Legumes are a vital component of agriculture, providing essential nutrients to both humans and soil through their ability to fix atmospheric nitrogen. However, the production of legume crops is often hindered by various biotic and abiotic stresses, limiting their yield and nutritional quality of crops by damaging plant tissues, which can result in lower protein content, reduced levels of essential vitamins and minerals, and compromised seed quality. This review discusses the recent advancements in technologies that are revolutionizing the field of legume crop improvement. Genetic engineering has played a pivotal role enhancing legume productivity. Through the introduction of genes encoding for enzymes involved in nitrogen fixation, leading to higher yields and reducing the reliance on synthetic fertilizers. Additionally, the incorporation of genes conferring disease and pest resistance has significantly reduced the need for chemical pesticides, making legume cultivation more sustainable and environmentally friendly. Genome editing technologies, such as CRISPR-Cas9, have opened new avenues for precision breeding in legumes. Marker-assisted selection and genomic selection are other powerful tools that have accelerated the breeding process. These techniques have significantly reduced time and resources required to develop new legume varieties. Finally, advancement technologies for legume crop improvement are aid and enhancing the sustainability, productivity, and nutritional quality of legume crops.

Background and AimsPrescribed burning is a widely used management technique, often employed to restore grasslands affected by woody plants encroachment. However, its interaction with pre-existing plant species in influencing soil properties remains unclear.MethodsWe conducted a diachronic soil survey to assess the evolution of several soil properties in the mid-term (up to 18 months) after burning, including physico-chemical parameters and microbial biomass carbon on soils under vegetation patches of different plant functional types and life forms. Vegetation patches included Ericaceae and legume shrubs, ferns, and biocrusts dominated by lichens. Soil samples were taken pre-burning, immediately after burning and 9 and 18 months after.ResultsOur findings indicate that while some soil properties returned to pre-burning levels in the mid-term (i. e., soil cations and NH4+), others, such as available phosphorous (P Olsen), exhibited a significant decline that persisted even 18 months later. Furthermore, soils under legumes initially displayed higher levels of soil carbon and nitrogen compared to other vegetation patches, but this distinction diminished over time. This was likely due to legumes' susceptibility to fire damage, in contrast to the greater resilience of Ericaceae shrubs.ConclusionOur study highlights the complex vegetation patch-dependent effects of prescribed burning on soil properties. While legumes initially enhance soil carbon and nitrogen, their contribution decreases over time due to fire sensitivity. Some soil parameters recover in the mid-term, but nutrients like available phosphorus continue to decline. Fire management strategies should consider plant diversity and recovery time to mitigate soil fertility loss.

Alkaline stress imposes significant constraints on agriculture by reducing nutrient availability and inhibiting plant growth. This study examines the physiological and biochemical responses of chickpea (Cicer arietinum L.) seedlings to alkaline stress, with implications for improving crop resilience. Chickpea seedlings were subjected to combined Na2CO3 and NaHCO3 treatments, and changes in growth, root morphology, and nutrient uptake were evaluated. Alkaline stress led to substantial reductions in growth metrics (shoot and root length, fresh and dry weights), root-to-shoot ratio, and lateral root number, indicating pronounced root damage. This damage was associated with elevated hydrogen peroxide (H2O2) levels, increased membrane damage, and reduced cell viability. In response to alkaline stress, chickpea roots accumulated osmolytes (proline, soluble sugars) and upregulated antioxidant enzymes (catalase, ascorbate peroxidase) as an adaptive response to mitigate osmotic and oxidative stress. Ion homeostasis was disrupted, with decreased uptake of essential nutrients like K, P, Mn, Fe, and Zn, while the uptake of Na, Mg, and Ca increased, disturbing nutrient balance. These findings underscore the need for strategies, such as genetic improvement to enhance alkaline stress tolerance in chickpea, contributing to improved crop performance in challenging soil conditions.

The application of rhizobia-legume symbioses is a sustainable approach to alleviate water stress and restore damaged areas. In this context, three strains Bradyrhizobium sp. BA2, RDI18 and RDT46 previously isolated from root nodules of Retama dasycarpa grown in the Moroccan High Atlas Mountains, were selected to investigate their prominent drought-tolerance capacity and significant plant growth-promoting (PGP) traits under drought stress. Subsequently, we analyzed the impact of individual or combined inoculations by the three strains on R. dasycarpa responses to three water regimes (40, 70, and 100 field capacity). The three strains tolerate different concentrations of PEG 6000 and possess different PGP activities, including phosphate solubilization, production of siderophore, exopolysaccharides, and auxin, under osmotic stress. The inoculation had a positive impact on plant response under all applied water regimes as it improved shoot and root length biomass, and chlorophyll content. The water stress reduced shoot length and dry weight of all plants. However, the inoculated plants maintained the highest values. The water stress reduced the infectivity of strains BA2 and RDI18, but not strain RDT46, which is not competitive at any water regime. Furthermore, water stress had no effect on the three strains' symbiotic efficiency, whereas it increased considerably the efficiency index of strains BA2 and RDI18. Proline and protein content increased in non-inoculated plants; whereas the inoculation significantly increased the catalase activity in plants under 40 % FC. These results show that the inoculation with appropriate strains such as BA2 and RDI18, enhance plant resilience to drought season.

Enzyme-induced carbonate precipitation (EICP) is an attractive bio-geotechnical technique for soil improvement. As promising alternatives to commercial ureases, legume ureases crudely extracted from primary agricultural products can provide remarkable cost savings. This study investigated the bio-cementation effect of legume ureases with different protein contents on pore-scale, mechanical, and hydraulic properties of EICP-treated sand and revealed the causes, mechanisms, and effects of the bio-clogging induced by high protein level-legume urease. Urease centrifugal liquids of sword bean (JU), pigeon pea (PU), and soybean (SU) were prepared at equal activity of 10 mM/min for sand bio-cementation. Mechanical properties were analyzed based on CaCO3 content and soil strength. Pore-features were revealed by mercury intrusion porosimetry and scanning electron microscopy, and permeability was measured to evaluate the hydraulic properties. Results showed that JU and PU with lower protein content were more effective in multi-cycle EICP-treatments, since denser bio-cemented sands with higher strengths were obtained while being vertically uniform in CaCO3 distribution and pore structure. Conversely, the high protein level of SU induced uneven bio-cementation and surface bio-clogging, resulting in bad mechanical properties, such as low strength and a destruction pattern of bottom collapse. Bio-clogging virtually eliminated the effectiveness of subsequent EICP-treatments. SU exhibited an advantage over JU and PU in reducing soil permeability, as a dramatically lower permeability was achieved at a lower treatment cycle. Comprehensive analysis concluded that the high protein level, salting-out, different precipitation rate between protein and CaCO3, and limited soil filtration capacity were the key reasons for bio-clogging induced by SU.

Context or problem: Selective herbicides control weeds in cereal crops and break down over time, allowing safe planting of legumes in the following years. However due to climatic inconsistencies and changing farming practices, this is not always the case, and residues can inhibit formation of legume/rhizobia symbioses. Objective or research question: The objectives were to determine whether: i) exposure to triasulfuron, even at extremely low levels, reduces shoot and root growth and nodulation of five diverse and widely sown legume pasture cultivars in Australian farming systems; and ii) sowing legumes prior to recommended plant-back criteria being met for chlorsulfuron, triasulfuron herbicide, clopyralid, and pyroxasulfone herbicides results in unacceptable damage to subsequently sown pasture and crop legumes, causing reduced root and shoot growth, nodulation and N fixation. Methods: A series of glasshouse and field experiments explored herbicide residue impact on commonly used legumes in dryland farming systems. Results: A glasshouse study determined triasulfuron at concentration 0.000225 g a.i/ha, a (1/100,000) dilution of the label rate caused significant (p < 0.001) decrease in nodule count, root length, root, shoot weight for Trifolium spumosum cv. Bartolo and T. subterraneum cv. Dalkeith, and at 0.225 g a.i/ha and 2.25 g a.i/ha for all five cultivars tested. A bioassay assessed T. subterraneum cv. Dalkeith health when grown in field soil-cores taken 4, 7 and 10 months after herbicide application (chlorsulfuron, triasulfuron, clopyralid and pyroxasulfone) to a wheat crop. For all three, herbicide residues significantly decreased (p < 0.001) nodule number, shoot weight, root length and whole plant weight of T. subterraneum cv. Dalkeith compared to control. A field experiment assessed nodulation of five pasture and two crop legumes sown dry (dormant summer sowing), or following rainfall 10.5 months after initial herbicide application. Nodulation of all legume cultivars decreased in plots treated with clopyralid. Chlorsulfuron decreased nodulation for all cultivars except T. glanduliferum and T. subterraneum. Triasulfuron reduced nodulation for all cultivars except Ornithopus sativus and T. spumosum. Pyroxasulfone decreased nodulation of Biserrula pelecinus cv. Casbah and Lupinus angustifolius cv. Mandalup. Conclusions: Herbicide residues from preceding cereal crops reduced fitness and symbiotically fixed N in subsequently sown pasture or crop legumes. Implications or significance: Our study highlighted label plant-back recommendations should be strictly adhered to, despite conflict with modern farming approaches of dry or early sowing) to combat climate change. This outcome may consequently lower profitability and increase the carbon footprint of farming systems.

In recent decades, numerous studies have examined the effects of climate change on the responses of plants. These studies have primarily examined the effects of solitary stress on plants, neglecting the simultaneous effects of mixed stress, which are anticipated to transpire frequently as a result of the extreme climatic fluctuations. Therefore, this study investigated the impact of applied chitosan on boosting the resistance responses of peanuts to alkali and mixed drought-alkali stresses. Peanuts were grown in mid-alkaline soil and irrigated with full irrigation water requirements (100%IR), represented alkali condition (100% IR x alkali soil) and stress conditions (70% IR x alkali soil-represented mixed drought-alkali conditions). Additionally, the plants were either untreated or treated with foliar chitosan. The study evaluated various plant physio-chemical characteristics, including element contents (leaves and roots), seed yield, and irrigation water use efficiency (IWUE). Plants that experienced solitary alkali stress were found to be more vulnerable. However, chitosan applications were effective for reducing (soil pH and sodium absorption), alongside promoting examined physio-chemical measurements, yield traits, and IWUE. Importantly, when chitosan was applied under alkali conditions, the accumulations of (phosphorus, calcium, iron, manganese, zinc, and copper) in leaves and roots were maximized. Under mixed drought-alkali stresses, the results revealed a reduction in yield, reaching about 5.1 and 5.8% lower than under (100% IR x alkali), in the first and second seasons, respectively. Interestingly, treated plants under mixed drought-alkali stresses with chitosan recorded highest values of relative water content, proline, yield, IWUE, and nutrient uptake of (nitrogen, potassium, and magnesium) as well as the lowest sodium content in leaves and roots. Enhances the accumulation of (N, K, and Mg) instead of (phosphorus, calcium, iron, manganese, zinc, and copper) was the primary plant response to chitosan applications, which averted severe damage caused by mixed drought-alkali conditions, over time. These findings provide a framework of the nutrient homeostasis changes induced by chitosan under mixed stresses. Based on the findings, it is recommended under mixed drought-alkali conditions to treat plants with chitosan. This approach offers a promising perspective for achieving optimal yield with reduced water usage.

Population expansion and food insecurity as well as climate changes emphasize the need for advanced practices of agricultural sciences for enhancing the yield potential and nutritive qualities without damaging the environment. In this situation, legumes provide sustainable options for delivering multiple benefits in cropping sequences. Legumes as intercrops, green manure, or in rotation not only maintains soil quality but also break the cycle of insects, diseases, and weeds which are major problems in cereal-cereal cropping systems. Legumes also maintain soil biodiversity, fix atmospheric nitrogen in the soil, and ultimately reduce the need for agrochemicals. Legume residues have a low C:N ratio which enhances the carbon sequestration potential of soil. Apart from their environmental benefits, it significantly improves the nutritional quality of diets contributing to food security.

Legumes play a crucial role in the restoration and utilization of salinized grassland. To explore the physiological response mechanism of Astragalus membranaceus and Medicago sativa seedlings to salt stress, salt stress culture experiments with five NaCl concentration treatments (0 mmol/L, 50 mmol/L, 100 mmol/L, 200 mmol/L, and 300 mmol/L) were conducted on these two legume seedlings. Morphological characteristics, physiological features, biomass, and the protective enzyme system were measured for both seedlings. Correlation analysis, principal component analysis (PCA), and membership function analysis (MFA) were conducted for each index. Structural equation modeling (SEM) was employed to analyze the salt stress pathways of plants. The results indicated that number of primary branches (PBN), ascorbate peroxidase (APX) activity in stems and leaves, catalase (CAT) activity in roots, etc. were identified as the primary indicators for evaluating the salt tolerance of A. membranaceus during its seedling growth period. And CAT and peroxidase (POD) activity in roots, POD and superoxide dismutase (SOD) activity in stems and leaves, etc. were identified as the primary indicators for evaluating the salt tolerance of M. sativa during its growth period. Plant morphological characteristics, physiological indexes, and underground biomass (UGB) were directly affected by salinity, while physiological indexes indirectly affected the degree of leaf succulence (LSD). Regarding the response of the protective enzyme system to salt stress, the activity of POD and APX increased in A. membranaceus, while the activity of CAT increased in M. sativa. Our findings suggest that salt stress directly affects the growth strategies of legumes. Furthermore, the response of the protective enzyme system and potential cell membrane damage to salinity were very different in the two legumes.

Soil nitrogen is crucial for agriculture, but it is often limited, affecting crop yields. Deficiency requires synthetic fertilizers, but their improper use results in environmental damage and high costs. Bacteria of the genus Rhizobium , symbionts of legumes, offer a sustainable solution by fixing nitrogen, thus reducing dependence on fertilizers. This research determined the most probable number (MPN) of cells of Rhizobium spp. from two commercial biofertilizers of Ecuadorian and Mexican origin under greenhouse conditions. For this, direct inoculation with serial dilutions (10(-1) to 10(-10) ) was performed in pots with steam -sterilized pumice where Blue Lake variety snap bean ( Phaseolus vulgaris L.) plants were germinated. The following morphological indicators were evaluated at 45 days after sowing (DAS): leaf area, plant wet weight, plant height, and number of flowers, determining statistical differences between the type of biofertilizer and the concentration of each dilution. The experiment followed a randomized complete block design with a split -plot arrangement, with three replicates per dilution, considering temperature fluctuations in the study area. The MPN at 95% confidence was 4.45x10(7) rhizobia g -1 of pumice at a 10(-5) dilution for the Mexican biofertilizer, and 1.48x10(5) rhizobia g(-1) of pumice at a 10(-4) dilution for the Ecuadorian biofertilizer. The estimated optimal dilution for both products was 10(-8).