shows striking sequence similarity to KUP proteins from Chenopodium quinoa and Spinacia oleracea, and is localized to the endoplasmic reticulum membrane. The gene is predominantly expressed in leaves and is upregulated by NaCl treatment. Overexpression in Arabidopsis significantly improved salt tolerance, as indicated by enhanced photosynthetic efficiency, maintained Na+/K+ balance, elevated antioxidant enzyme activity, and higher osmolyte levels. Reduced MDA and ROS accumulation further supported the protective role of BvKUP13 under salt stress.DiscussionThese findings demonstrate that BvKUP13 enhances salt tolerance by regulating ion homeostasis and strengthening physiological and biochemical stress responses. BvKUP13 is a potential candidate gene for engineering salt-tolerant sugar beet varieties.

Brookite-phase TiO₂ nanoparticles were synthesized via a green route using Spinacia oleracea leaf extract and TiOSO4 as the precursor, and characterized by XRD, FESEM-EDX, FTIR, and UV-Vis/DRS analyses. The nanoparticles displayed a spherical morphology with sizes of 5-12nm. Photocatalytic tests showed that approximately 50% of methylene blue was degraded within 3h under UV light and 5h under visible light. Antibacterial assays revealed minimum inhibitory concentrations (MICs) of 1mg/mL for Escherichia coli (E. coli) and 2mg/mL for Staphylococcus aureus (S. aureus) in dark conditions, pointing to higher susceptibility of Gram-negative bacteria. Under blue light irradiation, the MIC values decreased to 0.5 and 1mg/mL, respectively, while bactericidal effects were observed at 0.5 and 2mg/mL for the same strains. SEM observations confirmed severe bacterial membrane damage, highlighting the role of photocatalytic reactive oxygen species in bacterial inactivation.

Spinach (Spinacia oleracea L.) is a nutrient-dense leafy vegetable characterized by its rapid growth rate, high antioxidant content, and adaptability to various environmental conditions. The elucidation of the genetic regulatory networks of spinach, particularly the transcription factor families are important for stress responses and are essential for improving adaptability and sustainability. A genome-wide analysis identified 42 member families of the Ethylene Response Factor family gene product. Within each clade, they were classified into three major subclades (AP2, ERF and RAV) consistent with the composition of structural domains. Gene mapping showed an uneven number of SpoERF genes on six chromosomes, many of which were clustered together for an unclear purpose and suggests that tandem duplication is an important mechanism responsible for gene expansion. Gene structure and motif analysis revealed highly conserved AP2 domains but varied intron–exon patterns, which suggest functional diversification. Synteny analysis identified phylogeographically strongly related genes between spinach and Arabidopsis thaliana, probably due to ancient duplication events and the conserved functional elements of the essential ERF regulators. Promoter analysis showed extensive enrichment for many cis-acting elements (Abre, DRE, LTR, W-box, G-box) and revealed involvement of SpoERFs in hormone, developmental, and environmental stress responses among SpoERF family. The findings of this study systematically identify and characterize the AP2/ERF gene family in spinach, revealing their chromosomal organization, evolutionary relationships, conserved structural features, and nitrogen-responsive expression patterns, thereby providing candidate regulatory genes for future functional studies and molecular improvement of nitrogen-use efficiency in spinach.

The Leafminers, representing a diverse group of insects from various genera within the Agromyzidae family, pose a significant threat to spinach (Spinacia oleracea L.) production. This study aimed to identify single nucleotide polymorphism (SNP) markers associated with leafminer resistance through a genome-wide association study (GWAS) and to evaluate the prediction accuracy (PA) for selecting resistant spinach using genomic prediction (GP). Using a dataset of 84 301 SNPs obtained from whole-genome resequencing, seven GWAS models, including BLINK, FarmCPU, MLM, and MLMM in GAPIT 3, as well as MLM, GLM, and SMR in TASSEL 5, were employed to perform GWAS on a panel of 286 USDA spinach germplasm accessions. Three SNP markers, namely 1_115279256_C_T, 3_157082529_C_T, and 4_168510908_T_G on chromosomes 1, 3, and 4, respectively, were identified as associated with leafminer resistance. In the 30 kb flanking regions of these markers, four candidate genes (SOV1g031330, SOV1g031340, SOV4g047270, and SOV4g047280), encoding LOB domain-containing protein, KH domain-containing protein, were discovered. Nodulin-like domain-containing protein, and SAM domain-containing protein, were discovered. The PA for leafminer resistance selection was estimated using ten different SNP sets, including two GWAS-derived marker sets (three and 51 SNPs) and eight random marker sets (ranging from 51 to 10 K SNPs) analyzed by seven GP models. The findings emphasized the superior performance of GWAS-derived SNP sets, reaching a PA of up to 0.79 using the cBLUP model. Notably, this research marks the pioneering application of GP in the context of insect resistance, providing a significant advancement in the understanding and management of leafminer resistance in spinach cultivation.

Insights on the translocation, metabolism, and subcellular distribution of mandipropamid enantiomers in spinach (Spinacia oleracea L.) and the effect of cultivation condition and heavy metal lead (Pb).

As a cool-season leafy vegetable, spinach ( Spinacia oleracea L.) is highly sensitive to high temperatures, which limits its year-round production in warm climates. Although many commercial cultivars are marketed as “heat tolerant,” their performance under high temperatures in hydroponic systems remains largely unverified. Full-cycle testing of many cultivars is time-consuming and resource intensive, highlighting the need for rapid, early-stage screening methods to identify heat-tolerant cultivars. Therefore, this study evaluated short-term (4-day) responses of 32 commercial spinach cultivars at two constant temperatures (20 and 30 °C) under indoor farming conditions. Changes in canopy area and petiole elongation, along with chlorophyll fluorescence parameters (variable fluorescence/maximum fluorescence and performance index) and soil plant analysis development (SPAD) index, were analyzed to classify cultivar-specific heat tolerance. At 20 °C, ‘Dallas’, ‘Amador’, and ‘Pawnie’ exhibited the greatest canopy expansion (114%–181%), whereas ‘Lizard’, ‘Sioux’, and ‘Space’ remained compact. A high temperature (30 °C) reduced canopy expansion in most cultivars; however, ‘Mandolin’, ‘SV2157’, and ‘SV3580VC’ maintained stable canopy growth, indicating high heat resilience. Compact, yet consistent, performers ‘Lakeside’, ‘Lizard’, and ‘Sioux’ also maintained stable growth under heat, suggesting suitability for production in warm climates. In contrast, ‘Hammerhead’, ‘Reflect’, and ‘Rangitoto’ exhibited poor canopy and petiole development, reflecting low heat tolerance. Chlorophyll fluorescence and SPAD index remained relatively constant, suggesting limited sensitivity to short-term heat exposure.

Green spinach (Spinacia oleracea) mediated synthesis of silver nanoparticles-alginate nanocomposites: A reusable platform for dual organic pollutant degradation and bacterial disinfection

Fresh baby leaves are commercially marketed in various mixing ratios and packaging amounts, creating very distinct microenvironmental conditions that significantly affect the postharvest quality of the fresh product. This study investigated the synergistic effect of mixing ratio (50LB, 50% lettuce + 50% spinach; 75LB, 75% lettuce + 25% spinach; 100LB, 100% lettuce) and packaging amount (125F, 125 g; 250F, 250 g) on the antioxidant qualities of baby lettuce and spinach mixes during 9 days of storage at 4 °C. The results showed that 50LB × 250F inhibited the degradation of chlorophyll and carotenoids and preserved 28% higher total antioxidant capacity (TAC), 43% higher total phenolic compounds (TPC), and 20% higher vitamin C (Vit.C) than the mean values of all samples, resulting in 0.8% lower O2 and 14.7% higher CO2 levels at the end of storage. TPC, Vit.C, and carotenoids were the main contributors to TAC, with strong correlations (p < 0.001). The total bacterial (TB) and yeast + mold (Y + M) counts were only affected by the mixing ratios, with TB increasing by only 1 Log10 cfu g−1 FW, and Y + M remaining within the same order of magnitude over time. After 9 days of storage, the leaves were still fresh and marketable. This study not only provides a practical strategy for the fresh-cut industry to enhance product quality but also underscores the significance of multifactorial synergism in salad mix packaging.

Deficiency of iron is a rampant nutritional dispute globally, particularly in developing and underdeveloped countries. Our investigation emphasizes evolving iron-rich cookies by adding Spinacia oleracea L. and Moringa oleifera Lam. leaf powders. They are abundant in vitamins, iron, magnesium and proteins, which are the nutrients essential to our body. These ingredients are dual delivered to cookies to improve nutritional content to address anaemia. The cookies prepared underwent physicochemical analyses. Here, colour, diameter, thickness, moisture and content were analysed. S. oleracea and M. oleifera leaf powder fortified cookies increased the nutrition in cookies when compared to conventional cookies. Sensory evaluation studies revealed the overall acceptability, appearance, flavour, taste and texture using a 9-point hedonic scale. The untutored members' panel revealed a favourable retort to the savoury and sweet selection of cookies. Using DPPH free radical scavenging activity antioxidant activity was investigated. 95.99 % of solid antioxidant potential was observed at a concentration of 10 μg/mL. These fortified cookies provide us with benefits to health, good sensory quality, which in turn makes them a quality food product with probable market value.

Bio-based carbon capture, utilization and storage (CCUS) presents a promising alternative to conventional CCU methods, primarily due to its inherent potential for valorization. In the present study, carbonic anhydrase extracted from spinach leaves (Spinacia oleracea) was immobilized onto citric acid-functionalized magnetite nanoparticles (Fe3O4@CA NPs). This bio-nano hybrid functions as an efficient catalyst for enhancing CO2 solubility by accelerating its conversion to bicarbonate (HCO3⁻), thereby overcoming the low aqueous solubility of gaseous CO2, a known limiting factor in photosynthetic autotrophs. Growth experiments using Escherichia coli cultures supplemented with these NPs demonstrated a ~62% increase in biomass production compared to the control group when the culture was sparged with atmospheric air, demonstrating that carbonic anhydrase-immobilized NPs effectively facilitated the uptake of atmospheric CO2 and redirected it into cellular biomass. Considering that 1 g E. coli dry cell weight can capture ~86 mg CO2, this approach can be used for carbon capture and production of fermentation-derived value-added products. Moreover, such systems hold significant potential for applications in algal biofuel production and the cultivation of slow-growing organisms, such as cyanobacteria, where efficient carbon assimilation is crucial for their growth.

Salinity stress is one of the major abiotic stresses limiting agricultural productivity and reducing crop yields worldwide. Halophilic bacteria play a crucial role in mitigating the adverse effects of saline conditions by producing plant growth-promoting (PGP) substances, thereby enhancing plant stress tolerance. This study aimed to isolate, identify, and purify halophilic PGP bacteria from the Marakkanam salt pan. The isolated colonies were selected based on distinct colony morphology. Molecular characterization based on partial 16S rRNA gene sequencing confirmed diverse halophilic bacterial strains. The isolates were evaluated in vitro at different NaCl concentrations. All strains tolerated NaCl up to 15%, whereas MKM11 grew even at 20%. Multiple plant growth-promoting (PGP) traits were detected, including indole-3-acetic acid (IAA) production, ammonia production, siderophore synthesis, and phosphate and potassium solubilization. A greenhouse experiment on Spinach crop (Spinacia oleracea) under saline stress conditions showed that inoculation with halophilic PGP bacteria remarkably enhanced crop yield, physiological and biochemical performance compared with the control. Treatment with Halobacillus marinus MKM3 increased shoot height by (≈ 85–90%), fresh biomass by (≈ 120–130%), dry biomass by (≈ 220–240%), and total chlorophyll content by (≈ 55–60%), while Halobacillus halophilus MKM11 improved these parameters by (≈ 65–70%), (≈ 100–110%), (≈ 180–200%), and (≈ 40–45%), respectively. Both strains also boosted antioxidant enzyme activities (SOD, POD, and CAT) and reduced lipid peroxidation, reflecting improved stress tolerance. These findings highlight their potential as effective bioinoculants for improving plant performance and enhancing stress resilience in saline soils.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-34907-2.

Elevated atmospheric CO2 is known to alter plant physiology, yet its specific effects on nutrient-rich leafy vegetables remain insufficiently quantified. This study aimed to examine how eCO2 influences yield and nutritional quality in kale (Brassica oleracea) and spinach (Spinacia oleracea) through the first meta-analysis focused exclusively on these crops. Following the Collaboration for Environmental Evidence (CEE) guidelines, we systematically reviewed eligible studies and conducted a random-effects meta-analysis to evaluate overall and subgroup responses based on CO2 concentration, crop type and exposure duration. Effect sizes were calculated using Hedges' g with 95% confidence intervals. The analysis showed that eCO2 significantly increased biomass in spinach (g = 1.21) and kale (g = 0.97). However, protein content declined in both crops (spinach: g = -0.76; kale: g = -0.61), and mineral concentrations, particularly calcium and magnesium, were reduced, with spinach exhibiting stronger nutrient losses overall. The variability in response across different CO2 concentrations and exposure times further underscores the complexity of eCO2 effects. These results highlight a trade-off between productivity and nutritional quality under future CO2 conditions. Addressing this challenge will require strategies such as targeted breeding programmes, biofortification, precision agriculture and improved sustainable agricultural practices to maintain nutrient density. This research provides critical evidence for policymakers and scientists to design sustainable food systems that safeguard public health in a changing climate.

Enhancing Spinacia oleracea growth under arsenic stress by biochar coated-phosphorus and rhizobacteria

The increasing demand for sustainable agriculture requires innovative strategies to enhance nitrogen use efficiency while minimizing environmental losses associated with conventional fertilizers. This study aimed to develop and compare ammonium chloride- and ammonium nitrate-modified nanobiochar as controlled-release nitrogen carriers and to elucidate their effects on nitrogen retention, soil properties, and physiological nitrogen utilization in spinach (Spinacia oleracea L.). Nitrogen-modified nanobiochar was synthesized using ammonium chloride (NB-AC) and ammonium nitrate (NB-AN) at three nitrogen rates (0.03, 0.06, and 0.12 g N g−1 NB) and applied to soil at 1% (w/w). Soil properties, nutrient dynamics, and plant growth and physiological traits were analyzed after 15 and 30 days. Nitrogen modification significantly improved soil nitrogen retention and nutrient availability compared with unmodified nanobiochar. The highest nitrogen loading treatments (NB-AC3 and NB-AN3) notably improved spinach growth, photosynthetic efficiency, pigment content, nitrogen metabolism enzymatic activities, and accumulation of key metabolites (soluble sugars, flavonoids). Nitrogen-release assessments indicated a pronounced controlled-release with reduced nitrogen leaching and greater retention, particularly under NB-AN3. Overall, this study demonstrates that nitrogen-modified nanobiochar functions as an effective nitrogen carrier that enhances nitrogen utilization and growth. These findings provide mechanistic insights into its potential as a sustainable alternative to conventional nitrogen fertilizers.