Search Results (111)

Pak choi (Brassica chinensis L.) has a strong adsorption capacity for the heavy metal cadmium (Cd), which is a big threat to human health. Traditional detection methods have drawbacks such as destructiveness, time-consuming processes, and low efficiency. Therefore, this study aimed to construct a non-destructive prediction model for Cd content in pak choi leaves using hyperspectral technology combined with feature selection algorithms and multivariate regression models. Four different cadmium concentration treatments (0 (CK), 25, 50, and 100 mg/L) were established to monitor the apparent characteristics, chlorophyll content, cadmium content, chlorophyll fluorescence parameters, and spectral features of pak choi. Competitive adaptive reweighted sampling (CARS), the successive projections algorithm (SPA), and random frog (RF) were used for feature wavelength selection. Partial least squares regression (PLSR), random forest regression (RFR), the Elman neural network, and bidirectional long short-term memory (BiLSTM) models were established using both full spectra and feature wavelengths. The results showed that high-concentration Cd (100 mg/L) significantly inhibited pak choi growth, leaf Cd content was significantly higher than that in the control group, chlorophyll content decreased by 16.6%, and damage to the PSII reaction centre was aggravated. Among the models, the FD–RF–BiLSTM model demonstrated the best prediction performance, with a determination coefficient of the prediction set (Rp²) of 0.913 and a root mean square error of the prediction set (RMSEP) of 0.032. This study revealed the physiological, ecological, and spectral response characteristics of pak choi under Cd stress. It is feasible to detect leaf Cd content in pak choi using hyperspectral imaging technology, and non-destructive, high-precision detection was achieved by combining chemometric methods. This provides an efficient technical means for the rapid screening of Cd pollution in vegetables and holds important practical significance for ensuring the quality and safety of agricultural products. Full article

This study evaluated the growth performance and physiological responses of 24 Korean landrace accessions of pak choi (Brassica rapa subsp. chinensis) under polyethylene glycol (PEG)-induced drought stress to identify indicators for selecting drought-resistance genotypes. Electrolyte leakage (EL) and chlorophyll fluorescence (Fv/Fm) analyses showed that resistance accessions (IT262109(11), IT279432(12), IT293143(20)) had minimal increases in EL and maintained high Fv/Fm values under stress, indicating superior membrane stability and photosystem II activity. In contrast, sensitive accessions exhibited a sharp rise in EL and a decline in Fv/Fm to approximately 0.3 under 25% PEG treatment, reflecting severe physiological damage. Principal component analysis (PCA) biplot based on integrated growth and photosynthetic parameters differentiated resistance and sensitive groups, with PC1 representing photosynthetic efficiency versus membrane injury. Growth trait responses interaction analysis using GGE biplot of six representative accessions (three resistance, three sensitive) demonstrated that resistance genotypes had smaller positional shifts across treatments, indicating greater growth stability, while sensitive genotypes showed pronounced variability and environment-specific responses. This study provides a framework integrating growth and physiological indicators for identifying drought-resistance pak choi accessions, offering valuable implications for breeding programs aimed at climate-resilient cultivar development. Full article

Black soil, as a vital environment for food production, is currently facing severe degradation. Earthworm tillage is recognized as an effective approach to improving black soil structure; however, its optimal implementation strategy remains unclear. In this study, a pot experiment using Pak Choi (Brassica rapa L. ssp. chinensis) was conducted under an orthogonal design with three factors—earthworm size, application timing, and quantity. Combined with yield measurement, analysis of variance (ANOVA), and grey relational analysis (GRA), the effects of earthworm application on plant growth and soil structure were systematically evaluated. In addition, Computer Tomography (CT) scanning and three-dimensional reconstruction were employed to visualize the pore structures of representative soil samples. The results showed that large earthworms significantly enhanced both leaf and root biomass of Pak Choi, exhibiting a stronger promoting effect than small earthworms. Application at the sowing stage resulted in the greatest yield improvement, whereas applications at other growth stages had limited effects. The number of earthworms did not show a statistically significant impact under the experimental conditions, and its potential influence requires further verification under more refined density gradients. Overall, this study elucidates the mechanisms by which earthworm tillage improves soil structure and promotes crop growth, providing a theoretical basis for the restoration and sustainable utilization of degraded black soil. Full article

Environmental factors like light, photoperiod, temperature, and water are vital for crop growth, and even slight deviations from their optimal ranges can cause seedling stress and reduce yield. Therefore, this study aimed to quantify seedling stress symptoms using image features analysis under varying light, photoperiod, temperature, and water conditions. Seedlings were grown under controlled low, normal, and high environmental conditions. Light intensity at 50 µmol m⁻² s⁻¹ (low), 250 µmol m⁻² s⁻¹ (normal), and 450 µmol m⁻² s⁻¹ (high), photoperiod cycles, 8/16 h (day/night) (low), 10/14 h (day/night) (normal), and 16/8 h (day/night) (high) day/night, temperature at 20 °C (low), 25 °C (normal), and 30 °C (high), and water availability at 1 L per day (optimal), 1 L every two days (moderate stress), and 1 L every three days (severe stress) were applied for 15 days. Commercial low-cost RGB, thermal, and depth sensors were used to collect data every day. A total of 1080 RGB images, which were pre-processed with histogram equalization and filters (Median and Gaussian), were used for noise reduction to minimize illumination effects. Morphological, color, and texture features were then analyzed using ANOVA (p < 0.05) to assess treatment effects. The result shows that the maximum canopy area for tomato was 115,226 pixels, while lettuce’s maximum plant height was 9.28 cm. However, 450 µmol m⁻² s⁻¹ light intensity caused increased surface roughness, indicating stress-induced morphological alteration. The analysis of Combined Stress Index (CSI) values indicated that the highest stress levels were 50% for pepper, 55% for tomato, 62% for cucumber, 55% for watermelon, 50% for lettuce, and 50% for pak choi. The findings showed that image-based stress detection enables precise environmental control and improves early-stage crop management. Full article

Lettuce (Lactuca sativa), pak choi (Brassica rapa), and basil (Ocimum basilicum) were grown in hydroponic NFT systems under four nitrate levels (80–180 mg L⁻¹ N). We measured natural microbial contamination by plating nutrient-solution samples and leaf washes to obtain colony-forming unit (CFU) counts of bacteria and fungi. Separately, postharvest leaves were artificially inoculated with Botrytis cinerea and stored at 22 °C or 4 °C for 7 days to assess gray mold. In lettuce, high N (180 mg L⁻¹) markedly increased culturable microbial loads in both solution and leaves, whereas pak choi microbial counts remained low at all N levels. Basil showed a non-linear response: CFU counts peaked at moderate N (120 mg L⁻¹) and were lower at both deficit and excess N. At 22 °C, gray mold severity in pak choi increased with N; leaves fertilized at N150–180 suffered about 1.5–2 times greater lesion area than those at N80. By contrast, lettuce exhibited the worst decay under N deficiency: N80 leaves developed the largest lesions by 4–7 DPI, while moderate N (120–150 mg L⁻¹) minimized disease progression. Basil was highly susceptible under warm storage: all N levels reached near-total decay by 7 days, though N120 delayed early infection slightly. Refrigeration (4 °C) greatly suppressed lesion development in lettuce and pak choi, although high-N pak choi still showed ~20–30% more infected area than low-N after 7 days. Basil, however, suffered chilling injury at 4 °C, and all refrigerated basil leaves decayed severely (regardless of N). These results indicate crop-specific nutrient and storage strategies: avoid excessive N in pak choi, maintain balanced N in lettuce, and handle basil with non-chilling methods to reduce postharvest gray mold. Full article

Lead (Pb) in soil poses serious environmental and health risks, and its removal requires complex and costly treatment methods to meet strict regulatory standards. To effectively address this challenge, innovative and efficient techniques are essential. Sepiolite-supported MnFe₂O₄ (MnFe₂O₄/SEP) composites were synthesized via a chemical co-precipitation method. The effects of MnFe₂O₄/SEP on soil pH, cation exchange capacity (CEC), available Pb content, Pb²⁺ uptake, and the activities of antioxidant enzymes in Brassica chinensis (Pak Choi) were examined. MnFe₂O₄/SEP showed superior Pb²⁺ adsorption compared to SEP alone, fitting Langmuir models, Dubinin-Radushkevich (D-R) models, Temkin models and pseudo-second-order kinetics. The maximum adsorption capacities at 298, 308, and 318 K were 459, 500 and 549 mg·g⁻¹, respectively. XPS analysis indicated that chemisorption achieved through ion exchange between Pb²⁺ and H⁺ was the main mechanism. MnFe₂O₄/SEP increased the soil pH by 0.2–1.5 units and CEC by 18–47%, while reducing available Pb by 12–83%. After treatment with MnFe₂O₄/SEP, acid-extractable and reducible Pb in the soil decreased by 14% and 39%, while oxidizable and residual Pb increased by 26% and 21%, respectively. In Brassica chinensis, MnFe₂O₄/SEP reduced Pb²⁺ uptake by 76%, increased chlorophyll content by 36%, and decreased malondialdehyde (MDA) levels by 36%. The activities of antioxidant enzymes—superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)—were decreased by 29%, 38% and 17%, respectively. These findings demonstrate that MnFe₂O₄/SEP is an efficient Pb²⁺ adsorbent that immobilizes Pb in soil mainly through ion exchange, thereby providing a highly effective strategy for remediating Pb-contaminated soils and improving plant health. Full article

The fate and risk identification of cyantraniliprole (CYA) and lufenuron (LUF) in pak choi were systematically analyzed through an investigation comprising field trials, dissipation kinetics, and dietary risk assessment. Initially, field experiments across ten Chinese provinces revealed half-lives of 3.04–5.41 d for CYA and 2.02–5.13 d for LUF, with dissipation following single first-order (SFO) kinetics or double first-order in parallel (DFOP) kinetics. Terminal residues (<limit of quantification (LOQ) to 0.29 mg/kg) were below maximum residue limits. Dissipation rates were significantly influenced by temperature, climate, and crop growth stage. Additionally, the multidimensional dietary assessment using deterministic and probabilistic models revealed acceptable long-term risk levels for CYA and LUF among consumer groups (risk quotients < 28.4%). Overall, this first comprehensive study from cultivation to consumption provides crucial insights for rational pesticide use in pak choi. Full article

Developing environmentally friendly and cost-effective substrates is critical to enhance resource efficiency and productivity in plant factories with artificial lighting (PFALs). This study employed a molded coconut coir substrate (coconut coir composited with polyurethane hydrophilic adhesive, MCCS) in PFALs to cultivate lettuce (Lactuca sativa L.) and pak choi (Brassica rapa ssp. chinensis). During the transplanting stage, the roots exposed outside the MCCS of lettuce and pak choi were 13.40% and 19.92% shorter, respectively, than in the sponge treatment, and more amenable to mechanical transplanting. This compensated for the neglect of operational efficiency in traditional lifecycle assessment (LCA). Furthermore, compared with sponge and rockwool, MCCS significantly enhanced the yield of lettuce and pak choi by up to 27.33% and 67.19%, respectively. Meanwhile, MCCS significantly increased the chlorophyll content of lettuce compared to sponge by 8.56%. Compared with rockwool, MCCS significantly increased the chlorophyll b content (7.36%), antioxidant content, and antioxidant activity (total phenolics by 13.59%, total flavonoid by 18.43%, FRAP by 12.96%, and DPPH by 19.87%) of lettuce. For pak choi, MCCS increased the soluble protein content in the blade and total phenolics content in the petiole by 32.01% and 14.76%, respectively. More importantly, the use of MCCS led to a significant reduction in the energy consumption per unit area yield of lettuce and pak choi, with maximum reductions of 22.98% and 40.91%, respectively. This eco-friendly substrate is suitable for replacing sponge and rockwool in the production of lettuce and pak choi in PFALs. Full article

This study investigates growth responses, heavy metal (Cd, As) uptake, translocation, and mineral nutrient regulation in leafy vegetables with varying heavy metal tolerance, addressing the threat posed by combined Cd and As pollution. Three high-tolerance, four moderate-tolerance, and one sensitive leafy vegetable were grown in Cd+As-contaminated hydroponics. Post-harvest yields and concentrations of Cd, As, and trace elements were assessed. Results showed that (1) compared with single heavy metal treatments, the combination of Cd and As significantly increased the translocation factor of Cd in black bean sprouts and white radish sprouts by up to 83.83% and 503.2%; (2) changes in mineral nutrient concentrations in leafy vegetables were similar between single and combined heavy metal stresses, but the regulatory patterns varied among different leafy vegetable species; (3) under Cd/As exposure, high-tolerance leafy vegetables (e.g., pak choi) had strong heavy metal accumulation abilities, and heavy metal stress positively regulated mineral elements in their roots; In contrast, sensitive leafy vegetables (e.g., pea sprouts) often exhibited suppressed mineral element content in their roots, which was a result of their strategy to reduce heavy metal uptake. These results offer key insights into resistance mechanisms against combined heavy metal pollution in leafy vegetables, supporting phytoremediation efforts and safe production. Full article

Microgreens, having short growth cycles and efficient nutrient uptake, are ideal candidates for biofortification. This study investigated the effects of selenium (Se) and zinc (Zn) on photosynthetic performance in four hydroponically grown Brassica microgreens (broccoli, pak choi, kohlrabi, and kale), using direct and modulated chlorophyll a fluorescence and chlorophyll-to-carotenoid ratios (Chl/Car). The plants were treated with Na₂SeO₄ at 0 (control), 2, 5, and 10 mg/L or ZnSO₄ × 7H₂O at 0 (control), 5, 10, and 20 mg/L. The results showed species-specific responses with Se or Zn uptake. Selenium enhanced photosynthetic efficiency in a dose-dependent manner for most species (8–26% on average compared to controls). It increased the plant performance index (PI_tot), particularly in pak choi (+62%), by improving both primary photochemistry and inter-photosystem energy transfer. Kale and kohlrabi exhibited high PSII-PSI connectivity for efficient energy distribution, with increased cyclic electron flow around PSI and reduced Chl/Car up to 8.5%, while broccoli was the least responsive. Zinc induced variable responses, reducing PI_tot at lower doses (19–23% average decline), with partial recovery at 20 mg/L (9% average reduction). Broccoli exhibited higher susceptibility, with inhibited Q_A re-oxidation, low electron turnover due to donor-side restrictions, and increased pigment ratio (+3.6%). Kohlrabi and pak choi tolerated moderate Zn levels by redirecting electron flow, but higher Zn levels impaired PSII and PSI function. Kale showed the highest tolerance, maintaining stable photochemical parameters and total electron flow, with increased pigment ratio (+4.5%) indicating better acclimation. These results highlight the beneficial stimulant role of Se and the dual essential/toxic nature of Zn, thus emphasizing genotype and dose-specific optimizations for effective biofortification. Full article

Salinization severely impairs crop growth by inducing oxidative stress and disrupting cellular homeostasis. This study systematically investigates the synergistic effects of salt-tolerant plant-growth-promoting rhizobacteria (ST-PGPR) and foliar silicon fertilizer spraying (FSFS) on antioxidant responses in Pak choi under salt stress. Two-season pot experiments were carried out to evaluate key indicators, including antioxidant enzyme activities (superoxide dismutase: SOD; peroxidase: POD; catalase: CAT), oxidative stress (malondialdehyde: MDA), osmolyte accumulation (proline, soluble protein), and hormones (Jasmonic Acid: JA; Salicylic Acid: SA; Abscisic acid: ABA). The results demonstrate that combining ST-PGPR with FSFS significantly enhances SOD (6.18–2353.85%), POD (3.44–153.29%), and CAT (25.71–319.29%) activities while reducing MDA content (8.12–35.87%). Proline and soluble protein levels increased by 1.56–15.71% and 5.03–188.87%, respectively. Hormonal regulation increased JA, SA, and ABA levels by 1.05–31.81%, 2.09–34.29%, and 3.18–30.09%, respectively. Notably, ST-PGPR treatments at 10⁴ and 10⁶ cfu·mL⁻¹, combined with foliar silicon application, consistently ranked highest in overall antioxidant performance across both seasons based on a principal component analysis. These findings provide novel insights into microbial–mineral interactions for sustainable saline agriculture. Full article

Biofertilizers derived from microalgae are increasingly used as promising materials for improving crop growth and development, producing fewer catastrophic environmental effects. Hence, the large-scale production of eco-friendly and broad-spectrum microalgae biofertilizers is mandatory. Therefore, this study was designed to examine the potential efficacy of isolated algae strains, such as Spirulina platensis, Spirulina maxima, and Chlorella vulgaris, to improve the growth and development of Pak Choi. A completely randomized design (CRD) was carried out, with five replications and six levels (0, 0.5, 1.0, 1.5, 2.0, and 2.5 g) of each microalga biofertilizer, using Pak Choi as the test plant. Treatment with microalgae biofertilizers was found to increase Pak Choi’s overall growth performance, biochemical development, and nutritional composition. The application of Spirulina platensis and Spirulina maxima microalgae at 2 g as a biofertilizer showed significant (p < 0.05) positive impacts on above- and below-ground biomass, photosynthetic parameters, biochemical composition, and the nutritional attributes of different parts of Pak Choi tissues. With the addition of biofertilizer, incorporating Chlorella vulgaris (2.5 g) showed remarkable (p < 0.05) impacts on the development of above- and below-ground biomass and biochemical and nutritional attributes. Thus, our results highlight that Chlorella vulgaris (2.5 g) outperforms other biofertilizer treatments and could be considered a sustainable approach for producing leafy vegetables. Full article

Postharvest leaf senescence is a pivotal determinant influencing the quality and shelf life of leafy vegetables, exemplified by pak choi (Brassica rapa L. subsp. chinensis). While the regulatory role of gibberellin (GA) in modulating leaf senescence has been documented across diverse plant species, the underlying physiological and molecular mechanisms remain insufficiently characterized. This study, through a combination of transcriptomic and metabolomic analyses, investigated the effect of exogenous GA on postharvest leaf senescence in pak choi. GA treatment alleviated etiolation, maintained chlorophyll levels, reduced conductivity and malondialdehyde content, and delayed the onset of senescence symptoms in postharvest pak choi. Transcriptome profiling indicated that GA suppressed the expression of the senescence-associated genes BraSRGs and BraSAGs. In addition, GA influenced chlorophyll degradation and preserved chlorophyll content by modulating the expression of genes implicated in chlorophyll metabolism, including BraPPH, BraSGR1, BraNYCI, and BraPAO. GA treatment impacted lipid levels and regulated the degradation of membrane phospholipids. Furthermore, exogenous GA treatment disrupted the efficacy of the jasmonic acid signal pathway, primarily through the transcriptional downregulation of key regulatory genes, including BraJAZ10 and BraJAR1. These results provide insights into the role of GA in delaying postharvest leaf senescence and highlight potential targets for improving postharvest management in leafy vegetables. Full article

This study investigated the effects of dietary iron supplementation on water quality, plant growth, and fish health in an aquaponic system over 90 days. Iron supplementation significantly improved plant growth, with increased plant height, stem diameter, leaf count, and fruit yield in tomatoes (Solanum lycopersicum) and pak choi (Brassica rapa subsp. Chinensis) (p < 0.05). The water pH fluctuated with varying iron content, and higher iron levels promoted better plant growth by improving iron availability (p < 0.05). During the first 60 days, all red blood cell counts and hemoglobin levels increased, but the growth and nutritional composition of mirror carp (Cyprinus carpio var. specularis) showed no significant differences. By day 90, fish in the T3 group (800 mg/kg iron) exhibited significantly reduced growth and feed conversion rates (p < 0.05). Histological analysis of liver tissue indicated iron-induced liver damage; additionally, excessive iron intake suppressed erythropoiesis, leading to lower red blood cell counts and hemoglobin levels (p < 0.05). The results indicate that moderate iron supplementation improves plant growth, but excessive iron can negatively impact fish health, particularly liver function and blood formation. These findings provide valuable insights for optimizing iron levels in aquaponic systems. Full article

Among the Brassica species in China, including Chinese cabbage, pak-choi, caixin, zicaitai, and wucai, Brassica rapa plays an important role in vegetable production. Purple resources from the species itself are scarce. It is worth noting that the tissue positions expressing a purple phenotype vary greatly between purple pak-choi and zicaitai. In this study, the genetic patterns of the purple phenotype were analyzed in purple pak-choi and zicaitai, and the F₁ showed purple leaves and green stems, which indicated that purple traits in the leaves and stem were inherited independently. In conjunction with field identification, RNA-seq was used to sequence the transcriptomes of the purple expression sites of purple pak-choi, zicaitai, and their F₁. The high expression of the regulatory genes Dark_pur and BrTT8 affected the purple color of pak-choi and caused the high expression of structural genes of the anthocyanin metabolism pathway and the accumulation of anthocyanins in leaves. The regulatory genes BrPAP₂ and BrTT8 affected the purple color of zicaitai stems, were significantly upregulated, and caused high expression of related structural genes, leading to the accumulation of anthocyanins in the stem epidermis. This suggested that BrPAP₂ and Dark_pur were both R2R3-MYB transcription factors, which were tissue-specific for the regulation of purple color traits in B. rapa. They also had a gene epistatic effect, which influenced the expression of purple traits in the F₁. The gene MYBL2 was highly expressed in all purple tissue sites. The present study on the regulatory genes of the purple phenotype of zicaitai and purple pak-choi provides a theoretical basis for revealing the influence of purple traits on B. rapa leaves and stems, and it may lay the foundation for the selection and breeding of purple vegetables of B. rapa. Full article