Paddy Fields Research Articles

Alterations in Soil Bacterial Community and Its Assembly Process within Paddy Field Induced by Integrated Rice–Giant River Prawn (Macrobrachium rosenbergii) Farming

Integrated rice–aquatic animal farming has become a vital strategy for enhancing food security. To assess the effects of integrated rice–giant river prawn (Macrobrachium rosenbergii) farming (IRPF) on agricultural ecosystems, we used 16S rRNA gene sequencing to analyze soil bacterial communities in comparison with traditional rice monoculture (RM). Our study revealed that the IRPF did not significantly affect the diversity of the soil bacterial community. However, during the initial culture stage, IRPF markedly increased the relative abundance of the phylum candidate division NC10 and the genus Candidatus Methylomirabilis, enhancing nitrogen-cycling-related functions within the bacterial community. Additionally, IRPF reduced the complexity and stability of these communities in the early to middle culture stages. While stochastic processes usually dominate the assembly of these communities, IRPF restricted bacterial migration and reduced the influence of these stochastic processes. Furthermore, IRPF had a significant impact on environmental factors within paddy soils, strongly correlating with shifts in bacterial communities, particularly through variations in soil nitrite concentration. In conclusion, the influence of IRPF on the bacterial community in paddy soils was primarily observed during the early and middle culture stages, and the impacts of IRPF on the soil bacterial community were primarily driven by environmental changes, especially soil nitrite concentration. These findings provide theoretical insights and a reference for understanding the microbiological impacts of different integrated rice–fish farming systems on agricultural ecosystems.

Use of native and human-modified habitats by different mammal guilds in West Africa

Over millennia, mammals have coexisted with humans across the forest-savannah mosaics characterising part of West Africa. While some savannahs have long been used for rice cultivation in Guinea-Bissau, savannas and forests are now being rapidly converted into cashew monocultures. To understand how species cope with such land-use changes, we investigated how mammals make use of forest patches, cashew orchards and rice paddies over two contrasting periods: early and late rainy season. Using camera-trapping, we examined mammal diversity and trophic guild activity across seven landscapes, each with one sampling site per habitat type in Northern Guinea-Bissau. Based on 937 records from 21 species, species richness and activity were similar across habitat types, but generally higher in the late-rainy season. In this season, species composition differed between the cashew orchards and rice paddies. At the guild-level, carnivore activity was lower in the rice paddies than in forests, while herbivore activity was lower in the cashew orchards in comparison to that in forests in the early-rainy season. The relatively similar assemblage-wide diversity across habitat types seems to be enabled by the high habitat heterogeneity, but likely offset by previous extinctions from the area. Yet, guild-level habitat use highlighted the fundamental role of forests to sustain functionally healthy mammal assemblages. Maintaining habitat heterogeneity, including patches of native forests, seems to be key in optimizing the long-term conservation of mammal diversity in rural West Africa.

Germination Biology of Three Cyperaceae Weeds and Their Response to Pre- and Post-Emergence Herbicides in Paddy Fields

(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.

Green manure combined with reduced nitrogen reduce NH3 emissions, improves yield and nitrogen use efficiencies of rice

Background Green manure is an important source of organic fertilizer. Exploring green fertilizer and nitrogen fertilizer reduction is important for agricultural production. However, few studies have been conducted, especially on the effects of different green fertilizers along with reduced nitrogen fertilizer application on soil ammonia volatilization emissions, rice yield, and nitrogen fertilizer uptake and utilization. Methods In this study, the effects of different types of green manure and reduced nitrogen fertilizer application on soil ammonia volatilization emissions, aboveground population characteristics of rice, and nitrogen fertilizer uptake and utilization were explored. This study was based on a field-positioning experiment conducted between 2020 and 2022. Six treatments were established: no nitrogen fertilizer application (CK), conventional fertilization in wheat-rice (WR), villous villosa-rice (VvR), vetch sativa-rice (VsR), rapeseed seed-rice (RR), and milk vetch-rice (GR), with a 20% reduction in nitrogen fertilizer application. The amounts of phosphorus and potassium fertilizers remained unchanged. The characteristics of ammonia volatilization loss in rice fields, agronomic traits of rice, yield traits, and nitrogen uptake and utilization were investigated. Results The results indicated a significant difference (P < 0.05) in the impact of different treatments on ammonia volatilization emissions from rice in the two-year experiment. Compared with WR treatment, VvR, VsR, RR, and GR treatments reduced the total ammonia volatilization loss by 23.58 to 39.21 kg ha−1, respectively. Compared with the conventional WR treatment, other treatments increased rice yield by 0.09 to 0.83 t ha−1. GR treatment was significantly higher than other green fertilizer treatments, except for VsR (P < 0.05). It increased the nitrogen uptake of rice by an average of 4.24%–22.24% and 13.08%–33.21% over the two years, respectively. The impact of different types of green manure on the nitrogen uptake and utilization of rice varied greatly, indicating that the combination of green manure and fertilizer is a sustainable fertilization model for crops to achieve high yields. In particular, the Chinese milk vetch as green manure was more beneficial for ammonia volatilization reduction in paddy field and stable grain production of rice.

Membangun Pemberdayaan Masyarakat yang Berkembang dan Maju Melalui Pelatihan Pembukuan Keuangan UMKM di Desa Srimukti

Srimukti Village has great potential in the development of Micro, Small, and Medium Enterprises (MSMEs). This can be seen from the fact that most of the areas of Srimukti Village are rice fields that are used as a source of income. However, based on the results of observations and data obtained, there are still many MSME actors in Srimukti Village who do not have adequate knowledge and skills in managing their business finances. This study describes the implementation of the Community Service Program (KKN) with the theme "Building Developing and Advanced Community Empowerment Through MSME Financial Bookkeeping Training in Srimukti Village". This program aims to improve the knowledge and skills of MSME actors in managing their business finances, so that they can improve the development and progress of MSMEs in the village, as well as increase community income and contribute to improving the village economy. The research techniques used were observation, interviews, and documentation. The results of the study showed that the MSME financial bookkeeping training program to build developing and advanced community empowerment in Srimukti Village has been successfully implemented and has shown positive results. This program has increased the knowledge and skills of MSME actors in managing their business finances, so that it can improve the development and progress of MSMEs in the village, as well as increase community income and contribute to improving the village economy.

MiRNA-mediated insect-resistant transgenic rice poses no risk to a non-target parasitoid, Cotesia chilonis, via direct feeding or through its target host.

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 tier1 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.

A natural glutathione S-transferase gene GSTU23 confers metabolic resistance to metamifop in Echinochloa crus-galli

Herbicides are essential for farmers to control weed. However, prolonged use of herbicides has caused the development of herbicide resistance in weeds. Here, the resistant Echinochloa crus-galli (RL5) was obtained by continuous treatment with metamifop for five generations in paddy fields. RL5 plants showed a 13.7-fold higher resistance to metamifop compared to susceptible E. crus-galli (SL5) plants. Pre-treatment with GST inhibitor (NBD-Cl) significantly increased the susceptibility of RL5 plants to metamifop. Faster metamifop metabolism and higher GST activity in RL5 plants than in SL5 plants were also confirmed, highlighting the role of GST in metabolic resistance. RNA-Seq analysis identified EcGSTU23 as a candidate gene, and this gene was up-regulated in RL5 and field-resistant E. crus-galli plants. Furthermore, the EcGSTU23 gene was overexpressed in the transgenic EcGSTU23-Maize, and the EcGSTU23-Maize showed resistance to metamifop. In vitro metabolic studies also revealed that the purified EcGSTU23 displayed catalytic activity in glutathione (GSH) conjugation, and metamifop was rapidly metabolized in the co-incubation system containing EcGSTU23 protein. These results provide direct experimental evidence of EcGSTU23's involvement in the metabolic resistance of E. crus-galli to metamifop. Understanding the resistance mechanism can help in devising effective strategies to combat herbicide resistance and breeding of genetically modified herbicide resistant crops.

Effect of Agricultural Pesticide, Cypermethrin on Changes in Behavioural and Protein profile of larvivorous fish Aplocheilus lineatus

Cypermethrin is a synthetic pesticide that is widely used in agricultural fields and domestic areas to control pests and insect vectors. Cypermethrin considered to be a synthetic pyrethroid is extremely lethal on insects, and fishes and has a low impact on mammals and Aves. The present study aimed to investigate the acute toxicity of cypermethrin on the larvivorous fish Aplocheilus lineatus, which is the most common fish seen in pools, ponds, streams, paddy fields, and similar wetlands. The fish is highly significant in controlling vector-borne diseases prevailing in tropical countries. The LC50 value was determined to be 1.8 µg/L after 96 hrs of exposure to cypermethrin and the lethal value was 4 µg/L. The fish showed various behavioral changes during the experiment, including convulsions, vigorous gasping for air, erratically swimming, and loss of equilibrium. The results showed that even low concentrations of cypermethrin can exert acute effects on the biochemical constituents and behavioral aspects of A. lineatus. Total protein, structural protein, and soluble protein decreased from 1.33 ± 0.003 to 0.746 ± 0.015 mg/g, 0.967 ± 0.024 to 0.476 ± 0.0272 mg/g, and 0.444 ± 0.09 to 0.360 ± 0.018 mg/g, respectively, at 96 hours of exposure to 1 µg/L of cypermethrin. At the same time, glycogen levels also decreased from 1.11 ± 0.054 to 0.51 ± 0.019 mg/g. These variations in the behavioral and biochemical content of the fish after exposure indicate the toxic effect of cypermethrin. Hence the present study suggests monitoring and regulatory use of this pesticide.

Pemberdayaan Ekonomi Perempuan melalui Usaha Mikro: Kasus Pembuatan Triplek di Desa Jerukgiling Kabupaten Kendal

This study examines microeconomic activities in the form of part-time plywood manufacturing in Jerukgiling Village, Kendal Regency, which has been running for two years and involves ten workers. Plywood production is carried out by housewives as an additional job after completing household chores and activities in the rice fields. With a price of Rp1,200 per sheet, plywood production provides additional income for families in the village. The raw materials for making plywood come from sengon and jagon wood, provided by Mr. Gunawan, a boss from Brayu Hamlet, Kertosari Village, Singorojo Subdistrict, Kendal District. The production process is carried out in a special place that is now available, unlike before when it was done in each house. Plywood is collected every day with a production quantity of 200-300 pieces, although payment is made at a later date. The study also found that working hours are flexible, with production activities extending into the evening. The health center routinely checks the health of the workers every month to ensure that their health conditions are maintained. The analysis concludes that this plywood-making business not only provides economic benefits, but also provides flexibility for housewives in carrying out their dual roles. The main resource person for this research was Mrs. Karomah, one of the workers, who provided a detailed description of the dynamics and challenges faced in running a plywood-making business while taking care of their children

Diverse mechanisms confer bensulfuron-methyl resistance in Schoenoplectiella juncoides (Roxb.) lye

The effectiveness of bensulfuron-methyl in controlling Schoenoplectiella juncoides (Roxb.) Lye has significantly decreased in rice fields in China. Hence, a bensulfuron-methyl-resistant S. juncoides population (W15) was collected from Dandong City, Liaoning Province, China, to investigate the underlying resistance mechanisms. Whole-plant dose-response experiments and ALS activity assay confirmed that W15 has evolved high-level resistance to bensulfuron-methyl compared with the susceptible S. juncoides population (W4). Molecular analysis revealed a Pro-197-Ser mutation in ALS1, while there was no significant difference in the relative ALS gene expression between W15 and W4. LC-MS/MS analysis showed W15 metabolized bensulfuron-methyl more rapidly than W4. Furthermore, bensulfuron-methyl resistance in W15 was significantly alleviated by malathion and 4-chloro-7-nitrobenzoxadiazole (NBD-Cl). Glutathione S-transferase activity was higher in W15 than in W4. Meanwhile, W15 displayed cross-resistance to halosulfuron-methyl and multi-resistance to MCPA-Na. In summary, these findings demonstrated for the first time that both target- and non-target-site resistance are relevant in the resistance of S. juncoides to bensulfuron-methyl.

Evidence of Potential Anammox Activities from Rice Paddy Soils in Microaerobic and Anaerobic 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.

A kinetics-coupled multi-surface complexation model deciphering arsenic adsorption and mobility across soil types

The diversity of soil adsorbents for arsenic (As) and the often-overlooked influence of manganese (Mn) on As(III) oxidation impose challenges in predicting As adsorption in soils. This study uses Mössbauer spectroscopy, X-ray diffraction of oriented clay, and batch experiments to develop a kinetic coupled multi-surface complexation model that characterizes As adsorbents in natural soils and quantifies their contributions to As adsorption. The model integrates dynamic adsorption behaviors and Mn-oxide interactions with unified thermodynamic and kinetic parameters. The results indicate that As adsorption is governed by five primary adsorbents: poorly crystalline Fe oxides, well crystalline Fe oxides, Fe-rich clay, Fe-depletion clay, and organic carbon (OC). Fe oxides dominate As adsorption at low As concentrations. However, at higher As concentrations, soils from carbonate strata, with higher content of Fe-rich clay, exhibit stronger As adsorption capabilities than soils from Quaternary sediment strata. The enrichment in Fe-rich clay can enhance the resistance of adsorbed As to reduction processes affecting Fe oxides. Additionally, extensive redox cycles in paddy fields increase OC levels, enhancing their As adsorption compared to upland fields. This model framework provides novel insights into the intricate dynamics of As within soils and a versatile tool for predicting As adsorption across diverse soils.

Special Issue: Recent advances in biology and fertility studies of paddy field soil

Special Issue: Recent advances in biology and fertility studies of paddy field soil

Rice Growth and Leaf Physiology in Response to Four Levels of Continuous Drought Stress in Southern China

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.

Hydrus-1D Model for Simulating Potassium Transport in Rice Crop Irrigated with Alternate Wetting and Drying Practice

ABSTRACT Potassium (K) is one of the essential nutrients that play a crucial role in rice fields; however, its availability, transport, and balance components can be influenced by alternating wetting and drying (AWD) irrigation practice. This study used the Hydrus-1D solute transport model to simulate K transport and balance components in AWD irrigated rice fields. Thirty lysimeter field experiment plots with three different irrigation treatments (No: no soil water stress, MS: mild soil water stress (400 cm), and SS: severe soil water stress (750 cm)) were used for rice cultivation. Daily measurements of soil matric potential head (SMPH) and ponding water depth (PWD) were recorded. Throughout the rice-growing season, leachate water samples from the surface (ponding water) and soil profiles were collected to measure K content. Using the lysimeter field experiment data, the Hydrus-1D model simulated K transport in the AWD rice field. The simulation results indicate that the K distribution predominantly occurred within the top puddled soil layer (0–20 cm) in AWD practice. This suggests that the recommended K fertilizer dose with a 4–5 cm PWD and SMPH of 400 cm optimizes K availability for rice while limiting K leaching loss. The Hydrus-1D model proves to be a valuable management tool, aiding in determining optimal K application rates and ponding water depths for AWD irrigation, ensuring sufficient K nutrients for rice, and controlling K loss for sustainable rice production.

Biochar manure decreases ammonia volatilization loss and sustains crop productivity in rice paddy

Biochar manure decreases ammonia volatilization loss and sustains crop productivity in rice paddy

Causality-inspired crop pest recognition based on Decoupled Feature Learning.

Ensuring the efficient recognition and management of crop pests is crucial for maintaining the balance in global agricultural ecosystems and ecological harmony. Deep learning-based methods have shown promise in crop pest recognition. However, prevailing methods often fail to address a critical issue: biased pest training dataset distribution stemming from the tendency to collect images primarily in certain environmental contexts, such as paddy fields. This oversight hampers recognition accuracy when encountering pest images dissimilar to training samples, highlighting the need for a novel approach to overcome this limitation. We introduce the Decoupled Feature Learning (DFL) framework, leveraging causal inference techniques to handle training dataset bias. DFL manipulates the training data based on classification confidence to construct different training domains and employs center triplet loss for learning class-core features. The proposed DFL framework significantly boosts existing baseline models, attaining unprecedented recognition accuracies of 95.33%, 92.59%, and 74.86% on the Li, DFSPD, and IP102 datasets, respectively. Extensive testing on three pest datasets using standard baseline models demonstrates the superiority of DFL in pest recognition. The visualization results show that DFL encourages the baseline models to capture the class-core features. The proposed DFL marks a pivotal step in mitigating the issue of data distribution bias, enhancing the reliability of deep learning in agriculture. © 2024 Society of Chemical Industry.

Effect of wind speed and net radiation on the oasis effect in temperate rice paddy fields

Effect of wind speed and net radiation on the oasis effect in temperate rice paddy fields

Effects of Artificial Aging on Rice Lysophospholipids.

Lysophospholipids (LPLs) represent a major class of polar lipids crucial for rice's nutritional and functional properties. This study investigates the impact of varying storage temperatures (20, 30, and 40 °C) and humidity (50 and 95%) on the nonstarch and starch LPLs of paddy and milled rice. The findings revealed that the average nonstarch LPL content in paddy rice aged at 20 °C (82.6 μg/g) and 40 °C (83.6 μg/g) was significantly lower than that at 30 °C (95.0 μg/g). The nonstarch LPL content of milled rice aged at 20 °C (78.0 μg/g) was significantly higher than that at 30 and 40 °C. High storage temperature (40 °C) and humidity (95%) resulted in a significant reduction in rice total starch LPC and LPE content when compared to low humidity (50%). The ratio of rice starch/nonstarch LPL components such as LPC16:0 and LPC18:2 remarkably increased with increased storage temperature and humidity.

Bioaccumulation mediated by water solubility leads to differences in the acute toxicity of organophosphorus insecticides to zebrafish (Danio rerio).

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20-60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06-190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72-47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69-74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish.