Search Results (160)

Vertical farming systems offer an efficient solution for sustainable food production in urban areas. However, managing nitrate (NO₃⁻) levels remains a significant challenge for improving crop yield, quality, and safety. This study evaluated the effects of nitrate availability on growth performance, nutrient uptake, and water use efficiency in a vertical hydroponic system that intercropped lettuce (Lactuca sativa) with alfalfa (Medicago sativa). The experiment was conducted in a controlled vertical hydroponic system using Nutrient Film Technique (NFT) channels, with nitrogen levels set at 0, 33, 66, 100, and 133% of the standard concentration. The results indicated that the intercropping treatment with 66% nitrate (IC-N_66%) improved water use efficiency by 38% and slightly increased leaf area compared to the other intercropping treatments. However, the control group, which consisted of a monoculture with full nitrate supply, achieved the highest overall biomass. Ion concentrations, including nitrate, calcium, magnesium, and micronutrients, were moderately affected by the intercropping strategy and nitrate levels. These findings suggest that moderate nitrate input, combined with nitrogen-fixing legumes, can enhance resource efficiency in hydroponic systems without significantly compromising yield. These findings offer a promising framework for incorporating legumes into hydroponic systems, minimizing the need for synthetic inputs while maintaining yield. These results support the use of agroecological intensification strategies in highly efficient soilless systems. Full article

Salinity stress is a major environmental challenge that adversely impacts the physiological and biochemical processes of pasture, consequently resulting in reduced yields and compromised quality. Biochar amendment has recently emerged as a promising strategy to alleviate the deleterious effects of salinity stress. However, the interactive influences of salinity stress and wheat straw biochar on the physiological, biochemical, and growth characteristics of alfalfa (Medicago sativa L.) remain underexplored. A factorial experiment was conducted using a randomized complete design with five salinity levels (0, 25, 50, 75, and 100 mM NaCl) and three application rates of biochar (0, 25, and 50 g kg⁻¹) to evaluate wheat straw biochar’s potential in alleviating salinity stress in alfalfa. Results showed that salinity stress increased oxidative stress (hydrogen peroxide and malondialdehyde) and reduced chlorophyll fluorescence (maximum quantum efficiency of photosystem II by 1–27%), leading to decreasing photosynthetic parameters, thereby constraining biomass accumulation by 9–77%. Wheat straw biochar amendment under the highest salinity stress, particularly at 25 g kg⁻¹, mitigated oxidative stress by reducing H₂O₂ and MDA levels by 35% and 33%, respectively, while decreasing the antioxidant enzymes activities of CAT, POD, and SOD by 47%, 42%, and 39%, respectively, compared to the control (non-biochar addition). Concurrently, biochar restored the osmoregulatory substance concentrations of proline and soluble sugar by 59% and 33%, respectively, compared to the control. Furthermore, wheat straw biochar amendment increased the net CO₂ assimilation rate by 98%, thereby increasing biomass by 63%. Our study demonstrates that wheat straw biochar can contribute to protecting alfalfa against salinity stress by modulating physiological and biochemical responses. These findings demonstrate that the 25 g kg⁻¹ wheat straw biochar application had the best performance, suggesting this amendment could be a viable strategy for improving alfalfa productivity in salt-affected soils. Future research should explore long-term field applications and the underlying mechanisms of biochar–plant–soil–plant interactions under diverse saline-alkali environments. Full article

This study presents an investigation on the potential of using one-year-old field-stored Medicago sativa (alfalfa) as a raw material for a multi-output biorefinery. The main objective was to fractionate the biomass into valuable components—crude protein, hemicellulose-derived polysaccharides, lignin, and cellulose—and to explore the latter’s suitability in papermaking. To this end, three pretreatment strategies (water, alkaline buffer, and NaOH solution) were applied, followed by soda pulping under varying severity conditions. Both solid and liquid fractions were collected and chemically characterized using FTIR, HPLC, and standardized chemical methods. Water-based pretreatment was most effective for protein extraction, achieving over 40% protein content in precipitated fractions. The harshest pulping conditions (20% NaOH, 160 °C, 60 min) yielded cellulose-rich pulp with high glucan content, while also facilitating lignin and hemicellulose recovery from black liquor. Furthermore, the pulps derived from alfalfa stems were tested for papermaking. When blended with old corrugated cardboard (OCC), the fibers enhanced tensile and burst strength by 35% and 70%, respectively, compared to OCC alone. These findings support the valorization of unexploited alfalfa deposits and suggest a feasible biorefinery approach for protein, fiber, and polymer recovery, aligned with circular economy principles. Full article

The critical nitrogen dilution curve (CNDC) model enables precise nitrogen management by quantifying the threshold of nitrogen deficiency in crops, thereby enhancing both crop productivity and nitrogen use efficiency. However, its applicability to perennial crops remains unclear. In this study, alfalfa (Medicago sativa L.), a perennial leguminous forage, was used as the model crop. Based on two years of field experiments, CNDC models of aboveground biomass were constructed under two nitrogen fertilizer regimes: urea (0, 80, 160, and 240 kg·ha⁻¹, applied in a 6:2:2 basal-to-topdressing ratio) and controlled-release urea (CRU; 0, 80, 160, and 240 kg·ha⁻¹, applied as a single basal dose). Using these models, the nitrogen nutrition index (NNI) and cumulative nitrogen deficit (N_and) models were developed to diagnose alfalfa nitrogen status, and the optimal nitrogen application rates were determined via regression analysis. The results showed that critical nitrogen concentration and aboveground biomass followed a power function relationship under both fertilizer types. For CRU treatments, parameters a and b were 3.41 and 0.20 (first cut), 3.15 and 0.12 (second cut), and 2.24 and 0.40 (third cut), respectively. For urea treatments, a and b were 3.13 and 0.35 (first cut), 2.21 and 0.16 (second cut), and 1.75 and 0.73 (third cut). The normalized root mean square error (n-RMSE) of the models ranged from 3.1% to 13%, indicating high model reliability. Based on the NNI, N_and, and yield response models, the optimal nitrogen application rates were 175.44~181.71 kg·ha⁻¹ for urea and 145.63~153.46 kg·ha⁻¹ for CRU, corresponding to theoretical maximum yields of 14.76~17.40 t·ha⁻¹ and 16.76~20.66 t·ha⁻¹, respectively. Compared to urea, CRU reduced nitrogen input by 18.41~20.47% while achieving equivalent or higher theoretical yields. This study provides a scientific basis for nitrogen status diagnosis and precision nitrogen application in alfalfa cultivation. Full article

Alfalfa (Medicago sativa L.) is a globally significant forage crop with notable economic value. Gibberellins (GA₃) promote dormancy breaking and early germination whereas auxins (IAA) predominantly influence bud regeneration. This study investigated the effects of exogenous gibberellins and indole acetic acid on the regeneration and biomass of crown buds in two alfalfa varieties with different dormancy levels. The experiment involved five concentrations each of gibberellins (0 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, and 40 mg/L) and auxins (0 mg/L, 5 mg/L, 10 mg/L, 15 mg/L, and 20 mg/L). The results indicated that both exogenous gibberellins and auxins significantly increased the endogenous levels of these hormones in the crown buds, while decreasing abscisic acid (ABA) levels. There was also a significant increase in sugar and total nitrogen content in the buds. Treatments with exogenous gibberellins enhanced the number of crown buds and the aboveground biomass per plant, with the best results at 30 mg/L. Auxin treatments showed the largest increase in aboveground biomass per plant at 15 mg/L. In summary, 30 mg/L gibberellins or 15 mg/L auxins is recommended as the optimal spraying concentration. This research provides practical evidence for the regulation of exogenous growth regulators in alfalfa cultivation. Full article

Soil salinization represents a significant global environmental challenge, necessitating the urgent amelioration of saline–alkali lands. As a critical functional component of the soil system, soil aggregates play a pivotal role in enhancing soil structure and are essential for nutrient cycling and plant growth. However, the synergistic effects of plants and microorganisms on alterations in soil aggregate composition, stability, and nutrient content in saline–alkali soils remain inadequately understood. In this study, three saline soil gradients from the Yellow River Delta were analyzed: low saline soil (S1, 1.65 g/kg), medium saline soil (S2, 4.54 g/kg), and high saline soil (S3, 6.57 g/kg). For each gradient, four experimental treatments were established: (1) inoculation of Bacillus tropicus YJ33 alone (B), (2) planting of alfalfa alone (M), (3) combined alfalfa cultivation with B. tropicus YJ33 inoculation (MB), and (4) an unamended control (CK). These treatments were implemented in controlled laboratory pot experiments to evaluate the individual and synergistic impacts of alfalfa and B. tropicus YJ33 on saline soil aggregate stability and structural organization. Overall, B. tropicus YJ33 inoculation significantly promoted the growth and nutritional quality of alfalfa. B, M, and MB treatment increased the contents of total carbon (TC), total nitrogen (TN), and available phosphorus (AP) and promoted the activities of soil alkaline phosphatase (S-ALP) and soil urease (S-UE) in the soil. Simultaneously, these treatments resulted in a reduction in the proportion of micro-aggregates, an increase in the proportion of large and small aggregates, and significantly enhanced mean weight diameter (MWD) and geometric mean diameter (GMD), improving the stability of soil aggregates. Random forest analysis identified AP, B. tropicus YJ33, salinity, TC, and available nitrogen (AN) as key determinants of alfalfa biomass. Partial least squares (PLS) modeling further corroborated the role of B. tropicus YJ33 in enhancing soil nutrient content, improving aggregate stability, and increasing alfalfa yield. In conclusion, B. tropicus YJ33 was demonstrated to enhance the stability of soil aggregates and nutrient availability in saline–alkali soils, thereby significantly promoting the growth, yield, and nutritional quality of alfalfa. Full article

This study evaluates the environmental impacts of different biomass pretreatment methods used for biomethane production using a life cycle assessment (LCA) approach. The three examined pretreatment technologies—CO₂ injection, rumen fluid, and biological products—were applied to manure, alfalfa biomass, and winter wheat straw. The results indicate that cow manure pretreatment with CO₂ increases fossil fuel depletion from 0.37 MJ/m³ to 17.31 MJ/m³ and increasing global warming potential by 1.08 kg CO₂ eq/m³. Rumen fluid pretreatment moderately improves fossil fuel conservation but raises acidification (from 1.57 × 10⁻⁴ kg SO₂ eq/m³ to 2.49 × 10⁻⁴ kg SO₂ eq/m³) and eutrophication (from 2.67 × 10⁻⁵ kg PO₄ eq/m³ to 5.3 × 10⁻⁵ kg PO₄ eq/m³). Winter wheat straw CO₂ pretreatment demonstrates the most favorable environmental profile, reducing human toxicity (from 0.1 kg 1,4-DB eq/m³ to 0.0058 kg 1,4-DB eq/m³) and minimizing fossil fuel depletion. The environmental trade-offs of biomethane production suggest that optimizing pretreatment strategies is essential to ensuring sustainable production. Full article

Alfalfa (Medicago sativa L.) is an important perennial leguminous forage; however, its high sensitivity to aluminum (Al) stress severely restricts its cultivation in regions with acidic soil. Therefore, this study conducted an integrated assessment of Al stress tolerance by performing systematic evaluations of 11 growth and physiological parameters across 30 alfalfa cultivars under Al stress, and calculated the Al tolerance coefficients based on these parameters. The results revealed that Al stress markedly inhibited root growth and biomass accumulation in alfalfa, thereby triggering increased malondialdehyde (MDA) content in roots across most cultivars, the scope of increase is 0.19–183.07%. Moreover, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) increased by 7.50–121.44%, 2.50–135.89%, and 3.84–70.01%, respectively. Based on the comprehensive evaluation value (D) obtained via principal component analysis and membership function, the 30 alfalfa cultivars were categorized into four distinct groups: 4 highly Al-tolerant cultivars, 11 moderately high-Al-tolerant cultivars, 9 moderately low-Al-tolerant cultivars, and 6 low-Al-tolerant cultivars. Stepwise linear regression analysis identified root elongation rate, root-to-shoot ratio, root volume, SOD, MDA, CAT, root dry weight, POD, and root length as pivotal indicators for predicting and evaluating Al stress tolerance in alfalfa cultivars. The qRT-PCR analysis showed dynamic changes in ABC transporter gene expression in alfalfa roots over time under aluminum stress. Therefore, this study comprehensively evaluated Al tolerance by systematically investigating the morphophysiological effects of Al stress across 30 alfalfa cultivars using principal component analysis (PCA), membership function, and hierarchical clustering analysis. It provides a practical solution for expanding alfalfa planting in acid soil and improving feed production in acidic environments. Full article

High pH, ${\mathrm{Na}}^{+}$, and $({\mathrm{CO}}_3^{2-}+{\mathrm{HCO}}_3^{-}$) are the primary characteristics of soda saline–alkali soil. Current strategies for ameliorating soda saline–alkali soil often involve the combined use of cow manure and maize straw, the addition of biochar (BC), and the inoculation of Bacillus subtilis (BS). In this study, B. subtilis-loaded biochar (BSC) was prepared using an adsorption technique. An incubation experiment was conducted. The treatments were as follows: soda saline–alkali soil amended with maize straw and cow manure (T₁), which was used as a control; T₁ supplemented with earthworms (T₂); and T₂ supplemented with BS (T₃), BC (T₄), or BSC (T₅). After a 60-day incubation, T₅ showed the most significant reduction in pH, ESP, and (${\mathrm{H}\mathrm{C}\mathrm{O}}_3^{-}$ + ${\mathrm{C}\mathrm{O}}_3^{2-}$) concentrations, with reductions of 0.24 units, 3.26%, and 120 mg kg⁻¹, respectively, compared to the T₁ treatment. The content of soil humic acid, available potassium, and available nitrogen and the activities of β-glucosidase and urease were highest in T₅, increasing by 33.5%, 70.1%, 26.1%, 19.0%, and 17.9%, respectively. Microbial sequencing analysis revealed that the Bacillus abundance in T₃ was highest during the first 45 days (2.51–3.65%), while the Bacillus abundance in T₅ peaked at 3.22% after the 60-day incubation. The soil that was cultivated for 60 days in the experiments was then used for planting alfalfa. T₅ showed the highest alfalfa aboveground biomass and peroxidase, increasing by 30.1% and 73.1%, respectively, compared with T₁. This study demonstrated that loading onto biochar is beneficial for the survival of B. subtilis in soda saline–alkali soil. When traditional organic materials are used, the combination of earthworms and B. subtilis-loaded biochar significantly alleviates the constraints of soda saline–alkali soil. Full article

Increasing soil salinity is threatening agricultural productivity which implies the development of new sustainable strategies to deal with this challenge. The main objective here is to assess the potential for improving the tolerance of alfalfa to salinity by combining inoculations with rhizobia and AMF. However, the distinguishing feature of this study is the comparison of two alfalfa varieties’ microbial response to salinity. The greenhouse trial was conducted on an Australian variety Siriver and an indigenous Demnate population, which were inoculated with Rhizoglomus irregulare and/or native AMF, and/or a RhOL1 rhizobial strain. The RhOL1 strain was selected from nine rhizobia tested for their plant growth promoting rhizobacteria (PGPR) activities. In addition to its ability to tolerate high salinity levels (769 mM) and solubilize insoluble phosphate as well as potassium, it can also synthesize auxins such as IAA. The application of these biofertilizers was carried out in the absence and the presence of the saline stress (0 and 120 mM NaCl). The double inoculations of native AMF and RhOL1 significantly improve the shoot and root dry biomass, plant elongation, number of formed leaves, and mineral nutrition, as well as the number of nodules and the rate of mycorrhizal root colonization. The synergistic effects between the native AMF and RhOL1 strain have been demonstrated in this study. However, the behavior of alfalfa genotypes towards microbial inoculation was significantly different. The ability to react to the double indigenous RhOL1 + AMF inoculation is more important in the Siriver than in the Demnate population. Thus, the possibility of formulating biofertilizers is based on the AMF–rhizobia–hote tripartite combination for alfalfa production in saline areas. Full article

In this study, alfalfa (Medicago sativa L.) is evaluated for suitability of variable rate irrigation (VRI) by analyzing within-field variation in crop water productivity (CWP) under uniform irrigation. The objectives were to (1) measure within-field variation in crop evapotranspiration (ET), (2) quantify spatial variability of alfalfa biomass yield, and (3) assess whether a bivariate analysis of CWP and yield could inform VRI management zones. Research was conducted on a 22.6 ha center-pivot irrigated alfalfa field near Rexburg, Idaho, USA, over three harvest intervals (HIs) in 2021 and 2022. Using a water balance method at 66 field points, ET exhibited significant spatial clustering for each HI (p < 0.001 for all HIs), though spatial patterns varied among HIs. Biomass yield, measured via the quadrat method, ranged from 2.1 to 9.7 Mg ha⁻¹, with significant spatial clustering (p < 0.001 for all HIs). The CWP ranged from 0.07 to 0.54 Mg ha⁻¹ cm⁻¹, also showing significant spatial clustering (p < 0.001 for all HIs). Bivariate cluster analysis indicated 12–18% more area of the field was over-watered than under-watered, suggesting potential for optimizing irrigation with VRI. Reducing irrigation in these over-watered zones could improve CWP, supporting alfalfa as a viable candidate for VRI. Full article

Amending saline–alkali soils to improve agricultural productivity is critical for addressing global food security challenges. Biochar is a promising soil amendment, and its modified composites offer significant potential for soil remediation. In this study, we developed a novel phosphoric acid–mineral-comodified biochar composite for saline–alkali soil improvement. SEM and XRD analyses indicate that chemical interactions between phosphoric acid, minerals, and biochar result in the formation of distinct mineral phases on the composite surface. Furthermore, FTIR analysis reveals that these interactions give rise to functional groups such as Si-O-Si, and thermogravimetric analysis demonstrates that the modified biochar composite exhibited enhanced stability. Compared with raw biochar, the modified biochar composites exhibited significant decreases in pH, EC, and base cation content (especially Na⁺), with maximum reductions of 7.26 pH units, 639.5 μS/cm, and 3.69 g/kg, respectively. In contrast, the contents of P, Si, and Ca increased significantly, with maximum increases of 140.04 g/kg, 90.32 g/kg, and 114.27 g/kg, respectively. In addition, the specific surface area and pore volume of the modified biochar composite increased by up to 5.2 and 15 times, respectively. Principal component analysis indicates that mineral type was the primary factor influencing the properties of the composites: hydroxyapatite enhanced porosity and phosphorus levels, whereas kaolinite and montmorillonite increased silicon content. Pot experiments show that the modified biochar composite increased alfalfa plant height by 17.36–20.27% and shoot biomass by 107.32–125.80% in saline–alkali soils. Overall, the newly developed phosphoric acid–mineral–biochar composites were evaluated to have high application potential for saline–alkali soil amendment. Full article

Soil carbon (C), nitrogen (N), and phosphorus (P) cycling and microbial metabolism limitations are key factors affecting nutrient cycling and vegetation development. Extracellular enzyme activity (EEA) plays a key role in carbon and nutrient cycling in ecosystems, and their activities can serve as indicators of microbial nutrient requirements. At present, there is insufficient research on the nutrient limitations of microorganisms during ecosystem transition in abandoned jujube forests on the Loess Plateau. Four modes were selected: jujube forest replanted with Pinus tabulaeformis (CP), with Platycladus orientalis (PO), with medicinal materials (MM), and with alfalfa (AL). An abandoned jujube forest (CK) was used as a control. Soil physical and chemical properties, microbial biomass carbon, nitrogen, and phosphorus, as well as changes in the activities of β-1,4-glucosidase (BG), leucine aminopeptidase (LAP), N-acetylglucosamine (NAG), and alkaline phosphatase (AP), were studied. Analysis of changes in soil microbial nutrient limitations was performed. Compared with those in the CK treatment, the activities of soil C, N, and P extracellular enzymes significantly increased (p < 0.05) in the forest transition treatments, and the C:N_EEA, C:P_EEA, and N:P_EEA ratios of extracellular enzymes tended to decrease. Within the treatments, the activities of soil C, N, and P extracellular enzymes decreased as the soil layer deepened, whereas the enzyme stoichiometric ratio increased as the soil layer deepened, with significant differences observed between the soil layers. The vector model was used to quantify nutrient limitations in microbial metabolism and revealed that microbial metabolism in surface soil was limited mainly by C and P and that in the 10–20 cm and 20–40 cm layers, soil microbial metabolism was limited mainly by C and N. Correlation analysis revealed that SOC, pH, MBC, and MBN were the main factors affecting soil extracellular enzyme activity. Mantel’s test revealed that (NAG + LAP), AP, C:N_EEA, and C:P_EEA were important factors affecting vector length and angle. RAD analysis revealed that microbial properties had a greater impact on enzyme stoichiometry and microbial metabolic limitations than physicochemical indicators did. This study highlights the importance of vegetation in determining microbial metabolic processes and enhances our understanding of how ecological changes in jujube forests affect soil nutrient cycling and microbial metabolic constraints on the Loess Plateau. Forest transformation modes have important impacts on soil extracellular enzyme activity and microbial nutrient limitation. Full article

Aluminum (Al) toxicity is a serious environmental constraint facing crop production in acidic soils, primarily due to the oxidative damage it causes to plant tissues. Alfalfa (Medicago sativa), a globally important forage crop, is highly susceptible to Al-induced stress, necessitating the development of Al-tolerant cultivars for sustainable forage production. In this study, we investigated the regulatory role of miR156 in Al stress response in alfalfa. Transcript analysis revealed significant downregulation of miR156 in alfalfa roots after 8 h of Al exposure, suggesting a negative role for miR156 in response to Al. To further investigate the role of miR156 in regulating agronomic traits and alfalfa’s Al tolerance, we utilized the short tandem target mimic (STTM) method to silence miR156 in alfalfa (MsSTTM156), which led to an upregulation of SQUAMOSA PROMOTER BINDING-LIKE (SPL) target genes, albeit with variable miR156 dose-dependent effects across different transgenic genotypes. Morphological characterization of MsSTTM156 plants revealed significant negative changes in root architecture, root and shoot biomass, as well as flowering time. Under Al stress, overexpression of miR156 in alfalfa (MsmiR156OE) resulted in stunted growth and reduced biomass, whereas moderate MsmiR156 silencing enhanced root dry weight and increased stem basal diameter. In contrast, MsmiR156OE reduced plant height, stem basal diameter, shoot branching, and overall biomass under Al stress conditions. At the molecular level, silencing miR156 modulated the transcription of cell wall-related genes linked to Al tolerance, such as polygalacturonase 1(MsPG1) and polygalacturonase 4 (MsPG4). Furthermore, miR156 influenced the expression of indole-3-acetic acid (IAA) transport-related genes auxin transporter-like protein (MsAUX1) and auxin efflux carrier components 2 (MsPIN2), with MsSTTM156 and MsmiR156OE plants showing lower and higher transcript levels, respectively, upon Al exposure. These findings reveal the multi-layered role of miR156 in mediating Al tolerance, providing valuable insights into the genetic strategies that regulate response to Al stress in alfalfa. Full article

Soil cadmium pollution poses significant environmental risks, prompting global concern. Previous studies have demonstrated that 24-epibrassinolide (Brs) can enhance plant photosynthesis, thereby potentially improving the efficiency of soil cadmium remediation by increasing biomass. Therefore, this study investigated the use of Brs to enhance Cd remediation by willow and alfalfa. After four months, we analyzed soil physicochemical properties, plant physiological and biochemical responses, biomass, Cd fractionation, plant Cd concentrations, and bioaccumulation factor (BCF). Willow and alfalfa cultivation without Brs increased soil pH and carbonates, reduced the exchangeable Cd fractionation, and increased Cd bound to Fe-Mn oxides and organic matter (p < 0.05). Conversely, Brs application increased soil total acids, increasing the bioavailable Cd (p < 0.05). Willow grown for four months accumulated Cd in leaves, stems, and roots at concentrations of 141.83−242.75, 45.91−89.66, and 26.73−45.68 mg kg⁻¹, respectively, with leaf BCF ranging from 14.53 to 24.88. After five months, leaves of willow planted in Cd-contaminated soil (9.65 mg kg⁻¹) contained 187.90−511.23 mg kg⁻¹ Cd, with BCFs of 19.25−52.38. Brs also increases plant biomass by improving photosynthesis, detoxification, and antioxidant defenses. Treatments with Brs and willow extracted 1.57−1.81 times more Cd (0.56−1.37 mg pot⁻¹) than without Brs (0.31−0.87 mg pot⁻¹). This study offers guidelines for Cd phytoremediation and highlights an effective strategy to enhance Cd accumulation. Full article