Search Results (658)

Weeds pose a significant challenge to agricultural productivity, requiring control strategies that are both effective and environmentally sustainable. Therefore, this study evaluated the inhibitory potential of aqueous extracts from Ricinus communis L. leaves to manage the weeds Oryza sativa L. (weedy rice) and Cyperus ferax. Extracts were obtained through pressurized liquid extraction using water as the solvent. Bioassays were conducted during pre- and post-emergence stages by foliar spraying 15 and 30 days after sowing (DAS). The effect of extraction time (1–30 min) on inhibitory efficacy was also assessed. Chemical profiles of the extracts were characterized using high-performance liquid chromatography. The extracts significantly inhibited seed germination, with suppression rates reaching 92.7%. Plant growth was also diminished, particularly with earlier treatments (at 15 DAS), resulting in reductions of up to 32% and 53% in shoot length, and 69% and 73% in total dry mass for O. sativa L. and C. ferax, respectively. Mortality rates of O. sativa L. and C. ferax reached 64% and 58%, respectively. Phenolic compounds were identified in the extracts, and higher concentrations were observed at shorter extraction times. These findings underscore the potential of R. communis L. leaf extracts as an ecologically sustainable alternative for weed management, providing an effective and natural approach that may reduce reliance on synthetic herbicides and mitigate their environmental impact. Full article

Late sowing and spring low temperatures have a great impact on the growth and maturation of wheat in the rice–wheat rotation region. In order to analyze the impacts of cold stress in February in early spring on yield formation and agronomic traits of wheat on different sowing dates, a controlled pot experiment was performed using the widely promoted and applied spring-type wheat variety Yangmai23 (YM23). The yield of wheat treated with late sowing date II (SDII, 21 November) and overly late sowing date III (SDIII, 9 December) were both lower than that of wheat sown on the suitable date I (SDI, 1 November). The yield of late-sown wheat decreased by 40.82% for SDII and by 66.77% for SDIII, compared with SDI, and these three treatments of wheat all grew under the natural conditions as the control treatments. The plant height, stem diameter of the internode below the ear, flag leaf length and area, and total awn length of the spike, as well as the spike length of late-sown wheat, were all significantly lower than those of wheat in SDI treatment. Early spring low temperatures exacerbated the decline in yield of wheat sown on different dates, to some extent. Despite showing higher net photosynthetic rate, stomatal conductance, and transpiration rate in flag leaves of the SDIII treatment under low-temperature stress than those of the other treatments at anthesis, overly late sowing led to minimal leaf area, shorter plant height, fewer tillers, and smaller ears, ultimately resulting in the lowest yield. Our study suggested that additional focus and some regulation techniques are needed to be studied further to mitigate the combined negative impacts of late sowing and low-temperature stress in early spring on wheat production. Full article

Sheath blight (ShB), caused by the necrotrophic fungus Rhizoctonia solani (R. solani), poses severe threats to global rice production. Developing a resistant variety with an ShB-resistance gene is one of most efficient and economical approaches to control the disease. Here, we identified a highly conserved chloroplast-localized stem-loop-binding protein encoding gene (OsCSP41b), which shows great potential in developing an ShB-resistant variety. OsCSP41b-knockout mutants exhibit chlorotic leaves and increased ShB susceptibility, whereas OsCSP41b-overexpressing lines (CSP41b-OE) display significantly enhanced resistance to R. solani, as well as to drought, and salinity stresses. Notably, CSP41b-OE lines present a completely comparable grain yield to the wild type (WT). Transcriptomic analyses reveal that chloroplast transcripts and photosynthesis-associated genes maintain observably elevated stability in CSP41b-OE plants versus WT plants following R. solani infection, which probably accounts for the enhanced ShB resistance of CSP41b-OE. Our findings nominate the OsCSP41b gene as a promising molecular target for developing a rice variety with stronger resistance to both R. solani and multi-abiotic stresses. Full article

This study assessed the host plant selection behavior of female stalk-eyed flies (SEFs) or Diopsis apicalis, where a Y-tube olfactometer was used to compare SEF attraction to the odor of leaves from four rice varieties (ITA306, WAB56-104, CG14, and RAM55). Another step of the evaluation consisted of pairing leaf odors from two rice varieties. Also, potted plants of the tested varieties were displayed in a screened cage and submitted to female SEF selection. The results indicated that the odor produced by leaves from rice varieties CG14, WAB56-104, and ITA306 significantly attracted SEFs, at rates of 81%, 70%, and 97%, respectively, while SEF females were rarely attracted by the odor of leaves from the resistant rice variety RAM55, at a rate of 35%. The results suggested that the use of a Y-tube olfactometer was similar to the use of a screened cage. The resistance exhibited by rice variety CG14 against SEFs is related to an antibiosis interaction acting as bait, while that in RAM55 is an antixenosis one. Farmers can plant the traditional CG14 variety on the edge of rice fields to draw SEFs and poison their larvae. However, RAM55 can be inserted in an intercropping system to repel SEFs from laying eggs. The authors recommend CG14 and RAM55 as candidates for breeding to create resistant lines against SEF. Full article

Straw returning inhibits tillering at the early stage of rice growth and thus affects grain yield. Sulfur-coated urea (SCU) has been expected to increase nitrogen use efficiency (NUE) and yield, save labor input, and reduce environmental pollution in crop production. Nevertheless, the sulfur coatings of SCU are easy to break and then shorten the nutrient release cycle. Whether there was a complementary effect between straw returning and SCU in NUE and grain yield had remained elusive. To investigate the effects of straw returning combined with the application of SCU on NUE and rice yield, a two-year field experiment was conducted from 2022 to 2023 with three treatments (straw returning combined with conventional urea (SRU), no straw returning combined with SCU (NRS), straw returning combined with SCU (SRS)). We found that straw returning combined with the application of SCU increased rice yield and NUE significantly. Compared with SRU and NRS, SRS treatments significantly increased grain yield by 14.61–16.22%, and 4.14–7.35%, respectively. Higher effective panicle numbers per m² and grain numbers per panicle were recorded in NRS and SRS treatments than SRU. SRS treatment increased nitrogen recovery efficiency by 79.53% and 22.97%, nitrogen agronomic efficiency by 18.68% and 17.37%, and nitrogen partial factor productivity by 10.51% and 9.81% compared with SRU and NRS treatment, respectively. The enhanced NUE in SRS was driven by higher leaf area index, SPAD value, net photosynthetic rate, carbon metabolic enzyme (RuBP and SPS) activity, nitrogen metabolic enzyme (NR, GS, and GOGAT) activity, sucrose and nitrogen content in leaves, and nitrogen accumulation in plant during grain filling. Moreover, the improved yield in SRS was closely related to superior NUE. In conclusion, straw returning combined with application of SCU boosted grain yield and NUE via enhanced carbon–nitrogen metabolism during the late growth period in rice. Full article

Arsenic (As) and cadmium (Cd) in rice grains are major global food safety concerns. Iron (Fe) can help reduce both, but current Fe treatments suffer from poor stability, low leaf absorption, and fast soil immobilization, with unclear underlying mechanisms. To address these issues, an Fe-based metal–organic framework (MIL-88) was modified with sodium alginate (SA) to form MIL-88@SA. Its stability as a foliar inhibitor and its leaf absorption were tested, and its effects on As and Cd accumulation in rice were compared with those of soluble Fe (FeCl₃) and chelating Fe (HA + FeCl₃) in a field study on As–Cd co-contaminated rice paddies. Compared with the control, MIL-88@SA outperformed or matched the other Fe treatments. A single foliar spray during the tillering stage increased the rice yield by 19% and reduced the inorganic As and Cd content in the grains by 22.8% and 67.8%, respectively, while the other Fe treatments required two sprays. Its superior performance was attributed to better leaf affinity and thermal stability. Laser ablation inductively coupled plasma–mass spectrometry (LA–ICP–MS) and confocal laser scanning microscopy (CLSM) analyses revealed that Fe improved photosynthesis and alleviated As–Cd stress in leaves, MIL-88@SA promoted As and Cd redistribution, and Fe–Cd co-accumulation in leaf veins enhanced Cd retention in leaves. Full article

The plant cuticle, a protective barrier against external stresses, and abscisic acid (ABA), a key phytohormone, are crucial for plant growth and stress responses. Heterologous expression of AtNCED3 in plants has been widely studied. In this research, by comparing the japonica rice cultivar Zhonghua 10 and its AtNCED3 over-expressing lines during the vegetative growth stage through multiple methods, we found that AtNCED3 over-expression increased leaf ABA content, enhanced epidermal wax and cutin accumulation, modified wax crystal density, and thickened the cuticle. These changes reduced leaf epidermal permeability and the transpiration rate, thus enhancing drought tolerance. This study helps understand the role of endogenous ABA in rice cuticle synthesis and its mechanism in plant drought tolerance, offering potential for genetic improvement of drought resistance in crops. Full article

Rice is a staple food for over half of the world’s population, and it is grown in over 100 countries. Rice blast disease can cause 10% to 30% crop loss, enough to feed 60 million people. Breeding for resistance can help farmers avoid costly fungicides. This study assessed the relationship between rice blast disease and zinc or anthocyanin content in biofortified rice. Susceptibility to foliar and panicle blast was assessed in a rice panel which differed on grain zinc content and pigmentation. A rice panel (n = 23) was challenged with inoculum of two isolates of Magnaporthe oryzae in a screenhouse-based assay. The zinc content with foliar blast severity was analyzed in the leaves and grain of a subset of non-inoculated rice plants. The effect of foliar zinc supplementation on seedlings was assessed by varying levels of zinc fertilizer solution on four blast susceptible cultivars at 14 days after planting (DAP), followed by inoculation with the blast pathogen at 21 DAP. Foliar blast severity was scored on a 0–9 scale at 7 days after inoculation. The rice panel was scored for anthocyanin content, and the data were correlated with foliar blast severity. The panel was grown in the field, and panicle blast, grain yield and yield-related agronomic traits were measured. Significant differences were observed in foliar blast severity among the rice genotypes, with IRBLK-KA and IR96248-16-2-3-3-B having mean scores greater than 4, as well as BASMATI 370 (a popular aromatic variety), while the rest of the genotypes were resistant. Supplementation with foliar zinc led to a significant decrease in susceptibility. A positive correlation was observed between foliar and panicle blast. The Zn in the leaves was negatively correlated with foliar blast severity, and had a marginally positive correlation with panicle blast. There was no relationship between foliar blast severity and anthocyanin content. Grain yield had a negative correlation with panicle blast, but no correlation was observed between Zn in the grain and grain yield. This study shows that Zn biofortification in the grain may not enhance resistance to foliar and panicle blast. Furthermore, the zinc-biofortified genotypes were not agronomically superior to the contemporary rice varieties. There is a need to apply genomic selection to combine promising alleles into adapted rice genetic backgrounds. Full article

Rice production faces new challenges from emerging diseases due to intensive cultivation practices and climate warming in China. A new rice leaf bacterial disease has recently occurred in Northeast China. The symptoms of the disease are similar to those of bacterial leaf blight. Disease lesions spread along leaf edges and are later dried up due to water loss. In this study, 17 bacterial isolates were identified as the causal agents of the new disease following Koch’s postulates. These strains are categorized into two groups based on colony morphology and molecular characterization. Phylogenetic analysis using the five housekeeping genes leuS, gyrB, fusA, pyrG, and rplB reveals that the two groups of the isolates belong to Pantoea ananatis and P. eucalypti, respectively. The new rice disease is caused by P. ananatis, P. eucalypti, or a combination of both bacterial species. A complete genome map has also been assembled for P. eucalypti. Meanwhile, some important virulence factors have been predicted based on gene annotation and determination of extracellular enzymes. Collectively, this study represents the first report of a new rice leaf disease caused by P. eucalypti and the first high-quality genome assembly of P. eucalypti that infects rice leaves. Full article

Crop chlorophyll contents affect growth, and accurate assessment aids field management. SPAD (Soil Plant Analysis Development) values of leaves were mainly used to estimate chlorophyll content. Background interference affects the accuracy of SPAD value inversion. To address this issue, a rice leaf SPAD inversion method combining deep learning and feature selection is proposed. First, a leaf segmentation model based on U-Net was established. Then, the color features of leaf images were extracted. Seven color features highly correlated with SPAD were selected via the Pearson correlation coefficient and recursive feature elimination optimization. Finally, leaf SPAD inversion models based on random forest, support vector regression, BPNNs, and XGBoost were established. The results demonstrated that the U-Net could achieve accurate segmentation of leaves with a maximum mean intersection over union (MIoU) of 88.23. The coefficients of determination R² between the anticipated and observed SPAD values of the four models were 0.819, 0.829, 0.896, and 0.721, and the root mean square errors (RMSEs) were 2.223, 2.131, 1.564, and 2.906. Through comparison, the method can accurately predict SPAD in different low-definition and saturation images, showing a certain robustness. It can offer technical support for accurate, nondestructive, and expedited evaluation of crop leaves’ chlorophyll content via machine vision. Full article

Cadmium (Cd) pollution in rice and selenium (Se) deficiency in humans have attracted widespread attention. In this study, we investigated the effects of the combined application of biological nanoselenium (B-SeNPs) foliar spray and biochar (BC) on Se enrichment and Cd content reduction in rice. A pot experiment was established by designing four levels each of BC and B-SeNPs to be applied to rice plants. The results revealed that soil Cd bioavailability decreased by 3.26–16.67%, while soil Se bioavailability increased by 0.76–7.63% in the combined BC and B-SeNPs treatments, with rice photosynthesis showing significant enhancement during each growth period. Both BC and B-SeNPs treatments significantly enhanced the levels of antioxidant components (glutathione, phytochelatins, catalase, peroxidase, and superoxide dismutase) while reducing oxidative stress markers (malondialdehyde and superoxide anion radical) in rice leaves. Additionally, these treatments effectively modulated the subcellular distribution of Se and Cd, demonstrating their potential in alleviating Cd toxicity and enhancing Se homeostasis. These changes were accompanied by a marked reduction in lipid peroxidation (indicated by malondialdehyde) and superoxide radical accumulation, suggesting that BC and B-SeNPs treatments strengthened the antioxidative defense system in rice leaves. Additionally, compared with the BC0Se0 treatment, the combined application of BC and B-SeNPs significantly enhanced grain Se content by 7.14–221.43% while significantly reducing Cd content by 30.77–76.92%. The efficacy of grain Se enrichment and Cd reduction followed the sequence B-SeNPs + BC > Se only > BC only, where the BC5Se20 treatment demonstrated the most pronounced effects on both Se accumulation and Cd decrease in grains. Therefore, the combined application of foliar-applied B-SeNPs and biochar not only reduces Cd bioavailability in soil but also effectively suppresses Cd uptake by rice while simultaneously enhancing Se enrichment. Full article

Organic fertilizer replacing a portion of chemical fertilizers is a key strategy for improving grain qualities and economic benefits. Fragrant rice, favored by consumers for its superior quality and rich aroma, has garnered significant attention. However, there is little information on the effect of organic fertilizer replacing a portion of chemical fertilizers on the grain yield and 2-AP of fragrant rice. Taking Meixiangzhan2 and Qingxiangyou19 as experimental materials, five different experimental treatments were designed: all urea (T1), 33.3% organic fertilizer substitution for urea (T2), 66.7% organic fertilizer substitution for urea (T3), all organic fertilizer (T4), and no fertilizer as a control (CK). The results showed that the T2 treatment could significantly increase the grain yield of Meixiangzhan2 to 62.50 g·pot⁻¹ and Qingxiangyou19 to 67.88 g·pot⁻¹ due to the increase of 27.90% and 26.03% over T1, and 72.18% and 59.45% over CK, respectively. Compared with T1, the T2 treatment could markedly enhance the 2-AP content in Meixiangzhan2 (418.01 μg kg⁻¹, up by 7.70%) and Qingxiangyou19 (378.53 μg kg⁻¹, up by 9.12%). Relative to CK, the aroma content of these two varieties under the T2 treatment rose by 22.05% and 31.04%, respectively. The main reasons were due to the increase in pyrroline-5-carboxylic acid, 1-pyrroline, proline dehydrogenase, and pyrroline-5-carboxylate synthase. The dry matter accumulation, leaf area, and photosynthetic rate of Meixiangzhan2 and Qingxiangyou19 were also significantly increased, and the activities of nitrate reductase and glutamine synthetase were also significantly improved. Moreover, the activities of peroxidase and catalase in rice sword leaves were remarkably improved, and the content of malondialdehyde was significantly decreased. The results showed that 33.3% of organic fertilizer instead of chemical fertilizer had the positive effect of increasing the grain yield and improving the aroma of rice, which was worth further popularization and application. Full article

Cadmium (Cd) contamination in paddy soils severely threatens rice safety and human health. Currently, the high costs and technical barriers of existing Cd remediation methods limit their development, so it’s urgent to find an economical and feasible method. Herein, the synergistic effects of rhodochrosite slag and biochar on Cd immobilization in slightly acidic Cd-contaminated paddy soils have been investigated. A field experiment with four treatments—control (CK), rhodochrosite slag (R), biochar (B), and combined rhodochrosite slag + biochar (RB)—was conducted in Hunan Province, China. Results demonstrated that RB treatment significantly increased soil pH, transferred the mobile Cd to the residual fraction, and reduced Cd availability in the soil. Cd concentrations in rice roots, stems, leaves, and brown rice decreased by 26.37%, 47.20%, 31.03%, and 51.85%, respectively, under RB treatment, achieving the lowest TF and BCF values. Furthermore, RB treatment increased rice yield by 18.73%. The synergistic interaction between biochar’s adsorption capacity and rhodochrosite slag-derived competitive ions effectively transformed Cd into stable fractions, reducing bioavailability. This study proposes a novel remediation strategy that not only enhances the Cd immobilization ability of biochar but also achieves simultaneous waste valorization and soil remediation. Full article

Rice blast disease is a major threat to rice yields. Sustainable control relies on resistant varieties, where plant immunity is triggered by pattern recognition receptors like receptor-like proteins (RLPs). The rice RLP chitin-elicitor binding protin (CEBiP) recognizes fungal chitin and confers blast resistance to pathogen Magnaporthe oryzae. However, understanding of the broader signaling and metabolomic pathways associated with CEBiP activation remains limited. Here, we performed an integrated transcriptomic and metabolomic analysis of the rice Zhonghua 11 genotype and CEBiP knockout plants. Both plants were infected with M. oryzae, and infected leaves were harvested at 24, 48, and 72 hpi for RNA sequencing and Liquid Chromatography-Tandem Mass Spectrometry analysis. Transcriptomics identified a total of 655 genes that were differentially regulated upon knockout of CEBiP; they were mainly related to diterpenoid/phenylpropanoid biosynthesis, nitrogen metabolism, the mitogen-activated protein kinasesignaling pathway, plant–pathogen interaction, and plant hormone signal transduction. The presence of a large number of pathogenesis-related protein 1 family genes indicates the key role of salicylic acid (SA) in CEBiP immunity. Metabolomics detected a total of 962 differentially accumulated metabolites and highlights the roles of caffeine and glutathione metabolism in CEBiP-mediated immunity. Since caffeine and glutathione metabolism can regulate SA signaling, we propose that SA signaling plays a central role in the CEBiP immune function. Full article

Bacterial leaf blight (BLB) is a destructive disease caused by Xanthomonas oryzae pv. oryzae (Xoo). It has been proven that BLB adversely influences the growth and production of rice, resulting in substantial losses in yield. Nanoparticle–antimicrobial compounds possess excellent physicochemical properties, which have generated groundbreaking applications in protecting rice against BLB attacks. However, there is less research focused on the interaction between nanoparticles and the microbiome of BLB rice leaves, particularly the structure and function of endophytic bacteria, which are essential to plant health and pathogenesis. Therefore, the study explored how Cu-Ag nanoparticles influenced the endophytic bacteria’s composition and functions in healthy and BLB rice leaves. The data demonstrated that the relative abundance of beneficial bacteria, Burkholderiales, Micrococcales, and Rhizobiales, increased after the introduction of Cu-Ag nanoparticles on the leaves of BLB rice. The examination of PAL activity demonstrated that nanoparticles limited the spread of Xoo in rice leaves. Furthermore, endophytic community functional prediction demonstrated that nanoparticles may regulate the physiological process associated with potential stress resistance and growth-promoting function in the endophytic communities. This investigation may enhance the understanding of interactions between nanoparticles and the composition of rice endophytic microbiome, which can contribute to the exploration and application of nanomaterials in crop pathogen management. Full article