Search Results (1,217)

An unmanned aerial vehicle (UAV) multi-spectral system provides a monitoring platform to rapidly obtain crop spectral information that can reflect crop nitrogen status for the generation of dynamic variable-rate nitrogen (VRN). To improve the accuracy of VRN prescription maps, a method of generating VRN prescription maps on the basis of the vegetation index was proposed, and the effects of UAV flight time and altitude on VRN prescription maps were analyzed. The experimental site was located in Dacaozhuang, Hebei Province, China, and the experimental crop was winter wheat (Lunxuan 145). The flight altitudes of the UAV system were set to 50, 70 and 90 m. The flight times were set to 8:00 a.m., 11:00 a.m., 2:00 p.m. and 5:00 p.m. local time. The flight area was 1.18 ha with a 60° rotation angle under a three-span center pivot irrigation system with an overhang. UAV flight missions were executed during the jointing, heading, and grain filling phases of winter wheat. There were 90 management zones with pie shapes in total, which were composed of a 10° angle in the rotation direction and 4 sprinklers along the lateral direction. The vegetation indices (VIs) which are closely related to crop nutrient status were selected and used to generate distribution maps, which were superimposed with the management zones to generate VRN prescription maps. The results demonstrated that the red-edge soil adjusted vegetation index (RESAVI) was relatively more sensitive to the nitrogen status of winter wheat than the other VIs were. The RESAVI distributions were stable during periods with a solar elevation angle greater than 50° (11:00 a.m.–2:00 p.m. local time), and the VRN prescription maps were similar, with the overlap percentage of the same fertilization grade being greater than 80% and the relative error of the fertilization amount being less than 5%. Compared with that at 2:00 p.m., the overlap percentage of the same fertilization grade was 56.6% in both seasons at 8:00 a.m., whereas flights at 5:00 p.m. exhibited overlaps of 70.9% and 44.6% in the 2023 and 2024 seasons, respectively. Conversely, the flight altitude had little influence on the fertilizer amount and VRN prescription maps. The difference in the amount of fertilizer used was less than 3% at different flight altitudes. The required time is half of that for a 50 m flight when the flight altitude is 70 m and one third of that when the flight altitude is 90 m. Our study recommended operating the UAV multi-spectral system at solar elevation angles greater than 50° when generating VRN prescription maps of winter wheat, and the flight height can be adjusted according to the field area and the endurance time of the UAV. Full article

Maw-sit-sit jade resembles kosmochlor-jadeitite in appearance and is spatially associated with it in the Myanmar Jade Belt. However, the mineral composition, microstructure, and petrogenesis of this type of jade remain unclear. To address this gap, this study investigated high-quality Maw-sit-sit jade using a range of analytical techniques, including conventional gemological tests, infrared spectroscopy, petrographic observations, electron probe microanalysis (EPMA), and backscattered electron (BSE) imaging. Results show that Maw-sit-sit jade primarily consists of albite and chromium-omphacite, with minor amphibole (eckermannite and richterite). Jadeite and relict chromite are absent in the studied samples. Its high albite content gives it lower refractive index (RI: 1.55–1.56) and specific gravity (SG: 2.69–2.73) compared to kosmochlor-jadeitite and jadeite jade. Additionally, Maw-sit-sit jade exhibits punctate or banded fluorescence under ultraviolet (UV) light, distinguishing it from kosmochlor-jadeitite and jadeite jade (both inert). Petrographically, euhedral albite fills interstices between early-formed Cr-omphacite and eckermannite, which is textural evidence of its late-stage origin. Eckermannite and Cr-omphacite occur as enclosed grains with embayed boundaries and dissolution pores, indicating they experienced mechanical disruption and chemical dissolution during subsequent geological processes. Petrogenetically, Maw-sit-sit jade (defined as “Cr-omphacite-albitite”) forms via a two-stage process: (1) Under high-pressure/low-temperature (HP/LT) conditions in the subduction zone, Na-Al-Si-rich fluids metasomatize chromite-bearing serpentinite protoliths, generating an early assemblage of jadeite, Cr-omphacite and amphiboles; (2) During subsequent plate exhumation and decompression, jadeite underwent retrograde metamorphism under low-pressure/low-temperature (LP/LT) conditions involving residual Na-Al-Si fluids, resulting in the formation of albite. This process led to the replacement of early-formed minerals by euhedral albite, ultimately generating the Ab+Cr-Omp+Eck symplectic texture. This study elucidates the mineralogical, gemological identity and petrogenesis of high-quality Maw-sit-sit jade, advancing our understanding of fluid evolution within a subduction zone. Full article

The normal metabolism of transient starch in leaves plays a vital role in determining photosynthesis and final crop yield. However, the molecular mechanisms linking abnormal transient starch metabolism to premature leaf senescence remain unclear. Here, we isolate a rice mutant, lses1, with leaf yellowing and premature senescence, as well as excessive accumulation of starch granules in chloroplasts. Genetic analysis revealed that this trait is controlled by a single recessive nuclear gene. Through BSA-seq preliminary gene mapping, map-based cloning, and sequencing alignment, the candidate gene was pinpointed to LOC_Os02g40860 on chromosome 2, which encodes OsCKI1, a casein kinase I family member. The identity of LSES1 was confirmed functionally: genetic complementation with the native genomic sequence rescued the wild-type phenotype, while CRISPR/Cas9 knockout of the gene in wild-type plants recapitulated the premature senescence. This confirmed that LSES1/OsCKI1 is involved in the regulation of leaf senescence. Notably, one improved knockout line, KO-2, displayed significant agronomic improvements in grain length, grain width, number of productive ears, and number of filled grains per panicle, along with a significant increase in grain yield per plant, highlighting its potential breeding value. Subcellular localization and tissue-specific expression analysis showed that LSES1 is primarily nuclear-localized and constitutively expressed. Full article

Phenology is a key factor influencing the accuracy of regional-scale winter wheat-yield estimation. This study proposes a yield-estimation modeling framework centered on phenological zoning. Based on the remote sensing monitoring results of the heading stage of winter wheat in the Huang-Huai-Hai region from 2016 to 2021, the KNN-Ward spatial constraint clustering method was adopted to divide the Huang-Huai-Hai region into four consecutive wheat phenological zones. The results indicate a consistent spatio-temporal gradient in the phenology of winter wheat across the Huang-Huai-Hai region, characterized by later development in the northern areas and earlier development in the southern areas. The median day of year (DOY) for the heading stage in each zone varies by approximately 4 to 5 days, demonstrating a high degree of interannual stability. Building upon the phenological zoning outcomes, a multi-source data-driven random forest model was developed for wheat-yield estimation by integrating remote sensing data and meteorological variables during the wheat grain filling stage. This model incorporates remote sensing vegetation indices, crop growth parameters, and climatic factors as key input variables. Results show that the phenological zoning strategy significantly improves model prediction performance. Compared with the non-zoning model (R² = 0.46, RRMSE = 13.02%), the phenological zone model shows strong performance under leave-one-year-out cross-validation, with R² ranging from 0.54 to 0.68 and RRMSE below 12.50%. The phenological zoning model also exhibits more uniform residuals and higher prediction stability than models based on non-zoning, traditional agricultural zoning, and provincial administrative zoning. These results confirm the effectiveness of phenology-based zoning for regional yield estimation and provide a reliable framework for fine-scale crop yield monitoring. The phenological zoning model also demonstrates superior residual uniformity and prediction stability compared with models based on non-zoning, traditional agricultural zoning, and provincial administrative zoning. These results confirm the effectiveness of the multi-factor-driven modeling framework based on crop phenological zoning for regional yield estimation, providing a robust methodological foundation for fine-scale yield monitoring at the regional level. Full article

Agricultural drought poses a critical constraint to food security and regional sustainable development, particularly in the Huang-Huai-Hai Plain, a major grain-producing region characterized by high spatial heterogeneity in drought risk. Previous studies have demonstrated that the Crop Water Stress Index (CWSI) outperforms traditional meteorological indices in detecting agricultural droughts in various regions. However, there is limited research specifically focusing on its spatiotemporal dynamics and the complex relationships with environmental factors, particularly in the Huang-Huai-Hai Plain. To fill this gap, this study first estimated CWSI using remote sensing evapotranspiration data and systematically assessed the spatiotemporal dynamics of agricultural drought in the Huang-Huai-Hai Plain from 2005 to 2020. Then, an integrated analytical framework that combines Local Indicators of Spatial Association (LISA) with Random Forest (RF) modeling has been proposed to identify primary environmental drivers. Results revealed a general downward trend in CWSI over the study period, with drought hotpots primarily concentrated in the central plains and along the eastern foothills of the Taihang Mountains. LISA identified four distinct spatial cluster types and revealed significant spatial associations between CWSI and six environmental variables. The major driving factors of CWSI included vegetation conditions (NDVI), land surface temperature (LST), rainfall, and temperature-related factors (SAT, DSR), with LST and SAT exhibiting the strongest correlations with CWSI in multiple regions. Among these, LST and SAT exhibited strong positive correlations with CWSI in multiple regions. By integrating spatial clustering and variable importance analysis, we found that agricultural drought patterns are shaped by interacting environmental factors, with region-specific dominant mechanisms. This study provides a novel analytical framework that bridges remote sensing, spatial statistics, and machine learning, offering valuable insights and tools for drought monitoring and attribution at regional scales. Full article

The soil–water characteristic curve (SWCC) is essential for understanding hydraulic behavior in geotechnical applications involving coarse granular materials. However, existing models often overlook the coupled effects of key factors. This study systematically investigates the influence of grain size distribution, density, and contact angle on the SWCC using a numerical approach that combines the discrete element method (DEM) with an enhanced pore morphology method incorporating locally variable contact angles (Lvca-PMM). The results show that smaller uniformity coefficients ($C_u$), larger median grain sizes ($D_{50}$), higher porosity ($\phi$), and larger contact angles ($\theta$) shift the SWCC to the left, reducing both the air entry value (${\Psi }_a$) and residual suction (${\Psi }_r$). Specifically, linear relationships were identified between ${\Psi }_a$, ${\Psi }_r$, $C_u$, $\phi$, and cos($\theta$), while a power-law relationship was observed with $D_{50}$. Furthermore, the interaction of these factors plays a critical role, where a change in one property can amplify or diminish the effects of others. Based on these findings, empirical equations for predicting ${\Psi }_a$ and ${\Psi }_r$ were developed, offering practical tools for engineers to efficiently estimate the SWCC. This research provides deeper insight into the water retention properties of coarse soils and supports the optimized design of granular fills and drainage systems. Full article

The accumulation of photoassimilates in the sinks during the grain filling stage is affected by the conditions of the various source organs. This study was conducted to investigate changes in various source and sink organs when the flag leaves and spikes were shaded from heading to harvest in wheat. Shading the flag leaves increased chlorophyll content and chlorophyll fluorescence in the uppermost leaves by 34.9% and 0.3% in 2022 and 75.3% and 3.3% in 2023, respectively, maintaining a relatively high photosynthetic rate from heading to the mid-grain filling stage. However, shading the spikes had a more substantial negative impact on spike growth than the flag leaf shading. On the other hand, the uppermost leaves continued to serve as a source more actively even when the flag leaves were shaded, implying a compensating effect. At 35 days after treatment (DAT), the relative water content (RWC) of the spike in the spike shading (SS) treatment was 19.4% and 49.7% higher than that of the control in 2022 and 2023, respectively. However, grain weight in the SS treatment decreased by 39.7% in 2022 and 5.3% in 2023 compared with the control. In the flag leaf shading (FS) treatment, grain weight declined by 3.5% and 6.2% in 2022 and 2023, respectively. These results indicate that the reduction in grain weight due to shading was less pronounced in the SS treatment than in the FS and combined flag leaf and spike shading (FSS) treatments. The results suggest that spikes play a buffering role when assimilate-transport functions decline in the source organs. Our results provide a better understanding of the architectural properties, including flag leaf, spike, and the uppermost leaf, for photosynthetic contribution to grain filling in wheat. Also, identifying target characteristics for improving photosynthetic source organs will be valuable for developing wheat varieties with high yield stability. Full article

Paclobutrazol (PBZ) is extensively used to modulate plant architecture in rice. However, its comprehensive effects on grain yield and aroma in aromatic rice have not been thoroughly investigated. This study used the local aromatic rice cultivars (Meixiangzhan 2 and Xiangyaxiangzhan) as experimental materials to evaluate the impacts of foliar-applied PBZ at three concentrations (0 (CK), 150 (T1), and 300 (T2) mg L⁻¹) on grain yield, photosynthetic characteristics, fragrance formation, and radiation use efficiency (RUE). Field experiments revealed that T1 significantly reduced the leaf area index (LAI) by 10.12% and intercepted photosynthetically active radiation (IPAR) by 10.74%, meanwhile significantly increasing SPAD values by 12.94% and net photosynthetic rate (Pn) by 9.95%, leading to improved RUE up to 25.21%. These changes contributed to a larger number of grains per panicle and increased 1000-grain weight, ultimately enhancing grain yield. In contrast, T2 resulted in a sharp reduction by 24.84% in IPAR and a significant decline in Pn by 10.07% during the late grain-filling stage, thus limiting the supply of photosynthetic assimilates, eventually reducing grain yield. PBZ application also significantly elevated 2-acetyl-1-pyrroline (2-AP) content by 28.74% under T1 and 17.51% under T2, compared to the control. The increase in 2-AP was mainly associated with elevated levels of key precursors, including proline, Δ1-pyrroline-5-carboxylic acid, and Δ1-pyrroline. In spite of differences in traits between cultivars, the traits responded to PBZ in the same pattern. These results indicate that foliar application of PBZ at 150 mg L⁻¹ can effectively improve both yield and aroma of aromatic rice, offering a promising cultivation strategy for high-quality aromatic rice production. Full article

This study investigates the water-stability performance and stabilization mechanism of a hybrid-modified dredged muck sampled from the protection channel of the southern seawall, Cangnan County, China, and explores the feasibility of reusing the modified soil as backfill or non-structural fill behind the dike body. The muck was amended with two industrial by-products: (i) coarse-grained spoil excavated from an adjacent power-plant project, serving as a particle-size modifier, and (ii) ordinary Portland cement, acting as the chemical stabilizer. Unconfined compressive strength (UCS) tests were conducted on specimens cured for 7 d and 28 d under both saturated and unsaturated conditions, complemented by scanning electron microscopy (SEM) to elucidate microstructural evolution. An optimal mix proportion that satisfies the prescribed water-stability criterion while maintaining cost-effectiveness was thereby identified. Experimental results demonstrate that cement content, coarse-spoil fraction and curing age govern the water-stability behavior, with cement dosage exerting the most pronounced influence. A 28 d cured blend containing only 5% cement yielded a low water-stability coefficient (31.8%) and negligible post-immersion strength. Conversely, a ternary mixture comprising 40% muck, 60% coarse spoil and 15% cement achieved the highest water stability, recording UCS values of 1582 kPa (saturated) and 2025 kPa (unsaturated), corresponding to 78.1%. These findings provide a theoretical basis and practical guidance for the valorization of waste soils in coastal engineering and for the design/construction of seawalls. These findings not only provide a theoretical basis and practical guidance for the valorization of waste soils in coastal engineering and for the design/construction of seawalls, but also substantially expand the available material source, drive down construction costs, and markedly mitigate the environmental impacts associated with the off-site disposal of excavated waste. Full article

The Hetao Irrigation District in Inner Mongolia is a major spring wheat production region in China. To synergize high wheat yield, water conservation, and carbon emission reduction in this region, a 2023 and 2024 field experiment was conducted. This study systematically analyzed the effects of organic fertilizer substitution for chemical nitrogen (T1:0%, T2:25%, T3:50%, T4:75%, T5:100%) on soil carbon emissions dynamics and carbon footprint of wheat fields, under two irrigation regimes: water-saving irrigation (twice at jointing and heading stages, 2W) and conventional irrigation (four times at tillering, jointing, heading, and grain-filling stages, 4W). The results showed that during the wheat-growing season, soil CO₂ emission rate exhibited a single-peak trend (peak at flowering stage), while cumulative soil CO₂ emission showed a “decrease-increase-decrease” pattern (peak at jointing to heading). At different growth stages, both CO₂ emission and its rate increased with higher organic fertilizer substitution ratios, and were higher under 4W than 2W. Irrigation and substitution treatments significantly affected the total carbon emissions, carbon sequestration, and carbon footprint: total emissions increased with substitution ratios, while sequestration and footprint first increased then decreased; all three indices were higher under 4W than 2W. Regression analysis revealed that maximum net carbon budget was achieved at 21.6–31.7% substitution (1402.3–1879.9 kg ha⁻¹) under 2W, and 31.0–33.8% substitution (2295.5–2822.0 kg ha⁻¹) under 4W. In conclusion, water-saving irrigation (900 m³ ha⁻¹ per application at jointing and heading stages) combined with an optimal organic-nitrogen ratio (1008.0 kg ha⁻¹ organic fertilizer, 193.1 kg ha⁻¹ chemical nitrogen) effectively coordinates water conservation and carbon emission reduction. This study provides a basis for synergizing these goals in Hetao’s wheat production. Full article

Waterlogging is an increasing constraint to crop productivity under climate change, yet information on quinoa’s sensitivity to excess water remains limited. This study aimed to identify the most vulnerable phenological stage of quinoa to waterlogging stress. A greenhouse experiment was conducted using the variety Tunkahuan, applying waterlogging (12 days) at six growth stages according to the BBCH scale, plus a well-drained control. Growth, chlorophyll content, biomass, yield components, and harvest index were assessed. Waterlogging significantly reduced growth and yield at all stages (p ≤ 0.05). Early vegetative stress reduced canopy cover and chlorophyll, with partial recovery after stress removal, but caused 73% plant mortality at BBCH 25. Reproductive stress, especially at anthesis (BBCH 60–67), was most critical, reducing yield by 71–77% compared to the control due to severe declines in grain number and harvest index. Stress during grain filling caused moderate yield reductions (22–28 g plant⁻¹). We conclude that quinoa is sensitive to waterlogging throughout its development, but anthesis is the most vulnerable stage for irreversible yield loss. These findings highlight the need for breeding programs targeting waterlogging tolerance and improved management practices to minimize flooding risk during flowering. Full article

This study investigates meteorological factors’ effects on summer maize growth, agronomic traits and yield in northeastern Sichuan, China, under different sowing dates. A five-gradient sowing date experiment was conducted with three varieties from 2023 to 2024. The results showed delayed sowing prolonged total growth period mainly in the joint–tasseling and silking–maturity stages. Early sowing (5th May and 20th May) significantly improved key agronomic traits and increased grain yield, with Xianyu 1171 achieving the highest yield of 9.77 t ha⁻¹ under early sowing. Meteorological factors had limited influence during vegetative growth but strongly affected reproductive growth. Among them, average temperature (AT) and growing degree days (GDDs) were critical throughout the growth cycle, though their effects varied by stage. These findings suggest that adjusting sowing dates to align key growth stages with favorable weather—particularly by avoiding high-temperature stress during flowering and ensuring sufficient warmth during grain filling—can enhance yield stability. This study provides a basis for constructing a climate-resilient cultivation system and promoting stable and high summer maize yields in the hilly areas of northeastern Sichuan. Full article

Background: The oral microbiota is the largest and most diverse microbial community in the human body, shaped by numerous factors such as body composition, dietary habits, and oral health status. However, relationships between these parameters and the salivary microbiota in adolescents are not yet well understood. Objectives: This study aimed to characterize the salivary microbiota of healthy Turkish adolescents and to examine its associations with body mass index (BMI), diet quality, decayed-missing filled teeth (DMFT) index, and community periodontal index of treatment needs (CPITN). Methods: A descriptive, cross-sectional study was conducted among 40 adolescents aged 14–18 years, classified into four BMI z-score categories (underweight, normal weight, overweight, and obese). Anthropometric measurements, nutritional information, and oral health parameters (DMFT, CPITN) were assessed. Unstimulated saliva samples were collected, and the V3–V4 region of the 16S rRNA gene was sequenced using Illumina MiSeq. Alpha and beta diversity, differential abundance (LEfSe), and correlations with HEI components were analyzed. Results: Underweight adolescents exhibited significantly higher alpha diversity than obese participants (p = 0.024), while beta diversity did not differ across BMI, HEI, DMFT, or CPITN categories. LEfSe analysis revealed BMI-specific taxa: Leptotrichia sp., Haemophilus sp., and Treponema socranskii were enriched in the underweight group; Prevotella denticola in the obese group; and Selenomonas sputigena in the normal-weight group. HEI components, including whole fruits, whole grains, and plant-based proteins, showed positive correlations with Desulfobacterota and Proteobacteria. Poor oral hygiene was associated with higher species richness but not with large shifts in community structure. Conclusions: Salivary microbiota diversity and composition in adolescents vary with BMI, diet quality, and oral hygiene. These patterns are consistent with the idea that targeted nutritional and oral health interventions could influence the salivary microbiome during adolescence. Full article

This study explored how top-dressed biogas slurry at winter wheat’s (Triticum aestivum L.) jointing stage (JS) and grain-filling period (GP) affects soil enzyme–microbe interactions, aiming to address nutrient supply–crop demand mismatches. A field experiment with five treatments (water [CK], chemical fertilizer [CF], and three biogas slurry topdressing regimes [S1–S3]) was conducted. Soil samples (0–20 cm) were collected at JS, flowering stage (FS), GP, and reaping period (RP) to analyze soil properties (total nitrogen [TN], available phosphorus [AP], available potassium [AK], soil organic matter [SOM], ammonium nitrogen [AN], pH), enzyme activities (urease [UE], neutral phosphatase [NP], sucrase [SC], catalase [CAT]), and microbial community abundance (via Illumina NovaSeq sequencing). Results showed biogas slurry altered enzyme activities, microbial structure (e.g., Actinomycetota, Ascomycota), and their interactions by regulating soil properties. JS application boosted Pseudomonadota and UE activity, GP application increased Ascomycota and CAT activity, and S3 had the most complex enzyme–microbe network, enhancing nutrient cycling. The analysis indicated that UE activity was strongly and positively correlated with several bacterial phyla (e.g., Planctomycetota, Verrucomicrobiota) (p < 0.01) and fungal phyla (e.g., Ascomycota) (p < 0.01). Full article

High temperatures during grain filling degrade rice quality, yet the metabolite-level basis of varietal tolerance—particularly root contributions—remains unclear. We compared the heat-tolerant ‘Fusaotome’ and the widely grown ‘Akitakomachi’ under control and high-temperature conditions. Panicles and roots were sampled at heading and profiled by capillary electrophoresis–mass spectrometry (CE–MS), followed by PCA, univariate testing, and KEGG pathway analysis. PCA resolved treatment and cultivar differences in an organ-specific manner. In panicles, ‘Fusaotome’ showed 8 increased metabolites (≥1.5-fold) and 11 decreased (≤1/1.5), whereas ‘Akitakomachi’ showed 19 increases and 6 decreases (p < 0.05). In roots, 12 metabolites increased in ‘Fusaotome’ and 9 in ‘Akitakomachi’; no significant decreases were detected. Pathway analysis indicated activation in ‘Fusaotome’ panicles of tryptophan, nicotinate/nicotinamide, arginine/proline, glycolysis/TCA, pyruvate, and vitamin B6 pathways, while ‘Akitakomachi’ emphasized phenylpropanoid, isoquinoline alkaloid, caffeine, and ubiquinone/terpenoid–quinone biosynthesis. In roots, ‘Fusaotome’ prioritized phenylalanine/phenylpropanoid, aromatic amino acids, lysine degradation, branched-chain amino acids, glycerophospholipids, and alkaloids, whereas ‘Akitakomachi’ favored nitrogen- and antioxidant-related routes. Collectively, the tolerant cultivar maintained antioxidant capacity and energy supply while coordinating root–panicle metabolism, whereas the susceptible cultivar shifted toward secondary defenses. These signatures nominate candidate metabolic markers and targets for breeding and management to stabilize rice production under warming climates. Full article