Rice Varieties Research Articles

Native Fungi as a Nature-Based Solution to Mitigate Toxic Metal(loid) Accumulation in Rice

Heavy metal contamination in paddy fields poses serious risks to food safety and crop productivity. This study evaluated the potential of native soil fungi as bioinoculants to reduce metal uptake in rice cultivated under contaminated conditions. Eight fungal strains—four indigenous and four allochthonous—were selected based on their plant growth-promoting traits, including siderophore production and phosphate solubilization. Additional metabolic analysis confirmed the production of bioactive secondary metabolites. In a greenhouse experiment, three rice cultivars were grown under permanent flooding (PF) and alternate wetting and drying (AWD) in soil enriched with arsenic, cadmium, chromium, and copper. Inoculation with indigenous fungi under AWD significantly reduced the arsenic accumulation in rice shoots by up to 75%. While AWD increased cadmium uptake across all cultivars, fungal inoculation led to a moderate reduction in cadmium accumulation—ranging from 15% to 25%—in some varieties. These effects were not observed under PF conditions. The results demonstrate the potential of native fungi as a nature-based solution to mitigate heavy metal stress in rice cultivation, supporting both environmental remediation and sustainable agriculture.

Study on the induction of exogenous plant hormones to enhance the weed suppression ability of allelopathic and non-allelopathic rice accessions

Background Increasing the induced-allelopathic potential of rice at the seedling stage by chemical induction is an important strategy in weed management. More in-depth work is needed to find inducing agents for effectively improving the weed-suppressive activity of allelopathic and non-allelopathic rice accessions via the modulation of root morphology and allelochemicals production. Methods Grown in Hoagland’s solution, two rice cultivars—allelopathic PI312777 (PI) and non-allelopathic Lemont (LE)—were treated using various phytohormones to evaluate root growth and allelopathic potential. Optimal phytohormones (ABA and EBL) were selected based on root growth responses. Extraction of rice leaf and root exudates, subsequently assessed on lettuce seedlings, revealed induced allelopathy. WinRHIZO software was used to investigate root morphologies; HPLC and GC-MS evaluated phenolic acids and terpenoids in rice tissues. The transcription of genes related to phenolic acid and terpenoid biosynthesis was measured by qPCR. ANOVA and correlation analysis were applied in data analysis. Results The results showed that the optimal induction conditions were abscisic acid (ABA, three µmol/L) or 24-epibrassinolide (EBL, 0.5 nmol/L) for 3 days. Under these conditions, the induced-allelopathy (IA) values of rice root exudates induced by three µmol/L ABA were 9.62% in PI31277, and 13.76% in Lemont, while the IA values of PI31277 and Lemont after 0.5 nmol/L EBL treatment were 7.83% and 11.51%, respectively. ABA mainly affected the root length and volume at 0–0.2 mm diameter, while EBL mostly affected root length and volume at 0–1.0 mm diameter. The total content of phenolic acids in root-exudates of PI31277 and Lemont induced by EBL were 1.16 and 2.33 times greater, respectively, while ABA induction also increased the phenolic acid content by 1.48 and 1.87 times, respectively. Most genes related to phenolic acid and terpenoid synthesis, such as PAL, C4H, F5H, MK, SQS, and PS, were upregulated after EBL induction, while most genes were downregulated after ABA treatment. Moreover, correlation analysis confirmed that root morphology, allelochemicals production, and related gene expression levels were significantly correlated with induced-allelopathy caused by ABA or EBL treatment.

Efficacy of Chlorantraniliprole 5DT against Yellow Stem Borer (Scirpophaga incertulas Walker) and Leaf Folder (Cnaphalocrocis medinalis Guenee) of Rice

Aim: An experiment was conducted to evaluate the bio-efficacy of Chlorantraniliprole 5DT at various doses compared to other chemicals for management of yellow stem borer and leaf folder in rice Study Design: Randomised Block Design with nine treatments and three replications Place and Duration of Study: Regional Agricultural Research Station, Anakapalle, Andhra Pradesh during 2020 and 2021. Methodology: Thirty days old seedlings of rice variety, RGL 2537 were transplanted with a spacing of 20 ×15 cm2 in a plot of 5×8 m2 and all agronomical practices recommended for the region were followed to raise the crop except for the plant protection measures for pests. Nine treatments(chlorantraniliprole 5DT @ 30 ga.i/ha, Chlorantraniliprole 5DT @ 40 ga.i/ha, Chlorantraniliprole 5DT @ 50 ga.i/ha, Chlorantraniliprole 5DT @ 60 gm a.i/ha, Chlorantraniliprole 5DT @ 70 gm a.i/ha, Chlorantraniliprole 0.4%GR @ 40 ga.i/ha, Fipronil 80%WG @ 50 ga.i/ha, Cartap hydrochloride 4%GR @ 10 ga.i/ha (chemical check) and untreated control) were imposed and the time of application was 15-25 days after transplanting and again after 20-25 days after the first application. Results: The results revealed that the treatment Chlorantraniliprole 5DT @ 70 ga.i. ha-1recorded 79.35 per cent reduction over control followed by Chlorantraniliprole 5DT @ 60 ga.i. ha-1which recorded 78.07 per cent reduction over control with regard to yellow stem borer. Similarly, with regard to leaf folder, Chlorantraniliprole 5DT @ 70 g a.i. ha-1recorded 96.35 per cent reduction over control followed by Chlorantraniliprole 5DT @ 60 ga.i. ha-1which recorded 95.62 per cent reduction over control. Highest yield was recorded in the treatment Chlorantraniliprole 5DT @ 60 ga.i. ha-1 (48.40 qha-1 during 2020and 51.22 qha-1 during 2021) which was followed by Chlorantraniliprole 5DT @ 70 ga.i. ha-1 (46.32 qha-1 during 2020 and 50.40 qha-1 during 2021). Conclusion: Chlorantraniliprole 5DT @ 70 gm a.i. ha-1 and Chlorantraniliprole 5DT @ 60 gm a.i. ha-1 were most effective in management of yellow stem borer and leaf folder in rice also recorded higher yield.

Price Transmission and Market Segmentation in the Philippine Rice: A Correlational Analysis of Regional Yields and Quality-Based Price Spreads

This study conducted a detailed scan of the National Rice Market. It gave a region-by-region analysis, using average yields in palay and the 'money price' paid at harvest for different types of fine rice to determine whether the market was fragmented. This study used a correlation analysis to find the relation between the average yield of palay, the average wholesale price, and the spread in retail-level prices. The outcome is that there was no significant correlation between average wholesale price and average palay yield, indicating production factors may not be the main determinants of the retail price of rice. However, there were significantly positively correlated average wholesale prices and prices spread for premium rice and well-milled, indicating that an effective relationship is maintained between wholesale and retail prices for these types of rice. However, regular milled rice doesn't have a significant relationship. In addition, different types of rice had regional price differences. This revealed possible price inefficiencies, disruptions to the market, and various ways of fixing prices for rice quality in the Philippines. The lash-up of supply and demand relationship dynamics and its governmental intervention resulted in the Rice Pricing pattern in the Philippines. The study's findings can be utilized to address market inefficiencies in the rice market of the Philippines and assist in creating a reform roadmap through the adoption of the recommended policy in this study.

Identification of candidate genes for Nilaparvata lugens (stål) resistance through genomic dissection from diverse Indigenous rice genotypes.

Identification of candidate genes for Nilaparvata lugens (stål) resistance through genomic dissection from diverse Indigenous rice genotypes.

Transfer of deeper rooting and phosphorus uptake QTL into the popular rice variety 'maudamani' via marker-assisted backcross breeding.

Rice suffers from drought stress due to its shallow roots, hindering water uptake from deeper soil layers. Transfer of deeper rooting QTL will modify the root architecture of the plant allowing it to extract moisture from deeper layers of the soil. Furthermore, poor soil conditions, particularly phosphorus deficiency is a common problem in the rainfed rice ecology of India which requires adequate phosphate fertilizer for obtaining higher yield. In this current investigation, two QTL (DRO1 and DRO3) for deeper rooting and one QTL for phosphorus uptake (Pup1) were introgressed into a popular variety, 'Maudamani' through marker-assisted backcross breeding. The target QTL were transferred from a pre-breed genotype, CR3996-19-9-45-1 into the popular variety. Foreground selection was performed using the tightly linked microsatellite markers in the backcross generations progenies to select plants carrying the target QTL. Background selection in each backcross generations was performed using 123 polymorphic SSR markers spread across twelve chromosomes. In each backcross generations, plants carrying all three target QTL and with highest recurrent parent genome recovery percentage was used to backcross with the popular variety, Maudamani. In BC2F2 generation, five plants (CR6508-111-101-129, CR6508-111-101-267, CR6508-111-101-413, CR6508-111-101-537 and CR6508-111-101-713) were selected which were homozygous for all three target QTL. The pyramided lines were evaluated for deeper rooting, low phosphorus stress tolerance and various agro-morphologic including quality traits. Progenies of those five pyramided plants showed similarity with the recipient parent for the 14 agro-morphologic and quality traits in their BC2F3 and BC2F4 generations. The introgressed lines demonstrated significantly improved root traits, including increased number of deeper roots, longer root length and higher shoot and root dry weight, compared to Maudamani under both moisture-deficit and normal conditions. Furthermore, those lines exhibited enhanced phosphorus uptake and grain yield compared to the recipient parent, Maudamani under low phosphorus conditions.

Impact of generational differences on rice farmer’s perception and challenges in Champassak, Laos

Champassak province and particularly its’ rice agriculture, plays a pivotal role in Laos’ economy. However, there is a lack of research on how generational differences impact rice productivity, especially considering farmers’ perceptions and challenges. This study aimed to explore farmer characteristics and perceptions regarding farming practices, post-harvest processes, rice nutrition, and key challenges affecting rice production in Champassak. To do so, we conducted face-to-face interviews with 100 rice farmers in Champassak in 2024 using a structured questionnaire format. Chi-square and regression analyses were employed to identify differences and factors influencing rice farming among Millennial (28–43 years), Gen X (44–59 years), and Boomer II (60–69 years) farmers. Key findings indicate significant generational differences in gender, rice farming experience, and farming practices, with Millennials comprising 45% and Gen X/Boomer II 55% of the sample. Post-harvest management preferences varied, with Millennials favoring rice storage and older farmers opting for direct selling. Millennials preferred rice varieties with market demand-driven traits, while older farmers valued drought tolerance. Despite improvements in rice quality, farmers faced challenges in securing optimal prices for their produce. Household size and irrigation based on soil moisture were inversely associated with increased rice yields. Overall, our findings offer critical insights into the rice farming community in Champassak and suggest policy interventions to improve farming practices and marketing strategies among rice farmers to support the long-term viability of rice farming in Laos.Graphical

Polarimetric SAR descriptor to map coexisting heterogeneous paddy phenology in the coastal delta using single-date SLC and GRD products of Sentinel-1

ABSTRACT Rice at different phenological stages is affected differently by cyclones, leading to varying impacts on yield. Therefore, studying rice phenology in coastal delta regions provides more convincing insights. The present study was conducted at three coastal delta sites of Tamil Nadu, categorized by heterogeneous and homogeneous rice phenology, and reported to experience frequent cyclonic storms. In the present study, an empirical descriptor, ‘PS(0–99) (Paddy Stages from 0 to 99 according to the BBCH standard)’, was proposed from SLC and GRD products of a single-date dual polarized Sentinel-1 (C-band) data to map the three major phenological phases of rice crops and their corresponding growth stages. The performance of the PS(0–99) for the site with heterogeneous phenology was found to be promising in mapping i) the major phenological phases of the paddy crops (F1 = 86%, Kappa Coefficient = 0.78, AUC = 0.73), particularly the Ripening phenology (F1 = 0.88), and ii) six growth stages under Vegetative and Ripening phenological phases (F1: Transplanting = 0.81, Tillering = 0.76, Stem Elongation = 0.82, Development of fruit = 0.84, Ripening = 0.84, Senescence = 0.85). Similar results were found for the other two sites with homogenous rice phenology. The PS(0–99) demonstrated promising performance in accurately categorizing the predominant phenological phases, even under heterogeneous phenological conditions. However, the proposed descriptor was found to be less effective in distinguishing the growth stages under reproductive phenology due to consistent volumetric scattering and plant water content across these stages. This study provides new insights into the effectiveness of the proposed SAR descriptor in mapping diverse rice phenology and its growth stages using single-date data.

Molecular Analysis of Xa4 and xa5 Resistance Genes Involved in the Response to Bacterial Lieaf Blight in Conventional Rice Lines in Burkina Faso

Rice is a staple crop in Burkina Faso, but its production is threatened by bacterial leaf blight, which caused yield losses of up to 50% between 1998 and 2004. To address this issue, new rice varieties have been developed through crosses with IRBB lines carrying multiple resistance genes, particularly Xa genes. This study aimed to identify the presence or absence of Xa4 and xa5 resistance genes in these new varieties and their parental lines. The plant material consisted of 12 rice lines, including five new varieties and their respective parents. Molecular detection was performed using PCR-based markers ; MP1 for the Xa4 gene and RM122 for the xa5 gene. Genomic DNA was extracted using a modified Permingeat protocol, and amplification products were analyzed by electrophoresis on 3.5% agarose gel in 0.5X TAE buffer. Results showed that six lines carried the xa5 gene: the parents CT21376-F3-9-1, IRBB60, and the new varieties AR19L018-F4-27, AR19L018-F4-22, and AR19L025-F4-117. The Xa4 gene was detected in seven lines: the parents IRBB50, IRBB60, CT21376-F3-9-1, and the new varieties AR19L018-F4-22, AR19L018-F4-27, AR19L021-F4-99, and AR19L025-F4-117. Notably, three new varieties AR19L018-F4-22, AR19L018-F4-27, and AR19L025-F4-117 possess both Xa4 and xa5, suggesting a pyramiding of resistance genes that may provide durable protection against multiple Xanthomonas oryzae pv. oryzae strains. Field trials in disease-endemic areas are recommended to validate their resistance and agronomic performance.

Rice proteome revealed antagonistic interactions between signaling components of cytokinin and ABA phytohormones during drought stress.

Rice proteome revealed antagonistic interactions between signaling components of cytokinin and ABA phytohormones during drought stress.

Transcriptional Dynamics of Rice Under Individual, Combined, and Sequential Abiotic Stresses: Insights Across Stress Severity and Recovery in Contrasting Genotypes.

Plants in natural environments frequently encounter multiple abiotic stresses, which may occur individually, simultaneously, or sequentially, significantly impacting crop productivity. The transcriptional response to these stresses varies across genotypes, and understanding these variations at the molecular level is critical for improving stress resilience. In a previous study, we identified two contrasting rice genotypes, Lomello (highly stress-tolerant) and C57-5043 (highly stress-sensitive), from a screen of ~400 genotypes for abiotic stress tolerance. Here, we performed time-course transcriptomic profiling to dissect the molecular basis of their differential stress responses under varying severity levels (mild, moderate, and severe) of high temperature (HT), drought (D), submergence (S), combined heat and drought stress (HTD), and post-submergence drought (PSD). Our results reveal that transcriptional responses are highly context-dependent, with distinct expression patterns emerging under individual, combined, and sequential stress conditions. Notably, while submergence induced significant transcriptomic changes within the first few days, subsequent drought exposure, particularly at higher severity levels, did not elicit a strong transcriptional response, likely due to transcriptional silencing resulting from physiological damage. Comparative analysis between genotypes showed that Lomello exhibits constitutively higher expression of genes involved in phytoalexin biosynthesis, even in the absence of stress, potentially conferring a preemptive defense advantage. Furthermore, Lomello demonstrated a robust induction of genes associated with reactive oxygen species (ROS) scavenging, abscisic acid (ABA) biosynthesis and signaling, and secondary metabolite production in response to stress, followed by a rapid reversion to near-baseline expression levels during recovery. These findings suggest that Lomello's superior stress tolerance is driven by enhanced secondary metabolite accumulation, efficient ROS detoxification, and a stronger recovery response. This study provides novel insights into genotype-specific transcriptional strategies for stress resilience, offering potential targets for breeding climate-resilient rice varieties.

Agronomic Characteristics and Kinship Of 10 High Yielding Inbred Rice Varieties (Oryza Sativa L.) In West Java

Background. The success of rice production is influenced by many factors, one of which is the selection of varieties. Varieties, as a supporting factor in increasing agricultural productivity, will be able to show values according to potential yields with optimal farming management. Aims. This study aims to examine the differences in agronomic characteristics and kinship of 10 high-yielding inbred rice varieties (Oryza sativa L.) in West Java. The experiment was conducted at the Variety Display Land, Pamekaran Village, Soreang District, Bandung Regency. The experiment was conducted from April to August 2024. The experimental location was situated at an altitude of 700 m above sea level. Methods. The agronomic characteristic experiment method used a qualitative descriptive approach. In the experimental approach, a Randomized Block Design (RBD) was employed with 10 inbred rice phenotype treatments, repeated three times. The materials used in this experiment were 10 high-yielding inbred rice varieties. Result. Based on the study's results, similarities were observed in morphological characters among several inbred rice varieties, including those in Group I, Inpari 32 HDB, and Situ Bagendit, with a similarity level of 100%. In Group II, the Mekongga, Inpari 42, Inpari 33, and Inpari 30 varieties, and in Group III, the Ciherang and Padjadjaran Cakrabuana Agritan varieties, achieved a coefficient value of 78%. Conclusion. The similarity is 0.10 or 100% with a similarity coefficient level of 100% seen from the morphological character data based on the Rice UVOP Table

Whole-transcriptome sequencing reveals the global molecular responses and ceRNA regulatory network involved in programmed cell death of rice cultivars zyk639 and zyk-lm

BackgroundProgrammed cell death (PCD) can be triggered by biotic stress or abiotic stress in rice, which is a crucial factor throughout the lifecycle. Long non-coding RNAs (lncRNAs) have important roles in a variety of biological processes. However, the regulatory relationship between lncRNAs and rice PCD occurrence is unclear.MethodsIn this study, messenger RNAs (mRNAs) and lncRNAs associated with PCD regulation were identified in two rice cultivars: japonica rice (Oryza sativa) cultivar zheyoukang639 (zyk639) and its mutant zyk639-lesion mimic (zyk-lm). Besides, these data were used for weighted gene co-expression analysis (WGCNA) and construction of competitive endogenous RNAs (ceRNAs).ResultsAs a result, 5,289 lncRNAs and 39,475 mRNAs were identified, of which 1,873 lncRNAs and 11,930 mRNAs were differentially expressed. In addition, WGCNA showed that the blue module was critical for the development of PCD in rice. The construction of the ceRNA regulatory network associated with the occurrence of PCD in rice identified 101 pairs of relationships, including 9 lncRNAs, 11 miRNAs and 76 mRNAs. Importantly, three major lncRNAs in zyk-lm, including MSTRG.24301.2, MSTRG.17476.1 and MSTRG.24898.1, may be involved in leaf PCD, with MSTRG.24898.1 binding to osa-miR580 to regulate transcription factors. Furthermore, the lncRNAs co-expression mRNAs rpl27-1 and OsRPS27, which were associated with ribosomal genesis, and Os11g0490900, a WRKY family transcription factor, may also regulate PCD genesis.ConclusionsModels of protein synthesis regulation associated with zyk-lm PCD were discussed, lncRNAs may serve as key factors in regulating PCD and provide ideas for understanding PCD and genetic messaging.

Mapping of a Novel Quantitative Trait Locus Conferring Bacterial Blight Resistance in the Indigenous Upland Rice Variety ULR207 Using the QTL–Seq Approach

Bacterial blight (BB) disease is a serious stress that affects up to 80% of rice yield. Utilizing an elite resistant variety was previously thought to be an alternative way to control disease outbreaks. The indigenous upland rice variety ULR207 is a high-potential donor for the BB resistance breeding program. However, the quantitative trait loci (QTLs) associated with bacterial blight resistance in this variety have not yet been discovered. Therefore, QTLs associated with BB resistance need to be identified. In this study, we identified the QTLs associated with BB resistance in the F2:3 population crossed between the BB resistance variety ULR207 and Maled Phai, as well as a susceptible variety, via QTL-seq analysis and bulk-segregant analysis. We found a new QTL-associated BB resistance locus (qBBchr8) mapped on chromosome 8. Five positions were candidates, including Os08g0110700, Os08g0115200, Os08g0131300, Os08g0139500, and Os08g0163900. Afterwards, Kompetitive Allele-Specific PCR (KASP) markers specific to the SNP variant and the position of each gene were designed. These markers, associated with the disease lesion length phenotype, were validated with another 178 individual plants of the F2 population via single-marker analysis. This analysis revealed that the position Os08g0110700 was the strongest locus, with a PVE of 15.00%. The results suggest that this KASP SNP marker could be used to improve elite rice for BB resistance.

Genetic dissection of root traits in a rice ‘global MAGIC’ population for candidate traits to breed for reduced methane emission

Rice cultivation is critical for global food security. The largely practiced method of rice cultivation by transplantation under flooded fields contributes significantly to methane (CH4) emissions, posing challenges to climate-smart agriculture. This study uses a multi-parent advanced generation inter-cross (MAGIC) population of 250 rice genotypes to understand the genetic basis of root traits that may govern CH4 mitigation. Phenotyping under controlled greenhouse conditions revealed significant variation in root diameter (0.122–0.481 mm) and porosity (5.344–56.793 g), and strong correlations between root diameter and porosity traits (r = 0.40–0.50, p < 0.001). Association studies revealed key candidate genes including Os05g0411200 (thermosensitive chloroplast development), Os10g0177300 (chalcone synthase), and Os04g0405300 (alcohol dehydrogenase), which regulate aerenchyma formation and auxin homeostasis. Protein-protein interaction networks linked these genes to flavonoid biosynthesis (KEGG map00941) and N-glycan pathways, earlier identified as critical for root architecture. Haplotype-phenotype analysis revealed 8 superior haplotypes across 7 genes for average root porosity, base root porosity, root diameter, and tip root porosity. These findings provide the foundation for breeding high-yielding rice varieties with reduced methane emissions, addressing the challenges of food security and climate change.

The labor market impact of technological advancements: Evidence from the Green Revolution in Bangladesh

Abstract This paper investigates the labor market impacts of the Green Revolution (GR) in Bangladesh using newly digitized subdistrict‐level data from the 1970s to the 2000s. I use a panel fixed‐effects model and find heterogeneous impacts on agricultural labor markets based on the labor intensity of different rice types—Boro, Aus, and Aman. HYV adoption reduced agricultural labor share by up to 6%, with Aman displacing more labor due to mechanized transplanting, while Boro remained labor‐intensive due to irrigation needs. Despite productivity gains, there is no corresponding rise in nonagricultural employment or industrialization, and in some cases, rural unemployment increased. To address endogeneity, I use an instrumental variable based on groundwater constraints. These findings highlight the need for policies addressing labor market disruptions amid technological change.

Synergistic Effect of Nitrogen Fertilizer Management on Rice Productivity and Quality

This study investigated how nitrogen fertilizer management influences the yield and grain quality of two rice cultivars, Nanjing 9108 (a late-maturing medium japonica) and Ming 1 Youzhenzhan (a three-line indica hybrid). Three field experiments were conducted to assess different nitrogen application strategies, including total nitrogen reduction, panicle-stage nitrogen reduction, and substitution of chemical fertilizer with compound fertilizer. The experiments analyzed changes in rice nitrogen uptake and transport efficiency, yield and its components, and quality and its components under different nitrogen application treatments, and fitted a function based on the effect of total nitrogen fertilizer on quality. Taking into account four quality indicators and ensuring yield reduction is less than 30%, replacing 100% chemical fertilizer with compound fertilizer in Nanjing 9108 was the optimal strategy for significantly improving quality. Reducing panicle fertilizer by 50% or omitting it also significantly improved quality. Replacing chemical fertilizers with 50% compound fertilizer also maintained nutritional quality. Reducing total nitrogen fertilizer by 25% in Ming 1 Youzhenzhan was the optimal strategy for significantly enhancing quality. Replacing chemical fertilizer with 100% compound fertilizer significantly improved quality. Reducing panicle fertilizer by 50% and substituting 50% of chemical fertilizer with compound fertilizer also significantly improved quality. Taking into account the synergistic effects of nitrogen application measures on rice yield and quality, the performance of the two rice varieties is not identical. The results showed that nitrogen fertilizer management significantly affected both yield and quality, with responses varying between the two varieties. But the two varieties can ensure optimal quality under yield conditions by reducing panicle fertilizer application by 50% and replacing chemical fertilizers with compound fertilizers.

Effect of fertilizer on the nutrient concentration and uptake of local fine rice varieties in Haor areas of Bangladesh

The experiment was conducted at the farmers’ fields of Bahadurpur and Noagaon village at Sadarupazilla and Dakshin Sunamganj, respectively under the Dekharhaor (wetland) of Sunamganj district, Bangladesh during November, 2015 to May 2016 to observe the nutrients concentration and uptake by the local fine rice varieties under different rates of fertilizers application. The experiment comprised four varieties viz. Tapiboro (V1), Begun bichi (V2), Rata boro (V3), Atobshail (V4), and three fertilizers package treatments- F1= Farmers’ practice, FP (NPK @ 41.4-4.2-10.5 kg ha-1), F2= Recommended Fertilizer Dose, RFD (NPKSZn@69-22.4-31.7-6.7-0.65 kg ha-1) and F3= Soil test based fertilizers, STB (NPKSZn@61-17.5-33.5-3.1-0.7 kgha-1). The experiment was laid out in two factors Completely Randomized Block Design (RCBD) with three farmers’ replications. Data were collected on yield, nutrients concentration and uptake of rice. Tapiboro produced the highest grain yield of 3.10 tha-1and straw yield of 5.49 tha-1. The grain and straw yield varied significantly due to application of different fertilizer doses. Application of STB fertilizer were produced the highest grain yield of 2.95 tha-1 and straw yield of 4.85 tha-1. The highest amount of NPKSZn concentration was found in Tapiboro and application of STB fertilizers. Tapiboro uptakes the highest amount of NPKSZn. The NPSZn apparent balance was found positive and negative K balance was found in all treatments. Tapiboro with STB based fertilizers application was the best option in the haor area for the farmers’. J. Sylhet Agril. Univ. 11(2): 43-52, 2024

Deciphering the translocation of cadmium in indica rice under high-cadmium soil conditions.

The migration and translocation dynamics of cadmium (Cd) across the growth spectrum of indica rice, including two conventional (C1, C2) and two hybrid (H1, H2) cultivars, were deciphered through a field experiment at a high Cd-contaminated site for the first time. It was determined that the phloem was the most important transport route for Cd in the grains for both conventional and hybrid cultivars under high Cd conditions. This is supported by the evidence that the translocation factor TFleaves-brown rice exhibited highly significant positive correlations with the Cd concentration in brown rice for C1, C2 and H2 (p < 0.01), with correlation coefficients being 0.59 for C1, 0.87 for C2, and 0.50 for H2 respectively. A highly significant correlation between TFstem-brown rice and the Cd concentration in brown rice was revealed for H1 and H2 only (p < 0.01). Soil microbial diversity was generally higher after rice cultivation, and a negative correlation between Cd content and microbial richness was determined. At phylum level, it was verified that Firmicutes were more abundant in soils with medium or severe Cd pollution, and MBNT15 were typically enriched in conventional rice types, including both japonica and indica. The abundance of Bacteroidota were enhanced under high Cd conditions, and Gemmatimonadetes may be dominant only under low to medium Cd pollution conditions. At the other levels, it was inferred that both hybrid and conventional rice can enrich Bacillus, and SBR1031 played a more important role, contributing to higher Cd content in the brown rice of H2.

The Development of an Air Suction Precision Seed-Metering Device for Rice Plot Breeding

To address the lack of specialized seeding equipment and low manual seeding efficiency in rice plot breeding, this study developed an air suction precision seed-metering device for rice plot breeding, featuring automatic seed-switching and seed-clearing functions controlled by an STM32 microcontroller. Firstly, based on morphological analysis and MATLAB image processing, an active contour method was used to construct a suction hole model. Secondly, to meet the non-contaminated switching requirements between rice varieties, an electrically controlled seed-switching and seed-clearing mechanism was developed based on QR code-based precise recognition and positioning. Using 10 rice varieties as experimental materials, performance tests were conducted. The results showed that the seed-switching mechanism had single and cumulative errors under 0.4°, and the seed-clearing rate reached 100% with an average clearing time below 0.88 s. At a rotational speed of 20 r·min−1 and negative pressure of 3200 Pa, seed-filling performance was optimal for all rice varieties. Among them, the rice variety Nayou 6388 exhibited the best seed-filling performance, with a 0.8% missing seed rate, 97.6% single and double seed rate, and 1.6% multiple seed rate. In double-row coordinated tests, each seed-metering device independently completed seed switching and maintained synchronized operation, meeting agronomic requirements for accurate seed switching/clearing and precision seed filling in rice plot breeding.