Search Results (331)

Alfalfa (Medicago sativa L.) is an important forage crop with significant economic value. Alternating partial root-zone irrigation (APRI) is a promising water-saving technique that has been shown to improve water use efficiency in various crops. In this study, the effects of APRI on root water uptake, photosynthetic indices, and physiological responses in alfalfa were investigated. Polyethylene glycol (PEG 6000) was used to simulate water stress, and four irrigation treatments were established: conventional irrigation (CI), deficit irrigation (DI), fixed partial root-zone irrigation (FPRI), and APRI. Principal component analysis (PCA) revealed that APRI reduced stomatal conductance (Gs) by 19.82% and transpiration rate (E) by 19.16%, which was associated with increased abscisic acid (ABA) content, thereby enhancing instantaneous water use efficiency (iWUE) by 47.93%. Meanwhile, APRI promoted root growth, leading to a 14.09% increase in root–shoot ratio, which in turn enhanced the photosynthetic rate by 22.06%. APRI enhanced methyl jasmonate (MeJA) content in alfalfa leaves by 45.23%, which was associated with a 24.13% improvement in water absorption capacity. In conclusion, APRI induced positive physiological responses in alfalfa, with the effectiveness ranked as follows: APRI > CI > FPRI > DI. These findings provide a theoretical basis for the rational application of APRI in alfalfa forage production. Full article

Water scarcity and poor soil fertility are major limiting factors constraining agricultural production in the arid and semi-arid regions of Northwest China. Water–nitrogen synergistic regulation is an important approach to improving crop growth and enhancing agricultural productivity. In this study, four irrigation levels—severe water deficit (W1: 45–65% θ_f), moderate water deficit (W2: 55–70% θ_f), mild water deficit (W3: 65–80% θ_f), and full irrigation (W4: 75–90% θ_f)—and four nitrogen application rates—no nitrogen (N0, 0 kg·ha⁻¹), low nitrogen (N1, 80 kg·ha⁻¹), medium nitrogen (N2, 160 kg·ha⁻¹), and high nitrogen (N3, 240 kg·ha⁻¹)—were established to systematically analyze the effects of water–nitrogen coupling on osmotic adjustment substances, yield, and forage quality of alfalfa (Medicago sativa L.) leaves. The results showed that: (1) Proline (Pro) content increased significantly with intensified water deficit, with W1 being 82.29% higher than W4 on average. Soluble protein (SP) and soluble sugar (SS) contents increased with increasing water availability, with their average values under W4 being 26.50% and 36.92% higher than those under W1, respectively. Increasing nitrogen application significantly improved the accumulation of osmotic adjustment substances, with Pro reaching the lowest value at N2, SP peaking at N2, and SS peaking at N3. (2) Yield increased significantly with higher irrigation, and increased first and then decreased with nitrogen application. Yield under W4 was 94.20% higher than under W1, and N2 increased yield by 12.45–50.65% compared with other nitrogen levels. (3) Under the W4N2 treatment, crude protein (CP) content and relative feed value (RFV) increased by 34.54% and 51.10%, respectively, compared with W1N0, while acid detergent fiber (ADF) and neutral detergent fiber (NDF) decreased by 28.74% and 24.44%, respectively. (4) Correlation analysis indicated that Pro content was significantly positively correlated with ADF and NDF but negatively correlated with yield, CP, and RFV. In contrast, SP and SS contents were significantly negatively correlated with ADF and NDF and positively correlated with yield, CP, and RFV. (5) Principal component analysis identified that the combination of full irrigation (W4: 75–90% θ_f) and medium nitrogen application (N2, 160 kg·ha⁻¹) optimizes both yield and forage quality by balancing osmotic adjustment substances. Full article

Oats (Avena sativa L.) are a staple grain and forage crop with substantial market demand. In China, they are the second most-imported forage grass, only after alfalfa (Medicago sativa L.). Enhancing the salt tolerance of oats to facilitate their cultivation in saline areas can thereby increase forage yield and promote the utilization of saline land, which constitutes an important reserve land resource in China. This study aimed to identify the bacterial strain Bacillus sp. LrM2 (hereafter referred to as strain LrM2) to determine its precise species-level classification and evaluate its effects on oat photosynthesis and growth under salt stress through indoor pot experiments. The results indicated that strain LrM2, capable of urease production and citrate utilization, was identified as Bacillus mojavensis. The strain LrM2 had a positive effect on shoot and root growth of oats under 100 mM NaCl stress conditions. Strain LrM2 inoculation modulated osmotic stress in oats under 100 mM NaCl stress by significantly increasing soluble sugar and decreasing proline content in leaves. It inhibited Na⁺ uptake and promoted K⁺ absorption in the roots, thereby reducing Na⁺ translocation to the leaves and mitigating ionic toxicity. Inoculation with strain LrM2 significantly increased photosynthetic pigment content (chlorophyll a, carotenoids), improved gas exchange parameters (stomatal conductance, transpiration rate, net rate of photosynthesis), enhanced PSII photochemical efficiency (maximum quantum yield, coefficient of photochemical quenching, actual photosynthetic efficiency of PSII, electron transfer rate), and reduced the quantum yield of non-regulated energy dissipation. These improvements, coupled with increased relative water content and instantaneous water use efficiency, thereby collectively enhanced the overall photosynthetic performance. In conclusion, strain LrM2 represents a promising bio-resource for mitigating salt stress and promoting growth in oats, with direct applications for developing novel biofertilizers and sustainable agricultural strategies. Full article

The goal of this study was to elucidate the genetic and molecular regulatory mechanisms underlying agronomic traits in elite alfalfa (Medicago sativa L.). Through the analysis of 44 varieties and lines, we measured 19 yield-related traits and performed transcriptome sequencing to investigate the factors driving yield variation. The results indicated extensive variation in agronomic traits among the tested accessions, with the coefficients of variation (CVs) ranging from 7.85% to 42.66%, suggesting substantial potential for genetic improvement. Correlation analysis revealed that seed yield was significantly and positively correlated with the number of reproductive branches and inflorescences at maturity, whereas early vegetative growth was negatively correlated with 100-seed weight. The 44 accessions were categorized into three clusters: Cluster II (the largest group) exhibited balanced traits; Cluster I showed vigorous early growth but low pod yield; and Cluster III was characterized by the highest pod and branch numbers. Principal Component Analysis (PCA) explained 65.88% of the total variation (first six components), identifying GNS31 and GNS43 as the superior and inferior genotypes, respectively. Furthermore, transcriptome profiling detected the highest number of differentially expressed genes (10,089 DEGs) in pod tissues, with 66% being upregulated. Functional enrichment analyses (GO and KEGG) highlighted that varietal differences were primarily enriched in secondary metabolism, lipid metabolism, and plant hormone signal transduction pathways. Notably, within the auxin pathway, the SAUR and GH3 families displayed significant tissue-specific expression in pods. Full article

Phosphorus (P) is a key nutrient limiting crop growth and productivity, particularly in saline-alkali soils with low P availability. Arbuscular mycorrhizal fungi (AMF) have the potential to enhance P uptake in alfalfa (Medicago sativa L.); however, the synergistic effects and underlying biological mechanisms by which AMF improve P acquisition and utilization efficiency under varying P application levels remain unclear. To explore P acquisition strategies associated with AMF status, root morphology traits, rhizosphere carboxylate exudation, soil properties and microbial biomass, we conducted a pot experiment growing alfalfa in saline-alkali soil under four P application levels (0, 5, 10, and 20 mg kg⁻¹), with or without AMF inoculation. Our results showed that AMF colonization and P application synergistically increased alfalfa biomass and shoot/root P concentrations. Notably, at a low P application level of 5 mg kg⁻¹, the mycorrhizal contribution to P absorption and P-utilization efficiency reached their highest levels, while both declined under high P conditions (20 mg kg⁻¹), suggesting an interaction between P availability and AMF efficacy. Structural equation modeling (SEM) and regression analysis revealed that rhizosphere carboxylate concentrations were positively associated with P-utilization efficiency, whereas soil available P, microbial biomass P (MBP) and carbon (MBC) negatively affected it. Among these factors, AMF-induced enhancement of rhizosphere carboxylate exudation played a critical role in promoting P-utilization efficiency in alfalfa under low-P conditions. In contrast, higher P availability reduced rhizosphere carboxylate concentrations, resulting in lower P-utilization efficiency. In conclusion, the combination of AMF colonization and low P application synergistically improves P acquisition and utilization efficiency in alfalfa, providing valuable insights for sustainable nutrient management in saline-alkali soils with limited P availability. Full article

Applying non-thermal plasma (NTP) to seeds prior to sowing is recognized for its ability to enhance germination and promote plant growth. This study investigated the effects of NTP seed treatment on alfalfa seed surface characterization, germination, growth, and biochemical traits under varying water conditions. NTP modified seed surface properties by decreasing water contact angle, roughening the coat, and reducing O–H/N–H and C–H band intensities, while major functional groups remained intact. Short plasma exposures (<2 min) enhanced germination, whereas prolonged treatment (10 min) reduced viability, indicating embryo sensitivity. In pot experiments, both 1 and 5 min treatments improved fresh and dry weight, stem and root elongation, pigment accumulation, and protein content, particularly under normal and moderate water stress, while extended exposure (10 min) offered limited benefits and could be detrimental under severe drought. Root growth was most responsive, suggesting enhanced water and nutrient uptake. Plasma had modest effects on polyphenols and flavonoids but influenced early physiological responses and antioxidant activity. These findings highlight NTP as a promising seed priming tool to improve alfalfa performance, though further studies are needed to clarify the mechanisms and specific contributions of plasma components. Full article

Alfalfa (Medicago sativa L.), a perennial leguminous herb, can tolerate cold and saline–alkaline conditions. In this study, alfalfa cultivars LJ and 218TR were exposed to saline–alkaline, cold, and saline–alkaline–cold conditions and compared in terms of phenotypes, physiological indices, key metabolite contents, and stress-responsive gene expression. Malondialdehyde, soluble sugar, proline contents and phenylalanine ammonia-lyase (PAL), superoxide dismutase, catalase, and peroxidase activities initially increased under individual stress conditions, but decreased when stresses were combined. Photosystem II maximum photochemical efficiency and chlorophyll contents decreased under individual and combined stress conditions. Nitroblue tetrazolium-stained leaves revealed that the combined stress treatment significantly increased cell mortality rates and superoxide anion levels. LJ was more tolerant to saline–alkaline, cold, and combined stress treatments than 218TR. Metabolite analyses indicated that for LJ and 218TR, salicylic acid (SA) was the most responsive metabolite to combined stress conditions. Additionally, the expression of isochorismate synthase (ICS) and PAL genes critical for SA biosynthesis was upregulated under single or combined stress conditions, leading to SA accumulation and improved tolerance to saline–alkaline–cold conditions. This study revealed the physiological indices and molecular changes underlying alfalfa responses to saline–alkaline stress combined with cold stress, providing a theoretical basis for breeding stress-tolerant cultivars. Full article

Background: The Songnen Plain in China contains soda saline–alkaline soil, wherein salinity and alkalinity severely constrain crop productivity. Alfalfa (Medicago sativa L.) is a forage legume that has adapted to moderate saline–alkaline conditions, but how its rhizosphere microbial community facilitated this adaptation remains unclear. Methods: Using 16S rRNA gene sequencing, we compared alfalfa rhizosphere bacteria in saline–alkaline soil (AS) and control soil. Bacteria isolated from AS were screened for plant growth-promoting traits, with the most effective strains validated in pot experiments involving 50 mM NaHCO₃. Results: Compared with the control soil bacterial community, the AS bacterial community was significantly enriched with Methylomirabilota and unclassified bacteria (phylum level), with the genus RB41 identified as the most discriminative biomarker. Gene functions predicted using PICRUSt2 reflected the responsiveness of this community to environmental stressors. Inoculations with Pseudomonas laurentiana strain M73 and Stenotrophomonas maltophilia strain M81, which were isolated from AS, significantly improved alfalfa growth and health under NaHCO₃ stress. Conclusions: Saline–alkaline conditions in the Songnen Plain reshape the alfalfa rhizosphere bacterial community, enriching for specific taxa and potentially enhancing microbial functions associated with stress resistance. Strains M73 and M81 can effectively promote stress tolerance, making them useful microbial resources for improving soil conditions. Full article

Alfalfa (Medicago sativa L.) is an underutilized source of phytonutrients and easily digestible protein, containing all essential amino acids, highlighting its potential for food applications. This study aimed to produce alfalfa protein concentrates (APC) from frozen aerial parts and evaluate how conventional extraction and ultrasound-assisted extraction (UAE) affect the extraction yield, physicochemical properties, functional attributes, color parameters, phytochemical composition and antioxidant activity. The influence of extraction pH and the type of acid used for isoelectric precipitation was also evaluated. Paired t-tests (p ≤ 0.05) showed that UAE (37 kHz, 25 °C, 15 min) increased the extraction yield by 20.5–39.7%, the protein content in APC by 2.5–12.1% and the in vitro protein digestibility by 5.6–11.03%, depending on the extraction conditions. Ultrasound treatment decreased the levels of chlorophyll and carotenoids, modified the color parameters and increased the total polyphenols and flavonoids content. Improvements in the textural, foaming and emulsifying properties of APC were also observed. UAE also reduced the scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. However, the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•⁺) scavenging activity significantly increased in aqueous APC extracts, reaching 3118.8 mg TE/100 g DW. Overall, UAE proved effective in improving the yield and functionality of APC, supporting its application in the development of alfalfa-based protein ingredients. Full article

Root exudates play a critical role in enabling plants to respond to environmental stresses and mediate information exchange within the rhizosphere. These compounds regulate plant–rhizosphere interactions and significantly influence the structural and functional properties of the rhizosphere micro-ecosystem. Under continuous cropping systems, allelochemicals derived from root exudates progressively accumulate in the root zone, thereby contributing to the development of continuous cropping obstacles. In this study, root exudates were collected from wolfberry (Lycium barbarum L.) and four forages under controlled conditions to test their effects on seed germination and seedling growth in mangold (Betu vulgaris L.) and wolfberry, as well as on the root rot pathogen. Our research shows that forage root exudates could promote wolfberry seedling growth. White clover (Trifolium repens L.) and alfalfa (Medicago sativa L.), especially, could have their growth increased by up to 61% and 90% (p < 0.05). Wolfberry root exudates could promote the seed germination and seedling growth of white clover and mangold, the seed germination of Ryegrass (Lolium perenne L.), and the seedling growth of alfalfa. In addition, mangold root rots were identified as Molds, Aspergillus niger, and Fusarium solani and wolfberry root rots were Mucor cirrus, Rhizopus, Fusarium oxysporum, and Fusarium solani. What is more, wolfberry root exudates could promote Fusarium plaque expansion and mycelial growth. Ryegrass inhibited the growth of Mucor, Fusarium putrum, and oxysporum, and alfalfa and white clover promoted the plaque expansion of Rhizopus, Aspergillus niger, and Fusarium fulcrum, but inhibited the mycelial growth of related pathogens; mangold root exudates could inhibit wolfberry root rot, which affects interspecific relationships. This study provides robust technical support for elucidating interspecific relationships and promoting the development and application of the wolfberry-forage intercropping system. Full article

Endophytic rhizobia have the functions of dissolving organic phosphorus, secreting auxin, fixing nitrogen, and promoting growth. The proliferation of endophytic rhizobia in alfalfa and their symbiotic nodulation with alfalfa seedlings are regulated by various plant hormones. In this study, the alfalfa seeds (Medicago sativa L.) containing CFP-labeled rhizobium R.gn5f (isolated from the seeds of Gannong No.5 alfalfa) were used as materials, and the concentrations of 3-indoleacetic acid (3-IAA), 6-benzylaminopurine (6-BA) and homobrassinolide (HBR) suitable for the growth of R.gn5f were used for seed soaking treatment, and distilled water was used as the control. The proliferation of endophytic rhizobium, plant nodulation, nitrogen fixation performance and plant growth ability of alfalfa at different growth stages were determined. The effects of hormone types and concentrations on the proliferation and nitrogen fixation of endophytic rhizobia were analyzed to provide a theoretical basis for accurately promoting the nodulation, nitrogen fixation and growth-promoting ability of endophytic rhizobia in seeds. The results showed that the optimal concentrations of 3-IAA, 6-BA and HBR were 12 mg·L⁻¹, 16 mg·L⁻¹ and 2.47 mg·L⁻¹, respectively. The nitrogen fixation performance of endophytic rhizobium plants containing three hormones was higher at the branching stage and budding stage. The growth ability of the plant was better at the flowering stage. The hormone 2.47 mg·L⁻¹ of HBR was beneficial to the proliferation, nodulation, nitrogen fixation and plant growth of endophytic rhizobia in alfalfa at the vegetative and reproductive growth stages, and the number of R.gn5 f in the seeds of HBR plants at the mature stage was the largest (281.25 CFU·g⁻¹). Therefore, the hormone 2.47 mg·L⁻¹ of HBR was better for the proliferation of endophytic rhizobia R.gn5 f and plant growth in alfalfa. These findings provide a theoretical basis for precisely leveraging the nodulation and nitrogen-fixing capabilities of seed-borne endophytic rhizobia, thereby laying a foundation for the symbiotic breeding of alfalfa and rhizobia. Full article

Seed physical dormancy, also known as hard-seededness, is a characteristic commonly found in higher plants, which functions to prevent water and oxygen from passing through the impermeable seed coat. Background: Notably, seed dormancy has emerged as a critical factor in the domestication of leguminous plants. Alfalfa (Medicago sativa L.) is a globally cultivated high-quality legume forage crop, while the seeds from different varieties maintain varying degrees of hard-seededness. However, the molecular mechanisms underlying physical dormancy in alfalfa seeds remain poorly understood. In particular, the regulatory mechanisms at the transcriptomic level remain unclear, which has hindered the breeding process of varieties with low hard-seededness. Methods: In this study, we performed global transcriptome analysis to discover the genes specifically expressed in the alfalfa seed coat and provide insights into alfalfa seeds’ physical dormancy domestication traits. RNA sequencing was performed on various alfalfa tissues, including roots, stems, leaves, flowers, and seed coats. Results: This analysis led to the identification of 4740 seed coat-specific expressed genes, including key genes such as KNOX4 (a class II KNOTTED-like homeobox gene), qHs1 (encoding endo-1,4-β-glucanase), GmHs1-1 (encoding a calcineurin-like metallophosphoesterase), and KCS12 (β-ketoacyl-CoA synthase). In addition, several seed coat-specific transcription factor families were identified, including ERF, B3, and NAC, among others. Furthermore, a comparison of gene expression profiles between seeds with and without physical dormancy revealed 60 upregulated and 197 downregulated genes associated with physical dormancy. Crucially, functional enrichment analysis demonstrated that these genes are predominantly associated with lipid metabolism pathways, particularly those involved in the formation of “monolayer-surrounding lipid storage bodies.” Conclusions: This key finding suggests that the establishment of physical dormancy is closely linked to the biosynthesis and deposition of specialized lipid-based layers in the seed coat, which likely constitute the primary barrier to water penetration. Our study thus provides fundamental insights and a valuable genetic resource for future functional studies aimed at deciphering and manipulating physical dormancy in alfalfa. Full article

An imbalance between the supply and demand of nutrients within the crop–soil system has resulted from the prevalent practice of excessive fertilization in agricultural agriculture. In order to increase crop growth, improve resource usage efficiency, and reduce agricultural nonpoint source pollution, appropriate cropping management techniques are essential. This study examined the effects of four nitrogen application rates (0 kg·ha⁻¹ (C0), 80 kg·ha⁻¹ (C1), 160 kg·ha⁻¹ (C2), and 240 kg·ha⁻¹ (C3)) and three alfalfa cropping systems (traditional flat planting, FP; ridge-covered biodegradable mulch, JM; and ridge-covered conventional mulch, PM) on soil inorganic nitrogen transport, nitrogen allocation within alfalfa plants, and soil N₂O emissions. Throughout the alfalfa growth phase, the dynamics of nitrogen balance within the soil–plant–atmosphere system were quantitatively examined. The findings showed: (1) The concentrations of soil NO₃⁻–N and NH₄⁺–N rose with the rate of nitrogen application but decreased with soil depth. The PMC3 treatment had the largest inorganic nitrogen reserves at the end of the alfalfa growth period. (2) The pattern of PM > JM > FP for nitrogen uptake and nitrogen accumulation in biomass in alfalfa leaves and stems peaked at the C2 nitrogen treatment rate. (3) As nitrogen application rates increased, grass-land N₂O emission flow and total emissions also followed PM > JM > FP. (4) The PMC2 treatment showed apparent nitrogen balances of 9.73 kg·ha⁻¹ and 1.84 kg·ha⁻¹ during the two-year growing season, with apparent nitrogen loss rates of 6.08% and 1.15%, respectively, both significantly lower than other treatments, according to nitrogen balance analysis. In summary, the nitrogen application pattern combining ridge-covering conventional plastic mulch with moderate nitrogen application levels can achieve nitrogen balance in alfalfa grassland systems within the Yellow River irrigation district of Gansu Province, China, and similar ecological zones. Full article

Plant-derived volatile organic compounds (VOCs) are widely used as insect attractants for population monitoring, offering an efficient and eco-friendly approach to pest management. Since thrips are the dominant pest species in alfalfa (Medicago sativa) crops, alfalfa volatiles produced in the presence of Odontothrips loti and compounds with attractive potential to both O. loti and Frankliniella occidentalis were investigated. Using gas chromatography–mass spectrometry (GC-MS), 96 VOCs were identified from seven alfalfa cultivars with varying levels of thrips resistance with and without damage by O. loti. Eleven volatiles were selected for Y-tube olfactometer assays. The semiochemical p-Menth-8-en-2-one, which was suppressed in alfalfa subject O. loti damage, significantly attracted both O. loti and F. occidentalis in Y-olfactometer bioassays; the response rates were 2.05~3.07 times compared to control (p < 0.05). Further experiments confirmed p-Menth-8-en-2-one, dispensed through PE (Polyethylene) vials, was the most effective lure material with the concentrations of 10 ng/μL. This study demonstrated that the alfalfa-derived volatile p-Menth-8-en-2-one, shows significant attraction to thrips, which can be utilized for monitoring and management of odontothrips loti and frankliniella occidentalis. Full article

The physicochemical properties of soil have a significant impact on plant growth, and fertilizers that improve soil quality play a crucial role in promoting crop development. Abandoned crop straw, once composted and converted into organic fertilizer, is an important resource for agricultural production. However, the mechanisms by which straw compost regulates plant growth remain incompletely understood. In previous work, we demonstrated that low-temperature-fermented straw compost significantly promoted the growth and yield of rice. To further investigate the effects of low-temperature-fermented straw compost on alfalfa growth, this study incorporated 10% and 30% straw compost into soil for alfalfa cultivation and systematically compared plant growth and soil quality indicators. Results showed that compost application increased alfalfa leaf length by 30.55%, with significant improvements observed in multiple physiological parameters. Furthermore, straw compost amendment raised soil pH to 6.88, substantially enhanced soil organic matter content, and increased the activities of sucrase and urease by approximately 181.77% and 223.81%. The abundance of soil microorganisms, including fungi and actinomycetes, increased by approximately 129.59% and 444.44%, respectively, indicating that straw compost effectively improves soil conditions and promotes alfalfa growth. Overall, the study demonstrates that low-temperature-fermented straw compost exerts a promoting effect on crop growth and provides an important theoretical basis for promoting low-temperature straw fermentation technology and the application of straw composting in agricultural and animal husbandry production. Full article