Improve Rice Growth Research Articles

Studies on the Efficacy of AGMA-Foliar (Kazuki Gold/Yoshi Gold) for Growth Development and Yield of Paddy (Oryza sativa)

Rice (Oryza sativa L.) is a principal staple food, with significant production worldwide. In 2021, rice covered 161.77 million hectares globally, with India as the second-largest producer. For sustained output, rice (Oryza sativa L.), a major crop around the world, needs balanced fertilization. Overuse of fertilizers degrades the soil, requiring the use of bio stimulants as an alternative. This study evaluates AGMA Foliar (Kazuki Gold/Yoshi Gold) and AGMA Energy on rice cultivar IET 4786 (Satabdi) during the kharif season of 2021-22 at C-block farm, Bidhan Chandra Krishi Vishwavidyalaya, Kalyani, Nadia, and West Bengal. A randomized block design with seven treatments and three replications was used. Treatments included AGMA Kazuki Gold and Kazuki Energy applied at various stages. AGMA treatments significantly enhanced plant height, dry matter, grain count, and yield. Results indicated that T3 treatment (Kazuki Gold applied twice at 25-30 and 40-45 DAT) achieved the highest plant height (93.00 cm), dry matter (983.66 g m-²), grain count (180.05 grains panicle-1), and grain yield (5.26 t ha-1), with statistical significance confirmed by F-tests at 5% level. T6 treatment (AGMA Foliar (Kazuki Energy) showed comparable results. Chlorophyll content was also highest in T3. Control plots consistently showed the lowest values. The study emphasizes the effectiveness of AGMA Foliar bio stimulant applications, which significantly improve rice growth, yield, and nutrient efficiency. It highlights their potential as sustainable agricultural inputs and suggests optimal application stages for maximizing benefits.

Bacterial endophyte Pseudomonas mosselii PR5 improves growth, nutrient accumulation, and yield of rice (Oryza sativa L.) through various application methods

BackgroundPseudomonas spp. have drawn considerable attention due to their rhizospheric abundance and exceptional plant growth-promoting attributes. However, more research is needed on the optimal application methods of Pseudomonas mosselii for rice growth, nutrient accumulation, and yield improvement. This research explored the application of the endophytic bacterium P. mosselii PR5 on rice cultivar BRRI dhan29 with four treatments: control, seedling priming, root drenching, and bacterial cell-free culture (CFC) foliar application.ResultsPR5 led to better rice growth, improved nutrient acquisition, and higher yields compared to the control, regardless of the application method used. The highest results in fresh weight of root (146.93 g/pot), shoot (758.98 g/pot), and flag leaf (7.88 g/pot), dry weight of root (42.16 g/pot), shoot (97.32 g/pot), and flag leaf (2.69 g/pot), and grains/panicle (224.67), were obtained from seedling priming treatment, whereas root drenching resulted in maximum plant height (105.67 cm), root length (49.0 cm), tillers/pot (23.7), and panicles/pot (17.67). In all three application methods, rice grain yield per pot was higher in PR5 inoculated treatments, compared to the control. The amount of P, Mg and Zn in the shoot and N, P, Ca, Mg and Si content in the flag leaf was significantly increased along with effective suppression of naturally occurring blast disease in bacterial CFC foliar application, validated by multivariate analysis.ConclusionOur results indicated that rice seedlings priming with PR5 improved rice growth, yield and nutrient uptake, whereas CFC foliar application significantly increased the concentration of most nutrients in the rice plant and suppressed the naturally occurring rice blast disease. This research highlights the significant potential of P. mosselii PR5 in enhancing rice growth, yield, and nutrient uptake, particularly through seedling priming and CFC foliar application methods.

Integrating Biofertilizers with Organic Fertilizers Enhances Photosynthetic Efficiency and Upregulates Chlorophyll-Related Gene Expression in Rice

Biofertilizers offer a sustainable method for improving rice growth and productivity, yet their effects on the interaction between plant growth, photosynthetic activity, and gene expression remain under-researched. This study examines how biofertilizer influences rice physiology, focusing on photosynthetic regulation and expression of chlorophyll-related genes. Eight fertilizer treatments were applied: control (CNT), biofertilizer (BF), deactivated biofertilizer (DABF), rice straw (RS), rice straw with biofertilizer (RS+BF), organic fertilizer (OF), organic fertilizer with biofertilizer (OF+BF), and inorganic fertilizer (IOF). Plant height, tiller number, SPAD, NDVI, chlorophyll content, and photosynthesis rates were measured, while gene expression analysis was conducted using RT-qPCR. The OF+BF treatment produced the most significant results, leading to a 31% increase in plant height, a 135% increase in tiller number, and a 42% increase in chlorophyll content (SPAD values) compared to the control. Additionally, OF+BF enhanced photosynthetic efficiency by 74%, with the highest net photosynthetic rate of 48.23 μmol CO2 m−2 s−1. Gene expression analysis revealed that OF+BF upregulated key photosynthesis-related genes, such as OsChlD and OsCHLM, showing a 70% and 90% increase in expression. These findings highlight the potential of integrating biofertilizers with organic fertilizers to sustainably boost rice growth and productivity, contributing to global food security and climate change mitigation.

Straw Incorporation with Exogenous Degrading Bacteria (ZJW-6): An Integrated Greener Approach to Enhance Straw Degradation and Improve Rice Growth.

Rice straw is an agricultural waste, the disposal of which through open burning is an emerging challenge for ecology. Green manufacturing using straw returning provides a more avant-garde technique that is not only an effective management measure to improve soil fertility in agricultural ecosystems but also nurtures environmental stewardship by reducing waste and the carbon footprint. However, fresh straw that is returned to the field cannot be quickly decomposed, and screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. This study aimed to reveal the potential mechanism of influence exerted by exogenous degradative bacteria (ZJW-6) on the degradation of straw, growth of plants, and soil bacterial community during the process of returning rice straw to the soil. The inoculation with ZJW-6 enhanced the driving force of cellulose degradation. The acceleration of the rate of decomposition of straw releases nutrients that are easily absorbed by rice (Oryza sativa L.), providing favorable conditions for its growth and promoting its growth and development; prolongs the photosynthetic functioning period of leaves; and lays the material foundation for high yields of rice. ZJW-6 not only directly participates in cellulose degradation as degrading bacteria but also induces positive interactions between bacteria and fungi and enriches the microbial taxa that were related to straw degradation, enhancing the rate of rice straw degradation. Taken together, ZJW-6 has important biological potential and should be further studied, which will provide new insights and strategies for the appropriate treatment of rice straw. In the future, this degrading bacteria may provide a better opportunity to manage straw in an ecofriendly manner.

Formulation of soil ameliorant material based on humic and silica to reduce Fe concentration in acid sulfate soils and improve rice growth

Abstract Applying soil ameliorants can suppress the Iron (Fe) toxicity of paddy cultivation in acid-sulfate soils. Humic materials can interact with Fe and Al metal ions to form chelates so that their solubility decreases. Silica plays a role in reducing the uptake of Fe and Al, reducing the Fe content on the surface of rice roots by increasing the oxidizing strength of rice roots. The research aim was to study the effect of ameliorant material formulation based on humate and silica on decreasing the Fe content in acid sulfate soils and increasing the growth of rice plants. The research was conducted in the Greenhouse, Swampland Agricultural Research Institute, Banjarbaru, from March to October 2022. The experimental design was randomized complete block factorial with the following treatments: Factor 1. Formula of soil ameliorant (F0 = 100% agricultural lime, F1 = 30% humate manufacturer+30% rice husk ash+40% agricultural lime, F2=30% water hyacinth humate+30% rice husk ash+40% agricultural lime, F3=30% water hyacinth humate+30% rice husk biochar + 40% agricultural lime, F4 = 30% humate manufacturer+30% rice husk biochar+40% agricultural lime), Factor 2. Dosage of soil ameliorant (D1 = 1 t/ha, D2 = 2 t/ha, D3 = 4 t/ha). Parameters observed were soil Fe content, available P and soil pH, plant height, and number of rice tillers every two weeks. The results showed that the formula F3, namely 30% water hyacinth humic acid + 30% rice husk biochar + 40% agricultural lime, was capable of decreasing soil Fe levels from 540ppm (F0) to 422 ppm and increasing soil pH from 4.23 (F0) to 4.48 and availability of P from 27 ppm (F0) to 55.20 ppm in acid sulfate soils. In addition, the formula can also increase the growth of rice plants. Improvements in soil chemical properties and plant growth are expected to increase the productivity of Inpara 8 rice plants in acid-sulfate soils.

Plant growth-promoting rhizobacteria and biocontrol agents triggered plant defence responses against phytopathogenic fungi and improved rice growth

This study examined the antifungal activity and plant growth-promoting (PGP) traits of 30 beneficial bacterial strains isolated from Brassica campestris (L.) rhizosphere in rice. Among these, the PRB-8 strain exhibited potent antifungal activity against rice pathogens and produced a robust biofilm and a variety of PGP compounds. Based on our results, the PRB-8 showed distinct antifungal activity against fungal pathogens such as Rhizoctonia solani (75 %) > Alternaria alternata (74.5 %) > Sclerotium rolfsii (70 %) > Macrophomina phaselina (68 %) > Fusarium oxysporum (67 %). The isolate PRB-8 also increased the germination efficiency and length of rice seedlings under in-vitro conditions. The isolate PRB-8 was identified as Klebsiella pneumoniae (accession no. MT672588) and the absence of a hydrolysis zone on sheep blood agar plate suggests that PRB-8 is non-pathogenic. Inoculation of PRB-8 to R. solani and F. oxysporum-infected rice seedlings promotes length, dry biomass, and photosynthetic pigments and decreases the disease index in rice. Furthermore, PRB-8 potentially enhanced the defense responses in rice by increasing phenylalanine ammonia-lyase (PAL), β-1,3 glucanase, polyphenol oxidase (PPO), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), which play a significant role in protecting plants from phytopathogens. Thus, it can be concluded that the use of the PRB-8 strain enhances rice growth and resistance to phytopathogens while simultaneously offering agroecosystems and environmentally friendly choices. Shortly, natural antagonistic PGPR may be used as biocontrol agents to sustainably enhance biotic stress tolerance and global food production.

Effectiveness of nanomaterials and their counterparts in improving rice growth and yield under arsenic contamination.

Arsenic (As) pollution in rice (Oryza sativa L.), a staple food for over 3.5 billion people, is a global problem. Mixed effects of Zn, Cu, and Si amendments on plant growth and yield, including in the presence of As pollution have been reported in previous studies. To better investigate the effectiveness of these amendments on rice growth, yield, and As accumulation, we conducted a rice greenhouse experiment with 11 treatments, including control pots with and without As contamination and pots with amendments of ZnO, CuO, and SiO2 nanoparticles (ZnO NPs, CuO NPs, and SiO2 NPs), their ionic counterparts (ZnSO4, CuSO4, and Na2SiO3), and bulk particles (ZnO BPs, CuO BPs, and SiO2 BPs). Compared with the background soil, the treatment of adding As decreased rice plant height, panicle number, and grain yield by 16.5%, 50%, and 85.7%, respectively, but significantly increased the As accumulation in milled rice grains by 3.2 times. Under As contamination, the application of Zn amendments increased rice grain yield by 4.6-7.3 times; among the three Zn amendments, ZnSO4 performed best by fully recovering grain yield to the background level and significantly reducing grain AsIII/total As ratio by 46.9%. Under As contamination, the application of Cu amendments increased grain yield by 3.8-5.6 times; all three Cu amendments significantly reduced grain AsIII/total As ratio by 20.2-65.6%. The results reveal that Zn and Cu amendments could promote rice yield and prevent As accumulation in rice grains under As contamination. Despite the observed reduction in As toxicity by the tested NPs, they do not offer more advantages over their ionic counterparts and bulk particles in promoting rice growth under As contamination. Future field research using a broader range of rice varieties, investigating various As concentrations, and encompassing diverse climate conditions will be necessary to validate our findings in achieving more extensive understanding of effective management of arsenic contaminated rice field.

Earthworms enhance the performance of organic amendments in improving rice growth and nutrition in poor ferralsols

In the Highlands of Madagascar, providing organic amendments (OAs) is the main farmer fertilization practice in upland rainfed agrosystems dominated by nutrient-depleted Ferralsols. Therefore, enhancing the performance of OAs on plant functions is particularly important for improving both plant productivity and agrosystem sustainability. Earthworms are well-known ecosystem engineers involved in the decomposition of organic matter and play a critical role in nutrient turnover. Inoculating earthworms could be a promising approach to improve the fertilizer performance of OAs. However, there is limited knowledge regarding the interaction between earthworms and OAs of varying biochemical qualities on plant growth and nutrition. In this microcosm experiment, we assessed the effect of different types of OAs (i.e., unamended control, conventional farmyard manure, kraal manure, improved farmyard manure, compost, vermicompost, urban waste, taroka, poultry droppings, pig manure) and earthworm inoculation (with and without earthworms) on the growth and nutrition of rice. The endogeic species Pontoscolex corethrurus (Rhinodrilidae) was used in the experiment. After eight weeks of growth, the poultry droppings had the best fertilizer performance, followed by improved farmyard manure and pig manure in treatments without earthworms. The main driver of fertilizer performance appeared to be the quality of OAs. However, other mechanisms, such as an increase in soil pH, may also play a significant role. The inoculation of earthworms significantly enhanced the fertilizer performance of OAs but the magnitude of this enhancement depends on the OAs. Overall, OAs with low fertilizer performance showed a more pronounced response to earthworms. Additionally, earthworms improved the performance of high-quality OAs likely by enhancing the availability of P and Mg. Our findings emphasize the synergistic effects of earthworms and OAs of various qualities on plant growth and nutrition, offering valuable insights for improving fertilization practices in nutrient-poor Ferralsols of Madagascar.

Isolation, and selection of indigenous potassium solubilizing bacteria from Vietnam Mekong Delta rhizospheric soils and their effects on diverse cropping systems

Potassium (K) is an essential nutrient for plant growth, biosynthesis, and metabolism. It enhances plant tolerance to salinity and acidity by triggering various defense mechanisms. These characteristics are particularly important to agricultural production in the Vietnam Mekong River Delta, experiencing increased saltwater intrusion, precipitation extremes and unpredictable drought. This study isolated and selected indigenous potassium-solubilizing bacteria (PSB) from Vietnam Mekong Delta rhizospheric soils collected from three different ecological systems producing rice, maize, kumquat, and green onion. Experiments were conducted to evaluate the effect of indigenous PSB on rice seedlings and future potential as biostimulants for commercial field application. To isolate PSB, solid Aleksandrov medium supplemented with 0.2% muscovite was used. The soluble K was quantified using the atomic absorption method at a wavelength of 766.5 nm. Among 24 isolates, Burkholderia vietnamiensis L1.1 and Staphylococcus hominis T7.3 exhibited the highest K solubilization, releasing 567 μg L−1 and 488 μg L−1 liquid medium, respectively. The study explored the optimal conditions for K release, revealing that a temperature of 35 °C, a pH 5, and NaCl concentration up to 1 % in a medium favored K solubilization. B. vietnamiensis L1.1 significantly enhanced rice seed germination (95.3 %) compared to the control treatment without PSB (82 %). Furthermore, the combined application of B. vietnamiensis L1.1 and S. hominis T7.3 notably improved rice growth under K deficient conditions. This research suggests that these indigenous PSB can effectively increase plant available K and improve the productivity of rice and other crops grown under saline and acidic stresses.

Genome-wide identification and expression analysis of EIN3/EIL gene family in rice (Oryza sativa)

The nuclear-localized ethylene-insensitive3/ethylene-insensitive3-like (EIN3/EIL) proteins regulate the ethylene signaling pathway for growth and stress responses. This study presents a genome-wide analysis of nine Oryza sativa EIN3/EIL genes, exhibiting three clads in an ML phylogenetic tree. These proteins are conserved in both exon-intron organization and motif architecture aligned with their phylogenetic clustering. The EIN3/EIL proteins harbor the EIN3, EIN3 superfamily, and RDV-p3 conserved domains. OsEIN3/EIL expression profiling revealed consistently high transcript levels of LOC_Os03g20790 and LOC_Os02g36510 in leaf blades across vegetative and reproductive stages and in the endosperm, indicating a potential role in growth and yield enhancement. Additionally, LOC_Os03g20790, LOC_Os02g36510, LOC_Os07g48630, and LOC_Os09g31400 are highly expressed at later stages of root development, showing potential in nutrient signaling for seed-filling. Moreover, elevated expression of LOC_Os04g38400, LOC_Os09g31400, LOC_Os03g20790,LOC_Os08g39830, and LOC_Os07g48630 were detected under mannitol treatment, while LOC_Os04g38400 and LOC_Os08g39830 were highly upregulated in root and leaf tissues under drought stress exposure. The EIN3/EIL genes also intricately interacted with MPK1, MPK5, and MYC genes, underscoring their potential involvement in growth and stress tolerance. Altogether, our findings lay a foundation for improved rice growth and yield enhancement.

The role of an Sb-oxidizing bacterium in modulating antimony speciation and iron plaque formation to reduce the accumulation and toxicity of Sb in rice (Oryza sativa L.)

Microbial antimony (Sb) oxidation in the root rhizosphere and the formation of iron plaque (IP) on the root surface are considered as two separate strategies to mitigate Sb(III) phytotoxicity. Here, the effect of an Sb-oxidizing bacterium Bacillus sp. S3 on IP characteristics of rice exposed to Sb(III) and its alleviating effects on plant growth were investigated. The results revealed that Fe(II) supply promoted IP formation under Sb(III) stress. However, the formed IP facilitated rather than hindered the uptake of Sb by rice roots. In contrast, the combined application of Fe(II) and Bacillus sp. S3 effectively alleviated Sb(III) toxicity in rice, resulting in improved rice growth and photosynthesis, reduced oxidative stress levels, enhanced antioxidant systems, and restricted Sb uptake and translocation. Despite the ability of Bacillus sp. S3 to oxidize Fe(II), bacterial inoculation inhibited the formation of IP, resulting in a reduction in Sb absorption on IP and uptake into the roots. Additionally, the bacterial inoculum enhanced the transformation of Sb(III) to less toxic Sb(V) in the culture solution, further influencing the adsorption of Sb onto IP. These findings highlight the potential of combining microbial Sb oxidation and IP as an effective strategy for minimizing Sb toxicity in sustainable rice production systems.

Effects of Straw Returning and New Fertilizer Substitution on Rice Growth, Yield, and Soil Properties in the Chaohu Lake Region of China

Recently, replacing chemical fertilizers with straw returning and new fertilizers has received considerable attention in the agricultural sector, as it is believed to increase rice yield and improve soil properties. However, less is known about rice growth and soil properties in paddy fields with the addition of different fertilizers. Thus, in this paper, we investigated the effects of different fertilizer treatments, including no fertilization (CK), optimized fertilization based on the medium yield recommended fertilizer amount (OF), 4.50 Mg ha−1 straw returning with chemical fertilizers (SF), 0.59 Mg ha−1 slow-release fertilizer with chemical fertilizers (SRF), and 0.60 Mg ha−1 water-soluble fertilizer with chemical fertilizers (WSF), on rice growth, yield, and soil properties through a field experiment. The results show that compared with the OF treatment, the new SF, SRF, and WSF treatments increased plant height, main root length, tiller number, leaf area index, chlorophyll content, and aboveground dry weight. The SF, SRF, and WSF treatments improved rice grain yield by 30.65–32.51% and 0.24–1.66% compared to the CK and OF treatments, respectively. The SRF treatment increased nitrogen (N) and phosphorus (P) uptake by 18.78% and 28.68%, the harvest indexes of N and P by 1.75% and 0.59%, and the partial productivity of N and P by 2.64% and 2.63%, respectively, compared with the OF treatment. However, fertilization did not significantly affect the average yield, harvest indexes of N and P, and partial productivity of N and P. The contents of TN, AN, SOM, TP, AP, and AK across all the treatments decreased significantly with increasing soil depth, while soil pH increased with soil depth. The SF treatment could more effectively increase soil pH and NH4+-N content compared to the SRF and WSF treatments, while the SRF treatment could greatly enhance other soil nutrients and enzyme activities compared to the SF and WSF treatments. A correlation analysis showed that rice yield was significantly positively associated with tiller number, leaf area index, chlorophyll, soil NO3−-N, NH4+-N, SOM, TP, AK, and soil enzyme activity. The experimental results indicate that SRF was the best fertilization method to improve rice growth and yield and enhance soil properties, followed by the SF, WSF, and OF treatments. Hence, the results provide useful information for better fertilization management in the Chaohu Lake region of China.

Effects of fulvic acid on rice growth and phosphorus absorption

Fulvic acid (FA) is a complex substance with multiple functional groups produced by organic waste composition. It can promote plant growth and affect phosphorus (P) fertilizer. However, the mechanism of its action and the optimal application rate of FA have remained unclear. This study set different concentrations of FA to explore the effect on rice growth and P. These results indicated exogenous addition FA can significantly increase plant height, chlorophyll concentration and biomass, and the P content, P uptake and distribution in different rice plant parts. Moreover, FA treatments improved root morphogenesis and the expression of transcript-level P transporter genes (OsPHT1s). Different concentrations of FA treatments had different effects on rice, especially T1 (40 mg/L) treatment had the best. In conclusion, basic nutrients and the addition into FA at moderate doses can promote root growth and phosphorus utilization to improve rice growth. Therefore, FA can be used as an effective component of a new type biological phosphorus fertilizer designed for sustainable agricultural production.

Bacillus altitudinis LZP02 improves rice growth by reshaping the rhizosphere microbiome

Bacillus altitudinis LZP02 improves rice growth by reshaping the rhizosphere microbiome

Comparative Assessment of Gamma-Polyglutamic Acid and Bacillus subtilis cells as Biostimulants to Improve Rice Growth and Soil Quality

Comparative Assessment of Gamma-Polyglutamic Acid and Bacillus subtilis cells as Biostimulants to Improve Rice Growth and Soil Quality

Rhizosphere Bacteria Isolated from Medicinal Plants Improve Rice Growth and Induce Systemic Resistance in Host Against Pathogenic Fungus

Rhizosphere Bacteria Isolated from Medicinal Plants Improve Rice Growth and Induce Systemic Resistance in Host Against Pathogenic Fungus

Bacillus Strains with Catalase Enzyme Improve the Physiology and Growth of Rice (Oryza sativa L.)

Catalase can decompose hydrogen peroxide in plants under controlled and stressed conditions. In a stressed environment, an increase in hydrogen peroxide production makes catalase activity a major defense system for plant growth. The current study was conducted to evaluate the catalase activity of the pre-isolated and identified bacterial strains Bacillus aryabhattai (AN30), Bacillus megaterium (AN24), Bacillus megaterium (AN31) and Bacillus megaterium (AN35) and their potential for rice seedling growth promotion. These strains were characterized for quantitative catalase, urease, siderophore and exopolysaccharide production using LB media. Subsequently, the effectiveness of these strains was checked by quantifying the catalase activity in the rhizosphere, roots and shoots of rice seedlings. The secretion of organic and phenolic compounds produced by the tested strains in liquid culture was also investigated. Plant growth parameters were also studied in a growth room trial. Our results showed that the strain AN24 showed the maximum catalase activity (1.36 mol cm−1), urease activity (1.35 mol cm−1) and exopolysaccharide (4.20 µg mL−1) and siderophore (2.32%) production in LB media. All tested strains showed significantly higher catalase activity in soil compared to the control. Among sole applications, strain AN24 showed better results; however, the consortium application of strains AN24 + AN30 + AN35 + AN31 showed the maximum improvement in dry biomass, shoot and root length, and increase in catalase activity of rice seedlings. The results showed that a consortium of these Bacillus strains with catalase activity has greater potential to enhance the antioxidant defense system and growth promotion of rice seedlings. However, further experimentation under natural conditions is required before using these strains as potential bioinoculants for improving rice growth and yield.

Azospirillum brasilense improves rice growth under salt stress by regulating the expression of key genes involved in salt stress response, abscisic acid signaling, and nutrient transport, among others.

Major food crops, such as rice and maize, display severe yield losses (30-50%) under salt stress. Furthermore, problems associated with soil salinity are anticipated to worsen due to climate change. Therefore, it is necessary to implement sustainable agricultural strategies, such as exploiting beneficial plant-microbe associations, for increased crop yields. Plants can develop associations with beneficial microbes, including arbuscular mycorrhiza and plant growth-promoting bacteria (PGPB). PGPB improve plant growth via multiple mechanisms, including protection against biotic and abiotic stresses. Azospirillum brasilense, one of the most studied PGPB, can mitigate salt stress in different crops. However, little is known about the molecular mechanisms by which A. brasilense mitigates salt stress. This study shows that total and root plant mass is improved in A. brasilense-inoculated rice plants compared to the uninoculated plants grown under high salt concentrations (100 mM and 200 mM NaCl). We observed this growth improvement at seven- and fourteen days post-treatment (dpt). Next, we used transcriptomic approaches and identified differentially expressed genes (DEGs) in rice roots when exposed to three treatments: 1) A. brasilense, 2) salt (200 mM NaCl), and 3) A. brasilense and salt (200 mM NaCl), at seven dpt. We identified 786 DEGs in the A. brasilense-treated plants, 4061 DEGs in the salt-stressed plants, and 1387 DEGs in the salt-stressed A. brasilense-treated plants. In the A. brasilense-treated plants, we identified DEGs involved in defense, hormone, and nutrient transport, among others. In the salt-stressed plants, we identified DEGs involved in abscisic acid and jasmonic acid signaling, antioxidant enzymes, sodium and potassium transport, and calcium signaling, among others. In the salt-stressed A. brasilense-treated plants, we identified some genes involved in salt stress response and tolerance (e.g., abscisic acid and jasmonic acid signaling, antioxidant enzymes, calcium signaling), and sodium and potassium transport differentially expressed, among others. We also identified some A. brasilense-specific plant DEGs, such as nitrate transporters and defense genes. Furthermore, our results suggest genes involved in auxin and ethylene signaling are likely to play an important role during these interactions. Overall, our transcriptomic data indicate that A. brasilense improves rice growth under salt stress by regulating the expression of key genes involved in defense and stress response, abscisic acid and jasmonic acid signaling, and ion and nutrient transport, among others. Our findings will provide essential insights into salt stress mitigation in rice by A. brasilense.

Melatonin activates the OsbZIP79–OsABI5 module that orchestrates nitrogen and ROS homeostasis to alleviate nitrogen-limitation stress in rice

Melatonin (Mel) has previously been reported to effectively alleviate nitrogen-limitation (N-L) stress and thus increase nitrogen-use efficiency (NUE) in several plants, but the underlying mechanism remains obscure. Here, we revealed that OsbZIP79 (BASIC LEUCINE ZIPPER 79) is transcriptionally activated under N-L conditions, and its expression is further enhanced by exogenous Mel. By the combined use of omics, genetics, and biological techniques, we revealed that the OsbZIP79–OsABI5 (ABSCISIC ACID INSENSITIVE 5) module stimulated regulation of reactive oxygen species (ROS) homeostasis and the uptake and metabolism of nitrogen under conditions of indoor nitrogen limitation (1/16 normal level). OsbZIP79 activated the transcription of OsABI5, and OsABI5 then bound to the promoters of target genes, including genes involved in ROS homeostasis and nitrogen metabolism, activating their transcription. This module was also indispensable for upregulation of several other genes involved in abscisic acid catabolism, nitrogen uptake, and assimilation under N-L and Mel treatment, although these genes were not directly transactivated by OsABI5. Field experiments demonstrated that Mel significantly improved rice growth under low nitrogen (L-N, half the normal level) by the same mechanism revealed in the nitrogen-limitation study. Mel application produced a 28.6% yield increase under L-N and thus similar increases in NUE. Also, two OsbZIP79-overexpression lines grown in L-N field plots had significantly higher NUE (+13.7% and +21.2%) than their wild types. Together, our data show that an OsbZIP79–OsABI5 module regulates the rice response to N insufficiency (N limitation or low N), which is important for increasing NUE in rice production.

Unveiling the significance of foliar-applied silicon, selenium and phosphorus for the management and remediation of arsenic in two different rice genotypes

Under paddy soil conditions, rice plants are vulnerable to arsenic (As) accumulation, thus causing potential threat to human health. Here we investigated the influence of foliar-applied phosphorus (P: 10 and 20 mg L−1), silicon (Si: 0.6 and 1.5 g L−1) and selenium (Se: 5 and 10 mg L−1) on As accumulation, morphological and physiological attributes of two contrasting rice genotypes (KSK-133 and Super Basmati) under As stress (25 mg kg−1 as arsenate). Silicon foliar dressing significantly (p < 0.05) reduced grain As uptake (up to 67%) and improved rice growth and chlorophyll content (28–66%) in both rice genotypes over their controls. Phosphorus foliar application resulted in a notable decrease (17%) in grain As uptake of coarse rice genotype (KSK-133), while it slightly increased grain As uptake in the fine one (Super Basmati; 6%) compared to controls. However, foliar-applied Se did not show significant effects on rice plants growth attributes and As uptake in both genotypes. Similarly, biochemical and enzymatic attributes (i.e., lipid peroxidation, electrolyte leakage, peroxidase and catalase) were improved with Si application in rice plants, except for P treatment that was only effective for coarse one. Foliar-applied Si also resulted in reduced cancer risk and hazard quotient (< 0.10) for both rice genotypes. This study advances our understanding on critical role of different foliar-applied nutrients and rice genotypes, which is imperative to develop effective As remediation and management strategies in coarse and fine rice genotypes and protect human health.