Crop Plants Research Articles

Cutting-edge developments in agro-waste derived carbon nanomaterials and their multifaceted applications in agriculture: enhancing crop imaging, nutrient efficiency, and plant health.

The rising global population is a contributing factor to the exponential rise of agricultural output. Agro-wastes are now recognized as a substitute substance to produce sustainable, affordable, and renewable bio-based products. Abundant farm products due to a lack of processing capacity or storage room are frequently lost. A substantial amount biopolymer is present in agricultural residues. It's interesting that nanotechnology has the potential to more easily convert agricultural wastes into valuable and affordable products, eliminating the need to use toxic chemicals, which can lead to a variety of health and environmental problems. Recently, there has been a rise in interest in environmentally beneficial carbon nanomaterial (CNM) manufacturing methods that make use of agricultural waste extracts. Therefore, the goal of this review is to look into the various agro-waste sources, synthesis techniques of CNMs, characterization methods, surface functionalization chemistry, mechanistic approach and potential applications in imaging crops, nutrient utilization, and upgradation of crop health.

Moisture-responsive root-branching pathways identified in diverse maize breeding germplasm.

Plants grow complex root systems to extract unevenly distributed resources from soils. Spatial differences in soil moisture are perceived by root tips, leading to the patterning of new root branches toward available water in a process called hydropatterning. Little is known about hydropatterning behavior and its genetic basis in crop plants. Here, we developed an assay to measure hydropatterning in maize and revealed substantial differences between tropical/subtropical and temperate maize breeding germplasm that likely resulted from divergent selection. Genetic analysis of hydropatterning confirmed the regulatory role of auxin and revealed that the gaseous hormone ethylene locally inhibits root branching from air-exposed tissues. Our results demonstrate how distinct signaling pathways translate spatial patterns of water availability to developmental programs that determine root architecture.

The regulation of tobacco growth under preceding crop planting: insights from soil quality, microbial communities, and metabolic profiling

The regulation of tobacco growth under preceding crop planting: insights from soil quality, microbial communities, and metabolic profiling

In silico, in vitro, and in vivo characterization of thiamin-binding proteins from plant seeds.

Thiamin, an essential micronutrient, is a cofactor for enzymes involved in the central carbon metabolism and amino acid pathways. Despite efforts to enhance thiamin content in rice by incorporating thiamin biosynthetic genes, increasing thiamin content in the endosperm remains challenging, possibly due to a lack of thiamin stability and/or a local sink. The introduction of storage proteins has been successful in several biofortification strategies, and similar efforts targeting thiamin have been performed, leading to a 3-4-fold increase in white rice. However, only one thiamin-binding protein (TBP) sequence has been described in plants, more specifically from sesame seeds. Therefore, we aimed to identify and characterize TBPs, as well as to evaluate the effect of their expression on thiamin concentration, using a comprehensive approach integrating in silico, in vitro, and in vivo methods. We identified the sequences of putative TBPs from Oryza sativa (Os, rice), Fagopyrum esculentum (Fe, buckwheat), and Zea mays (Zm, maize) and pinpointed the thiamin-binding pockets through molecular docking. FeTBP and OsTBP contained one pocket with binding affinities similar to the Escherichia coli TBP, a well-characterized TBP, supporting their function as TBPs. In vivo expression studies of TBPs in tobacco leaves and rice callus resulted in increased thiamin levels, with FeTBP and OsTBP showing the most pronounced effects. Additionally, thermal shift assays confirmed the thiamin-binding capabilities of FeTBP and OsTBP, as observed by the significant increases in melting temperatures upon thiamin binding, indicating protein stabilization. These findings offer new insights into the diversity and function of plant TBPs and highlight the potential of FeTBP and OsTBP to modulate thiamin levels in crop plants.

Sustainable Agricultural Alternatives to Cope with Drought Effects in Semi-Arid Areas of Southern Mozambique: Review and Strategies Proposal

Drought, pests, soil fertility depletion, environmental challenges, and the limited use of agricultural inputs continue to plague food production in many developing countries such as Mozambique. As a response to these production constraints, sustainable strategies must be defined to cope with these problems. One strategy, largely applied worldwide, is the combination of the usage of plant growth-promoting microorganisms, conservation tillage, intercropping, and crop residue management. The above can help smallholder farmers to become more resilient, sustainable, and productive, in a framework where the limitations imposed by global climate change are being exacerbated. The impacts of these strategies are less known and lack studies in Mozambique. Here, we provide a comprehensive review based on the relevant scientific literature published in the last three decades which evaluated the effects of diverse sustainable alternatives for crop production, mainly oriented to enhance crop tolerance to drought. The use of these strategies and their promising potential to increase crop yields under drought conditions emerge as one of the most sustainable approaches, leading to both an increase in agricultural productivity and the amelioration of soil properties in Southern Mozambique. However, to achieve this goal, it is critical to perform studies that enable positive impacts and also take full account of the specific socio-economic and environmental contexts in which agricultural production is developed in the semi-arid areas of Southern Mozambique. Hence, future field studies assessing conservation agriculture practices effects on yield productivity and environment under drought conditions are suggested to address issues concerned to sustainable agricultural productions which allow us to achieve Sustainable Development Goal 1 (SDG 1) and SDG 2.

Adaptive spatial-channel feature fusion and self-calibrated convolution for early maize seedlings counting in UAV images

Accurate counting of crop plants is essential for agricultural science, particularly for yield forecasting, field management, and experimental studies. Traditional methods are labor-intensive and prone to errors. Unmanned Aerial Vehicle (UAV) technology offers a promising alternative; however, varying UAV altitudes can impact image quality, leading to blurred features and reduced accuracy in early maize seedling counts. To address these challenges, we developed RC-Dino, a deep learning methodology based on DINO, specifically designed to enhance the precision of seedling counts from UAV-acquired images. RC-Dino introduces two innovative components: a novel self-calibrating convolutional layer named RSCconv and an adaptive spatial feature fusion module called ASCFF. The RSCconv layer improves the representation of early maize seedlings compared to non-seedling elements within feature maps by calibrating spatial domain features. The ASCFF module enhances the discriminability of early maize seedlings by adaptively fusing feature maps extracted from different layers of the backbone network. Additionally, transfer learning was employed to integrate pre-trained weights with RSCconv, facilitating faster convergence and improved accuracy. The efficacy of our approach was validated using the Early Maize Seedlings Dataset (EMSD), comprising 1,233 annotated images of early maize seedlings, totaling 83,404 individual annotations. Testing on this dataset demonstrated that RC-Dino outperformed existing models, including DINO, Faster R-CNN, RetinaNet, YOLOX, and Deformable DETR. Specifically, RC-Dino achieved improvements of 16.29% in Average Precision (AP) and 8.19% in Recall compared to the DINO model. Our method also exhibited superior coefficient of determination (R²) values across different datasets for seedling counting. By integrating RSCconv and ASCFF into other detection frameworks such as Faster R-CNN, RetinaNet, and Deformable DETR, we observed enhanced detection and counting accuracy, further validating the effectiveness of our proposed method. These advancements make RC-Dino particularly suitable for accurate early maize seedling counting in the field. The source code for RSCconv and ASCFF is publicly available at https://github.com/collapser-AI/RC-Dino, promoting further research and practical applications.

Analysis of the Spatiotemporal Evolution Patterns and Driving Factors of Various Planting Structures in Henan Province Based on Mixed-Pixel Decomposition Methods

Understanding the spatiotemporal evolution patterns and drivers of cropping structures is crucial for adjusting cropping structure policies, ensuring the sustainability of land resources, and safeguarding food security. However, existing research lacks sub-pixel scale data on planting structure, where planted area data are mainly derived from manual counting results. In this study, remote sensing technology was combined with geostatistical methods to realize the spatiotemporal evolution of crop planting structure at sub-pixel scale. Firstly, the spatial distribution of the multiple cropping structure in Henan Province was extracted based on a mixed-pixel decomposition model, and spatiotemporal evolution of the crop planting structure was analyzed using a combination of Sen’s slope estimator and Mann–Kendall trend analysis, as well as centroid migration. Then, Pearson correlation coefficients were calculated to explore the contribution of driving factors. The results indicate the following: (1) from 2001 to 2022, the cropping structure in Henan Province shows a slightly obvious increase. (2) The centroid of different cropping structures migrates to the main production areas as a whole. (3) Among the driving factors, there was a positive correlation with the labor force and a negative correlation with the urbanization rate. This study provides new insights into the evolution of large-scale crop planting structures and offers significant theoretical and practical value for sustainable agricultural development and the optimization of agricultural planting structures.

Risk Assessment of Carcinogenic Metals in Soils and Food Crops Near Brick Kiln Cluster

A study was conducted in the Charia area, Hathazari, Chattogram district, Bangladesh to determine the levels of carcinogenic metals Cd and Pb in soils and crop plants in the vicinity of brick kiln clusters. The health risk was evaluated by computing cancer risk using the US EPA model. The amounts of Cd and Pb in the soils and the parts of crop plants were determined by AAS. The soils of the study area were acidic. Metal concentrations indicating the anthropogenic input of Cd and Pd in the soils was in the range from 0.27 to 1.07 mg/kg dry soil and from 19.07 to 52.07 mg/kg dry soil respectively. Accumulation of Cd (0.00 to 0.27 mg/kg) and Pb (0.09 to 0.13 mg/kg) in the studied crops. A significantly high correlation (r = 0.89, p < 0.001) of the elements between soil and plant suggests that the source of contamination is the soil under study. 72% of all the studied edible plant parts exceeded the recommended threshold risk limit of the cumulative cancer risk (ƩILCR), which was higher in the edible part of fruit crops than in root crops. Cd was the dominant carcinogen in the study area. J. Asiat. Soc. Bangladesh, Sci. 50(1-2): 17-31, June-December 2024

Plants & Fungi of Niue NaturaList: a compilation of the indigenous and introduced flora and mycota of a Polynesian island

ABSTRACT A checklist of the flora and mycota of Niue (https://plantsniue.nu/#!/checklist) is presented using the NaturaList app platform. The Plants & Fungi of Niue NaturaList was compiled from information presented in the flora treatments of TG Yuncker (1943. The flora of Niue island. In: Bernice P. Bishop Museum Bulletin. 178) and WR Sykes (1970. Contributions to the flora of Niue. New Zealand DSIR Bulletin 200. Wellington: Government Printer), with additional literature documenting the indigenous flora, rare plants, and invasive species. International databases such as iNaturalist and Plants of the World Online were consulted for taxa documented as occurring in Niue. Checklist information presented includes biostatus, Niuean vernacular names, synonyms, references, and images. Kingdom Fungi, mainly comprising Ascomycota and Basidiomycota, are included. The majority of fungi records are derived from surveys of diseases of agricultural crops and food plants, along with recent collections of lichenised fungi. Five additional phyla of Fungi comprise 15 records, with the mycota comprising a total of 270 taxa. Also listed are single species of Bacteria and Protozoa, and 9 taxa of Protista. Kingdom Plantae is represented by the vascular Polypodiophyta (ferns), Pinophyta (conifers), Lycopodiophyta (clubmosses), Cycadophyta (cycads) and Magnoliophyta (flowering plants). The Niue NaturaList includes indigenous (191 species), naturalised (376 species), Polynesian introductions (57 species), and cultivated (382 species) vascular taxa. The cultivated flora includes garden ornamentals and crop plants. The non-vascular Bryophyta (mosses) and Marchantiophyta (liverworts) are represented by 41 taxa. With the floras of Yuncker and Sykes out-of-print and recent literature often disparate and not readily accessible, the Plants & Fungi of Niue NaturaList provides a single, electronic and up-to-date compilation. This is necessary to improve knowledge of and access to Niue's indigenous biota and introduced cultivated and naturalised plants. It also informs and encourages further study relating to conservation of indigenous species and ecosystems, invasive species management, food security, and climate change adaptation. An appendix lists 37 new records of naturalised and cultivated plants made in 2024.

Boron contributes to enhance antimony tolerance in rice (Oryza sativa L.) by activating antioxidant system, modifying the cell wall component and promoting cell wall deposition of Sb.

Boron (B) is essential for plant growth and helps mitigate metal toxicity in various crop plants. However, the potential role and underlying mechanisms of B in alleviating antimony (Sb) toxicity in rice remain unexplored. In this study, we investigated the effects of H₃BO₃ supplementation (30, 50, and 75μM) on morphological growth, physiological and biochemical traits, Sb content, and the subcellular distribution of Sb in rice plants under 100μM Sb stress during the seedling stage in a hydroponic system. The results revealed that Sb toxicity severely impaired rice growth, reducing shoot biomass by 38.3%, shoot and root length by 38.9% and 23.2%, and leaf relative water content by 15.5%. Supplementation with 30μMB mitigated these adverse effects by enhancing photosynthesis and chlorophyll synthesis, restoring root activity, and improving oxidative balance through increased antioxidant enzyme activities in rice tissues. Furthermore, B supplementation significantly reduced Sb concentration in roots by 56.28%, while promoting Sb distribution in the cell wall (CW) fraction. Scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDS) microanalysis confirmed that B enhanced Sb adsorption on root CWs. Fourier transform infrared spectroscopy (FTIR) analysis indicated increased carboxyl groups in the CWs following B application under Sb treatment. Moreover, B supplementation increased the levels of pectin and hemicellulose and elevated pectin methylesterase (PME) activity by 22.0%, 69.0%, and 29.0% in roots, respectively, thus promoting Sb chelation onto the CWs. Taken together, our results provide a scientific basis and theoretical guidance for applying B to alleviate Sb toxicity in crops.

Decrypting proteomics, transcriptomics, genomics, and integrated omics for augmenting the abiotic, biotic, and climate change stress resilience in plants.

As our planet faces increasing environmental challenges, such as biotic pressures, abiotic stressors, and climate change, it is crucial to understand the complex mechanisms that underlie stress responses in crop plants. Over past few years, the integration of techniques of proteomics, transcriptomics, and genomics like LC-MS, IT-MS, MALDI-MS, DIGE, ESTs, SAGE, WGS, GWAS, GBS, 2D-PAGE, CRISPR-Cas, cDNA-AFLP, HLS, HRPF, MPSS, CAGE, MAS, IEF, MudPIT, SRM/MRM, SWATH-MS, ESI have significantly enhanced our ability to comprehend the molecular pathways and regulatory networks, involved in balancing the ecosystem/ecology stress adaptation. This review offers thorough synopsis of the current research on utilizing these multi-omics methods (including metabolomics, ionomics) for battling abiotic (salinity, temperature (chilling/freezing/cold/heat), flood (hypoxia), drought, heavy metals/loids), biotic (pathogens like fungi, bacteria, virus, pests, and insects (aphids, caterpillars, moths, mites, nematodes) and climate change stress (ozone, ultraviolet radiation, green house gases, carbon dioxide). These strategies can expedite crop improvement, and act as powerful tools with high throughput and instant database generation rates. They also provide a platform for interpreting intricate, systematic signalling pathways and knowing how different environmental stimuli cause phenotypic responses at cellular and molecular level by changing the expression of stress-responsive genes like RAB18, KIN1, RD29B, OsCIPK03, OsSTL, SIAGL, bZIP, SnRK, ABF. This review discusses various case studies that exemplify the successful implementation of these omics tools to enhance stress tolerance in plants. Finally, it highlights challenges and future prospects of utilizing these approaches in combating stress, emphasizing the need for interdisciplinary collaborations and bio-technological advancements for sustainable agriculture and food security.

Revealing the process and mechanism of non-grain production of cropland in rapidly urbanized Deqing County of China.

Non-grain production of cropland (NGPCL) is a common consequence of rapid urbanization, but excessive NGPCL threatens food security and sustainable cropland use. However, the evolutionary processes and mechanisms of different NGPCL types remain largely unknown, compromising the scientific basis for NGPCL management. Thus, taking rapidly urbanized Deqing as the study area, this research constructed an NGPCL theoretical framework from the perspective of agricultural location, classified NGPCL types using Landsat images, random forest algorithm and Google Earth Engine, and revealed their spatiotemporal changes and different influencing factors through the Multinomial Logit Regression model, and provided targeted zoning and categorized policy suggestions. Our constructed theoretical framework modeled NGPCL by the complex interactions among geographical location, natural conditions, socioeconomic levels, and policy forces. From 2000 to 2022, NGPCL in Deqing County had a high degree and significantly increased from 68.65% to 89.19%. Pond farming and horticultural crops increased by 4046.46ha (38.0%) and 1307ha (27.1%), while tree planting slightly decreased by 54ha (-2.5%). However, these NGPCL expansions resulted in a drastic decrease of 5299ha (-65.5%) in grain crops plantation. Different NGPCL types showed varied spatial distribution characteristics and differentiated driving mechanism. Horticultural crops depended on geographical location and socioeconomic factors and were widely planted near towns and roads with high population density and economic strength. Pond farming mainly extended along the eastern flat rivers and relied on resource endowment. Tree planting was closely related to the natural condition and was concentrated in the sparsely populated mountainous areas. The NGPCL is the result of balancing various factors, and under conditions of extremely scarce cropland resources, the Chinese government needs to strike a reasonable threshold for non-grain production and propose targeted policies of zoning classification to prevent excessive NGPCL from threatening grain yield security.

Seed and Color Preferences of Wild Carrion Crows From Cafeteria Experiments.

Birds can cause significant damage to agricultural fields, notably in Europe, where corvid species like carrion crows (Corvus corone) and rooks (Corvus frugilegus) target spring crops, posing challenges for conservation and wildlife management. Among targeted crops, sunflower and maize suffer the highest levels of damage from corvids' foraging. While both lethal and non-lethal strategies are employed to mitigate bird damage, their effectiveness is limited and context-dependent. Consequently, there is growing interest in identifying natural bird repellents. To improve our understanding of corvid food selection and explore potential non-lethal management strategies, we conducted (1) cafeteria trials with five common seed types (maize, sunflower, soy, pea, and wheat) and (2) two-choice color tests with maize seeds in four colors (blue, green, orange, and red) on an urban population of carrion crows accustomed to human presence. Results indicated a marked preference for sunflower and wheat, while soy and pea were largely avoided, and maize was moderately consumed. The crows also demonstrated a preference for green-colored maize over blue, orange, red, and natural maize seeds. These findings suggest that strategic planting of preferred crops like wheat alongside sunflower or maize may help mitigate damage. Further, incorporating colors into repellent seed coatings could reinforce the aversive learning process in birds, although color may play a less significant role in food selection when seeds are sown.

PlantGENE: Advancing plant transformation through community engagement.

Plant transformation is an important part of plant research and crop improvement. Transformation methods remain complex, labor intensive, and inefficient. PlantGENE is a community of scientists from academia, industry, non-profit research institutes, and government organizations working to improve plant transformation. PlantGENE hosts virtual training, interactive webinars, and a website with career opportunities, directories, and more. The plant science community has shown great interest and support for PlantGENE.

Climate-adaptive optimal water resources management: A multi-sectoral approach for the Munneru river basin, India.

Climate change profoundly affects water resource allocation by disrupting the availability, distribution, and quality of water across various regions. Optimal allocation of water resources represents a comprehensive strategy for water resource management by addressing the intricate connections between water allocation systems and their repercussions on the environment, society, and economy. In this study, an Optimal Water Resources Management (OWRM) framework was developed, focusing on the optimal allocation of water resources and crop planting structures across various sectors. The Munneru river basin, located in the lower Krishna River region of India, was selected as the study area to validate the proposed framework. Five distinct water-demanding sectors-irrigation, domestic, livestock, industrial, and irrigation water requirements for major agricultural seasons-were identified in the study area, and their sectoral water demands were calculated at the basin level. The crop water and irrigation water requirements for various crops were estimated using the CROPWAT tool, while the framework also optimized crop planting structures to maximize returns and resource efficiency. The Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was applied, with two objectives focused on equity and economic value. Superior solutions were then identified using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The OWRM framework was applied after identifying critical cases of water availability in future periods under climate change scenarios. Through this integrated approach, an average annual increase of 52.6% in agricultural sector returns was achieved for the simulation period (2016-17 to 2022-23). For a condition of providing at least 90% water supply to each sector, the optimal crop patterns led to revenue increases of 136.4%, 59.2%, and 74.7% compared to actual revenues for the water years 2020-21, 2021-22 and 2022-23 respectively. The developed OWRM methodology can be applied to other basins across the world that are impacted by climate change.

Transcription factor AtWRKY43 enhances drought tolerance by positively regulating the expression of AtSWEET5.

Drought exerts negative effects on plant growth and crop productivity. Sugars play a crucial role in enhancing drought tolerance by acting as osmoprotectants. Sugar transporters AtSWEETs are essential for maintaining sugar distribution equilibrium and facilitating effective adaptation to drought stress. In the study, transcriptomic analysis showed that WRKY transcription factor AtWRKY43 plays a key role in modulating gene expression patterns that enhance the plant's ability to accumulate sugars, which in turn supports osmotic adjustment and overall drought stress resilience. AtWRKY43 was identified as a promoter of sugar accumulation through its induction of transcriptional expression of AtSWEET5, thereby influencing drought tolerance. We observed an upregulation in the expression of the gene AtSWEET5 during drought stress. The mutant atsweet5 exhibited increased sensitivity to drought compared to Col-0, possibly due to increased H2O2 content and disrupted sugar homeostasis. Our research highlights the critical roles of AtWRKY43 and AtSWEET5 in modulating drought stress, providing new gene targets for developing crop varieties with enhanced sugar content. Therefore, it is imperative to understand the impact of drought stresses on sugar transport and transporters at both genetic and molecular levels in order to maintain optimal sugar balance in plants experiencing drought stress.

Energy and Exergy Analyses Applied to a Crop Plant System

Energy and Exergy Analyses Applied to a Crop Plant System

КОМПЛЕКСНОЕ ИСПОЛЬЗОВАНИЕ МИКРОБИОЛОГИЧЕСКИХ И МИНЕРАЛЬНЫХ УДОБРЕНИЙ В АГРОЦЕНОЗАХ ЯРОВЫХ ЗЕРНОВЫХ КУЛЬТУР

The aim of the study is to establish the effectiveness of the influence of microbiological preparations Azotovit and Phosphatovit used for pre-sowing seed treatment on the consumption of nutrients by spring wheat and spring barley plants from the soil and mineral fertilizers in the conditions of dark gray forest heavy loamy soils of the Ryazan Region. Field trials to study the effect of mineral fertilizers on spring wheat and spring barley crops in 2022–2023 were carried out at the Experimental Agrotechnological Station of the Federal State Budgetary Educational Institution of Higher Education Ryazan State Agricultural University. The object of the study was spring wheat variety Granni, spring barley variety Vladimir. Two field experiments with spring wheat and barley were laid out using a two-factor system: with seed treatment with microbiological fertilizers Azotovit + Phosphatovit (2 + 2 l/t) and control (without pre-sowing seed treatment) (factor A). In the experiment, mineral fertilizers (factor B) were used according to the following scheme: control (without fertilizers); N35 – ammonium nitrate = 1.0 c/ha; N35 – ammonium nitrate = 1.4 c/ha; N35 – ammonium nitrate = 1.9 c/ha; N35P35K35 – azophoska (16:16:16) = 2.1 c/ha. Under the influence of the preparations Azotovit and Phosphatovit against the background of complete fertilization at a dose of 2.1 c/ha, by the end of the crop vegetation period, a minimal decrease in the humus content in the soil to 0.17 % was observed compared to 0.3 % in the variant without fertilizer application. Microbiological preparations Azotovit and Phosphatovit contributed to an increase in the content of mobile forms of phosphorus and potassium in critical periods of crop development, which had a positive effect on the further development of grain crops. The maximum productivity of grain crop plants was formed in the variants using Azotovit + Phosphatovit (2 + 2 l/t) – 53.3 c/ha (NPK – 2.1 c/ha), 47.7 c/ha (N – 1.9 c/ha), which is 57.2 and 40.7 % higher than the yield of the variant without fertilizer application, respectively.

Paddy–Upland Rotation Improves Rice Growth and Reduces Greenhouse Gas Emissions in Winter Paddy Fields

From May 2019 to May 2022, a field experiment was conducted to clarify the effects of paddy–upland rotations on rice yield and greenhouse gas emissions in winter paddy fields. Four types of rotation pattern, rice–oilseed rape, rice–radish, rice–faba bean, and rice–fallow (flooded), were investigated and the N2O, CH4, and CO2 emissions in situ and rice yield were determined. The results showed that the paddy–upland rotation mode required fertilization during the winter cropping season. Compared with the rice–fallow (flooded) mode, the flux rate and annual cumulative emissions of N2O were significantly higher in the paddy–upland rotation modes. The rice–radish mode had the highest flux rate and annual cumulative emissions of N2O. When the soil in each paddy–upland rotation mode was exposed to air in winter, the soil redox potential increased and reducing substances were oxidized. Compared with the rice–fallow (flooded) mode, the flux rate and annual cumulative emissions of CH4 significantly decreased in the paddy–upland rotation modes, with the rice–radish mode producing the lowest flux rate and annual cumulative emissions of CH4. Fertilization and crop planting were conducted in winter, and the soil moisture was low. Compared with the rice–fallow (flooded) mode, the flux rate of CO2 of the paddy–upland rotation modes increased significantly. The flux rate of CO2 in the rice–oilseed rape mode was the highest. Furthermore, the N2O and CH4 emissions produced during the rice season and annually were significantly positively correlated with those in the winter season, indicating that the winter season had a significant effect on greenhouse gas emissions from winter paddy fields. Because of the significantly higher annual cumulative emissions of CH4 and the significantly lower rice yield in the rice–fallow (flooded) mode than in the paddy–upland rotation modes, this mode’s global warming potential (GWP) and greenhouse gas intensity (GHGI) during the rice season are significantly higher than those of the paddy–upland rotation modes.

Plant growth-promoting gene expression in Bacillus stercoris under atrazine contamination and their ability to stimulate growth of mung bean seedlings

ABSTRACT Herbicide residues can negatively impact crop rotation and plant growth-promoting bacteria. This study examined the effect of atrazine on the expression of genes related to IAA production and phosphate solubilisation in Bacillus stercoris B.PNR1 and B.PNR2 under in vitro conditions. Results showed that B.PNR2 exhibited a more significant upregulation of the genes encoding aldehyde dehydrogenase (locus tags NZD81_05285 and NZD81_18505) and glucose 1-dehydrogenase (locus tags NZD81_05445 and NZD81_17730) compared to B.PNR1 when exposed to 200 µg/L of atrazine in the culture medium (P < 0.05). Specifically, the expression levels of NZD81_05445 and NZD81_17730 were over 30 times higher at 200 µg/L compared to the control (P < 0.05). The growth of mung bean seedlings in atrazine-contaminated soil varied by inoculation method. Seeds soaked in bacterial cell suspension for 24 h had a low survival percentage (41.25% to 51.25%), while directly pouring the suspension into the soil or soaking root-protruded seeds resulted in better survival (75.00% to 94.29%). The expression of both genes may be associated with enhanced growth of mung bean seedlings in atrazine-contaminated soil, as B.PNR2 has demonstrated a more effective trend than B.PNR1 in both soil conditions. For instance, shoot lengths of mung beans in non-contaminated and atrazine-contaminated soil were 16.35 ± 0.23 cm and 12.49 ± 0.21 cm with B.PNR2, compared to 14.94 ± 0.26 cm and 12.47 ± 0.21 cm with B.PNR1. Applying B.PNR2 directly to the soil resulted in specific root lengths of mung bean seedlings grown in atrazine-contaminated soil measuring 3.14 ± 0.06 m/g. In contrast, B.PNR1 produced a specific root length of 2.86 ± 0.06 m/g. Both bacterial suspensions demonstrated significantly higher specific root lengths than the control group, which measured 1.84 ± 0.05 m/g (P < 0.05).