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• A MAE-IC-ICP-MS method was set up to determine Se species in rice plants. • The accumulated Se by rice plants in Se(VI)-added soil was higher than that in Se(IV)-added soil. • Arsenite and As(V) facilitated the conversion of Se(IV) into Se-Cys and Se-Me. • Arsenite and As(V) had higher antagonism on Se species in Se(VI)-added soil than that in Se(IV)-added soil. • Arsenite had higher inhibiting effect on the Se species than As(V) in Se(VI)-added soil. Selenium (Se) in paddy rice is one of the significant sources of human Se nutrition. However, the effect of arsenic (As) pollution in soil on the translocation of Se species in rice plants is unclear. In this research, a pot experiment was designed to examine the effect of the addition of 50 mg As/kg soil as arsenite or arsenate on the migration of Se species from soil to indica Minghui 63 and Luyoumingzhan. The results showed that the antagonism between inorganic As and Se was closely related to the rice cultivar and Se oxidation state in soil. Relative to the standalone selenate treatment, arsenite significantly (p < 0.05) decreased the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, sheaths, leaves, brans and kernels of both cultivars by 21.4%-100.0%, 40.0%-100.0%, 41.0%-100%, 5.4%-96.3%, 11.3%-100.0% and 26.2%-39.7% respectively, except for selenocystine in the kernels of indica Minghui 63 and selenomethionine in the leaves of indica Minghui 63 and the stems of indica Luyoumingzhan. Arsenate also decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, brans and kernels of both cultivars by 34.9%-100.0%, 30.2%-100.0%, 11.3%-100.0% and 5.6%-39.6% respectively, except for selenate in the stems of indica Minghui 63. However, relative to the standalone selenite treatment, arsenite and arsenate decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenite only in the roots of indica Minghui 63 by 45.5%-100.0%. Our results suggested that arsenite and arsenate had better antagonism toward Se species in selenate-added soil than that in selenite-added soil; moreover, arsenite had a higher inhibiting effect on the accumulation of Se species than arsenate. [Display omitted] [ABSTRACT FROM AUTHOR]

• Spider community composition changed during the rice growing season. • The rice field development generally decreased the number of horizontal web-building spiders and captured detritivorous prey. • Species identity and species traits of spider as well as environmental factors affect prey capture by web-building spiders. Understanding the effects of microhabitat changes on arthropod predator communities and their prey in agroecosystems is essential for field management and biocontrol. Few studies have investigated the trait composition of web-building spider communities in rice ecosystems. Here, we examined how temporal changes during the rice field development affect the abundance and traits of orb-web spiders, and how these effects consequently influence captured prey number and prey composition in irrigated rice ecosystems in southern Thailand. We used structural equation models to evaluate direct and indirect, spider-mediated effects of rice field development on captured prey numbers in each different guild. We found that the number of horizontal web-building spiders decreased during the rice field development, whereas there was no significant change in number of vertical web-building spiders. The number of captured detritivorous insects was positively related to the numbers of horizontal and vertical web-building spiders, while phytophagous insects and others were positively related only to the numbers of vertical web-building spiders. Moreover, the prey number captured by vertical web-building spiders seems to be indirectly increased through the decreasing number of horizontal web-building spiders in the late rice season. A fourth-corner analysis showed that spider species identity, spider traits (web type, web height and web diameter), vegetation height, and water level generally influenced the prey captured by web-building spiders. Horizontal web-building spider species with lower web placement during the flooding phase captured high numbers of detritus-feeding insects, while vertical web-building spider species with higher web placement captured high numbers of rice pests, predators and others. Our results suggest that the field development acted as an environmental factor that determined the species identity and traits of web-building spider communities. The findings of this study can help to predict the ecosystem services provided by the web-building spider community in rice ecosystems. [ABSTRACT FROM AUTHOR]

In this study, the agro-hydrological model Soil and Water Assessment Tool + (SWAT+) is used to simulate runoff in an uncontrolled agricultural catchment with paddy fields irrigated by plots submersion. The objectives are to evaluate the ability of this new, improved version of the SWAT model to reproduce the flows in a complex catchment and to analyse the evolution of these flows over the historical period 1986-2020 (35 years). Sensitivity analysis, calibration and validation were carried out with monthly flow data. The decision tables for irrigation operations and reservoir water release were filled in the SWAT+ Editor to establish the reservoir water balance. The Mann-Kendall trend test with the threshold of the standard normal statistic = 1.96, was applied to the time series of flows to the Nanan Reservoir. The results reveal that SWAT+ is more sensitive to eight parameters, including the new CN3_SWF parameter (-0.04329), which gave the user control of the soil saturation level. Good performances were obtained during calibration and validation, respectively: NSE (0.78; 0.69); R² (0.81; 0.70); PBIAS (-18.58; -23.9) and RSR (0.47; 0.56), with a tendency to slightly overestimate flows. The analysis shows that flows to the Nanan Reservoir are highly variable yearly, with a non-significant upward trend (|Z|=1.3<1.96) from 1986 to 2020. The water balance reveals that the runoff inflow generated will compensate for water withdrawals for irrigation of the Nanan paddy scheme during this period. Furthermore, this study provides a methodological framework for SWAT+ reservoir model calibration in an uncontrolled catchment. [ABSTRACT FROM AUTHOR]

• Accounting methods of agricultural methane are summarized. • Influencing factors of emission sources from agricultural sources were analyzed. • Mitigation strategies based on accounting and actual situation are proposed. Methane is one of the major greenhouse gases (GHGs) and agriculture is recognized as its primary emitter. Methane accounting is a prerequisite for developing effective agriculture mitigation strategies. In this review, methane accounting methods and research status for various agricultural emission source including rice fields, animal enteric fermentation and livestock and poultry manure management were overview, and the influencing factors of each emission source were analyzed and discussed. At the same time, it analyzes the different research efforts involving agricultural methane accounting and makes recommendations based on the actual situation. Finally, mitigation strategies based on accounting results and actual situation are proposed. This review aims to provide basic data and reference for agriculture-oriented countries and regions to actively participate in climate action and carry out effective methane emission mitigation. [Display omitted] [ABSTRACT FROM AUTHOR]

• Proposed a Hybrid Model for Paddy Crop prediction based on phenological parameters. • CNN-LSTM attained RMSE value of 0.219 t/ha compared to other existing methods. • Random Forest method achieved highest accuracy of 96.6% in paddy classification. Rice is one of the predominant food sources to fulfill the dietary requirements of well-being in India. Therefore, accurate and timely paddy crop yield prediction is crucial to ensure the food security of the country. In this direction, the present study proposed a hybrid deep-learning method based on Conv-1D and LSTM layers using the classification-derived phenological with meteorological parameters for paddy crop yield prediction. The paddy crop classification has been conducted using high-resolution (10 m) multispectral imagery based on GPS coordinates collected during the paddy field visits to extract the phenological parameters for input to the prediction model. In this context, the efficiency of Random Forest, Naïve Bayes, SVM, and Gradient Tree boost classifiers was assessed. Furthermore, we have also analyzed the accuracy of Landsat-8, Sentinel-1 GRD, and Sentinel-2 satellite imagery in paddy crop classification based on area estimation. The Statistical Abstract of Haryana was utilized to validate the paddy crop area estimation and yield prediction. The classification outcomes showed that the Random Forest method attained the highest accuracy of 96.6 % compared to other GEE-based classifiers. The proposed Hybrid Deep learning approach achieved an RMSE value of 0.219 t/ha compared to CNN, LSTM, CNN-Bi-LSTM, and Regression techniques for crop yield prediction. The study conclusion highlighted that the sentinel-2 satellite imagery performed well and found that the proposed hybrid approach provided an alternative for paddy crop yield prediction. [ABSTRACT FROM AUTHOR]

VIIRS flood products have been widely used by the National Weather Service (NWS) for river flood monitoring, and by the Federal Emergency Management Agency (FEMA) and the International Charter Program for rescue and relief efforts. However, some water bodies, like irrigated or flooded paddy rice fields, and water in seasonal wetlands, are detected as floodwater instead of permanent, seasonal, controlled, or normal water in the VIIRS flood products. Because these kinds of floodwater don't cause any severe disasters, they should be delineated as non-hazard floods to differentiate from real hazardous floods, the latter of which generally pose a significant risk and damage to human life, property, and the environment. Hazardous floods are usually caused by intensive rainfall, rapid snowmelt, or ice jams, they appear accidentally and tend to be short-term events. Non-hazard floodwaters generally result from tides, wetlands, agricultural irrigation, and other human activities, and thus they appear regularly and often stand for a longer time. Therefore, non-hazard floodwaters are some kind of standing water and usually have much larger long-time flood frequency or probability than hazardous floods. Based on this feature, it's possible to combine long-time flood frequency calculated as the ratio of total flooding days over total clear days, including both flooding and no-flooding days, from VIIRS flood products with some additional information, such as agriculture statistics and land cover and land use map, to identify non-hazard floodwater in paddy rice fields and wetland. In this study, non-hazard floodwater bodies are classified into four types: paddy rice fields, wetlands, riparian and coastal tidal flooding, and other non-hazard floods, including possible fishing ponds. In this study, we selected several examples, such as the 2023 California flood event and some large paddy rice fields in China, to demonstrate how to identify water in paddy rice fields. The Florida flood event due to Hurricane Ian in 2022 is used to demonstrate how to separate wetlands from real hazardous floods. In addition to non-hazard floodwaters in wetlands, some coastal tidal flooding in Florida is also detected. The non-hazard floodwaters extracted from the proposed methods are compared with change detection analysis and good agreement is found. The paddy rice fields obtained from this study are compared and evaluated with the rice distribution data from the USDA. The quantitative evaluation results from the confusion matrix calculation demonstrate that the accuracy is 99.96%, recall is 83.69%, precision is 61.57%, and the F1-score is 70.95%. The high accuracy indicates that the method developed in this study for paddy rice field extraction from the VIIRS flood products is feasible. [ABSTRACT FROM AUTHOR]

Anthropogenic methane emissions are a leading cause of the increase in global average temperatures, often referred to as global warming. Flooded soils play a significant role in methane production, where the anaerobic conditions promote the production of methane by methanogenic microorganisms. Rice fields contribute a considerable portion of agricultural methane emissions, as rice plants provide both factors that enhance and limit methane production. Rice plants harbor both methane- producing and methane-oxidizing microorganisms. Exudates from rice roots provide source for methane production, while oxygen delivered from the root aerenchyma enhances methane oxidation. Studies have shown that the diversity of these microorganisms depends on rice cultivars with some genes characterized as harboring specific groups of microorganisms related to methane emissions. However, there is still a need for research to determine the balance between methane production and oxidation, as rice plants possess the ability to regulate net methane production. Various agronomical practices, such as fertilizer and water management, have been employed to mitigate methane emissions. Nevertheless, studies correlating agronomic and chemical management of methane with productivity are limited. Moreover, evidences for breeding low-methane-emitting rice varieties are scattered largely due to the absence of coordinated breeding programs. Research has indicated that phenotypic characteristics, such as root biomass, shoot architecture, and aerenchyma, are highly correlated with methane emissions. This review discusses available studies that involve the correlation between plant characteristics and methane emissions. It emphasizes the necessity and importance of breeding low-methane-emitting rice varieties in addition to existing agronomic, biological, and chemical practices. The review also delves into the ideal phenotypic and physiological characteristics of low-methane-emitting rice and potential breeding techniques, drawing from studies conducted with diverse varieties, mutants, and transgenic plants. [ABSTRACT FROM AUTHOR]

Soil redox potential (Eh) plays an important role in the biogeochemical cycling of soil nutrients. Whereas its effect soil process and nutrients' availability under elevated atmospheric CO 2 concentration and warming has seldom been investigated. Thus, in this study, a field experiment was used to elucidate the effect of elevated CO 2 concentration and warming on soil Eh, redox-sensitive elements and root radial oxygen loss (ROL). We hypothesized elevated CO 2 and warming could alter soil Eh by promoting or inhibiting ROL. We found that soil Eh in the rhizosphere was significantly higher than that of non-rhizosphere. Elevated CO 2 enhanced soil Eh by 11.5%, which corresponded to a significant decrease in soil Fe2+ and Mn2+concentration. Under elevated CO 2 , the concentration of Fe2+ and Mn2+ decreased by 14.7% and 13.7%, respectively. We also found that elevated CO 2 altered rice root aerenchyma structure and promoted rice root ROL. Under elevated CO 2 , rice root ROL increased by 79.5% and 112.2% for Yangdao 6 and Changyou 5, respectively. Warming had no effect on soil Eh and rice root ROL. While warming increased the concentration of Mn2+ and SO 4 2− by 4.9% and 19.3%, respectively. There was a significant interaction between elevated CO 2 and warming on Fe2+ and Mn2+. Under elevated CO 2 , warming had no effect on the concentration of Fe2+ but decreased Mn2+ concentration significantly. Our study demonstrated that elevated atmospheric CO 2 in the future could increase soil Eh by promoting rice root ROL, which will alter some soil nutrients' availability, such as Fe2+ and Mn2+. [Display omitted] [ABSTRACT FROM AUTHOR]

The transformation of blue and green water is an important hydrological process at the watershed, which is an important supplement to the study of hydrological processes. The Soil and Water Assessment Tool (SWAT) was used to investigate the evolution characteristics of hydrological processes and the transformation mechanism at the watershed and ecosystem scales in the Dongjiang River. The results show that: (1) the annual average total water flows in the Dongjiang River Basin are 37.80 and 22.287 billion m³, respectively. The blue and green water flows during the wet season account for more than 75% of the total year. The blue and green flows of the grassland ecosystem increased significantly, with the most significant change in the downstream ecosystem. (2) From 1980 to 1990 and from 2010 to 2020, the Dongjiang River Basin experienced a transition from blue to green water flow. Blue water flow accounts for the majority of total water flow in the paddy field and dry cropland ecosystems, and green water flow changed to blue water flow from 1980 to 2010. (3) The correlation between blue and green flow and land use was weak throughout the year and during the wet season, but it was significant during the dry season. This study can serve as a model for the integrated management of water resources and ecosystems in the Dongjiang River Basin. [ABSTRACT FROM AUTHOR]

• Soil adhesion and resistance of soil-engaging components in paddy field are difficult problems. • Loach body surface is covered by scales, the scales have ridged non-smooth structure. • Rice direct-seeding machine bionic sliding plate is constructed based on the non-smooth structure of scales. • Drag reduction rate of ridge-shaped non-smooth structure is 4.21%. • Bionic technology is applied to reduce adhesion and resistance in paddy soil environment. Sliding plate has the problems of large sliding resistance and serious soil adhesion. Loach moves freely and flexibly in mud, has highly efficient lubrication and drag reduction effects. The sliding plate of rice direct seeding machine was selected as the research object and loach as the bionic prototype. The macroscopic and microscopic structure characteristics of loach were observed, the body surface of loach was covered by scales, which had a ridged non-smooth structure. The simulation analysis of the drag reduction performance of the non-smooth structure was carried out, the maximum drag reduction rate was 2.55% at the speed of 1 m/s. A bionic sliding plate of rice direct-seeding machine was constructed based on the non-smooth structure of loach body surface, and its working performance was simulated and analyzed. The results of orthogonal test show that the order of primary and secondary factors of bionic structure parameters affecting drag reduction rate was ribbed spacing > ribbed width > ribbed height. The optimal parameter combination was ribbing height 4 mm, ribbing width 4.5 mm, ribbing spacing, and the optimal drag reduction rate was 4.21%. The results of this study can provide theoretical support for bionic design of soil-engaging components in wet and soft paddy field. [ABSTRACT FROM AUTHOR]

• Bio-Cd and bio-As in rhizosphere soil increased before the heading stage. • Content of ΣPAHs showed a decreased trend during whole growth period of rice. • Massilia and Sphingomonas were dominant rhizobacteria in HM-PAH contaminated soil. • Rhizobacteria interacted with pollutants intensely at tillering and heading stage. • Bio-Cd and ΣPAHs were key factors influenced community structure of rhizobacteria. This study investigated the transformations of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in rhizosphere soils and adaptive responses of rhizobacterial community under the real field conditions during four growth stages (e.g., greening, tillering, heading, and maturity) of early rice (Zhongjiazao 17) and late rice (Zhongyou 9918) in Jiangshe village (JSV) and Yangji village (YJV). Results showed that rhizosphere soils of YJV were mildly polluted by Cd and PAHs compared to that of JSV. The relative abundance of bioavailable Cd (bio-Cd) and bioavailable As (bio-As) in rhizosphere soil increased before the heading stage but decreased at the subsequent growth stage, but the content of ΣPAHs in rhizosphere soil decreased gradually during whole growth period. The dominant rhizobacteria genera at YJV (e.g., Bacillus, Massilia, Sphingomonas , and Geobacter) increased at an abundance level from the tillering to heading stage. Rhizobacteria interacted with the above co-pollutant more intensely at the tillering and heading stage, where genes involved in HM-resistance and PAH-degradation appeared to have a significant enhancement. The contents of bio-Cd and bio-As in rhizosphere soil of early rice were higher than that of late rice at each growth stage, especially at the heading stage. Bio-Cd, ΣPAHs, and organic matter were key factors influencing the community structure of rhizobacteria. Results of this study provide valuable insights about the interactions between HM-PAH co-pollutant and rhizobacterial community under real field conditions and thus develop in-situ rhizosphere remediation techniques for contaminated paddy fields. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Aboveground biomass (AGB) is an essential factor in rice ecological research. Optical variables (e.g. reflectivity and vegetation index (VI)) are widely adopted in monitoring AGB while spatial information (e.g. texture) is less introduced into research. Limited research is available regarding the impact on the monitoring accuracy caused by the utility of VI and texture in AGB estimation at different combinations of growth stages. To compare the improvements caused by the involvement of texture at different combinations of growth stages, a hyperspectral camera was mounted on an unmanned aerial vehicle (UAV) to obtain images of rice field during the early growth stages (including the tillering, jointing and booting stage) under five nitrogen levels over two years. Spectral and spatial information derived from images was utilized to compute VIs and textures at different combinations of growth stages. After analyzing their correlations with AGB, multiple stepwise regression (MSR) and multiple linear regression (MLR) techniques were employed to establish rice AGB models using vegetation index (VI), vegetation index combined with the corresponding-band texture (VI-CBT) and vegetation index combined with the full-band texture (VI-FBT). It was found that the models using VI and texture enhanced the capability of the conventional VI to estimate AGB at different combinations of growth stages. The combination of VI and FBT achieved the most accurate estimation, followed by the VI-CBT. Different combinations of growth stages had diverse responses to textures. Overall, the tillering stage had the maximum response to the involvement of textures, followed by the booting stage. Models using VI-CBT and VI-FBT significantly improved the AGB estimation at the booting and tillering stage, respectively. The monitoring accuracy of the jointing stage showed a slight response to the involvement of texture. At the multiple growth stages, the monitoring effect of the tillering-booting stages was significantly improved, followed by the jointing-booting stages either using the model based on VI-CBT or VI-FBT. Models using VI and texture tended to yield larger improvements on the error values at the extreme AGB levels. Near-infrared and red-edge bands were the sensitive bands to estimate rice AGB, and MEA, COR were favorable textures to monitor the AGB. This study quantified the model improvements of using VI and texture in rice AGB estimation at different combinations of growth stages, delivering guidance for timely and accurate rice management in the field. [ABSTRACT FROM AUTHOR]

This research work involves data access and control of Unmanned Ground Vehicles (UGVs) which is designed for health monitoring of paddy crops as an exception from traditional monitoring system. The proposed scheme of autonomous navigation of drones is planned to be carried out as per the six milestones for disease detection and control in paddy crops. Drones serve as Unmanned Robotic Vehicles (URV) capable of performing desired tasks in unstructured, uncertain and potentially hostile environments and are remotely-operated without human intervention. URVs function completely as autonomous entities in diversified environments. Current UGVs adhere to different levels of automaticity. Typically the vehicle follows high level waypoints spaced for few hundred meters of distance to provide monitoring of agricultural fields and early detection of the various diseases that may occur in the paddy fields in a polyhouse. To increase the vehicle's abilities, tracking efficiency, obstacle avoidance, path planning or lead and follow up augmented control with Fuzzy Logic Controller (FLC) is incorporated. The distributed autonomous system for information gathering related to the paddy crops in polyhouse is enabled using different sensors, which is a data-intensive task. To increase the robustness of the system, fuzzy controllers are proposed to control the navigation of the proposed UGV in "All terrain conditions". They are needed to offer problem specific heuristic control knowledge for the Inference Engine Design which occurs due to imprecision and uncertainty of the sensor readings. It also requires low computation time which favours the polyhouse situations. The navigation of UGV and the FLC action will in turn depend on "All terrain traversability" and "dead zone" monitoring. The proposed UGV model is capable of measuring the parameters associated with the paddy crops inside a polyhouse. The various diseases in paddy crops are False Smut (FS), Sheath Blight (SB), Rice Blast (RB), Leaf Scald (LS), Brown Spot (BS), Bacterial Leaf Blight (BLB) and Bakane (BE) which are detected using Convolutional Neural Network (CNN). [ABSTRACT FROM AUTHOR]

• Total mercury and methylmercury were analyzed in different types of commercially available cereal-based foods in China. • Rice was the main source of mercury and methylmercury in cereal foods. • Mercury intake through rice-based snack food as supplementary cannot be ignored. Mercury (Hg), especially methylmercury (MeHg), accumulation in rice grain due to rice paddy possessing conditions conducive to Hg methylation has led to human Hg exposure through consumption of rice-based daily meals. In addition to being a food staple, rice is widely used as a raw material to produce a vast variety of processed food products. Little is known about Hg levels in snacking rice-food products and potential Hg exposure from consumption of them, besides previous studies on infant rice cereals. Aiming to provide complementary information for a more complete assessment on Hg exposure risk originated from Hg-containing rice, this study determined total Hg (THg) and MeHg levels in 195 rice-containing and rice-free processed food products covering all major types of snack foods marketed in China and the estimated daily intake (EDI) of dietary Hg from the consumption of these foods. The results clearly showed THg and MeHg contents in rice-containing foods were significantly higher than rice-free products, suggesting the transfer of Hg and MeHg from the rice to the end products, even after manufacturing processes. Moreover, significant positive correlations were observed between THg, MeHg, or MeHg/THg ratio and rice content for samples containing multiple grains as ingredients, further indicating the deciding role of rice for Hg levels in the end food products. Although the EDI of THg and MeHg via rice-based food products were relatively low compared to the reference dose, it should be considered these snacking food products would contribute additive Hg intake outside of the daily regular meals. [Display omitted] [ABSTRACT FROM AUTHOR]

• SC, Mg/SC and ZVI decreased concentrations of Cd and iAs in rice grain concurrently. • Mg/SC and ZVI simultaneously reduced Cd and iAs concentrations in soil porewater. • ZVI raised DMA concentrations in porewater and rice grain, but SC and Mg/SC didn't. • SC, Mg/SC and ZVI affected Cd/As accumulation through divergent mechanisms. Cadmium (Cd) and arsenic (As) co-contamination has threatened rice production and food safety. It is challenging to mitigate Cd and As contamination in rice simultaneously due to their opposite geochemical behaviors. Mg-loaded biochar with outstanding adsorption capacity for As and Cd was used for the first time to remediate Cd/As contaminated paddy soils. In addition, the effect of zero-valent iron (ZVI) on grain As speciation accumulation in alkaline paddy soils was first investigated. The effect of rice straw biochar (SC), magnesium-loaded rice straw biochar (Mg/SC), and ZVI on concentrations of Cd and As speciation in soil porewater and their accumulation in rice tissues was investigated in a pot experiment. Addition of SC, Mg/SC and ZVI to soil reduced Cd concentrations in rice grain by 46.1%, 90.3% and 100%, and inorganic As (iAs) by 35.4%, 33.1% and 29.1%, respectively, and reduced Cd concentrations in porewater by 74.3%, 96.5% and 96.2%, respectively. Reductions of 51.6% and 87.7% in porewater iAs concentrations were observed with Mg/SC and ZVI amendments, but not with SC. Dimethylarsinic acid (DMA) concentrations in porewater and grain increased by a factor of 4.9 and 3.3, respectively, with ZVI amendment. The three amendments affected grain concentrations of iAs, DMA and Cd mainly by modulating their translocation within plant and the levels of As(III), silicon, dissolved organic carbon, iron or Cd in porewater. All three amendments (SC, Mg/SC and ZVI) have the potential to simultaneously mitigate Cd and iAs accumulation in rice grain, although the pathways are different. [Display omitted] [ABSTRACT FROM AUTHOR]

Arsenite (As(III)) as the most toxic and mobile form is the dominant arsenic (As) species in flooded paddy fields, resulting in higher accumulation of As in paddy rice than other terrestrial crops. Mitigation of As toxicity to rice plant is an important way to safeguard food production and safety. In the current study, As(III)-oxidizing bacteria Pseudomonas sp. strain SMS11 was inoculated with rice plants to accelerate conversion of As(III) into lower toxic arsenate (As(V)). Meanwhile, additional phosphate was supplemented to restrict As(V) uptake by the rice plants. Growth of rice plant was significantly inhibited under As(III) stress. The inhibition was alleviated by the introduction of additional P and SMS11. Arsenic speciation showed that additional P restricted As accumulation in the rice roots via competing common uptake pathways, while inoculation with SMS11 limited As translocation from root to shoot. Ionomic profiling revealed specific characteristics of the rice tissue samples from different treatment groups. Compared to the roots, ionomes of the rice shoots were more sensitive to environmental perturbations. Both extraneous P and As(III)-oxidizing bacteria SMS11 could alleviate As(III) stress to the rice plants through promoting growth and regulating ionome homeostasis. [ABSTRACT FROM AUTHOR]

Recently, there has been a propensity to postpone dealing with the world's climate concerns until later, resulting in a 1.5 °C rise in temperature over the last century. Therefore, interest in biologically derived, inexhaustible energy sources based on solar energy is growing. Cyanobacteria have the potential to produce clean, renewable fuels in the form of hydrogen (H 2) gas, derived from solar energy and water. The current study reports the screening 11 cyanobacterial strains isolated from rice paddies and hotsprings for efficient H 2 producers. According to our findings, H 2 concentrations in the species ranged from 3.6 to 48.9 μmol mg−1 Chl a h−1. H 2 production by isolated species was shown to have a 2% positive influence on oxygen (O 2) and carbon dioxide (CO 2) concentrations and a 2% negative effect on all nitrogen gas (N 2) concentrations. It was discovered that at high CO 2 concentrations, photosynthesis is enhanced but H 2 production is suppressed. Anabaena variabilis BTA-1047 was found to be the most active H 2 -producing species, with an H 2 production activity of 21.3 μmol mg−1 Chl a h−1. Moreover, a 1% O 2 : 2% CO 2 gas mixture doubled the strain activity of H 2 production. The findings of the study called into the question the notion that only an anaerobic environment is required for H 2 production by N 2 -fixing cyanobacterial species and explored whether H 2 productivity can be increased by stimulating the micro-anaerobic environment with a carbon source. [Display omitted] • Eleven nitrogen fixing cyanobacteria species were isolated and identified from different ecosystems. • Four cyanobacterial strains were distinguished by nitrogenase activity and hydrogen production. • 2% CO 2 and O 2 gases influence was favorably for most strains to produce molecular hydrogen. • Supply with 1% O 2 :2% CO 2 gas ratio increased H 2 production activity in Anabaena variabilis BTA-1047 by 2-fold. [ABSTRACT FROM AUTHOR]

Agriculture contributes to global climate change by producing 20–25% of greenhouse gases (GHGs). CO 2 is released from deforestation and land conversion, methane from rice paddy fields, and nitrous oxides from overfertilization. An increasing world population requires a change in the agro food systems, including a reduction in chemical fertilizers and pesticides as well as the production and access to food. Greenhouse gas (GHG) emissions have created a global climate crisis which requires immediate interventions to mitigate the negative effects on all aspects of life on this planet. As current agriculture and land use contributes up to 25% of total GHG emissions, plant scientists take center stage in finding possible solutions for a transition to sustainable agriculture and land use. In this article, the PlantACT! (Plants for climate ACTion!) initiative of plant scientists lays out a road map of how and in which areas plant scientists can contribute to finding immediate, mid-term, and long-term solutions, and what changes are necessary to implement these solutions at the personal, institutional, and funding levels. [ABSTRACT FROM AUTHOR]

• NaCl inhibited the growth and increased Na and Cl concentrations in rice leaves. • Application of Fe mitigated adverse effects of NaCl on rice growth. • Fe-supply enahnced plant antioxidant enzymatic activity in rice plants. • Fe-supply improved CEC of the soil and limited Na uptake by rice. Soil salinity affects plant growth and results in decreased agriculture productivity throughout the world. The present study was carried out to elucidate underlying mechanisms responsible for soil salinity tolerance in rice under the application of iron (Fe) as Fe(NH 4) 2 (SO 4) 2 ·6H 2 O. Rice seedlings were grown in pots containing soils (pH >8.0) and exposed to 0 and 150 mM (EC of 5.25 dS m−1) NaCl stress both with and without 0.5 mM Fe(NH 4) 2 (SO 4) 2 ·6H 2 O. Plant growth attributes like root length, shoot length, roots and shoots biomass, leaf chlorophyll contents, salt ions, plant mineral concentrations, plant antioxidant activities and cation exchange of soil were determined. Application of NaCl at the rate of 150 mM reduced the leaf chlorophyll contents (34%), root fresh and dry weights (39% and 45%), shoot fresh and dry weights (35% and 53%), grain yield (39%), potassium (K) (59% and 48%), calcium (Ca) (39% and 24%), and magnesium (Mg) (59% and 50%) concentrations in roots and leaves, whereas enhanced the sodium (Na) (537% and 500%) and chloride (Cl) (425% and 156%) accumulation both in roots and leaves as compared to control. Interestingly, Fe-supply enhanced the Fe uptake by rice plants and mitigated the adverse effects of salinity on rice growth and yield by 30%. Moreover, plant antioxidant enzymatic activity and cation exchange capacity (CEC) of soil (cmol Na+ kg−1) were enhanced by Fe-supply. In conclusion, Fe-application enhanced tolerance in rice due to down regulation of Na and up-regulation of Fe and antioxidant enzymatic activity in leaves. In addition, increased Na adsorption onto the surface of soils suggests that Fe competes with Na at soil-root interface, thereby limiting Na uptake by the plants. [ABSTRACT FROM AUTHOR]

Rice is the most important food crop in the developing world, and more than half of the global population consumes it as a staple food. Mapping the area of rice cultivation in a timely and accurate manner is essential to ensure food safety and evaluate its environmental impact. Deep learning performs very well in high-resolution remote sensing classification; however, due to lack of high-quality training datasets and spatial semantic information of Landsat data, paddy rice mapping based on deep learning and Landsat data has received less attention. In this study, we constructed the first large-scale training dataset and a deep learning network, named full resolution network (FR-Net), for mapping paddy rice based on Landsat 8 OLI data. The pixel-wise annotated dataset is composed of 64 Landsat 8 OLI scenes covering the main areas producing rice in northeast China. To overcome the coarse segmentation borders resulting from other deep learning models, and especially with the low-resolution Landsat data, a new multi-resolution fusion unit (MRFU) was proposed to fuse different resolution streams and maintain the high-resolution streams of the model. In comparison with other models, the FR-Net acquired the highest accuracy, with MCC of 0.893 and F1 score of 0.898, and in particular, the results of different band combinations showed that the FR-Net perform better for feature extraction than other models. Without using the sensitive bands, i.e., short-wave infrared 1 and 2, the MCC of FR-Net was slightly decreased by 4.14%, smaller than other models, e.g., 8.51% for U-Net and 11.76% for RS-Net etc. The comparison showed the proposed FR-Net presented highest spatial precision among all these models, by which a fine boundary could be obtained for Landsat data to achieve high quality mapping result. The analysis of the performance in different temporal showed that FR-Net performed better at the beginning or the ending of growth stages, and the omission or false alarm main occurred in small size patches or the boundaries. In all, low-resolution characteristics of Landsat data should be more extensively investigated when developing and using deep learning in classification. [ABSTRACT FROM AUTHOR]

Arsenic (As)-contaminated rice paddy fields are spreading globally, and thus, rice grains with low As accumulation at a safe level for consumption is profoundly needed. Rice is highly susceptible to As accumulation, and the responses to As vary among rice varieties. Here, combinations of the AsIII-oxidizing bacteria Pseudomonas stutzeri strains 4.25, 4.27, or 4.44 and Cupriavidus taiwanensis KKU2500-3 were investigated with respect to their responses to As toxicity and rice growth promotion during the early growth stage. All bacterial strains enhanced antioxidant enzyme activities, including SOD, CAT, APX, GPX, and GR, under As stress in vitro. Uninoculated and coinoculated rice seedlings of three rice varieties (KDML105, RD6, RD10) were cultivated in hydroponic solution without and with a combination of toxic AsIII and less toxic AsV for 30 days. Compared with uninoculated seedlings, the inoculated seedlings showed higher growth parameters and lower As contents in roots, shoots and throughout the plants. The bioconcentration factor (BCF) and translocation factor were reduced in inoculated seedlings. The effective response of rice to As toxicity influenced by bacteria was highest in KDML105, followed by RD6 and RD10. The root sulfide content was correlated with As accumulation in roots, shoots, and total seedlings and the BCFs. P. stutzeri 4.44 and C. taiwanensis KKU2500-3 were the most promising combinations for application in KDML105 cultivation under As-contaminated conditions. Understanding the basic response of rice coinoculated with effective bacteria at the early stage will provide guidelines for rice cultivation under As conditions at other scales. • Bacteria induced antioxidant enzymes (SOD, CAT, APX, GPX, and GR) in rice. • Bacteria were most effective against As toxicity in KDML105, followed by RD6 and RD10. • Decreases in As accumulation, BCF, and TF were correlated with bacterial inoculation. • The root sulfide content was significantly enhanced by bacteria. • Antioxidant enzymes and As-S induced by bacteria play a role in As detoxification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning applied to automatic discrimination of weeds in rice field by stereo vision. • Stereo videos were processed under both natural (NLC) and controlled light conditions (CLC). • A hybrid neural network (NN)-PSO algorithm was used to select discriminative features. • A hybrid NN-imperialist competitive algorithm was used for classification purposes. • Classification accuracy reached 85.71% under NLC for the arithmetic mean (test set). • Classification accuracy reached 94.74% under CLC for the geometric mean (test set). A site-specific weed detection and classification system was implemented with a stereoscopic video camera to reduce the adverse effects of chemical herbicides in rice field. A computer vision and meta -heuristic hybrid NN-ICA classifier were used to accurately discriminate between two weed varieties and rice plants, under either natural light (NLC) or controlled light conditions (CLC). Preprocessing, segmentation, and matching procedures were performed on images coming from either right or left camera channels. Most discriminant features were selected from average, either arithmetic or geometric, images using a NN-PSO algorithm. Accuracy classification results with the stereo computer vision system under NLC were 85.71 % for the arithmetic mean (AM) and 85.63 % for the geometric mean (GM), test set. At the same time, accuracy classification results of the computer vision system under CLC reached 96.95 % for the AM case and 94.74 % for the GM case, being consistently higher than those under NLC. [ABSTRACT FROM AUTHOR]

Rice consumption is a major pathway for human cadmium (Cd) exposure. Understanding Cd behavior in the soil-rice system, especially under field conditions, is pivotal for controlling Cd accumulation. This study analyzed Cd concentrations and isotope compositions (δ114/110Cd) in rice plants and surface soil sampled at different times, along with urinary Cd of residents from typical Cd-contaminated paddy fields in Youxian, Hunan, China. Soil water-soluble Cd concentrations varied across sampling times, with δ114/110Cd water lighter under drained than flooded conditions, suggesting supplementation of water-soluble Cd by isotopically lighter Cd pools, increasing Cd phytoavailability. Both water-soluble Cd and atmospheric deposition contributed to rice Cd accumulation. Water-soluble Cd's contribution increased from 28‐52% under flooded to 58‐87% under drained conditions due to increased soil Cd phytoavailability. Atmospheric deposition's contribution (12‐72%) increased with potential atmospheric deposition flux among sampling areas. The enrichment of heavy Cd isotopes occurred from root-stem-grain to prevent rice Cd accumulation. The different extent of enrichment of heavy isotopes in urine indicated different Cd exposure sources. These findings provide valuable insights into the speciation and phytoavailability changes of Cd in the soil-rice system and highlight the potential application of Cd isotopic fingerprinting in understanding the environmental fate of Cd. [Display omitted] • Release of isotopically lighter Cd pools increases phytoavailability in drained soils. • As Cd accumulation increased, more heavy Cd isotopes were enriched in rice tissues. • More difference of Cd mass in rice tissues, more significance in their ∆114/110Cd. • Soil water-soluble Cd's contribution increased with Cd phytoavailability increased. • Atmospheric Cd's contribution varied with the industrialization of sampling area. [ABSTRACT FROM AUTHOR]

The co-contamination of arsenic (As) and cadmium (Cd) in rice fields presents a global imperative for resolution. However, understanding the complex microbially driven geochemical processes and network connectivity crucial for As and Cd bioavailability under the frequent redox transitions in rice fields remains limited. Here, we conducted a series of microcosm experiments, using flooding and drainage, alongside fertilization treatments to emulate different redox environment in paddy soils. Soil As significantly reduced in drained conditions following applications of biochar or calcium-magnesium-phosphate (CMP) fertilizers by 26.3 % and 31.2 %, respectively, with concurrent decreases in Cd levels. Utilizing geochemical models, we identified the primary redox cycles dynamically altering during flooding (Fe and S cycles) and drainage (Fe, Mn, and N cycles). PLS-SEM elucidated 76 % and 61 % of the variation in Cd and As through Mn and N cycles. Functional genes implicated in multi-element cycles were analyzed, revealing a significantly higher abundance of assimilatory N reduction genes (nasA, nirA/B, narB) in drained soil, whereas an increase in ammonia-oxidizing genes (amoA/B) and a decrease in nitrate reduction to ammonium genes were observed after CMP fertilizer application. Biochar application led to significant enrichment of the substrate-binding protein of the Mn transport gene (mntC). Moreover, Fe transport genes were enriched after biochar or CMP application compared to drained soils. Among 40 high-quality metagenome-assembled genomes (MAGs), microbial predictors associated with low Cd and As contents across different treatments were examined. Bradyrhizobacea harbored abundant Mn and FeIII transport genes, while Nitrososphaeraceae carried nitrification-related genes. Two MAGs affiliated with Caulobacteraceae, carrying diverse Fe transport genes, were enriched in biochar-applied soils. Therefore, applying CMP fertilizer or biochar in aerobic rice fields can synergistically reduce the bioavailability of Cd and As by specifically enhancing the circulation of essential elements. [Display omitted] ● Applying biochar or CMP fertilizer in aerobic soil mitigate Cd and As simultaneously. ● Moisture or fertilizer affects the onset conditions of key element redox cycles. ● In drained soil, Fe, Mn, N redox are key cycles to reduce Cd and As bioavailability. ● The nitrification and Mn transport gene abundance increase in aerobic soils. ● Functional gene abundance was regulated by microbial community composition. [ABSTRACT FROM AUTHOR]

Corbicula fluminea meal was added to a high-fat diet for eight weeks to determine its effects on growth, lipid metabolism, and intestinal microbiota in juvenile rice field eel (Monopterus albus). C. fluminea meal was made of dried and crushed soft parts of freshwater clam. The study included four diets: a normal fat diet (6.63% lipid, CON), a high fat diet (12.61% lipid, HFD), and a high fat diet supplemented with 1% or 2% C. fluminea meal (CFM1 and CFM2, respectively). The results showed that: (1) the growth performance was higher in the HFD, CFM1 and CFM2 group compared with the CON group, the hepatosomatic index (HSI) was significantly higher in fish fed the high-fat diet than in those fed other diets. (2) Compared with the CON group, The levels of serum triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C) contents, glutamate pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT) activities and the number of hepatic lipid droplets were significantly increased in the HFD group. The addition of C. fluminea meal both reduced liver damage and fat deposition. (3) The mRNA expressions of pparγ , fas , acc , me1 , srebp1 , g6pdh , hsl , lpl , cpt1, and cpt2 in the HFD group were significantly upregulated, while HFD supplemented with C. fluminea meal significantly downregulated the mRNA expressions of pparγ , fas , acc , me1 , srebp1 and g6pdh and significantly upregulated the mRNA expressions of hsl and lpl. (4) The alpha diversity of intestinal microbial community in the HFD group was higher than those in the CON and CFM1 groups. The beta diversity revealed the microbial composition differed in the HFD group from the CON and CFM1 groups. The abundance of Firmicutes in the HFD group increased significantly compared with the CON and CFM1 groups, while the abundances of Cetobacterium decreased. In conclusion, the high-fat diet resulted in abnormal liver fat deposits and intestinal microbiota dysfunction in M. albus , but HFD supplemented with 1% or 2% C. fluminea meal reduced these negative effects. • The effects of high-fat feed on lipid metabolism and intestinal flora of eels were revealed. • 1% or 2% C. fluminea meal can mitigated the negative effects of high-fat feeds on the liver. • 1% C. fluminea meal improving the intestinal flora structure of eel. • C. fluminea meal may play a vital role in liver protection and energy metabolism of eels. [ABSTRACT FROM AUTHOR]

Due to intensified land use, soil nitrogen cycling (N-cycling) and its ecological role are undergoing profound changes on a global scale. Currently, it is not clear how microbial involvement in nitrogen transformation is affected by land use conversion, including microbial diversity and environmental functions, which hinders the development of effective land management strategies. This study focused on microbial-mediated nitrogen cycling in converted black soil, transitioning from upland with maize to paddy with rice fields at two soil depths (0–15 cm and 15–30 cm). Functional gene (nifH , AOA, AOB, norB , and nosZ) abundances and critical functional groups were assessed using quantitative polymerase chain reaction (qPCR) and Miseq sequencing. There were significant disparities in N-cycling gene abundance and microbial communities between paddy and upland fields at both soil depths, with these differences being influenced by soil properties. Notably, land use emerged as a more influential factor than soil depth in reshaping N-cycling abundance and microbial communities. Soil pH, soil moisture (SM), and nitrate nitrogen (NO 3 --N) content primarily influenced variations in the N-cycling microbial community structure. The rise in ecological niche resulted in a decrease in species migration of denitrifying communities, as confirmed by estimated migration rates (M). Land use conversion induced a transition from stochastic to deterministic processes in the assembly of norB - and nosZ -harbouring communities at deeper depths, primarily governed by heterogeneous selection. This conversion led to increased diversity and network stability within the nifH -, norB -, and nosZ -harbouring communities. In upland and paddy fields, the nosZ - and nifH -harbouring communities emerged as major players in the multi-kingdom networks, respectively. These results suggest that paddy ecosystems should be regarded as suitable environments for improving soil N-cycling functions in the context of agroecosystems facing severe environmental changes. [Display omitted] • Land use impacts N-cycling microbes more than soil depth. • Paddy fields show higher microbial diversity, except for AOA. • Land use and soil depth together shape norB- and nosZ -community assembly. • Land use stimulates key species, influencing their roles in ecological networks. • Core species' contribution to nifH and norB gene abundance declined in paddy soil. [ABSTRACT FROM AUTHOR]

Methane, the primary substrate for aerobic methanotrophs, regulates the rate of methanotrophic activity and shapes the composition of the methane-oxidizing community. Given that methane-derived carbon may fuel the food web in the soil, methane availability can potentially be a key determinant, structuring the network of the interacting methane-oxidizing community. Here, we determined the response of the methane-driven interaction network to different methane concentrations (∼1.5 % v/v , 3 % v/v , and 7 % v/v), indicative of different levels of energy flow through the soil food web, using a stable isotope probing approach with 13C-methane coupled to a co-occurrence network analysis in a microcosm study. The accumulated 13C-atom fraction in the total carbon content increased from 1.08 % (background level) to an average of 7.2 % in the incubation under 7 % v/v methane, indicating that the carbon-flow via the methanotrophs can significantly contribute to the total carbon in the rice paddy soil. The 13C-enriched 16 S rRNA gene sequencing analysis revealed the predominance of gammaproteobacterial methanotrophs and Methylocystis. The composition of the actively growing (13C-labelled) bacterial community was dissimilar in the incubation under ∼3 % v/v than under 1.5 % v/v and 7 % v/v methane. This was also reflected in the co-occurrence network analysis, where the topological properties indicated a more complex and connected network in the incubation under 3 % v/v methane. It thus appears that moderate methane concentrations fostered closer associations among members of the methane-oxidizing community. Overall, our research findings showed that the methanotrophs can contribute to the total soil carbon, and methane concentrations not only shifted the bacterial community, including the methanotrophic composition, but also affected bacterial interactions. [ABSTRACT FROM AUTHOR]

Overusing chemical fertilizers (CFs) causes soil degradation, which can be mitigated by partially substituting CFs with green manure. This study investigated the impact of traditional vs. improved fertilization schemes that included Chinese milk vetch (CMV) on soil properties and bacterial communities in rice rhizosphere and bulk soil from plots over 12 years under fertilization. The treatments included the conventional fertilization (CF 100), CMV (22.5 t ha−1) with 100 % CF (CMV + CF 100), CMV with 80 % CF (CMV + CF 80), CMV with 60 % CF (CMV + CF 60), and CMV with 40 % CF (CMV + CF 40). CMV + CF40 increased the soil organic matter (SOM) content in the rhizosphere (bulk) soil by 38.02 % (37.86 %) compared to CF 100 (P < 0.05). The quality index in bulk soil increased by 5.49%–8.17 % through all CF combined with CMV. The rhizosphere bacterial diversity was 1.11%–2.30 % higher, and richness was 2.87%–4.93 % higher than in bulk soil. In the bulk soil, only the CMV + CF 40 increased the bacterial Shannon by 0.40 %, Ace by 0.84 %, and Chao1 indice by 0.89 %. Relative abundances of Geobacter in bulk soil were by 13.90%–52.27 %, Leptospirillum by 25%–77.12 %, and Desulfobacca by 7.42%–37.85 % higher than in the rhizosphere. The stability of the rhizosphere and bulk soil bacterial communities under the CMV input was predicted by the SOM and available phosphorus contents, as indicated by the degree of bacterial average variation. The CMV + CF 40 was recommended as the optimal alternative rate based on local soil ecological considerations. [ABSTRACT FROM AUTHOR]

• The periodic hydration intensified the conventional hydration. • Periodic operation reduced the rice hydration processing time in 41.47 % (mean value). • The temperature modulation showed no difference in the microstructure of the grains. • The diffusion model can well-fit simulate the periodic hydration of paddy rice. • Periodic operation change in the thermodynamic properties of the system. Hydration is an essential stage in the rice parboiling process, and it can be a time-consuming. We evaluated the effects of periodic operation in paddy rice hydration to reduce the processing time. Periodic hydration with temperature modulation (10 °C amplitude and 12 min periods) was compared with isothermal hydration (conventional) at mean temperatures of 25, 35, 45, 55, and 65 °C. The process comparison was based on mass transfer, process time reduction, change in grain microstructure and thermodynamic properties. The periodic process increased water absorption, with a 41.47 % average reduction in process time. The Diffusion model satisfactorily predicted the moisture uptake experimental data (R2 > 0.97). The significant increase (p < 0.05) in the 27.38 % average in the model parameter indicated that the periodic operation favored the mass transfer phenomenon. Micrographs of hydrated grains revealed that the hydrations at 55 e 65 °C favored starch gelatinization, being able to reduce a subsequent step in the process (steaming). The temperature modulation did not alter the grain microstructure when both processes were compared at the same temperature. However, it interfered with the thermodynamic properties of the system. Periodic operation revealed mean values higher to ΔH# and mean values lower to ΔS# and ΔG#. [Display omitted] [ABSTRACT FROM AUTHOR]

Caesium-137 (137Cs) is a major anthropogenic radionuclide released into the environment as a result of the TEPCO Fukushima Daiichi Nuclear Reactor Station accident (occurring on March 11, 2011). Rice, being a staple food in Asian countries, including Japan, and is predominantly cultivated in paddy fields. Consequently, 137Cs present in rice is absorbed from both soil and irrigation water, making it the most important crop for estimating internal radiation doses. In this study, over the 2018–2022 cultivation periods, flood water and pore water samples were collected biweekly from paddy fields. These samples were analyzed to measure the 137Cs activity concentration, as well as the potassium (K+) and ammonium (NH 4 +) concentrations. Under anaerobic conditions, the 137Cs + activity concentration in pore water increased markedly to reach a value 20-fold higher than that in flood water, correlating with NH 4 + concentration. However, despite the release of 137Cs + caused by increased NH 4 + concentrations in pore water due to reduction processes, the 137Cs+/K+ ratio did not increase, which was attributed to the simultaneous release of K+. The competition between 137Cs+ and K+ uptake by plants indicates that rice uptake of 137Cs is not necessarily enhanced during the waterlogging period. [Display omitted] • Uptake of 137Cs by rice competes with K. • 137Cs + activity concentration in pore water increases with NH 4 + concentration. • 137Cs+/K+ concentration ratio is uniform in flood and pore water. • Increase in NH 4 + in paddy pore water dose not affect 137Cs uptake in rice. [ABSTRACT FROM AUTHOR]

• Developed a novel Blood-Sucking Leech Optimizer (BSLO) inspired by blood-sucking leeches. • Evaluated the performance of BSLO using numerical experiments and six engineering problems. • Compared BSLO with ten meta-heuristic algorithms. • Validated the strong robustness and optimization efficiency of BSLO. • Demonstrated superiority of BSLO for diameter prediction of melt electrospinning writing fiber. In this paper, a new meta-heuristic optimization algorithm motivated by the foraging behaviour of blood-sucking leeches in rice fields is presented, named Blood-Sucking Leech Optimizer (BSLO). BSLO is modelled by five hunting strategies, which are the exploration of directional leeches, exploitation of directional leeches, switching mechanism of directional leeches, search strategy of directionless leeches, and re-tracking strategy. BSLO and ten comparative meta-heuristic optimization algorithms are used for optimizing twenty-three classical benchmark functions, CEC 2017, and CEC 2019. The strong robustness and optimization efficiency of BSLO are confirmed via four qualitative analyses, two statistical tests and convergence curves. Furthermore, the superiority of BSLO for real-world problems under constraints is demonstrated using five classical engineering problems. Finally, a BSLO-based Artificial Neural Network (ANN) predictive model for diameter prediction of melt electrospinning writing fibre is proposed, which further verifies BSLO's applicability for real-world problems. Therefore, BSLO is a potential optimizer for optimizing various problems. Source codes of BSLO are publicly available at https://www.mathworks.com/matlabcentral/fileexchange/163106-blood-sucking-leech-optimizer. [ABSTRACT FROM AUTHOR]

Weedy fallow presents a promising strategy for nitrogen (N) scavenging and reducing N losses from croplands. The study aimed to (1) reassess the N scavenging potential of winter fallow weeds, specifically foxtail grasses, within rice cropping systems and (2) determine the availability of N scavenged by winter fallow weeds in rice paddies to rice crops. A two-year on-farm investigation (2022 and 2023), a one-year 15N-tracing microplot experiment (2021), and a two-year field experiment (2022 and 2023) were conducted in Hunan Province, China. The on-farm investigation revealed that winter fallow weeds scavenged on average 10.6 g N m–2 in 2022 and 10.9 g N m–2 in 2023. In the 15N-tracing microplot experiment, a 24 % average recovery efficiency of N from winter fallow weeds, applied in conjunction with two rice varieties and two urea-N application rates, was observed. The field experiment showed that total N uptake by rice plants and grain yield of rice crops were linearly and quadratically related to the total N application rate (the sum of N in applied winter fallow weeds and urea), respectively, in both 2022 and 2023. These findings highlight the potential of winter fallow weeds in rice paddies to scavenge N effectively and reveal this scavenged N to be highly available to rice crops. This study offers insights into the dual advantages of winter fallow weeds within rice cropping systems, shedding light on their environmental benefits as well as their positive agronomic outcomes. • Winter fallow weeds in rice paddies have a significant capacity for scavenging N. • The N scavenged by winter fallow weeds is highly available to rice crops. • Winter fallow weeds may act as a green manure to supply N to rice crops. [ABSTRACT FROM AUTHOR]

• The direct-seeding path for rice covers the entire field. • Rice direct-seeding path includes the encircling path around the field blocks. • Encircling path planning algorithm is applicable to different shapes fields. • The path planning encompasses various patterns and path sequences. Path planning is one of the key technologies that determines the efficiency and quality of field operations using autonomous agricultural machinery. To date, there has been extensive research on global coverage path planning for unmanned agricultural machinery within the working area; however, the issue of "encircling and edging" left by the machinery during headland turns is often overlooked. This study focuses on the operational conditions of unmanned agricultural machinery in the rice fields of southern China. The path planning problem is abstracted under physical constraints, such as the space at the field headland, the agricultural environment (e.g., types of field ridges), the turning characteristics of the machinery, turning radius, working width, and minimum safety distance, into mathematical constraints. This yields an optimized path planning model and sequence combination. Based on the improved Reeds–Shepp curve, an en-circling and edging path planning algorithm is designed. The planned path for the unmanned agricultural machinery from start to finish consists only of arcs and straight lines, suitable for the right-angle turning, reversing, and 180° U-turn operations required for rice field machinery, thus significantly improving the coverage of field edges and missed areas at the headland. A rice direct-seeding machine was used as a test subject for encircling and edging field trials, with tests conducted in rectangular, trapezoidal, and irregular quadrilateral rice fields. The results show that, for rectangular plots, the full-field coverage rate of rice direct-seeding operations can reach 96.44%; for trapezoidal plots, the coverage rate is 95.47%; and for irregular quadrilateral fields, the coverage rate is 95.69%. These results are promising, indicating that the encircling and edging path planning based on the improved Reeds–Shepp curve can effectively increase the full-field coverage rate of unmanned agricultural machinery, improving work quality and meeting the needs of modernized, intelligent agricultural machinery operations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The relationship between soil surface roughness and fractal dimension was explored. • Soil surface roughness is used as a basis to regulate rotary tiller detachment. • An intelligent vibration detachment system for rotary tiller was developed. • The developed system can improve the tillage quality and reduce soil adhesion. The adhesion and winding problem between the rotary roller and the soil and straw stubble severely affect the quality of the tillage operation. In response to the practical requirements of adhesion reduction and detachment increment of rotary tiller in paddy fields, our study develops an intelligent vibration detachment system for rotary tiller based on soil surface roughness (SSR) dynamic characteristics. The working principle of the system is that the camera module captures the soil surface image after tillage and calculates the fractal dimension of the image. Based on the functional relationship model between fractal dimension and SSR parameters (root mean square height), the SSR results are obtained and fed back to the system for comparison with the preset SSR values. When the actual measured SSR is greater than the preset value due to soil adhesion and straw winding, the system issues a command to control the excitation device for rotary roller vibration detachment. To verify the superiority and reliability of the developed system, the comparative experiments were conducted via three types of tillage tools in paddy fields: a traditional rotary tiller (TT), a rotary tiller with the developed system (IDT) in this study, and a rotary tiller with mechanical detachment method (MDT). Taking the relevant indexes of TT as a reference, IDT improved by 29.45%, 6.43%, 14.19%, 6.30%, 7.90%, and 6.83% compared with MDT in terms of the improvement effect of these indexes such as adhesion mass, tillage depth stability coefficient, soil surface roughness, soil distribution uniformity, straw buried rate and soil broken rate. Adopting the adhesion mass as the index for judging the detachment performance, IDT has excellent adhesion reduction and detachment ability for high straw stubble and wet soil, and MDT has better anti-winding performance than TT. The indexes other than these were used to indicate the operation quality, with IDT being better than the other two, followed by MDT and TT being the worst. The experimental results showed that the developed system could enable the rotary tiller to make the corresponding detachment response according to the SSR dynamic characteristics, effectively improving the operation quality and detachment performance of the rotary roller, with high detachment efficiency and controllability. The results of the study contribute to realizing intelligent adhesion reduction and detachment increment of rotary tiller in paddy fields, which could provide theoretical reference for the optimization design of tillage equipment to improve quality and efficiency. [ABSTRACT FROM AUTHOR]

Exposure to particulate matter and endotoxin can lead to acute and chronic respiratory problems in workers. A study was conducted to quantify particulate matter with an aerodynamic diameter of ≤10 μm (PM10) and endotoxin levels in rice mills in northeast India. Sixty-four PM10 dust samples were collected from eight rice mills at two locations: the feeding and polishing sections for two varieties of paddy: Ranjit and Hali. Endotoxin exposures were analyzed using the Limulus Amoebocyte Lysate (LAL) gel clot test. The results showed that the geometric mean of the 8-h time-weighted average (TWA) PM10 dust concentration and endotoxin level in the rice mills were 10.69 mg/m³ and 2.2 EU/m³, respectively. Dust and endotoxin exposure were higher in the feeding section than in the polishing section. Endotoxin exposure in the feeding section during the milling of the Hali variety of paddy was 56.0 % higher than the milling of the Ranjit variety. Additionally, endotoxin exposure during the milling of the Hali variety was 24.2 % higher than that of the milling of the Ranjit variety in the polishing section. The dust exposure in the rice mills was 194.5 % higher than the standards set up by the United States Environmental Protection Agency. However, the exposure to endotoxin in rice mills was approximately 40.10 times below the recommended limit of 90 EU/m3. [Display omitted] • Exposure to particulate matter and endotoxin causes respiratory problems in workers. • Exposure to PM10 and endotoxin in rice mills workers analyzed at Northeast India. • Endotoxin exposures were analyzed using the Limulus Amoebocyte Lysate gel clot test. • The dust exposure in the rice mills was 194.5% higher and endotoxin was 40.1 times below than recommended limit. [ABSTRACT FROM AUTHOR]

The contamination of paddy fields by cadmium and lead is a major issue in China. The consumption of rice grown in heavy metals contaminated areas poses severe health risks to humans, where bioavailability and bioaccessibility remains the critical factor for risk determination. Selenium nanoparticles (Se-NPs) can mitigate the toxicity of heavy metals in plants. However, there exists limited information regarding the role of Se-NPs in dictating cadmium (Cd) toxicity in rice for human consumption. Moreover, the impact of Se-NPs under simultaneous field and laboratory controlled conditions is rarely documented. To address this knowledge gap, a field experiment was conducted followed by laboratory scale bioavailability assays. Foliar application of Se-NPs and selenite (at 5, 10 mg L−1) was performed to assess their efficiency in lowering Cd accumulation, promoting Se biofortification in rice grains, and evaluating Cd exposure risk from contaminated rice. Obtained results indicate that foliar treatments significantly reduced the heavy metal accumulation in rice grains. Specifically, Se-NP 10 mg L−1 demonstrated higher efficiency, reducing Cd and Pb by 56 and 32 % respectively. However, inconsistent trends for bioavailable Cd (0.03 mg kg−1) and bioaccessible (0.04 mg kg−1) were observed while simulated human rice intake. Furthermore, the foliage application of Se-NPs and selenite improved rice quality by elevating Se, Zn, Fe, and protein levels, while lowering phytic acid content in rice grains. In summary, this study suggests the promising potential of foliage spraying of Se-NPs in lowering the health risks associated with consuming Cd-contaminated rice. [Display omitted] • Foliar application of Se-NPs and selenite effectively achieved the safe rice production. • Se-NPs and selenite have shown potential in reducing the bioavailability of Cd in Caco-2 cells. • Se-NPs and selenite improved the rice quality and promoted the Se biofortification. • Se-NPs restricted the heavy metals translocation between the plant parts. [ABSTRACT FROM AUTHOR]

Rice production is essential for ensuring food security. Nitrogen fertilizers applied in rice fields are prone to loss through NH 3 emissions. We need to elucidate the responses of NH 3 emissions to different N inputs. With a national dataset, we identified that N application rate, N application frequency, soil temperature, and soil silt fraction were the key driving factors of NH 3 emissions. 190−210 kg N ha−1 was suitable for simultaneously reducing NH 3 emissions and increasing rice yields. The model showed that under the actual N application rate and N application frequency of 3, national NH 3 emissions were 0.852 Mt N each rice growing season, while national NH 3 emission factor was 12.7 %. We developed a portable software to conveniently assess China's NH 3 emissions from rice fields under different N inputs. The findings can help to optimize N inputs in rice fields to reduce NH 3 emissions and improve ecosystem health and agricultural sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]

While increasing rice yield, the irrational application of nitrogen fertilizers in paddy fields leads to diverse environmental impacts. However, there exists a dearth of comprehensive research systematically addressing these impacts, particularly in areas affected by salinization. This study employs the life cycle assessment (LCA) method to evaluate the environmental impacts of five commonly used fertilizers during rice production in saline-alkali paddy fields. Additionally, the economic benefits of these fertilizers were analyzed. Across all treatments, regardless of per unit yield and cultivated area, urea (U) treatment exhibited the highest total environmental impact potential (TEIP) value, while organic-inorganic compound fertilizer (OCF) treatment recorded the lowest. Notably, freshwater eutrophication contributes significantly to TEIP in each treatment compared to other midpoint impacts. For OCF treatment, the negative NEIP values of global warming and stratospheric ozone depletion indicate lower impacts than the other five treatments, respectively. The total endpoint damage potentials of OCF treatment per unit yield and unit area were −75.4331 Pt and −927.8271 Pt, respectively, both lower than the other five treatments. Furthermore, the yield and net income of OCF treatment stands at 12.30 t/ha and 29691.51 CNY/ha, surpassing all other five treatments. In summary, OCF emerges as an effective nitrogen fertilizer with low input, minimal risk, and substantial benefits when applied to rice production in salinized areas. This study introduces LCA to conduct a comprehensive analysis of rice production in saline-alkali areas, providing essential data for decision-makers to understand the potential environmental impacts of different nitrogen fertilizer applications. By considering various environmental risks and economic benefits simultaneously, this approach offers a methodological framework to support optimized fertilization strategies. This promotes the sustainable development of paddy fields in saline-alkali regions, advancing efficiency and emission reduction practices in rice cultivation. [Display omitted] • U exhibited the highest TEIP in saline-alkali paddy, while OCF records the lowest. • Freshwater eutrophication's contribution to TEIP outweighed other midpoint impacts. • Net income per unit area of OCF exceeds that of all other treatments. • OCF application effectively manages the TEIP in saline-alkali paddy fields. [ABSTRACT FROM AUTHOR]

• Leaf inclination angle (LIA) was first measured at three vertical layers during the growth period. • 1D canopy reflectance simulation with spherical leaf angle distribution (LAD) only holds before the jointing stage. • Vertical variation of leaf spectra affects canopy reflectance during the maturation stage. • Angularly-averaged clumping index (CI) slightly improves the 1D canopy reflectance simulations. • Leaf inclination angle (LIA) profile can remarkably improve the 1D canopy reflectance simulations. Physical model simulations have been widely utilized to simulate the reflectance of vegetation canopies. Such simulations can be used to estimate key biochemical and physical vegetation parameters, such as leaf chlorophyll content (LCC), leaf area index (LAI), and leaf inclination angle (LIA) from remotely sensed data via model inversion. In simulations, field crops are typically regarded as one-dimensional (1D) vegetation canopies with constant leaf properties in the vertical direction and across the growing season. We investigated the seasonal effects of these two simplifications, 1D canopy structure, and vertically constant leaf properties, on canopy reflectance simulations in a rice field using in situ measurements and the 3D discrete anisotropic radiative transfer model (DART). We also developed a new methodology for reconstructing 3D crop canopy architecture, which was validated using measurements of gap fraction and canopy reflectance. Our results revealed that the 1D canopy assumption only holds during the early stage of the growing season, then leaf clumping affects canopy reflectance from the jointing stage onwards. Consideration of the 3D canopy structure and its seasonal variation significantly reduced the deviation between simulated and measured canopy reflectance in the green and near-infrared wavelengths when compared to the typical 1D canopy assumption and produced the closest multi-angular distribution pattern to the measurements. The vertical heterogeneity of leaf spectra affected canopy reflectance weakly during the maturation stage when senescence started from the bottom of the canopy. Consideration of seasonal and vertical variation in LIAs significantly improved the results of 1D canopy reflectance simulations, including the multi-angular distribution patterns. In contrast, the directionally-averaged clumping index (CI) only slightly improved the 1D canopy reflectance simulation. To summarize, these findings can be used to reduce the simulation bias of canopy reflectance and improve the retrieval accuracy of key vegetation parameters in crop canopies at the seasonal scale. [ABSTRACT FROM AUTHOR]

Rice is widely consumed as a staple food, being cultivated worldwide. However, in West Africa, production is not enough to satisfy demand. Rice often suffers intensive damage by herbivorous arthropods that affect quality and quantity of the grain. Birds and bats have been shown to suppress arthropod pests, potentially enhancing rice productivity and food security. However, the degree to which these taxa provide nature-based solutions for mitigating pest-induced rice losses is poorly known, especially in West Africa. Here, we used experimental exclosures to investigate whether birds and bats reduce plant damage and boost rice yield by suppressing arthropod abundance. In a rural area in northern Guinea-Bissau, we established 14 sets of paired control and experimental exclosures parcels, precluding access of birds and bats to rice plants. We then quantified how the absence of birds and bats influenced arthropod communities, plant damage, and rice yield over a full rice production cycle (six months). Arthropod numbers in exclosures (10.1 ± 9.1 ind./plot) were nearly double those in control plots (5.8 ± 3.0 ind./plot), a result mostly due to a lower spider abundance in the controls. The percentage of leaf and grain damage showed no difference between exclosure and control. Using Structural Equation Models, we uncovered that the exclusion of birds and bats boosted arthropod abundance but had only marginal effects on rice damage and no detectable effect on yield. The exclusion of flying vertebrates led to a marked increase in spider abundance, suggesting an effect of mesopredator release, which in turn likely helped maintaining pest abundance low and potentially contributing to the small overall effect on rice damage and yield. Enhancing the abundance of birds and bats is an interesting option to suppress agricultural pests, but our results highlight the need for a better understanding of ecological interactions in agricultural landscapes in West Africa. We stress the need for more research to inform evidence-based policies using nature-based solutions that foster the natural consumption of pests by vertebrates, as a means to improve food security. • Pioneer experiment of arthropod consumption by birds and bats in West Africa. • Bird and bat exclusion doubled arthropod abundance mostly due to spiders. • Excluding flying vertebrates did not influence rice yield. • Exclosures may inadvertently promote mesopredator proliferation. • Further studies needed to unravel the complex trophic networks in rice paddies. [ABSTRACT FROM AUTHOR]

Rice paddies contribute to ∼48% of greenhouse gas emissions from cropland, with ∼94% from methane (CH 4). Elevated atmospheric CO 2 concentrations (eCO 2) due to human activities, generally stimulate the rice growth, and in turn affect CH 4 emissions from rice paddies. However, the effects of eCO 2 on CH 4 emissions from rice paddies are still unclear under in situ straw incorporation, the popular agricultural practice. Therefore, we conducted a 3-yr field experiment to investigate the effects of eCO 2 on CH 4 emissions under in situ straw incorporation in the rice-wheat cropping system, using the open-top chamber technology. We found that eCO 2 reduced the CH 4 emissions from rice paddies by 10.9–23.8%, but increased rice plant biomass by 4.2–35.6%. The eCO 2 reduced the soil NH 4 + and NO 3 - concentrations, but did not affect the soil dissolved organic C. The eCO 2 did not affect the abundance of methanogens and CH 4 production potential, whereas it stimulated the abundance of methanotrophs and CH 4 oxidation potential by 102.5% and 15.1%, respectively. The eCO 2 also shifted the community composition of methanotrophs and reduced the relative abundance of type Ⅱ methanotrophs by 8.5%. The random forest analysis identified that soil CH 4 oxidation potential is the most important factor affecting CH 4 emissions. Our findings indicate that eCO 2 can reduce the CH 4 emissions from rice paddies under in situ straw incorporation mainly through increasing the soil CH 4 oxidation potential. Our study suggests the effects of eCO 2 on CH 4 emissions from global paddies may be overestimated and underline the need for smart agricultural management to reduce CH 4 emissions. • Elevated CO 2 reduced CH 4 emission from paddies under in situ straw incorporation. • Elevated CO 2 stimulated abundance of methanotrophs and CH 4 oxidation potential. • Soil CH 4 oxidation potential is the most important factor affecting CH 4 emissions. [ABSTRACT FROM AUTHOR]

Amphibians are one of the taxa that are particularly vulnerable to roads and traffic. To mitigate amphibian roadkill, previous studies have used dead animal data to identify road segments with high risk of roadkill. However, the estimation using dead animal data may be spatially biased by traffic and scavenging. This study aimed to evaluate and compare the factors affecting occurrence of both live and dead amphibians on roads. We conducted a comprehensive route census and counted the occurrence of live and dead amphibians on road between July and October 2022 and May and October 2023. Additionally, we investigated the change of traffic and removal of dead animals along landscape gradient. We constructed joint species distribution models to explain the occurrence of live and dead animals by landscape factors. From these analyses, we compared the landscape factor affecting amphibian occurrence between live and dead animals. We observed 755 live and 483 dead animals of 11 species during all surveys. Effects of proportion of surrounding paddy fields differed between live and dead animals for many of target species. Dead animals were more likely to be detected in the intermediate landscape than live animals. Traffic volume was the highest in the intermediate landscape, which have caused many dead animals there. Differences in occurrence between live and dead animals for some species could not be sufficiently explained by traffic and removal of dead animals. We emphasized the importance to consider obtaining information not only from dead animals, but live animals to mitigate amphibian roadkill. • We evaluated the occurrence of amphibians on roads in both live and dead animals. • Landscape factors affecting occurrence differed between live and dead animals. • Traffic and scavenging would affect the occurrence of dead animals on roads. • It is important to focus on live animals when assessing amphibian roadkill risk. [ABSTRACT FROM AUTHOR]

The turnover of labile organic carbon (C) in the rhizosphere is rapid and affects the soil nutrient supply capacity. However, the mechanism by which rhizosphere labile organic C influences nutrient uptake is still unclear. The rhizosphere soils of summer rice among four upland-paddy rotation treatments of rice-winter fallow (RF), rice-potato with rice straw mulch (RP), rice-wheat (RW), and rice-Chinese milk vetch (RC) were characterized, and plant nitrogen (N) and phosphorus (P) uptake were quantified at the various growth stages. The results showed that labile organic C fractions differed at various growth stages. Readily oxidizable C was higher prior to than post the flowering stage; dissolved organic C was 118–151 % higher at the flowering stage than at the other stages, while microbial biomass C gradually decreased over the growth period. In addition, rotations with cover crops in winter crops and the N fertilizer input were conducive to increasing labile organic C and nutrient supply, and enzyme activities generally in the order of RP > RC > RW > RF. The RP treatment increased labile organic C fractions by 24–76 % and amount of available N and P in soil by 48–160 %. The effects of rotation and N treatments on labile organic C, N and P were associated with changes in the structure and composition of bacterial communities (RDA = 63–81 %). The structural equation model showed that the effects of rotation and N treatments on plant N and P uptake were partially regulated by labile organic C fractions (R 2 = 0.6–0.9) which in turn correlated with soil nutrient supply and enzyme activities. The concentrations of readily oxidizable C and microbial biomass C at early growth stages, as well as particulate and dissolved organic C in the late growth stages, showed promise as indicators for optimizing rotations and N application in the field. Future research should focus on validation of these indicators across a wider range of soil types and climatic conditions, and the correlation between these indicators and crop productivity should be investigated for further understanding the potential impacts on agricultural sustainability and soil management. • Dynamics of labile organic C (LOC) in rice rhizosphere is characterized. • The LOC fractions function differently at various rice growth stages. • Rotation with winter crops enhances soil nutrient availability and enzyme activity. • Nitrogen fertilization increased soil nutrient supply. • Changes of rhizosphere LOC fractions affect N and P uptake by rice plants. [ABSTRACT FROM AUTHOR]

The newly discovered complete ammonia oxidizer (comammox Nitrospira) is able to single-step nitrification capability, and increased our understanding of soil nitrogen cycling. However, the response of comammox and ammonia-oxidizing bacteria (AOB) and archaea (AOA) to long-term fertilization and rhizosphere effects in paddy soils and their relative contribution to the nitrification-derived N 2 O emissions is still unclear. Here, we collected rhizosphere and bulk soils with thirty years of different fertilization strategies, i.e., non-fertilization (CK), chemical N, P, and K application (NPK), and NPK plus pig manure application (NPKM), respectively, to test changes in nitrification potential rate (PNR), N 2 O emission fluxes, abundance of ammonia oxidizers and their significant drivers. The result showed that NPKM significantly increased soil C and N levels, the proportion of soil middle-size particles (40.35–148.00 μm class), and soil PNR, but decreased soil N 2 O emissions, especially in the drying time of paddy (P < 0.05), compared to NPK fertilization. NPKM had the highest values of AOA, AOB, and comammox clade A amoA gene copy numbers (P < 0.05), but clade B was increased by the NPK in the rhizosphere soil. Furthermore, fertilization showed greater effects on ammonia oxidizers (except for clade B) than the rhizosphere effect. Mantel test showed that SOM, TP, pH, NH 4 +, and NO 3 − were main abiotic factors causing the niche separation among ammonia oxidizers. Linear regression analysis and structural equation model (SEM) showed that both PNR and N 2 O emission fluxes were significantly associated with the abundance of AOB and comammox clade A (P < 0.05). Therefore, our results underline the importance of AOB together with comammox clade A in nitrification and N 2 O production in long-term organic fertilized paddy fields, which could provide new ideas for the mitigation of N 2 O emission by adopting organic fertilization scenarios in Chinese paddy fields. [Display omitted] • Organic fertilization significantly increased AOA, AOB, and comammox abundances. • The rhizosphere showed negligible impacts on AOA, AOB and comammox clade A. • SOM, NH 4 +-N, and pH were the main drivers of abundance of AOA, AOB and comammox. • AOB and comammox clade A contributed most to N 2 O fluxes in long-term fertilized paddy fields. [ABSTRACT FROM AUTHOR]

Domain of unknown function (DUF) protein families, which are uncharacterized and numerous within the Pfam database. Recently, studies have demonstrated that DUFs played crucial roles in plant development, but whether, or how, they function in drought resistance remain unclear. In this study, we identified the Os03g0321500 gene, encoding Os b ZIP72 b inding p rotein 1 (OsBBP1), as a target of OsbZIP72 using chromatin immunoprecipitation sequencing in rice. OsBBP1 is a novel member of DUFs, which localize both in the nuclei and cytoplasm of rice protoplasts. Furthermore, yeast one-hybrid and electrophoretic mobility shift assays confirmed the specific binding between OsbZIP72 and OsBBP1. Additionally, a luciferase reporter analysis illustrated that OsbZIP72 activated the expression of OsBBP1. Drought tolerance experiments demonstrate that the OsBBP1 CRISPER-CAS9 transgenic mutants were sensitive to drought stress, but the transgenic OsBBP1 over-expressing rice plants showed enhanced drought resistance. Moreover, drought tolerance experiments in a paddy field suggested that OsBBP1 contributed to less yield or yield-related losses under drought conditions. Mechanistically, OsBBP1 might confer drought resistance by inducing more efficient reactive oxygen species (ROS) scavenging. Several ROS scavenging-related genes showed increased expression levels in OsBBP1 overexpression lines and decreased expression levels in OsBBP1 CRISPER-CAS9 mutants under drought conditions. Thus, OsBBP1, acting downstream of OsbZIP72, contributes to drought resistance and causes less yield or yield-related losses under drought conditions. • We catch the Os03g0321500 gene, here identified as Os b ZIP72 b inding p rotein 1, OsBBP1 as one of the targets of OsbZIP72 by chromatin immunoprecipitation sequencing (Chip-seq) in rice. • The yeast one-hybrid and electrophoretic mobility shift assay confirm the specific binding between OsbZIP72 and its target OsBBP1. Additionally, the luciferase reporter analysis illustrate that OsbZIP72 activate the expression of OsBBP1. • The drought tolerance experiment demonstrate that the OsBBP1 CRISPER-CAS9 transgenic mutants are sensitive to drought stress, but the transgenic over-expression of OsBBP1 rice plants show enhanced drought resistance. • The OsBBP1 confers drought resistance by inducing more efficient reactive oxygen species scavenging. Several reactive oxygen species scavenging-related genes showed increased expression in OsBBP1 over-expression lines and decreased expression in OsBBP1 CRISPER-CAS9 mutants. [ABSTRACT FROM AUTHOR]

In the quest for sustainable, high-yield crop production, achieving the optimal balance between nitrogen (N) and potassium (K) stands as a pivotal goal. We carried out a 3-year field experiment to evaluate the impacts of the combined application of three N rates (90, 120,180 kg N ha−1) and three K rates (120, 160, 210 kg K 2 O ha−1) on rice yield, fertilizer use efficiency, greenhouse gas (GHG) emissions, global warming potential (GWP), GHG intensity (GHGI), and net ecosystem economic benefits (NEEB) in rice paddy. Our results showed that increasing K under the same N treatment proves beneficial for yield gains (average increase of 4.8 %). Such beneficial effect is also reflected in different N treatments, evidenced by the comparable grain yields between N 120 × K 160 (9.1 t ha−1) and N 180 ×K 120 (9.2 t ha−1). Increasing K significantly enhanced N use efficiency (NUE) through the stimulation of NR, GS/GOGAT, and GDH enzyme activities. This enhancement, along with the strengthened radiation use efficiency (4.7 %), contributed to an overall improvement in grain yield. Compared with N 180 ×K 120 , both rice varieties, under N 120 ×K 160 treatment, showed higher NUE with a 47.6 % increase in PFP N , 12.1 % in NHI, 7.6 % in NUEg, and 9.5 % in NUEb, respectively. Higher NUE also reduced GHGI and improved NEEB. Compared with N 180 ×K 120 treatment, the GWP and GHGI under N 120 ×K 160 treatment decreased by 32.7 % and 31.0 %, while the NEEB increased by $31 ha−1. The composite sustainability scores suggested that the N 120 ×K 160 treatment was generally more sustainable compared with other treatments. These findings underscore the significance of optimizing N and K application ratios in rice paddy cultivation, not only for maximizing yields and nutrient use efficiency but also for reducing greenhouse gas emissions and enhancing economic sustainability, ultimately promoting a more environmentally and economically responsible approach to rice farming. [Display omitted] • The combined application of nitrogen and potassium boosts grain yield and fertilizer use efficiency in hybrid rice. • Appropriately reducing nitrogen while upping potassium can lower GHG emissions and boost ecosystem economic benefits. • Employing a comprehensive assessment approach to evaluate agricultural sustainability under various nitrogen and potassium fertilizer combinations. [ABSTRACT FROM AUTHOR]

Reducing methane (CH 4) emissions is increasingly recognized as an urgent greenhouse gas mitigation priority for avoiding ecosystem 'tipping points' that will accelerate global warming. Agricultural systems, namely ruminant livestock and rice cultivation are dominant sources of CH 4 emissions. Efforts to reduce methane from rice typically focus on water management strategies that implicitly assume that irrigated rice systems are consistently flooded and that farmers exert a high level of control over the field water balance. In India most rice is cultivated during the monsoon season and hydrologic variability is common, particularly in the Eastern Gangetic Plains (EGP) where high but variable rainfall, shallow groundwater, and subtle differences in topography interact to create complex mosaics of field water conditions. Here, we characterize the hydrologic variability of monsoon season rice fields (n = 207) in the Indian EGP ('Eastern India') across two contrasting climate years (2021, 2022) and use the D e n itrification D e c omposition (DNDC) model to estimate GHG emissions for the observed hydrologic conditions. Five distinct clusters of field hydrology patterns were evident in each year, but cluster characteristics were not stable across years. In 2021, average GHG emissions (8.14 mt CO 2 -eq ha−1) were twice as high as in 2022 (3.81 mt CO 2 -eq ha−1). Importantly, intra-annual variability between fields was also high, underlining the need to characterize representative emission distributions across the landscape and across seasons to appropriately target GHG mitigation strategies and generate accurate baseline values. Simulation results were also analyzed to identify main drivers of emissions, with readily identified factors such as flooding period and hydrologic interactions with crop residues and nitrogen management practices emerging as important. These insights provide a foundation for understanding landscape variability in GHG emissions from rice in Eastern India and suggest priorities for mitigation that honor the hydrologic complexity of the region. • Diverse hydrological contexts lead to high variability on GHG emission estimations. • Blanket mitigation strategies may not be effective for all farmers in Eastern Indian. • Mitigation potential of irrigation practices is dependent of floodplains topology. • Interaction of nutrient management with field hydrology drives GHG emissions. [ABSTRACT FROM AUTHOR]

Amorphous iron (Fe) oxides are commonly deposited on rice roots, forming a distinctive Fe plaque, which has been observed as a notable hotspot for increased nitrous oxide (N 2 O) emission from paddy fields. However, the precise mechanisms underlying this phenomenon have remained uncertain. We hypothesized that the interaction between Fe plaque and rice root radial oxygen losses (ROL) leads to the generation of hydroxyl radical (•OH), thereby inhibiting N 2 O reduction and increasing N 2 O emission. To test this hypothesis, we transplanted rice seedlings with induced Fe plaque coating alongside those without Fe plaque coating into the same paddy soil. The results showed that paddy soil with Fe plaque-coated rice seedlings exhibited significantly higher concentrations of •OH and increased N 2 O emission rates, but a reduced abundance of the microbial N 2 O reduction gene (nosZ), compared to paddy soil with Fe plaque-free rice seedlings. These observed differences in N 2 O emission disappeared when we introduced an •OH scavenger into the paddy soil or shaded the rice leaves to reduce ROL. Furthermore, the supplementation of Fe (II) into the paddy soil with Fe plaque-free rice seedlings markedly increased •OH concentrations and N 2 O emissions. Our results demonstrate that Fe plaque, in conjunction with rice root ROL, facilitates •OH generation through the Fenton reaction. This •OH production effectively inhibits microbial N 2 O reduction, ultimately leading to increased N 2 O emissions from paddy soils. Our study uncovers a new mechanism whereby Fe plaque enhances N 2 O emissions from paddy soil. Minimizing Fenton reactions on Fe plaque may offer a promising strategy for reducing N 2 O emissions from paddy fields. [Display omitted] • Interaction of Fe plaque with rice root radial oxygen loss induces.•OH generation. • Rice root Fe plaque-induced.•OH generation is mediated by light exposure on rice leaves. • Fe plaque-induced.•OH enhances paddy soil N 2 O emissions by inhibiting N 2 O reduction. [ABSTRACT FROM AUTHOR]

Agricultural phosphorus (P) application leads to the accumulation and release of soil P, which pose ecosystem risks. Different farming systems carry substantial risks of soil P release. This study evaluated the risk of soil P release in three representative systems of paddy fields in China (rice fields (RF), integrated crayfish-rice fields (CRF), and crayfish fields (CF)) using indoor adsorption and desorption experiments and the diffusive gradient in thin films (DGT) technique, and compared the obtained results. The soils of RF and CRF showed higher levels of redox potential (Eh), free Fe–Al oxides (DCB-Fe, DCB-Al), and amorphous Fe–Al oxides (Ox-Fe, Ox-Al) compared to CF. Additionally, the soils of CRF and CF exhibited higher total organic carbon (TOC) content. The indoor experiments revealed a positive correlation between the contents of Ox-Fe, Ox-Al, bioavailable P (BAP), clay, and soil P adsorption characteristics. Desorption characteristics were primarily influenced by total P, TOC, and Ox-Fe content. Furthermore, the order of soil P release risk followed CRF > RF > CF. According to the in situ DGT measurements, the soil P release fluxes were 0.266 mg·m−2·d−1 for CRF, 0.548 mg·m−2·d−1 for RF, and 0.583 mg·m−2·d−1 for CF. Accordingly, the risk of soil P release followed the order CRF < RF < CF. The contrasting results from these two methods are attributable to the indoor experiments indicating the potential for soil P adsorption under specific experimental conditions and the in situ DGT reflecting natural soil P release in a more effective and suitable manner for evaluating soil P release. The findings improve our understanding of the risk of soil P loss in CRF and provides valuable insights into the two methods. • Different farming systems impact soil TOC, oxides, and P phases contents. • Indoor experiments indicated that the ranking of soil P release risk is CRF> RF>CF. • In-suit DGT indicated that the ranking of soil P release risk is CRF< RF