Search Results (439)

Drought is one of the most damaging abiotic stresses affecting global crop productivity, and its frequency and severity are projected to increase under ongoing climate change. Silicon (Si), although not classified as an essential nutrient, is increasingly regarded as a “quasi-essential” beneficial element that improves crop performance under water-limited conditions. This review summarises the physiological mechanisms of Si-induced drought tolerance, based mainly on literature published in the past five years. Rather than presenting these mechanisms as an inventory of separate physiological effects, the review reframes them as a coordinated stress-tolerance network linked by shared transcriptional regulation, and it organises the evaluation around three conceptual tensions that remain unresolved in the literature: the opposite direction of Si’s effect on transpiration, the extent to which Si-accumulating grasses and Si-excluding dicots rely on equivalent mechanisms, and the non-linearity of dose responses. Si uptake and transport via Lsi1, Lsi2, and Lsi6, and the resulting difference between Si-accumulating and Si-excluding species, are discussed together with the enhancement of root growth and aquaporin-mediated hydraulic conductance; stomatal and photosynthetic regulation; osmotic adjustment through compatible solute accumulation; enzymatic and non-enzymatic antioxidant defence; hormonal signalling involving abscisic acid, jasmonic acid, ethylene, and auxin; reinforcement of cell walls and vascular tissue; and the transcriptional networks coordinating these responses. Si’s influence on rhizosphere nutrient dynamics and the dependence of its efficacy on genotype, dose, and application method are also considered. A consolidated mechanistic scheme is presented, showing how these pathways converge on a drought-tolerant phenotype characterised by sustained growth, improved water-use efficiency, and faster recovery. Future research priorities, including field validation, standardisation of application protocols, multi-omics integration, and Si–microbiome interactions, are outlined to support the translation of these mechanistic insights into practical drought-management strategies. Full article

Flood events in agricultural floodplains reflect not only rainfall intensity but the vulnerability of the affected area at the moment of the event. This study examines the January–February 2026 flood in Larache Province, Morocco, through an integrated remote sensing workflow combining Sentinel-1 SAR, CHIRPS precipitation, and Dynamic World land cover in Google Earth Engine, processed via the rgee R package. Flood extent was mapped using SAR backscatter change detection and cross-checked against rainfall dynamics, yielding about 6660 ha of inundation (2.4% of the province), concentrated along the main Loukkos river corridor and adjacent floodplain around Ksar El Kebir, with smaller scattered patches to the south. Land cover was assessed across four temporal windows (spring 2025, pre-event, post-event, and spring 2026) to evaluate how the landscape entered the event and how it recovered. A significant share of normally cultivated land was in a bare-soil state before the flood, a condition that the literature associates with increased runoff. Post-flood analysis across 25 sample areas grouped into three geomorphic zones shows spatially uneven recovery, with cropland still below seasonal norms in spring 2026. These patterns are consistent with structural land-use conditions (wetland loss, intensive seasonal agriculture, drought-degraded soils) that may have amplified an already severe event. The findings support cover cropping, updated flood-hazard zoning, and targeted wetland restoration to reduce vulnerability in the Loukkos floodplain and comparable Mediterranean alluvial floodplains. Full article

Drought monitoring in arid regions commonly relies on climatic indices, yet the accumulation timescale that best represents surface soil moisture drought may vary spatially. This study evaluated the Standardized Precipitation Evapotranspiration Index (SPEI) at 1-, 3-, and 6-month accumulation periods against satellite-derived surface soil moisture across Saudi Arabia during 2003–2024. Temporal correspondence, grid-cell Spearman correlation, and receiver operating characteristic area under the curve (ROC-AUC) were evaluated. The analysis included 1462 grid cells meeting the minimum paired-observation criterion, representing 53.4% of the 2736 cells in the national domain. SPEI-1 consistently showed the strongest overall performance, with the highest temporal correspondence with surface soil moisture drought extent ($\rho =0.50$, versus 0.37 for SPEI-3 and 0.30 for SPEI-6), median grid-cell correlation ($\tilde{\rho }=0.290$, versus 0.255 and 0.175), and median ROC-AUC (0.629, versus 0.618 and 0.580). SPEI-1 was also the nominal highest-AUC timescale in 52.5% of analyzed cells, compared with 29.5% for SPEI-3 and 17.9% for SPEI-6. However, the median AUC difference between the first- and second-ranked timescales was only 0.033, and paired bootstrap comparisons showed that 94.8% of cells had no uniquely supported AUC winner. Regionally, nine of the 13 administrative regions showed a nominal majority preference for SPEI-1, whereas four had no single-timescale majority. The overall SPEI-1 > SPEI-3 > SPEI-6 ordering was also preserved under alternative soil moisture drought thresholds and temporal out-of-sample validation. These findings indicate that shorter SPEI accumulation periods generally provide the closest representation of near-surface soil moisture drought within the observed Saudi domain. The results provide practical guidance for selecting SPEI accumulation periods according to the land-surface drought process being monitored. Full article

Fennel (Foeniculum vulgare Mill.) is an aromatic species of culinary and medicinal value, but the metabolic basis of its drought response and the extent of variation among wild populations remain poorly characterized. We investigated eleven wild fennel accessions from the Mediterranean region of Croatia under control and drought conditions, combining morphological measurements with targeted profiling of 78 primary and 55 secondary metabolites. Drought significantly reduced biomass, leaf area, length, and width, while leaf dry matter content increased. Primary metabolism shifted markedly: amino acids accumulated, with asparagine and arginine increasing by over 20-fold, whereas TCA-cycle (tricarboxylic acid cycle) organic acids declined. Pathway analysis identified Alanine, aspartate, and glutamate metabolism as most strongly affected by drought treatment. A decline in the GSH/GSSG ratio indicated oxidative stress under water shortage. Among secondary metabolites, free hydroxycinnamic acids and flavonoid aglycones accumulated while most glycosylated flavonoids declined, and eight compounds showed genotype-dependent responses in drought conditions. These results reveal accession-specific metabolic adjustments to drought and characterize Croatian wild fennel as a genetic resource with distinct phytochemical profiles relevant to future conservation and breeding. Full article

Beaver dams can substantially modify flow conditions and increase local water retention, particularly in small urban and peri-urban streams exposed to hydrological alterations and increasing water deficits. This study evaluates the influence of beaver dams on hydraulic conditions, retention capacity, and water resources in the Junikowski Stream in Poznań, Poland. Field surveys, geodetic measurements, and spatial data were used to develop a one-dimensional hydraulic model in HEC-RAS. Three management scenarios were analysed: a channel without impoundment structures, the 2022 configuration including beaver dams and two artificial weirs, and the 2025 configuration representing a more developed beaver-dam cascade together with the functioning weirs. Simulations were conducted for a range of characteristic and probability flows to assess changes in water levels, inundation extent, and retained water volume. The results show that beaver dams exert the strongest effect under low-flow conditions, when they significantly increase water levels and improve local retention. Their hydraulic influence decreases with increasing discharge, although they continue to affect the spatial distribution of water in the valley. The proposed artificial structure may partly maintain retention benefits in the event of beaver dam degradation or removal. The findings demonstrate that beaver dams may function as effective nature-based solutions supporting water retention and potentially contributing to drought resilience and sustainable management of urban stream valleys. Full article

Major floods following prolonged drought can substantially alter ground cover, soil stability and pasture condition, yet longer-term trajectories of rangeland recovery remain poorly understood. This study assessed land condition at 62 monitoring sites in the Flinders River catchment, north-west Queensland, following the 2019 flood, with re-assessment in 2024. Land condition was evaluated using the A–B–C–D framework alongside rainfall, satellite-derived bare ground, land type, distance to drainage and flood-extent data. In March 2019, 79% of sites were classified as C or D, reflecting the combined influence of prolonged drought and flood disturbance. By 2024, 30 of 62 sites (48%) had improved by at least one class, and median condition shifted from class C to B, though change was spatially variable. Initial land condition was negatively correlated with net change (ρ = −0.47, p < 0.001, n = 62). Rainfall showed no significant association with land condition or net change among sites, whereas dry-season bare ground was significantly associated across multiple temporal windows. These findings indicate that land condition change following drought–flood disturbance is likely associated with site-level factors, particularly residual pasture structure and soil surface condition, and highlight the value of combining field and satellite data for rangeland monitoring following extreme climate events. Full article

Floodplains sustain fisheries, water supply, and climate regulation, and their services depend on the water regime—the extent, depth, frequency, duration, and connectivity of inundation—which dams, drought, and land-use change are altering. Remote sensing and GIS can supply evidence for managing these systems sustainably, yet the methods remain dispersed, and their fit to management needs has not been assessed. Following the PRISMA Extension for Scoping Reviews (PRISMA-ScR) and a publicly posted protocol, we retrieved peer-reviewed studies from Dimensions and OpenAlex (2004–2026), searched on 13 July 2026 and updated on 14 August 2026, and screened them in two stages with two reviewers. We charted data by study area, sensors, methods, variables, and drivers, then mapped them onto the decisions and Sustainable Development Goal targets they inform. Of 137 studies, 53% appeared since 2021; 2026 is only partially covered. Inundation extent dominates (83%), mapped mainly with Landsat (36%) and radar, whereas water level (28%), connectivity (21%), inundation frequency (14%), storage (13%), hydroperiod (12%), and depth (8%) remain scarce, as does evidence from data-scarce transboundary basins, including Central Asia. The attributes most needed for environmental-flow, allocation, and restoration decisions thus appear to be the least observed—a decision–observation mismatch that shapes monitoring priorities. Full article

To investigate photosynthetic physiological response mechanisms of rice (Oryza sativa L.) seedling leaves under drought stress, a pot experiment with controlled watering was conducted. Four treatments were applied—control (CK), mild drought (LD), moderate drought (MD), and severe drought (SD)—to four cultivars (H17B7, HY3015, LH1H, WNSM) at seedling stage. The results showed that, after drought stress, the morphological indicators and chlorophyll content of the four rice cultivars all showed decreased trend, but a compensatory effect appeared in some varieties under the LD treatment. As drought intensified, the chlorophyll fluorescence induction kinetics (OJIP) curves’ polyphasic rise was inhibited, mainly affecting the J-I and I-P phases. Under SD, the P-phase declined by 44.36%, 36.75%, 32.61% and 50.62% compared with CK, and positive L-band, K-band, and J-band. Chlorophyll fluorescence parameters showed dynamic changes. Most chlorophyll fluorescence parameters (e.g., F_v/F_m) decreased, whereas TR_o/CS_o and DI_o/CS_o exhibited cultivar-dependent variations. Principal components of the chlorophyll fluorescence parameters in seedling leaves of the four rice cultivars showed differences and were clearly distinguished. Plant height, chlorophyll content, etc., are highly significantly positively correlated with F_o, DI_o/CS_o, etc., as well as chlorophyll content with DI_o/CS_o. The OJIP/JIP-test responses suggest impairment of the PQ pool and downstream electron transport, with the extent of damage varying among cultivars. Full article

Cereal production is increasingly constrained by soil degradation, water scarcity, climate variability, and rising disease and weed pressure. This review synthesizes current knowledge on the role of regenerative agronomic practices in cereal production, with particular emphasis on soil health, plant disease management, water-use efficiency, and yield stability. Available evidence consistently indicates that the greatest benefits arise not from individual practices but from integrated systems combining reduced tillage, crop residue retention, diversified crop rotations including legumes, cover crops, organic fertilization, and biologically based pest management. Such practices can increase soil biological activity and its ability to limit disease by enriching functionally beneficial microbial communities and limiting pathogens through competition for resources and niches, antibiosis, hyperparasitism, and the induction of plant resistance. They can also improve soil structure, water infiltration, water retention, and crop resilience to drought stress and, under certain conditions, reduce erosion, nutrient losses, and yield variability. However, the effects of regenerative practices are strongly dependent on soil type, climate, nitrogen balance, pest pressure, and the extent of adoption of regenerative practices. Risks may arise during the transition period, including yield declines, nitrogen immobilization, weed infestation, and increased disease pressure. Evaluation of these systems should encompass not only yield but also the grain quality and phytosanitary status, soil organic carbon stocks throughout the soil profile, N₂O emissions, and production profitability. The review covers cereal systems from temperate, humid, arid and semi-arid zones, and the results were interpreted considering climate, soil quality, water availability, and agronomic practices, as the same practice can produce different effects in different agroecological zones. Further research should prioritize long-term, multifactorial experiments conducted across diverse agroecological environments that integrate agronomic performance, environmental sustainability, and crop quality. Full article

The relationship between climate change and migration remains widely debated, particularly regarding the extent to which environmental factors directly drive mobility. While climate-related stressors such as droughts, floods, and environmental degradation can disrupt livelihoods, migration decisions are rarely shaped by environmental factors alone. This study argues that climate change is often overstated as a primary driver of migration and may function instead as a secondary explanatory frame for mobility shaped by deeper socioeconomic and institutional constraints. Focusing on environmentally vulnerable regions of the Global South, this study examines the interplay between ecological stressors, structural inequalities, governance frameworks, and development conditions in shaping migration outcomes. It adopts a sustainability-oriented perspective to highlight how migration is embedded within broader adaptive and developmental processes rather than operating as a direct response to environmental change. The analysis demonstrates that effective policy responses must move beyond climate-deterministic narratives and instead adopt integrated approaches that combine environmental management, socioeconomic development, and migration governance. Strengthening adaptive capacity, improving institutional resilience, and promoting inclusive urban and rural development are identified as key policy priorities. By linking climate-related migration to the Sustainable Development Goals (SDGs)—notably SDG 10 (Reduced Inequalities), SDG 11 (Sustainable Cities and Communities), and SDG 13 (Climate Action)—the study contributes to a more holistic understanding of mobility in the context of environmental change. Overall, it calls for a re-evaluation of climate–migration dynamics in the Global South, emphasizing sustainable and context-sensitive governance approaches that reflect the complexity of migration processes. Full article

Salinity and drought are major abiotic stresses responsible for substantial losses in global agricultural productivity, particularly in arid and semi-arid regions. Although Bacillus spp. are widely studied as plant growth-promoting rhizobacteria (PGPR) capable of enhancing plant tolerance to abiotic stress, the extent to which this research has addressed combined salinity and drought stress remains underexplored. This study conducted a bibliometric analysis of scientific output and experimental evidence available in the Scopus-indexed literature published between 2016 and 2024 on Bacillus spp. as PGPR under combined salinity and drought stress conditions. A total of 479 documents were analyzed using the Bibliometrix R package v. 5.4.1 in R v. 4.5.3 and VOSviewer v. 1.6.20, applying Bradford’s and Lotka’s laws, keyword co-occurrence analysis, and citation analysis. Scientific output exhibited a compound annual growth rate of 24.5%, reaching 103 publications in 2024. China, India, and Pakistan were the leading contributors. Among the 495 eligible studies, only 2 studies identified through the primary Scopus search experimentally evaluated Bacillus spp. as PGPR under combined salinity and drought stress conditions. A third study was identified through a complementary external search, revealing a critical gap in experimental in vivo evidence under combined stress conditions. Addressing this gap is essential for advancing effective bioinoculant development for sustainable agriculture under combined abiotic stresses. Full article

Tropical–subtropical monsoon Asia faces pronounced hydroclimatic change under future warming, yet the regional patterns and emission scenario dependence of drought risk remain unclear. Using a 14-member CMIP6 multi-model ensemble from the NEX-GDDP-CMIP6 dataset, we assessed drought evolution under SSP1-2.6 and SSP5-8.5 (2015–2100). Combining the 3-month Standardized Precipitation Evapotranspiration Index (SPEI-3) with event-based run theory and Mann–Kendall trend analysis, we evaluated four complementary drought dimensions: annual mean SPEI, frequency, intensity, and duration. Regional drought area was used as a spatial diagnostic of extent. A persistent west-to-east moisture gradient characterizes present-day conditions: chronic deficits prevail in southwestern China, southern Myanmar, and Thailand, whereas southeastern China and the equatorial belt maintain relative surpluses. This contrast intensifies through the century, with negative SPEI anomalies deepening by 0.2–0.4 units and chronic drought zones expanding into previously marginal areas. Under SSP1-2.6, no metric shows statistically significant trends. By contrast, SSP5-8.5 produces robust drying, with 8.0% of the area showing significant SPEI declines and up to 30.9% exhibiting significant intensification. Scenario-driven increments affect 89–99.7% of the area across all indicators, confirming that higher emissions systematically elevate drought frequency, persistence, and severity. Scenario uncertainty surpasses model structural uncertainty first for intensity (2067), then area (2078), duration (2079), and frequency (2090), reflecting earlier model convergence on the forced thermodynamic shift than on threshold-dependent frequency counts. Stringent mitigation consistent with the Paris Agreement can largely stabilize regional moisture regimes, whereas continued high emissions will drive pervasive drought intensification across one of the world’s most populous and biodiverse forest regions. Full article

Global restoration frameworks, such as the Bonn Challenge and Forest Landscape Restoration, have endorsed multistakeholder engagement in agroforestry as key to reversing land degradation at scale. This paper follows shifts in how stakeholders have been organised, coordinated and steered since 2010 when Rwanda’s National Forestry Policy came into force, a year ahead of Rwanda’s pledge to the Bonn Challenge. The specific focus is on Bugesera District, representing a national policy shift from focusing on restoration in highland areas only. Bugesera is a lowland area facing complex socio-ecological and livelihood challenges including high rates of deforestation, recurrent drought and rapid population fluctuations. This paper analyses these changes by investigating which stakeholders were involved, how they were engaged (modes of participation) and why they participated (drivers of participation). Conceptually, this follows stakeholder mapping, Reed’s theory of participation and multi-level governance theory. Through thematic analysis, we triangulated data from 15 policy-related documents with semi-structured interviews with representatives from 24 organisations. Our findings show that both before and after 2010, stakeholder engagement has remained top-down. However, since 2010 this has been qualified by an asymmetrical form of collaboration that increasingly takes the form of top-down deliberation. Changes were observed in participation patterns, engagement approaches, and governance arrangements, driven by contextual conditions, power relations, process design, and spatial–temporal dynamics. Within a centrally coordinated government system, shaped by the post-genocide political context and culturally embedded structures such as Umuganda and Ubudehe, multistakeholder restoration initiatives have largely remained state-led, with structured approaches to coordination and implementation that have varied in the extent of local stakeholder engagement. Trust emerged as an important factor influencing stakeholder interactions. Despite more diverse and expanded institutional arrangements over time, variations in levels of participation and influence among stakeholders persist, with differences in how engagement and decision-making power are distributed. We conclude that effective stakeholder engagement is contingent on existing governance structures, the political will to engage with a diversity of actors at different levels, contextual conditions including spatial-temporal dynamics, and opportunities provided by global and regional restoration frameworks. Full article

Water deficit is a major abiotic constraint limiting maize growth and productivity worldwide. Although silicon (Si) is not classified as an essential element, its beneficial effects on numerous crop species are well documented. Silicon has been shown to promote plant growth and enhance tolerance to abiotic stresses, particularly drought stress. Seed priming, a pre-sowing technique known to stimulate early germination processes, has emerged as a promising approach to enhance seedling establishment and stress tolerance in crops. In the present study, silicon-based seed priming was investigated as a strategy to alleviate the adverse effects of water deficit in maize (Zea mays) using two sodium silicate priming-solution concentrations (10 and 20 mM). Maize plants were subjected to six experimental treatments based on seed priming: three under well-watered conditions (no silicon seed priming and seed priming with 10 and 20 mM sodium silicate solutions) and three corresponding treatments combined with irrigation withdrawal for 15 days to induce drought stress. Morphological traits, biomass accumulation, photosynthetic pigment content, plant water status, and PSI- and PSII-related photochemical parameters were evaluated. Drought stress markedly reduced plant growth, biomass production, relative water content, chlorophyll pigment levels, and photosystem photochemical performance, reflecting a strong negative impact of water deficit on most measured parameters. In particular, root and shoot fresh weights decreased by 75% and 71%, respectively, compared with those of well-watered unprimed control plants, indicating a substantial reduction in biomass accumulation under drought conditions. Furthermore, drought conditions impaired photochemical performance and increased non-regulated energy dissipation, indicative of impaired photosynthetic performance. Silicon seed priming mitigated several drought-induced effects in a trait-dependent manner. Under water-deficit conditions, 20 mM Si produced the strongest improvement in root and shoot fresh weights, whereas 10 mM Si showed stronger responses for selected shoot-growth and PSI-related parameters. Both Si treatments improved leaf water status and photosynthetic stability to varying extents. Collectively, these results indicate that sodium silicate seed priming partially improves drought-related responses in maize seedlings under the conditions of this study by sustaining growth performance, preserving plant water status, and maintaining photosynthetic stability under water-deficit conditions. Full article

This study addresses the dual challenges of seasonal water scarcity and urban flooding in the Garzan River basin, a region with a semi-arid climate. We propose and analyze an integrated water management system designed to mitigate these risks and promote both ecological and economic sustainability. Our methodology began with a comprehensive analysis of meteorological data from 2000 to 2024, which quantified the significant seasonal irregularity in the annual rainfall regime. The findings revealed that the bulk of the average 800 mm of rainfall occurs between January and May, while the summer months experience near-drought conditions. Based on this, we calculated the potential of various water conservation strategies. The system combines rainwater harvesting from a 1000 m² roof and a 500 m² parking lot, projected to collect 1020 m³ annually, with greywater reclamation and low-flow fixtures, which add a combined 400 m³ of annual savings. The total annual water savings of 1420 m³ were found to provide a gross annual economic benefit of $3550. Considering the installation and maintenance costs, the project’s payback period is estimated to be around 32 years. We also developed an annual precipitation prediction model providing a locally applicable early warning mechanism that forecasts total rainfall based on spring data. The use of proactive hydrometeorological data can improve the feasibility of long-term infrastructure projects to a certain extent. Finally, the proposed system’s design was confirmed to be eligible for multiple LEED certification credits, demonstrating its alignment with international sustainability standards. In conclusion, this research provides a comprehensive and viable solution that addresses local water issues and offers a valuable model for other regions facing similar challenges. Full article