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Fine-grained management of rice fields can enhance the yield and quality of rice crops. Challenges in achieving fine classification include interference from similar vegetation, the irregularity of natural field shapes, and complex scale variations. This paper introduces Rice Attention Cascade Network (RACNet), for the fine classification of rice fields in high-resolution satellite remote sensing imagery. The network employs the Hybrid Task Cascade network as the base framework and uses spectral and indices mixed multimodal data as input to reinforce the feature differentiation of similar vegetation. Initially, a Channel Attention Deformable-ResNet (CAD-ResNet) was designed to enhance the feature representation of rice on different channels. Deformable convolution improves the ability of CAD-ResNet to capture irregular field shapes. Then, to address the issue of complex scale changes, the multi-scale features extracted by the CAD-ResNet are progressively fused using an Asymptotic Feature Pyramid, reducing the loss of scale information between non-adjacent layers. Experiments on the Meishan rice dataset show that the proposed method is capable of accurate instance segmentation for fragmented or irregularly shaped rice fields. The evaluation metric AP50 of RACNet reaches 50.8%. [ABSTRACT FROM AUTHOR]

Because of the importance of the Central Valley of California, USA, to shorebirds along the Pacific Flyway, conservation investments have been made in the area's agricultural fields and managed wetlands. Increasingly, landowner incentive programs are being used to deliver shorebird habitat, presenting opportunities to answer remaining questions about which implementation strategies and field management practices are most effective at attracting birds. To provide management guidance for these investments, we collected and analyzed 5 years of data (2014–2018) on shorebird abundance in flooded rice fields enrolled in a dynamic habitat incentive program. The program incentivized flooding in fallow and post‐harvest rice fields in seasons when habitat is relatively sparse, specifically the early fall and late spring. Across nearly 9,000 field observations over 5 years, we explored the relationship between abundance and density (birds/ha) of shorebirds and vegetation cover, soil clay, landscape‐level flooding, and local flood timing, duration, and depth. We observed more shorebirds in fields that were approximately 50% flooded, had water depths of 5–10 cm, and had minimal rice straw or stubble cover, with strong or very strong evidence for each of these relationships. We found that the timing of habitat provisioning was important, with moderate evidence that earlier fall flooding and strong evidence that the duration of fall flooding was associated with higher shorebird density. We observed lower shorebird densities in locations with ample flooded rice habitat in surrounding areas, potentially because shorebirds spread out across the landscape. We found very strong evidence that flooding consistency, either at a site that was continually flooded over many months or a site that had been flooded in previous years, was associated with higher shorebird density. Soil clay content was associated with decreased observed shorebird density, potentially through its influence on the ability of shorebirds to forage for invertebrate prey. These results suggest best practices for shorebird habitat creation in agricultural landscapes, providing important information for conservation and population recovery. [ABSTRACT FROM AUTHOR]

• 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]

The current study focused on quantifying hazardous heavy metals (As, Cd, Cr, Pb, Ni, and Zn) in soil-rice systems near the Buriganga River in Bangladesh to assess their impact on human health and the environment. The mean concentrations of As, Cd, Cr, Ni, and Zn in soil exceeded FAO/WHO acceptable limits, and the metal pollution index (MPI) indicated that all soil samples collected from the rice fields were severely polluted (MPI˃30) than water and rice grain samples. According to the sum of pollution index (SPI) by studied metals, rice grains collected from Kamrangirchor (29.36), Dhakauddan (28.75), and Bosila (18.08) were severely polluted. Mean Bio-concentration factors (BCFs) and Transfer factors (TFgrain/soil) in rice grains were in the following order: Cd (6.034) > Zn (1.752) > Pb (0.697) ˃ Ni (0.666) > Cr (0.135) > As (0.037), and Cd (1.150) > Zn (0.421) > Ni (0.112) ˃ Pb (0.072) > Cr (0.015) > As (0.034) respectively indicating higher accumulation of Cd in rice grain than others toxic heavy metal. The potential ecological risk index (RI) showed that except for water in Kamrangirchar and Keraniganj rice fields, all other rice fields soil and water samples did not pose severe ecological pollution (RI˂110) by different toxic heavy metals. Health risk assessment showed that rice grains are unsafe for human consumption as the carcinogenic health risk (CHR˃10-3) and non-carcinogenic health risk (HI ˃1) quotients seem more than the safe level in all samples collected from rice fields surrounding the Buriganga River. Findings show that heavy metal concentrations are high in rice fields near the Buriganga River, endangering the environment and consumer health. [ABSTRACT FROM AUTHOR]

The yellow stem borer (YSB), Scirpophaga incertulas (Walker), is a major insect pest that significantly damages rice crop. This study investigates methods to predict YSB populations in rice fields, aiming to develop an early warning system. Traditionally, rice farmers rely on light traps to monitor YSB presence. However, this study goes beyond this approach by combining light‐trap data with weather information (temperature, humidity, rainfall) and utilizing powerful artificial intelligence (AI) techniques to forecast future YSB populations. Two AI methods, multilayer perceptron (MLP) and long short‐term memory (LSTM), were employed to estimate YSB populations and assess their performance. The results revealed that the LSTM model outperformed the MLP model based on statistical metrics like RMSE, MAE, and R2 values. Utilizing LSTM model with historical data, stakeholders in the Eastern Coastal Plains and Hills agro‐climatic zone of India can gain a significant advantage in predicting YSB populations well in advance. This early warning system can alert stakeholders of potential YSB outbreaks, allowing them to take timely management actions and protect their rice crops from substantial yield losses. [ABSTRACT FROM AUTHOR]

The modification of seed shattering has been a recurring theme in rice evolution. The wild ancestor of cultivated rice disperses its seeds, but reduced shattering was selected during multiple domestication events to facilitate harvesting. Conversely, selection for increased shattering occurred during the evolution of weedy rice, a weed invading cultivated rice fields that has originated multiple times from domesticated ancestors. Shattering requires formation of a tissue known as the abscission zone (AZ), but how the AZ has been modified throughout rice evolution is unclear. We quantitatively characterized the AZ characteristics of relative length, discontinuity, and intensity in 86 cultivated and weedy rice accessions. We reconstructed AZ evolutionary trajectories and determined the degree of convergence among different cultivated varieties and among independent weedy rice populations. AZ relative length emerged as the best feature to distinguish high and low shattering rice. Cultivated varieties differed in average AZ morphology, revealing lack of convergence in how shattering reduction was achieved during domestication. In contrast, weedy rice populations typically converged on complete AZs, irrespective of origin. By examining AZ population-level morphology, our study reveals its evolutionary plasticity, and suggests that the genetic potential to modify the ecologically and agronomically important trait of shattering is plentiful in rice lineages. [ABSTRACT FROM AUTHOR]

Brazil, a leading rice producer globally, faces challenges in systematically mapping its diverse rice fields due to varying cropping systems, climates, and planting calendars. Existing rice mapping methods often rely on complex techniques like deep learning or microwave imagery, posing limitations for large-scale mapping. This study proposes a novel approach utilizing Sentinel-2 spectral–temporal metrics (STMs) in conjunction with a random forest classifier for rice paddy mapping. By extracting diverse STMs and training both regional and global classifiers, we validated the method across independent areas. While regional models tended to overestimate rice areas, the global model effectively reduced discrepancies between our data and the reference maps, achieving an overall classifier accuracy exceeding 80%. Despite the need for further refinement to address confusion with other crops, STM exhibits promise for national-scale rice paddy mapping in Brazil. [ABSTRACT FROM AUTHOR]

Direct seeding is employed to circumvent the labor-intensive process of rice (Oryza sativa) transplantation, but this approach requires varieties with vigorous low-temperature germination (LTG) when sown in cold climates. To investigate the genetic basis of LTG, we identified the quantitative trait locus (QTL) qLTG11 from rice variety Arroz da Terra, which shows rapid seed germination at lower temperatures, using QTL-seq. We delineated the candidate region to a 52-kb interval containing GENERAL REGULATORY FACTOR14h (GF14h) gene, which is expressed during seed germination. The Arroz da Terra GF14h allele encodes functional GF14h, whereas Japanese rice variety Hitomebore harbors a 4-bp deletion in the coding region. Knocking out functional GF14h in a near-isogenic line (NIL) carrying the Arroz da Terra allele decreased LTG, whereas overexpressing functional GF14h in Hitomebore increased LTG, indicating that GF14h is the causal gene behind qLTG11. Analysis of numerous Japanese rice accessions revealed that the functional GF14h allele was lost from popular varieties during modern breeding. We generated a NIL in the Hitomebore background carrying a 172-kb genomic fragment from Arroz da Terra including GF14h. The NIL showed superior LTG compared to Hitomebore, with otherwise comparable agronomic traits. The functional GF14h allele from Arroz da Terra represents a valuable resource for direct seeding in cold regions. Author summary: Rice serves as a fundamental crop sustaining over half of the global population. With the rapid growth of the world's population, it will become increasingly important to improve rice productivity. On the other hand, the aging of rice farmers in Japan has resulted in a constant labor shortage. To address this, direct seeding, in which seeds are sown directly in rice fields without going through the most labor-intensive part of the rice cultivation process, i.e., seedling production and transplanting, has been recommended. However, prevalent elite rice varieties are known to be unsuitable for direct seeding due to their poor seed germination ability under low-temperature conditions. In this study, we show for the first time that GF14h gene from the Portuguese variety Arroz da Terra improves seed germination at low temperatures (LTG). In addition, a novel cross-bred line was generated by introducing the GF14h-containing genomic segment from Arroz da Terra into Hitomebore, a widely cultivated variety in northern Japan. This line is expected to be used as a pre-breeding material to enhance LTG. This study will provide a genetic basis for LTG and contribute to basic and applied research progress. [ABSTRACT FROM AUTHOR]

As socially engaged art has played a vibrant role in responding to the crisis of the postmodernist art regime, the current post-Occupy condition has manifested itself in artistic interventions in rural China. In contrast to social writing, which encompasses street art, designers going to the countryside, and industrial empowerment to construct "good cultural governance" or "good cultural taste," the term personal writing as used here describes a type of avant-garde intervention that has sparked interest in vernacular communities. It provides a socially minded critique of art production as bifurcated from the remaking of everyday social relations and subjectivities, political and cultural possibilities, and the rural Chinese future. Grounded in a contextual analysis of the social turn in Chinese contemporary art and the lingering "rural problem" under post-socialism, this article takes artist Mao Chenyu's Paddy Film project as an example of personal writing and proposes this artist's activisms at Dongting Lake as a specific intervening field, visual ethnography as a method, paddy rice as a distinctive "thing," and archival practices as a deconstructive pathway that together have promoted the emergence of a resistance narrative in artistic intervention in Chinese rural communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Methanogens are a group of microorganisms with the capability to convert inorganic or organic compounds into methane, impacting the global carbon cycle and greenhouse gas emissions. In anaerobic environments such as wetlands, paddy fields, and reservoirs, methanogens are the primary contributors to methane production. In this study, high-throughput sequencing of the mcrA functional gene was utilized to conduct a comprehensive analysis of the community structure, metabolic pathways, and influencing factors of methanogens in the sediment of 18 reservoirs on the northeastern Qinghai Plateau. The results indicated that the construction of reservoirs has altered the physicochemical properties of river water and sediments, significantly impacting the distribution and succession of methanogenic communities in the sediment. In general, this study can improve our understanding of the biological mechanisms of methane emissions from the reservoirs on the Qinghai Plateau. Reservoirs are a hotspot for methane emissions, a potent greenhouse gas. However, the microbial basis for methane production in the Qinghai Plateau reservoirs remains unclear. To explore the characteristics of methanogenic communities in reservoir sediments on the northeastern Qinghai Plateau, sediment samples were collected from 18 reservoirs in the Yellow River basin during May 2023 (dry season) and August 2023 (wet season). High-throughput sequencing technology was employed to analyze the community composition, diversity, and co-occurrence network of methanogens. Furthermore, FAPROTAX and Mantel analysis were used to assess the metabolic functions of methanogens and their influencing factors. The results showed that (1) the predominant genera of methanogens were Methanobacterium (28.87%) and Methanosarcina (21.67%). Hydrogenotrophic methanogenesis was the main pathway in the sediments. (2) Significant spatiotemporal differences were observed in the diversity of methanogenic communities (p < 0.05). The composition and diversity of these communities were found to be significantly influenced by temperature, pH, altitude, organic carbon, and total nitrogen (p < 0.05). (3) Methanosarcina, Methanobacterium, and Methanospirillum play crucial roles in maintaining the stability of methanogenic community networks. The co-occurrence network nodes are predominantly positively correlated (99.82%). These results provide data for further studies on carbon cycling in the Qinghai Plateau reservoirs. [ABSTRACT FROM AUTHOR]

Ratoon rice (RR) has emerged as an active adaptation to climate uncertainty, stabilizing total paddy rice yield and effectively reducing agriculture-related ecological environmental issues. However, identifying key remote sensing parameters for RR under cloudy and foggy conditions is challenging, and existing RR monitoring methods in these regions face significant uncertainties. Here, given the sensitivity of synthetic aperture radar (SAR) backscattering signals to the crop phenological period, this paper introduces a threshold model utilizing Sentinel-1A SAR data and phenological information for mapping RR. The Yongchuan District of Chongqing, which is often cloudy and foggy, was selected as a specific study region where VH-polarized backscatter coefficients of Sentinel-1 images were obtained at 10 m spatial resolution in 2020. Based on the proposed threshold model, the RR extraction overall accuracy was up to 90.24%, F1 score was 0.92, and Kappa coefficient was 0.80. Further analysis showed that the extracted RR boundaries exhibited high consistency with true Sentinel-2 remote sensing images and the RR extracted area was in good agreement with the actual planted area situation. This threshold model demonstrated good applicability in the studied cloudy and foggy region, and successfully distinguished RR from other paddy rice types. The methodological framework established in this study provides a basis for extensive application in China and other significant RR-producing regions globally. [ABSTRACT FROM AUTHOR]

In Asia, rice is the most consumed grain by humans, serving as a staple food in India. The yield of rice paddies is easily affected by nutrient deficiencies and leaf diseases. To overcome this problem and improve the yield productivity of rice, nutrient deficiency and leaf disease identification are essential. The main nutrient elements in paddies are potassium, phosphorus, and nitrogen (PPN), the deficiency of any of which strongly affects the rice plants. When multiple nutrient elements are deficient, the leaf color of the rice plants is altered. To overcome this problem, optimal nutrient delivery is required. Hence, the present study proposes the use of Fuzzy C Means clustering (FCM) with Improved Tunicate Swarm Optimization (ITSO) to segment the lesions in rice plant leaves and identify the deficient nutrients. The proposed ITSO integrates the Tunicate Swarm Optimization (TSO) and Bacterial Foraging Optimization (BFO) approaches. The Hybrid Convolutional Neural Network (HCNN), a deep learning model, is used with ITSO to classify the rice leaf diseases, as well as nutrient deficiencies in the leaves. Two datasets, namely, a field work dataset and a Kaggle dataset, were used for the present study. The proposed HCNN-ITSO classified Bacterial Leaf Bright (BLB), Narrow Brown Leaf Spot (NBLS), Sheath Rot (SR), Brown Spot (BS), and Leaf Smut (LS) in the field work dataset. Furthermore, the potassium-, phosphorus-, and nitrogen-deficiency-presenting leaves were classified using the proposed HCNN-ITSO in the Kaggle dataset. The MATLAB platform was used for experimental analysis in the field work and Kaggle datasets in terms of various performance measures. When compared to previous methods, the proposed method achieved the best accuracies of 98.8% and 99.01% in the field work and Kaggle datasets, respectively. [ABSTRACT FROM AUTHOR]

With growing concerns about global warming, it is crucial to adopt agronomic practices that enhance rice yields from paddy fields while reducing greenhouse gas (GHG) emissions for sustainable agriculture. An optimal nitrogen (N) fertilization rate and planting density are vital to ensure high rice yields, minimize GHG emissions, and understand emission behavior for better field management. We hypothesized that optimizing N application rates and planting density to improve nitrogen use efficiency (NUE) in rice cultivation would reduce resource losses and GHG emissions. To test this hypothesis, we implemented five treatments with a rice straw return cultural system: two planting densities (16 hills m−2 (traditional density, D1) and 20 hills m−2 (25% higher density, D2)) and three N application rates (no N fertilizer (N0), 180 kg N ha−1 (N1), and 144 kg N ha−1 (N2)). The control treatment (CK) was traditional planting density with no N fertilizer. The four new cropping modes were N1D1, N1D2, N2D1, and N2D2. We investigated the effects of N application rates and planting density on rice grain yield, NUE, and GHG emissions in multiple rice-growing seasons. The N1D2 treatment exhibited the highest grain yield over the three years, with a value of 10,452 kg ha−1, representing an increase of 12.2% compared to CK. Moreover, N uptake in N1D2 was the highest, averaging 39.2% (p < 0.05) higher than CK, and 8.5%, 3.5%, and 2.8% (p < 0.05) higher than N1D1, N2D1 and N2D2, respectively. N2D2 exhibited the highest NUE, with a value of 58.99 kg kg−1, surpassing all other treatments over the three years. GHG emissions, global warming potential (GWP), and greenhouse gas intensity (GHGI) in N2D2 were lower than in N1D1, N1D2, and N2D1. Additionally, reducing N application (comparing N1D1 to N2D1) and increasing plant density (comparing N1D1 to N1D2) improved N agronomic efficiency (NAE) and N partial productivity (PFPN). The negative correlation between the NAE and PFPN with GWP and GHG emissions further supports the potential for optimized N management and denser planting density to reduce environmental impact. These findings have important implications for sustainable rice cultivation practices in Southwest China and similar agroecosystems, emphasizing the need for integrated nutrient management strategies to achieve food security and climate change mitigation goals. [ABSTRACT FROM AUTHOR]

Drying involves the evaporation of moisture, accompanied by simultaneous heat transfer, mass transfer, and momentum transfer. While the diffusion law is considered an applicable model for explaining the drying phenomenon, the actual drying process cannot be accurately predicted using an analytical solution with a constant diffusion coefficient. Energy efficiency in the drying process is low due to an insufficient understanding of the mechanisms governing moisture migration from solids to air. The development of drying theory has stalled due to an unsolvable discrepancy between experimental results and analytical results. This study analyzes the effect of the binding energy of moisture in paddy rice on the diffusion coefficient. The theoretical relationship between water activity and drying rate in paddy rice was investigated, and the drying process was successfully explained by analyzing free energy transfer and transition theory. The mechanism of rice grain drying was described using a new theoretical solution for the drying process. These results provide new insights into the development of a scientific evaluation standard for assessing the efficiency of actual drying processes. [ABSTRACT FROM AUTHOR]

A precision agriculture approach that uses drones for crop protection and variable rate application has become the main method of rice weed control, but it suffers from excessive spraying issues, which can pollute soil and water environments and harm ecosystems. This study proposes a method to generate variable spray prescription maps based on the actual distribution of weeds in rice fields and utilize DJI plant protection UAVs to perform automatic variable spraying operations according to the prescription maps, achieving precise pesticide application. We first construct the YOLOv8n DT model by transferring the "knowledge features" learned by the larger YOLOv8l model with strong feature extraction capabilities to the smaller YOLOv8n model through knowledge distillation. We use this model to identify weeds in the field and generate an actual distribution map of rice field weeds based on the recognition results. The number of weeds in each experimental plot is counted, and the specific amount of pesticide for each plot is determined based on the amount of weeds and the spraying strategy proposed in this study. Variable spray prescription maps are then generated accordingly. DJI plant protection UAVs are used to perform automatic variable spraying operations based on prescription maps. Water-sensitive papers are used to collect droplets during the automatic variable operation process of UAVs, and the variable spraying effect is evaluated through droplet analysis. YOLOv8n-DT improved the accuracy of the model by 3.1% while keeping the model parameters constant, and the accuracy of identifying weeds in rice fields reached 0.82, which is close to the accuracy of the teacher network. Compared to the traditional extensive spraying method, the approach in this study saves approximately 15.28% of herbicides. This study demonstrates a complete workflow from UAV image acquisition to the evaluation of the variable spraying effect of plant protection UAVs. The method proposed in this research may provide an effective solution to balance the use of chemical herbicides and protect ecological safety. [ABSTRACT FROM AUTHOR]

Crop straw returning to the field is an effective practice for straw utilization to improve soil fertility and sustain crop productivity. However, little information is available about the long-term effects of paddy straw return on soil properties and rice yield under a double-rice system. The objectives of this study were to test the hypothesis of the effects of different amounts of paddy straw returned to the field on soil physicochemical properties and rice yield, and to clarify the correlation between crop yield and soil physicochemical properties as well as quick-acting nutrients under different straw-returning modes. The experiment, initiated in the 2005 rice season, utilized "Xiang 45" and "Xiang 13" long-grained rice cultivars within a double-season rice cropping system. Three straw-returning treatments were implemented: rotary tillage with full rice straw incorporation (RTS), incorporation of one-third of the rice straw (1/3RTS), and incorporation of two-thirds of the rice straw (2/3RTS). This study found that among the three straw return rates, 2/3RTS had the most significant impact on soil physicochemical properties. Soil nitrogen content was identified as a crucial factor influencing soil organic carbon (SOC) accumulation, while pH levels significantly affected rice yield. Straw incorporation effectively increased the content and stocks of SOC. [ABSTRACT FROM AUTHOR]

Based on the actual distribution data of Guizhou kam sweet rice in field records and literature, the Maximum Entropy Model (MaxEnt) optimised by the Kuenm packet was used to study the suitable regions of Guizhou kam sweet rice and the dominant climatic factors affecting the distribution of kam sweet rice under the historical and future climate scenarios, which provides a reference basis for rational planning of distribution of kam sweet rice production in the context of climate change. The results showed that: (1) during the historical period of 1970-2000, the potential suitable region of kam sweet rice were mainly concentrated in the southeastern part of Qiandongnan prefecture, Guizhou province, and the highly suitable regions were distributed in Congjiang, Rongjiang, and Liping counties. (2) Compared with the historical period, the highly suitable region of kam sweet rice under the SSP126 climate scenario increases in region and moves to higher altitude in 2041-2060, and decreases in region and moves to higher latitude in 2081-2100, and increases in region and moves to higher latitude in 2041-2060, and decreases in region and moves to higher latitude in 2081-2100 under the SSP245 climate scenario. In the SSP585 climate scenario, the highly suitable region of kam sweet rice increases in region and moves to higher altitudes in 2081-2100. (3) Among the 19 climate impact factors, the min. temperature of the coldest month and the mean diurnal range difference are the main climate factors affecting the distribution of kam sweet rice, with contribution rates of 34.8% and 13.8%, respectively. Generally speaking, climate change will lead to the expansion of the highly suitable region of kam sweet rice in 2041-2060 and the reduction of the region in 2081-2100, so it is necessary to pay attention to the climate change, and rationally plan the production layout of kam sweet rice to ensure the food security. [ABSTRACT FROM AUTHOR]

In floodplains, which are highly modified and less inundated, trees are expanding, thus raising concerns regarding their impact on freshwater organisms. We analyzed the relationship between forest expansion and the change in Odonata (dragonflies and damselflies) assemblage over an extended period of time in the floodplain with ponds of the Kiso River, central Japan. In the 1970s, the ponds were mainly surrounded by grasslands, and approximately 80% of Odonata species were non-forest species. However, the number of forest species increased and that of non-forest species largely decreased with the forest expansion over the past five decades, resulting in almost a similar number of forest and non-forest species in 2021. Whereas the abundance of the non-forest species had been greater than that of the forest species until the 2000s, the difference has been much smaller in the 2010s, and the non-forest species occupied approximately only 30% of the number of individuals in 2021. The forest expansion may have reduced the open-lentic habitats for the non-forest species, which require riparian grasslands for resting, foraging, and reproduction, and may disturb the immigration of non-forest species from the adjacent rice paddy fields and rivers. The development of canopy cover over the waterbodies may have decreased the light and temperature above and within the ponds, which might have caused a decline in species that prefer warm and open-water environments. Maintaining shifting-mosaic patterns of vegetation around the floodplain waterbodies through active management may be effective in conserving floodplain Odonata communities, including both forest and non-forest species. [ABSTRACT FROM AUTHOR]

Taking fresh soil samples from a rice–wheat rotation field (RW), a permanently flooded rice field (PF), and a double-rice cropping field (DR: DRE for the early rice; DRL for the late rice), we measured the CH4 production potential (MPP), the relative contribution of acetate-dependent methanogenesis (ƒac), soil properties, and methanogenic archaeal communities mainly in order to reveal the temporal variation and corresponding influencing factors of methanogenic pathways in paddy soils. Consistent with the change in dissolved organic C (DOC) content, the MPP generally decreased with rice growth in RW and DRL while increasing in PF and DRE. Based on the measurements of stable carbon isotopes, the estimated ƒac-value in PF dropped sharply from 54%-61% at the tillering stage to 30%-35% at the booting stage and rose again at the ripening stage. This variation pattern was positively correlated with that of acetate content, perhaps resulting from the activation of acetoclastic Methanosarcina. In contrast, the ƒac-value in RW and DR rose from 20%-44% at the tillering stage to 49%-59% at the ripening stage, possibly owing to the increase in the relative abundance of acetoclastic Methanothrix. The relative abundance of Methanosarcina in PF was 3%-4% higher than those in RW and DR, whereas that of Methanothrix was 3%-7% lower (P < 0.05). Soil acetate, DOC, and moisture contents significantly affected the methanogenic community composition. Our results demonstrate that the temporal variation of methanogenic pathways was influenced by the relative abundance of acetoclastic methanogens depending on the acetate level. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) residues (root and straw) are unique substrates for microbes in paddy soils. Microbial respiration (RH) of paddy soils is likely to be affected by substrate quality. However, no relevant study on the effects of changed rice residue chemistry by climate change on the temperature sensitivity (Q10) of the RH of soils amended with the residues is available. To fill this knowledge gap, we conducted an incubation experiment (at 15, 25, and 35 °C) with rice residues of which lignin, nonstructural carbohydrate (NSC), and carbon-to-nitrogen ratio (C/N) were modified by growing the rice plants under different CO2 and air temperature (Tair). Co-elevated CO2 and Tair decreased lignin and C/N but increased the NSC contents of the residues, leading to the greater RH in the soils amended with rice residues produced under co-elevated CO2 and Tair compared to other CO2 or Tair treatments. However, the Q10 values of the RH of soils amended with rice residues produced under different CO2 and Tair were marginally changed, probably due to other confounding factors such as soil enzyme activity and nutrient availability. Despite that, there was a negative relationship between NSC and Q10 for soils amended with straw of which C/N is lower than root, agreeing with the kinetic theory on "substrate quality–Q10 relationship". Our result suggests that residue chemistry may not affect the Q10 of soils with root residue, but for straw-amended soils, less-recalcitrant NSC rather than more-recalcitrant lignin of straw may be critical in determining the Q10 of the soils. [ABSTRACT FROM AUTHOR]

Irrigated and rain-fed rice fields are unique agroecosystems and anthropogenic wetlands whose main feature is seasonal flooding. Flooded soils are characterized by spatiotemporal shifts and oscillation of the oxygen status and redox potential, sustaining varieties of microbial metabolisms, where bacteria and methanogenic archaea play principal roles and thus have been the major research targets. In this review, we focus on the diversity and ecology of protists—often overlooked biological entities—in wetland rice field soils. Protists with different ecological functions, i.e., phagotrophs, phototrophs, saprotrophs, and parasites, inhabit a rice field soil with a community- and individual-level adaptation to the wide range of oxygen tensions and redox potential. Other agricultural managements like fertilization and char application also influence the protist community. They link to the material cycling in rice soil and affect the activities and community composition of the microorganisms involved in the biogeochemical cycles. Rice roots are the hot spot for protists, which control the rhizospheric bacterial community and could increase the plant productivity through enhancing nutrient release and altering bacterial activities. This review highlights the essential roles of protists in a wetland rice field soil and needs for further research to fill the gaps in knowledge regarding the diversity and functions of the protists in this unique agroecosystem. [ABSTRACT FROM AUTHOR]

AbstractThis study aimed to assess the efficacy of commonly used post-emergence herbicides under flooded rice fields, for Conyza spp. control. The greenhouse experiment employed a factorial setup with factor A denoting the presence or absence of a water layer post-application, and factor B representing different herbicides, to C. sumatrensis. In field trials, were applied when the rice plantation was on V3 stage. Evaluations were control (%), roots and shoot dry weight of Conyza spp., as well as injury (%), number of grains per panicle, and grain yield (ha−1) of rice. The applications of imazapyr + imazapic, florpyrauxifen-benzyl, imazethapyr, penoxsulam, quinclorac, bentazon, triclopyr-butyl, saflufenacil and ethoxysulfuron followed by water layer entry led to Conyza spp. control surpassing 80% at 28 DAA. The herbicides florpyrauxifen-benzyl, quinclorac, triclopyr-butyl, and saflufenacil, without flooding after application, demonstrated Sumatran fleabane control equal to or greater than 80% at 28 DAA. Effective water layer management is crucial for Conyza spp. control in zero-grade rice cultivation areas. [ABSTRACT FROM AUTHOR]

Peruvian watergrass (Luziola peruviana J.F. Gmel.) is a perennial weed often found in paddy fields in the southern region of Brazil. Its chemical control is performed mainly by herbicides such as glyphosate in burndown, whose efficacy depends on soil moisture. Under excess‐water soil conditions, glyphosate efficacy is reduced, probably due to reduced translocation and the involvement of photoassimilates partition. Furthermore, little is known about the stress tolerance of these plants subjected to water deficit. Based on that, we performed experiments to verify the effect of soil moisture on the biochemical parameters of Peruvian watergrass and glyphosate translocation to the stolon and roots. Total soluble sugars, sucrose, starch, and glyphosate concentrations in leaves, culms, roots, and glyphosate partitioning were quantified. The malondialdehyde content and the lipid peroxidation increased with the drainage. Under drainage conditions, superoxide production was higher in roots than leaves, while peroxide production was lower in roots than leaves. The electrolyte leakage increased with the drainage and glyphosate application. The total soluble sugar content varied in each organ with a significant increase in the culm 14 days after application in the draining treatment. Sucrose varied considerably and reached its maximum concentration at 21 days after herbicide application. The starch accumulation in the culm was 7 days after applying the highest glyphosate dose. The presence of glyphosate in the roots subjected to soil drainage indicates the movement of this herbicide. In conclusion, soil drainage profoundly impacts Peruvian watergrass physiology, increasing the photoassimilates and glyphosate translocation to the stolon and root. This explains why glyphosate efficacy is higher under drainage conditions. [ABSTRACT FROM AUTHOR]

Dry direct-seeding can get rid of the constraints of high-water demand, and is the simplest and most laborsaving mode in rice (Oryza sativa L.) cultivation. However, weeds are more prone to occur in dry direct-seeding rice fields, coupled with increased herbicide resistance, leading to confusion among growers regarding herbicide selection. In this study, our investigation results revealed total grass quantity reached 458.82 plants m-2. Two round of field experiments were conducted to determine suitable post-emergence herbicides for dry directseeding indica rice. The results showed that among the herbicides safe to indica rice, the efficacy of the combination of pyraquinate (a new 4-hydroxyphenylpyruvate dioxygenase inhibitor, 150.0 g ai ha-1) + florpyrauxifen-benzyl (13.5 g ai ha-1) on Leptochloa chinensis (L.) Nees, Eclipta prostrata (L.) L., Cyperus iria L., Fimbristylis miliacea auct., and total grasses were 89.1%, 97.8%, 97.2%, 90.1%, and 92.8%, respectively; the efficacy of metamifop (120.0 g ai ha-1) + florpyrauxifen-benzyl (18.0 g ai ha-1) and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD (148.5 g ai ha-1) on main weeds also exceeds 85.0%, except for cyhalofop-butyl-resistant L. chinensis. The combination of metamifop + florpyrauxifen-benzyl and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD can be selected for fields where L. chinensis is not resistant to acetyl-CoA carboxylase (ACCase) inhibitors. The combination of pyraquinate + florpyrauxifenbenzyl is the most promising combination to control multiple weeds, even ACCase inhibitors-resistant weeds. This study could also provide references for herbicides selection and management of ACCase inhibitors-resistant L. chinensis in dry direct-seeding indica rice field worldwide. [ABSTRACT FROM AUTHOR]

Background: Crop diversification is considered as an imperative approach for synchronizing the plant nutrient demands and soil nutrient availability. Taking two or more crops from the same field in one year is considered as multiple cropping. It improves the diversity and abundance of soil microbes, thereby improving the growth and yield of crops. Therefore, the present study was conducted to explore the effects of different multiple winter cropping on soil microbial communities in paddy fields. In this study, eight rice cropping patterns from two multiple cropping systems with three different winter crops, including Chinese milk vetch (CMV), rape, and wheat were selected. The effects of different multiple winter cropping on soil microbial abundance, community structure, and diversity in paddy fields were studied by 16 S rRNA high-throughput sequencing and real-time fluorescence quantitative polymerase chain reaction (PCR). Results: The results showed that different multiple winter cropping increased the operational taxonomic units (OTUs), species richness, and community richness index of the bacterial community in 0 ~ 20 cm soil layer. Moreover, soil physical and chemical properties of different multiple cropping patterns also affected the diversity and abundance of microbial bacterial communities. The multiple cropping increased soil potassium and nitrogen content, which significantly affected the diversity and abundance of bacterial communities, and it also increased the overall paddy yield. Moreover, different winter cropping changed the population distribution of microorganisms, and Proteobacteria, Acidobacteria, Nitrospira, and Chloroflexi were identified as the most dominant groups. Multiple winter cropping, especially rape-early rice-late rice (TR) andChinese milk vetch- early rice-late rice (TC) enhanced the abundance of Proteobacteria, Acidobacteria, and Actinobacteria and decreased the relative abundance of Verrucomicrobia and Euryarchaeota. Conclusion: In conclusion, winter cropping of Chinese milk vetch and rape were beneficial to improve the soil fertility, bacteria diversity, abundance and rice yield. [ABSTRACT FROM AUTHOR]

The global biodiversity that underpins wild food systems--including fisheries--is rapidly declining. Yet, we often have only a limited understanding of how households use and benefit from biodiversity in the ecosystems surrounding them. Explicating these relationships is critical to forestall and mitigate the effects of biodiversity declines on food and nutrition security. Here, we quantify how biodiversity filters from ecosystems to household harvest, consumption, and sale, and how ecological traits and household characteristics shape these relationships. We used a unique, integrated ecological (40 sites, quarterly data collection) and household survey (n = 414, every 2 mo data collection) dataset collected over 3 y in rice field fisheries surrounding Cambodia's Tonlé Sap, one of Earth's most productive and diverse freshwater systems. While ecosystem biodiversity was positively associated with household catch, consumption, and sold biodiversity, households consumed an average of 43% of the species present in the ecosystem and sold only 9%. Larger, less nutritious, and more common species were disproportionally rep-resented in portfolios of commercially traded species, while consumed species mirrored catches. The relationship between ecosystem and consumed biodiversity was remarkably consistent across variation in household fishing effort, demographics, and distance to nearest markets. Poorer households also consumed more species, underscoring how wild food systems may most benefit the vulnerable. Our findings amplify concerns about the impacts of biodiversity loss on our global food systems and highlight that utilization of biodiversity for consumption may far exceed what is commercially traded. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) have started to play an important role in pest control, and novel miRNA‐based transgenic insect‐resistant plants are now emerging. However, an environmental risk assessment of these novel transgenic plants expressing insect miRNAs must be undertaken before promoting their application. Here, transgenic miR‐14 rice, which has high resistance to the rice stem borer Chilo suppressalis, was used as an example for evaluation in this study. Taking the tier 1 risk assessment method in Bacillus thuringiensis (Bt) crops as a reference, the effects of the direct exposure of a non‐target parasitoid, Cotesia chilonis, to a high concentration of miRNA were evaluated. The results showed that direct feeding with miR‐14 at high concentration had no significant effects on the biological parameters of Co. chilonis, whereas when miR‐14 was injected into Ch. suppressalis‐parasitized larvae, the development duration of Co. chilonis was significantly affected. In combination with the real conditions of the rice paddy field, it could be inferred that transgenic miR‐14 rice has no significant negative effects on the important non‐target parasitoid, Co. chilonis. These results will provide a foundation for the establishment of a new safety evaluation system for novel RNAi‐based transgenic plants. [ABSTRACT FROM AUTHOR]

This study employs the stochastic frontier gravity model (SFGM) to objectively assess the determinants of India’s rice exports from 2001 to 2019 across 22 major export destinations, highlighting untapped export potential and providing actionable policy recommendations for enhancing competitiveness in global rice markets. Results show that India's economic growth (GDP) and the GDP of importing nations positively impact rice exports. Conversely, geographical distances (representing transportation costs) and higher import tariffs act as deterrents. The devaluation of the Indian rupee positively influences export revenues. Common language benefits exports, while regional trade agreements show minimal impact. The study estimates significant untapped export potential between India and its partners, emphasizing the need for improved trade facilitation, logistics, and agreements.To maximize India's rice export potential, policymakers should prioritize quality compliance, streamline regulations, and invest in infrastructure and R&D for rice cultivars. Negotiating favorable trade agreements and implementing existing export policies like the New Agricultural Export Policy will aid market access and competitiveness. [ABSTRACT FROM AUTHOR]

One of the most recent areas of research in agriculture is the detection along with classification of diseases from plant leaf images. Since rice is the most widely consumed staple food worldwide, it is crucial to increase paddy production’s quality and quantity. In the production of paddy, early detection of pests and diseases at various growth stages is very important. Utilising image processing scheme to spot diseases of agricultural plants will lessen the need for farmers to safeguard agricultural products. The use of VGG-16 along with a Convolutional Neural Network (CNN) for the classification and recognition of paddy leaf diseases is proposed in this work. The rice plant leaves images taken from the kaggle dataset is utilised for the purpose of image acquisition. The Gaussian filter is used in pre-processing. The clustering technique is utilised for the segmentation of the diseased part, the normal part, and the surroundings. The proposed model is then utilised for disease classification. This study classifies 10 categories of paddy images. VGG16, InceptionV3, MobileNetV2, and ResNet-152, among other transfer learning methods, are evaluated and contrasted with the experimental results. The outcome accuracy of the proposed model achieves of nearly 99.9%. [ABSTRACT FROM AUTHOR]

Background: Grain quality is an important index of rice production, particularly when plants are grown under stress. Arsenic (As) contamination in paddy fields severely affects rice grain yield and quality. Here, the effects of As and combinations of As(III)-oxidizing bacteria (Pseudomonas stutzeri 4.25, 4.27, and 4.44) and plant growth-promoting bacteria (Delftia acidovorans KKU2500-12 and Cupriavidus taiwanensis KKU2500-3) on enzymes related to starch accumulation in grains and the grain quality of Khao Dawk Mali 105 rice cultivated in As-contaminated soil under greenhouse conditions were investigated. Results: Arsenic affected the activities of starch biosynthesis-related enzymes, and decreases of up to 76.27%, 71.53%, 49.74%, 73.39%, and 47.46% in AGPase, SSS, GBSS, SBE, and SDBE activities, respectively, and 9.42–61.07% in starch accumulation in grains were detected after growth in As-contaminated soil. However, the KKU2500-3/4.25 and KKU2500-3/4.44 combinations yielded the greatest enzyme activities in grains, and compared with the results observed in uninoculated seedlings, increases in starch accumulation of up to 51.16% and 23.81% were found in the inoculated seedlings after growth in medium- and high-As-contaminated soils, at 10–17 and 10–24 days after anthesis, respectively. The bacteria increased the 2-AP content in rice under As stress, possibly via the induction of proline, a 2-AP substrate. Bacterium-inoculated rice had significantly greater 2-AP levels than uninoculated rice, and 2.16–9.93% and 26.57–42.04% increases were detected in rice plants grown in medium- and high-As-contaminated soils, respectively. Conclusions: Arsenic toxicity can be mitigated in rice growing under greenhouse conditions by maintaining starch biosynthesis, accumulating amylose, and increasing 2-AP content. The effectiveness of these bacteria should be validated in paddy fields; hence, safe rice grains with a good starch content and aroma could be produced. Highlights: As(III) oxidation and PGPB improved the quality of the KDML 105 rice grains. Bacteria maintained starch biosynthesis-related enzyme activity in As-contaminated soils. Bacteria increased starch accumulation and the 2-AP aromatic content in rice grains. Bacteria improved the crop yield and grain quality of As-stressed rice plants. [ABSTRACT FROM AUTHOR]

Agricultural Heritage Systems (AHS) are pivotal in preserving rich agricultural production experience and traditional culture, as well as in maintaining biodiversity and promoting sustainable development in agriculture and rural economies. However, climate change poses significant threats to these systems, such as ecological degradation, biodiversity loss, and shifts in agricultural production patterns. This study, grounded in theories of information asymmetry and bounded rationality, constructs evolutionary game models for adaptive management of AHS under market mechanisms and government guidance. By employing stability analysis and numerical simulation with Delay Differential Equations (DDE) that consider historical delays, and through sensitivity analysis, this research delves into the strategic evolutionary outcomes of stakeholders under various scenarios. It aims to provide theoretical insights and policy recommendations for the dynamic protection and adaptive management of AHS in the face of climate change. The findings indicate that the public goods nature of AHS, alongside externalities and information asymmetry, leads to market failure. Sole reliance on autonomous actions by farmers and meteorological departments is insufficient for optimal resource allocation and effective protection. Government intervention, through regulatory and incentive measures, can effectively mitigate market failures and steer adaptive management of AHS towards efficiency and sustainability. Moreover, the study identifies key factors for adaptive management, such as enhancing stakeholders' initial willingness to participate, reducing the costs of adapting to climate change, optimizing cooperative benefit distribution mechanisms, and increasing the profitability of resource cooperation. Sensitivity analysis of government subsidies and penalty mechanisms further reveals the complex and critical role these policy tools play in fostering stakeholder engagement. Based on these findings, the study recommends enhancing initial participation willingness, controlling transformation costs to alleviate economic burdens, optimizing benefit distribution mechanisms to boost cooperative resource profitability, and establishing dynamic subsidy and penalty mechanisms for optimal resource allocation. The theoretical and practical contributions of this research lie in applying theories of information asymmetry and bounded rationality to the adaptive management of AHS under climate change, enriching the theoretical framework in this field, and providing scientific decision-making support for policymakers. By demonstrating an effective path for AHS protection through combined government and market mechanisms in the context of global climate change, this research holds significant theoretical and practical implications for enhancing the efficiency of adaptive management of AHS, protecting, and inheriting valuable agricultural cultural heritage. [ABSTRACT FROM AUTHOR]

As one of the most widely cultivated grain crops, paddy rice is a vital staple food in China and plays a crucial role in ensuring food security. Over the past decades, the planting area of paddy rice in China has shown substantial variability. Yet, there are no long-term high-resolution rice distribution maps in China, which hinders our ability to estimate greenhouse gas fluxes and crop production. This study developed a new optical satellite-based rice mapping method using a machine learning model and appropriate data preprocessing strategies to address the challenges of cloud contamination and missing data in optical remote sensing observations. This study produced CCD-Rice (China Crop Dataset-Rice), the first high-resolution rice distribution dataset in China from 1990 to 2016. Based on 391,659 validation samples, the overall accuracy of the distribution maps in each provincial administrative region averaged 90.26 %. Compared with 20,759 county-level statistical data, the coefficients of determination (R 2) of single- and double-season rice in each year averaged 0.84 and 0.80, respectively. The distribution maps can be obtained at https://doi.org/10.57760/sciencedb.15865 (Shen et al., 2024a). [ABSTRACT FROM AUTHOR]

The rice–fish co-culture is an important model of carp farming in China; however, research on the dynamics and assembly of water bacterial communities in this system remains limited. Therefore, this study aimed to explore the dynamics and assembly of bacterial communities, as well as their correlation with environmental factors in paddy water. For these purposes, this study was divided into two groups: a rice–carp co-culture (WRC) group and a rice monoculture (WRM) group, with 20 rice fields in each group. After 60 days of farming, the concentrations of NH4+-N, NO2−-N, TN, and PO43− were significantly higher in the WRC group than those in the WRM group. Alpha diversity analysis showed that the Shannon index in the WRC group was significantly decreased compared with the WRM group. At the phylum level, the relative abundance of Actinobacteria significantly increased, while the relative abundance of Proteobacteria and Bacteroidetes significantly decreased in the paddy water of the WRC group. The neutral community model (NCM) indicated that a random process played a dominant role in the construction of bacterial communities in the two groups, and common carp cultivation increased migration rates, thereby affecting community assembly. The co-occurrence network displayed that common carp cultivation led to looser interactions between bacterial communities. In addition, the contents of nutrients significantly affected the abundance of bacteria in paddy water. In summary, carp cultivation decreased the diversity of bacteria and changed the relative abundance of dominant bacteria, thereby affecting the stability and assembly of bacterial communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Anammox microorganisms are beneficial for use in wastewater treatment reactors. However, the application is limited due to the slow growth, high sensitivity, and the lack of a pure culture. To expand the sources of anammox bacteria, we used terrestrial soils from rice paddy fields to enrich and detect the anammox bacteria. This approach revealed potential anammox activities in both microaerobic and anaerobic soil conditions. Anammox, a reaction in which microorganisms oxidize ammonia under anaerobic conditions, is used in the industry to remove ammonium from wastewater in an environmentally friendly manner. This process does not produce intermediate products such as nitrite or nitrate, which can act as secondary pollutants in soil and water environments. For industrial applications, anammox bacteria should be obtained from the environment and cultivated. Anammox bacteria generally exhibit a slow growth rate and may not produce a large number of cells due to their anaerobic metabolism. Additionally, their habitats appear to be limited to specific environments, such as oxidation-reduction transition zones. Consequently, most of the anammox bacteria that are used or studied originate from marine environments. In this study, anammox bacterial evidence was found in rice paddy soil and cultured under various conditions of aerobic, microaerobic, and anaerobic batch incubations to determine whether enrichment was possible. The anammox-specific gene (hzsA) and microbial community analyses were performed on the incubated soils. Although it was not easy to enrich anammox bacteria due to co-occurrence of denitrification and nitrification based on the chemistry data, potential existence of anammox bacteria was assumed in the terrestrial paddy soil environment. For potential industrial uses, anammox bacteria could be searched for in rice paddy soils by applying optimal enrichment conditions. [ABSTRACT FROM AUTHOR]

SUMMARY: Oocystaenium elegans Gonzalves & Mehra (Oocystaceae, Trebouxiophyceae) was collected from a paddy field in Japan. Its life history was reexamined based on detailed observations of cultured material, and an emended description is given. This species is a large spindle‐shaped green alga that grows in puddles and paddy fields and has been reported in India, Nepal and Cuba. Reproduction occurs asexually via autospore formation and sexually via oogamy. Although this oogamy is considered to involve fertilization by globular egg cells and antherozoids, the results of the present study revealed that the egg cells (female cells) remained spindle‐shaped and became globular zygotes after fertilization. The place on the egg cells where the antherozoid attached swelled to become a receptive papilla, after which the antherozoid invaded. Phylogenetic analysis based on nuclear 18S small subunit ribosomal RNA gene sequences showed that O. elegans is included in the family Oocystaceae. [ABSTRACT FROM AUTHOR]

Exploring the growth and physiological response mechanisms of rice under continuous drought stress circumstances can provide a significant scientific foundation and technological assistance for meeting drought difficulties, improving drought resistance and rice (Oryza sativa L.) output, and ensuring food security. In this study, a rice field experiment was conducted under a rain shelter with five different treatments set up: P1 (drought stress from tillering stage), P2 (drought stress from jointing–booting stage), P3 (drought stress from heading–flowering stage), P4 (drought stress from grain filling stage), and CK (adequate water management throughout the growth stage). Continuous drought stress from different growth stages with four levels (mild, medium, moderate, and severe). The results showed that the effects of different drought stress treatments on rice growth varied significantly. Compared with the CK treatment, plant height was reduced by 12.10%, 8.14%, 3.83%, and 1.06% in the P1, P2, P3, and P4 treatments, respectively, and the number of tillers was reduced by 23.83%, 18.91%, 13.47%, and 8.68%, respectively. With the increase in drought stress levels, SPAD values and Rubisco activity of rice leaf continued to decrease; SOD activity showed a decreasing trend, but the decreasing trend of POD and CAT activities was not significant, while MDA content showed an increasing trend. For yield components, continuous drought stress significantly reduced spike length of rice by an average of 3.5%, effective number of spikes by 18.9%, thousand grain weight by 3.7%, grain number per spike by 11.6%, and fruiting rate by 1.8%, respectively, compared to CK treatments during the growth period. In general, continuous drought stress during the early growth period affected the effective spike number and the grain number per spike. Continuous drought stress after the grain filling stage had the least effect on yield (17.62% of yield reduction), and water use efficiency (1.76 kg m−3) was much higher than other treatments. These researchers' findings provide insight into how rice physiology and growth react to continuous drought stress, which is significant for agricultural operations. [ABSTRACT FROM AUTHOR]

(1) Background: Cyperaceae weeds have become a major type of weed in local paddy fields in China. (2) Methods: We assessed the impact of environmental factors, including temperature, light, salinity, water stress and soil depth, on the germination and emergence of three dominant Cyperaceae weeds: Cyperus difformis L., C. iria L. and Fimbristylis littoralis Gaudich. Using the dish dipping method, the performances of the pre- and post-emergence herbicides commonly used in paddy fields on three Cyperaceae weeds were evaluated using the pot method. (3) Results: The seeds optimally germinated at 35 °C in constant conditions and 25 °C/40 °C in alternating conditions. The seeds of the three Cyperaceae weeds were sensitive to light and could not germinate under dark conditions. The germination rate of the three weeds decreased with the increase in the NaCl concentration and water potential; the three weeds could not germinate at a 320 mmol·L−1 NaCl concentration and −0.1 MPa water potential. When the pH levels were 4 to 9, the germination rates of the three weeds were all greater than 80%. The burial depths to inhibit 50% of the emergence of C. difformis, C. iria and F. littoralis were 0.27, 1.06 and 0.42 cm, respectively. The control efficacy of the pre-emergence herbicides of pretilachlor, butachlor and oxyfluorfen on the three weeds were all above 90% at the recommended dose in the field. Halosulfuron-methyl, florpyrauxifen-benzyl and bentazone could effectively control the three Cyperaceae weeds; their performances on the three weeds at the 3- to 4-leaf stage were all above 82%. (4) Conclusions: The three Cyperaceae weed seeds have a strong adaptability to temperature, water potential, salinity and soil depth, and these weeds are sensitive to most pre- and post-emergence herbicides. Therefore, taking Cyperaceae weed seeds into the deep soil layer by tillage or selecting appropriate herbicides according to their growth stages can effectively control Cyperaceae weeds in rice fields. [ABSTRACT FROM AUTHOR]

Tillage practices are of critical importance in maintaining soil quality on cropland and for food production, with rice cultivation representing a significant portion of the world's food production and greenhouse gas (GHG) emissions. While numerous studies have examined the effects of reduced and no-tillage on soil GHG emissions and rice yields, the impact of adopting a rotational approach to tillage practices on the rice cultivation cycle remains uncertain. In this study, we conducted a four-year (2017–2020) field experiment in a single rice-growing area in Northeast China with the aim of investigating the effects of different tillage practices on GHG emissions from paddy fields and rice yields under full straw return conditions. We set up three experimental treatments: rotary tillage, plowing, and rotational tillage (i.e., a combination of one year of plowing and one year of rotary tillage). The results showed that averaged across all treatments, average methane (CH4, 302.6 ± 51.1 kg ha−1) and nitrous oxide (N2O, 0.86 ± 0.361 kg ha−1) emissions and rice yield (9.0 ± 0.9 t ha−1) did not exhibit significant inter-annual variability during the entire experimental period and were comparable to the average for the region. The ranking of GHG emissions during the rice-growing season was as follows: rotary tillage > plowing > rotational tillage. Across the experimental period, CH4 and N2O emissions were 9.1% and 8.5% lower in the plowing treatment and 21.2% and 13.1% lower in the rotational tillage treatment compared to the rotary tillage treatment. During the experimental period, there was no significant effect of tillage treatments on rice yield. This reduction in emissions may be attributed to changes in soil penetration resistance. In the rotational and plowing treatments, soil penetration resistance was in a range more adapted to rice growth and GHG emissions reduction compared to the rotary tillage treatment. The yield-scale GHG emission intensity was reduced by 12.7% and 26.1% in the plowing and rotational tillage treatments, respectively, in comparison to the rotary tillage treatment. This suggests that rotational tillage is a management practice that can achieve greenhouse gas emission reductions in paddy fields and stabilize or possibly increase rice yields. Consequently, the results demonstrated that a rotational alternation of multiple tillage practices is a synergistic strategy for achieving low carbon and high yield in rice in the cold rice-growing region of Northeast China. [ABSTRACT FROM AUTHOR]

Paddy-rice cultivation using the traditional continuous flooding method requires much water, up to 2500 L, to produce 1 kg of rice. Decreasing water availability is being exacerbated by climate dynamics, i.e., droughts and rainfall variability negatively affecting food security in developing regions, particularly Africa. Alternate wetting and drying (AWD) practice is a climate-smart water management strategy that, together with puddling (a critical field preparation process), significantly affects soil hydrological and physicochemical regimes, such as soil water dynamics and oxidation states in paddy fields. However, there are limited reviews on the effects and interaction of the AWD duration on hydrological conditions in the paddy-rice rhizosphere continuum under AWD practice at different rice growth stages. Our review synthesizes key scientific literature to examine water management and hydrological properties of paddy soils under AWD practice with climate change and sheds light on why farmers are skeptical in adopting the practice. To develop this paper, we reviewed scientific information from published journal articles, reliable reports, and our knowledge on paddy-rice cultivation and water management with climate change in Asia and Sub-Saharan Africa. Several studies confirm that AWD practice increases water–rice–crop productivity, yields, and reduces methane emissions. Limitations and challenges of AWD irrigation, including changes in soil structure that influence irrigation water application, variations in hydraulic conductivity caused by the duration and frequency of irrigation cycles, and frequent manual water level (WL) monitoring, are discussed. Opportunities to improve the integration of AWD strategies within government policies, irrigation schemes, and farmer acceptance due to skepticism, limited knowledge, and fear of unreliable water hindering adoption are highlighted. Future research suggestions include the following: (i) long-term measurement of water stress indices using infrared thermometers; (ii) seasonal suitability mapping using NDVI, GIS, and remote sensing; and (iii) application of smart sensors based on the Internet of Things (IoT) to address AWD challenges for precision water management in paddy fields with climate change. [ABSTRACT FROM AUTHOR]

Regenerated rice, characterized by single planting and double harvesting, saves labor and costs, significantly contributing to global food security. Hyperspectral imaging technology, which integrates image and spectral data, provides comprehensive, non-destructive, and pollution-free vegetation canopy analysis, making it highly effective for crop nutrient diagnosis. In this study, we selected two varieties of regenerated rice for field trials. Hyperspectral images were captured during key growth stages (flush, grouting, and ripening) of both the first and regenerated seasons. Utilizing a two-dimensional convolutional neural network (2D-CNN) as a deep feature extractor and a fully connected layer for nitrogen content prediction, we developed a robust model suitable for estimating nitrogen content in regenerated rice. The experimental results demonstrate that our method achieves a mean squared error (MSE) of 0.0008, significantly outperforming the back-propagation (BP) network and multiple linear regression by reducing the MSE by 0.0151 and 0.0247, respectively. It also surpasses the one-dimensional convolutional neural network (1D-CNN) by 0.003. This approach ensures accurate nitrogen content prediction throughout the growth cycle of regenerated rice, aiding in yield and economic benefit enhancement. [ABSTRACT FROM AUTHOR]

Methanogenic and methanotrophic microbes together determine the net methane flux from rice fields. Despite much research on them as separate communities, there has been little study of combined community patterns, and how these vary between the rhizoplane (root surface), rhizosphere (soil surrounding the root) and bulk soil around rice plants, especially at larger spatial scale. We collected samples from 32 geographically scattered rice fields in east central China, amplicon targeting the mcrA gene for methanogenesis and pmoA gene for methanotrophy by using high‐throughput sequencing. Distinct communities of both methanogens and methanotrophs occurred in each of the three compartments, and predominantly positive links were found between methanogens and methanotrophs in all compartments indicating cross‐feeding or consortia relationships. Methanogens were acting as the network hub in the bulk soil, and methanotrophs in rhizoplane. Network complexity and stability was greater in the rhizosphere than rhizoplane and bulk soil, with no network hubs detected, suggesting the strongest effect of homeostatic influence by plant occurred in the rhizosphere. The proportion of determinism (homogeneous selection) and distance–decay relation (DDR) in rhizoplane was consistently lower than that in the rhizosphere for both communities, indicating weaker phylogenetic clustering in rice root surface. Our results have provided a better understanding of CH4 oxidation and emission in rice paddy fields and future agriculture management could take into consideration of the subtle variation among different soil compartments and interactions within methanogenic and methanotrophic communities. [ABSTRACT FROM AUTHOR]

Lymnaea rubiginosa as a snail host found in the Babura River, Medan City, is a type of snail that is known to be an intermediate host in the life cycle of several trematode worms. Lymnaea rubiginosa was collected using net sources at four research stations and there were 10 sub stations at each research station. Research in 2023 found Lymneae rubiginosa in juvenile form and only at station two was it found, and even then only in one collection and only one individual. Snails can be infected by Fasciola gigantica and by other trematodes such as Echinostoma sp. and Trichobilharzia sp. as well as oligochaete worms, namely Chaetogaster sp. Chaetogaster sp. infection in Lymnaea rubiginosa snails originating from rice fields and ponds shows that the spread of these worms is widespread. If it is suspected that the worm is capable of preying on the Fasciola gigantica miracidium, then Chaetogaster sp. more effective for use as a biological control. If the Lymnaea rubiginosa snail has been infected with E. hystricosum, then the snail cannot be infected again with other trematodes such as Trichobilharzia brevis. There seems to be a mechanism that inhibits the occurrence of mixed infections. Trematode and oligochaete worm infections in the snail's body can affect the development and growth of the snail. There is no mixed infection between two types of trematodes, namely Echinostoma sp. and Streigidae in a snail Lymnaea rubiginosa supports the phenomenon of antagonism. [ABSTRACT FROM AUTHOR]

The phenomenon of leveling off and environmental degradation that occurs as a negative impact of the excessive use of chemical fertilizers and pesticides encourages the development of organic farming systems that can produce crop yields that are not contaminated and free from synthetic chemicals and maintain a healthier environment. The research was conducted from October to December 2022 by taking soil samples from farmers' paddy fields in Tegal Regency using an organic (Cawitali Village) and conventional or non-organic (Jembayat Village) farming system. Composite soil samples were taken from a soil depth of 0 to 20 cm from the soil surface using a soil drill on lowland rice fields with organic farming systems and conventional farming after harvest. The analysis of the chemical properties of the soil carried out was C-organic (Walkley and Black), N-total (Kjeldahl), CEC and soil bases (exch-Ca, exch-Mg, exch-K, and exch-Na), total P (25% HCl) and available P (Bray I), while the observed soil biological properties were the total number of microbial and fungal populations. The results showed that organic paddy soil's chemical and biological properties were relatively higher than conventional paddy soil's. Total fungi in organic lowland soils were lower than in conventional paddy fields. The nutrient status of C-organic and N-total in organic rice fields tended to increase compared to conventional rice fields, namely from very low to low and low to moderate, respectively. In contrast, the other nutrient statuses observed tended to remain relatively unchanged. Generally, soil biological and chemical properties were better in organic farming than in conventional farming systems. [ABSTRACT FROM AUTHOR]

The Indonesian governments developed the Upsus Pajale policy to achieve a goal and solve the problem of food self‐sufficiency. Rice, corn, and soybean were the main commodities in the plan of Upsus Pajale Policy implementation. UPSUS Pajale improve rice, corn, and soybean production for food self‐sufficiency. This study examined UPSUS Pajale policy implementation at the province, district, subdistrict, and farmer levels. This study examined rice growing in Banyuasin's tidal lowlands, Ogan Komering Ilir's swamplands, and East Ogan Komering Ulu's irrigated rice fields. The research method used a combination model of quantitative and qualitative (mixed method). Sampling data used purposive sampling. NVivo 12 software examined provincial, district, subdistrict, farmer interviews, and group discussions. Results affected typology management constraints differently. Production input costs were the most common issue. This study found that policy was differently implemented at various levels. It would be impacted to the success of the policy. [ABSTRACT FROM AUTHOR]

Snails are the first intermediate host in the life cycle of trematodes. Previous research found that Trichopodus microlepis fish, cultured in earthen ponds in Tan Nhut Commune, Binh Chanh District, Ho Chi Minh City, Vietnam had a high infection rate with metacercariae of Centrocestus formosanus and Procevorum sp. It is necessary to investigate whether habitats supplying water to the ponds may contribute to the transmission by carrying intermediate hosts and/or cercariae into these ponds or not. A study of cercariae and snail composition in rice fields and canal supplying water directly to these Trichopodus microlepis ponds was carried out with six samplings in the years 2022 and 2023. A total of 1,151 snails were collected, and nine snail species belonging to 8 genera and 6 families were identified. Three snail species in both rice fields and canal were infected with trematode (cercariae stage) including Bithynia siamensis, Lymnaea viridis and Indoplanorbis exustus. The overall prevalence in the dry season (25.9%) was significantly higher than in the wet season (10.6%) (P<0.05). Three cercariae morphotypes were recovered from snails: xiphidio (in all three snails), echinostome (in Lymnaea viridis and Indoplanorbis exustus), and pleurolophocercous in Bithynia siamensis. This finding shows that Bithynia siamensis is one of the infected sources for Trichopodus microlepis fish cultured in ponds, as pleurolophocercous is also the cercariae in the family of Heterophyidae (including Centrocestus formosanus and Procevorum sp.). Further research should be done to clarify the transmission of fish-borne zoonotic diseases to cultured Trichopodus microlepis in other habitats including the actual fishponds, and sources of trematodes in order to produce Trichopodus microlepis free of metacercariae, contributing to clean aquaculture development and safe food for local people in the area. [ABSTRACT FROM AUTHOR]

Background: An experimental study was conducted during June-November 2020 at Tungjoy village of Manipur, India, to assess the assemblage pattern, abundance and seasonal dynamics of phytoplankton in simultaneously integrated paddycum-fish culture (IPFC). Methods: The experimental IPFC fields were prepared by enhancing width and height of dykes and constructing central refuge pond. Rice saplings were manually transplanted into the prepared fields in June 2020 while the common carp fingerlings were introduced 30 days after rice-transplantation. Both rice and fish were harvested in November 2020. Assemblage pattern, abundance and dynamics of phytoplankton, soil nutrients and water quality were analysed for three seasons (monsoon, postmonsoon and winter) in paddy fields without fish (PF) compared with IPFC fields. Relevant fish growth parameters were analysed on monthly basis. Result: The study recorded 37 genera of phytoplankton belonging to 25 families and 18 orders falling under class Bacillariophyceae, Chlorophyceae and Cyanophyceae. Bacillariophyceae was the most diverse class. Phytoplankton density ranges from 14.00±1.57 x 103 to 33.25±3.60 x 103 μL -1 and 9.05±2.27 x 103 to 33.06±3.45 x 103 μL -1 in PF and IPFC, respectively, wherein Chlorophyceae dominated during monsoon and post-monsoon. Phytoplankton in IPFC was lower than PF, indicating effective utilisation by the reared fish. Fish production from IPFC fields was 326 kg ha-1 with 83% survival rate while rice production was enhanced by 7.4% as compared to rice monoculture. [ABSTRACT FROM AUTHOR]