ARRW publishes peer reviewed original research articles, short communications and review articles on all aspects of rice research, covering basic and applied work on crop improvement, crop management, crop protection and environmental security.
Genetic variability and character association studies of wild rice (Oryza nivara and Oryza rufipogon) germplasm for yield and yield-related traits
The present study evaluated 40 late-maturing wild rice germplasm lines obtained from the National Research Center on Plant Biotechnology, New Delhi. The germplasm lines were assessed at Banaras Hindu University, Varanasi during the Kharif seasons of 2019 and 2020 to estimate genetic parameters for 12 yield and yield-related traits. Analysis of variance revealed highly significant differences among genotypes for all traits, indicating the presence of considerable genetic variability. The highest genotypic and phenotypic coefficients of variation (GCV and PCV) were observed for total grain yield per plant, followed by panicle weight. Total grain yield per plant exhibited the highest heritability estimate, followed by total grain number per panicle. Genetic advance, expressed as a percentage of the mean, was highest for plant height, while grain number per plant and filled grains also showed relatively high values. Correlation and path coefficient analyses indicated that filled grains per panicle and panicle weight had strong positive effects on grain yield. Therefore, these traits may serve as reliable selection criteria for yield improvement in rice breeding programs. Among the evaluated genotypes, WRG(NKS)-440, WRG(NKS)-434, and WRG(NKS)-421 consistently exhibited superior performance for yield and yield-related traits and may serve as promising parental lines for hybridization aimed at improving grain yield in rice.
Genetic variability, heritability, character association, path analysis and rice
Copyright (c) 2026 ORYZA-An International Journal of Rice http://creativecommons.org/licenses/by/4.0
Farmers' perceptions and trait preferences for improved non-basmati rice varieties: Insights from an action research in Eastern India
Understanding farmers' perceptions and trait preferences is critical for developing rice varieties with high adoption potential. This study adopts an action research approach to evaluate farmer-perceived traits of eight improved rice varieties released within the last decade by Central Rice Research Institute (CRRI), Cuttack, India. Data were collected from 202 farmers (n = 202) across eleven districts in four eastern Indian states - Odisha, West Bengal, Bihar, and Chhattisgarh using household surveys, personal interviews, and focus group discussions conducted after on-farm demonstrations in the farmers' fields. Farmers rated five agronomic traits (tillering capacity, insect and pest resistance, disease resistance, weed competitiveness and lodging resistance) and three market related traits (grain type, cooking quality and marketability) on a 10-point scale. Non-parametric analyses (Kruskal-Wallis H test and Dunn's post hoc test) revealed significant variation in trait perceptions across varieties. CR Dhan 314 was consistently preferred for agronomic performance, while CR Dhan 315 and CR Dhan 510 received the highest ratings for grain type, cooking quality, and marketability. Farmers primarily valued tillering capacity, lodging resistance, and insect-pest resistance in the demonstrated varieties. Demonstration yields were consistent with farmers perceptions of key agronomic traits. The findings indicate that farmers' varietal choices are shaped by a combination of field performance, market potential, and livelihood considerations. Integrating farmer preferences into rice breeding and dissemination strategies following participatory and action research approaches can enhance adoption and impact.
Optimization of rice byproducts based feed formulation for Indian major carps using linear programming modelling
The escalating cost of conventional feed ingredients has intensified the demand for alternative, cost-effective, and sustainable inputs in aquaculture nutrition. Rice byproducts, including rice bran, rice polish, broken rice, and de-oiled rice bran, offer considerable potential owing to their abundance, nutrient density, and low market price. This study investigates the optimization of rice-byproduct-based feed formulations for Indian major carps using linear programming (LP) modelling. Rice byproducts, considered waste, were evaluated as cost-effective and nutrient-rich alternatives to conventional aquafeed ingredients. Proximate composition data were incorporated into a linear programming framework to formulate 100 kg of feed using these ingredients, in order to determine optimal combinations that minimize production costs while fulfilling species-specific nutritional requirements for growth and health. Results indicated that for a 100 kg feed formulation, protein contents of 22.17%, 21.32%, and 20.45% could be obtained from the mixture, costing approximately Rs 1693.70, Rs 1704.95, and Rs 1670.95, respectively. This indicates that the formulation will cost less than Rs 20 per kg of feed, without compromising the nutrient content required for the growth of fish at different stages. This will help increase the productivity and profitability of fish farming.
Copyright (c) 2025 ORYZA-An International Journal of Rice http://creativecommons.org/licenses/by/4.0
Development and performance evaluation of battery assisted weeder for paddy crop
A battery-assisted single-row weeder was developed and evaluated in comparison with a conventional manually operated cono-weeder for wetland rice cultivation. The developed weeder consists of a frame, DC motor, battery pack, transmission system, controller, cutting unit, handle, and support wheel. Power from the battery-operated DC motor is transmitted to the cutting unit through a chain-sprocket mechanism, while a controller regulates uniform power supply and operational speed. Three cutting units-J-type, L-type, and cage wheel type-were evaluated at a row spacing of 20 cm. Performance parameters such as field capacity, field efficiency, weeding efficiency, plant damage, labour requirement, cost economics, and energy consumption were assessed. Results indicated that the battery-assisted weeder achieved an actual field capacity of 0.03 ha h-1, which was more than twice that of the manually operated cono-weeder. It also recorded higher field efficiency (85%), lower plant damage (1.94%), and reduced labour requirement (34 man-h ha-1). The cost of operation was Rs. 4108 ha-1, which was lower than that of the cono-weeder (Rs. 4712 ha-1). Overall, the battery-assisted weeder significantly reduced labour drudgery and operational time while lowering weeding costs, indicating its potential as an efficient mechanized weeding option for small and medium-scale rice farmers.
Spatial variability and assessment of major nutrients in paddy growing sodic soils of Sultanpur Region, Uttar Pradesh
Rice cultivation in the Sultanpur district of Uttar Pradesh is increasingly constrained by soil salinization and nutrient depletion, particularly in alkali soils. This study aimed to assess the nutrient status and physicochemical properties of rice-growing alkali soils in the region. A total of 56 geo-referenced soil samples were collected and analyzed for pH, electrical conductivity (EC), organic carbon, available nitrogen (N), phosphorus (P), potassium (K), and sulphur (S). Spatial distribution patterns were evaluated using Inverse Distable Weighting (IWD). Results revealed that all soils were non-saline (EC < 4 dS m-1), highly alkaline, with 42.85% of samples classified as very strongly alkaline (pH > 9.0). Organic carbon levels were low to moderate (0.1-1.4%; mean 0.549%), while available nitrogen ranged from 12.54 to 301.06 kg ha-1 (mean 85.33 kg ha-1), indicating widespread N deficiency. In contrast, phosphorus and potassium were generally in the medium range, and sulphur was found to be medium to high. The low organic matter and nitrogen levels are likely attributed to intensive cropping, imbalanced fertilization, and high temperatures accelerating nutrient loss. These findings underscore the urgent need for site-specific nutrient management strategies to restore soil fertility and sustain rice productivity in the salt-affected landscapes of eastern Uttar Pradesh.
Physiological and biochemical alterations induced by hexavalent chromium (Cr6+) in pot-cultured wheat and rice seedlings
Chromium (Cr6+) is a highly toxic heavy metal that adversely affects plant growth, physiology, and metabolism. This study evaluated the physio-biochemical responses of pot-cultured wheat (Triticum aestivum L. cv. HD-2932) and rice (Oryza sativa L. cv. Lalata) seedlings under varying Cr6+ concentrations, along with the ameliorative effects of chelating agents, diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA). Chromium exposure significantly reduced shoot and root growth, biomass, and photosynthetic pigments in a concentration-dependent manner, with maximum reductions of 64.3% in wheat and 32.3% in rice at 80 mg L-¹. Chlorophyll and carotenoid contents declined markedly due to oxidative damage and impaired biosynthesis. Biochemically, protein and soluble sugar contents decreased, whereas proline accumulation increased, indicating stress-induced metabolic disruption. Antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), were significantly enhanced, reflecting increased reactive oxygen species (ROS) scavenging. Chelator application alleviated Cr6+ toxicity, with DTPA showing greater efficacy than EDTA. DTPA improved growth, pigment stability, and biochemical attributes, and enhanced antioxidant enzyme activities, particularly in roots. At 20 mg L-¹ Cr6+, DTPA increased wheat shoot length, chlorophyll-a, protein content, and SOD activity compared to untreated controls. Overall, DTPA effectively reduced Cr toxicity and oxidative stress, suggesting its potential role in phytoremediation and improving crop tolerance under chromium-contaminated conditions.
Selenium-mediated modulation of cadmium and lead stress in black gram and rice seedlings
Cadmium (Cd) and lead (Pb) are pervasive environmental contaminants that severely affect plant health, productivity, and food safety. This study evaluated the effects of Cd and Pb stress on biomass production, pigment composition, biochemical parameters, antioxidant enzyme activity, and metal accumulation in black gram (Vigna mungo (L.) Hepper, cv. Prasad) and rice (Oryza sativa cv. Khandagiri) seedlings grown under hydroponic conditions, with a focus on the ameliorative effects of selenium (Se). Both metals caused significant reductions in biomass, chlorophyll content, protein levels, and soluble sugars, while enhancing proline accumulation and antioxidant enzyme activities (POX, CAT, and SOD), particularly in root tissues. Selenium supplementation effectively alleviated metal-induced stress by restoring pigment and protein levels, improving sugar content, enhancing antioxidative responses, and reducing Cd and Pb accumulation in shoot tissues. Metal tolerance indices, bioconcentration factor (BCF), total accumulation rate (TAR), tolerance index (Ti), and transportation index (TI)-were significantly improved under Se co-treatment. Comparative analysis revealed that rice exhibited slightly greater physiological resilience and metal handling capacity than black gram. These results highlight selenium's protective potential in alleviating Cd and Pb toxicity through the modulation of antioxidant defense mechanisms and metal homeostasis, offering promising applications for improving crop tolerance and ecological safety in metal-contaminated environment.
Spatiotemporal asymmetry in temperature amplitude and its impact on rice in Asia
Over half of the world's population relies on rice as a staple food, with Asia accounting for about 90% of both its production and consumption, making it central to global food security. Climate warming has increasingly altered the diurnal temperature range (DTR), with night-time temperatures rising faster than day-time temperatures, leading to pronounced diurnal asymmetry. This asymmetric warming shortens rice growth duration, increases spikelet sterility, reduces grain-filling period, and heightens respiratory losses, ultimately lowering grain yield and quality. Over the course of the 20th century, global average surface temperatures rose sharply, with warming rates nearly doubling in the latter half, largely due to anthropogenic activities. Climate data indicate that night-time temperatures are rising more rapidly than day-time temperatures-globally, at 1.4 times the rate, affecting more than half of the Earth's land surface between 1983 and 2017. Night-time heat is particularly harmful for rice; even a 1°C increase above the critical night-time threshold (~24°C) can cut grain yield and biomass by up to 10%. Elevated night-time temperatures during the reproductive stage disrupt respiration, nutrient translocation, and biomass allocation, and degrade grain quality, causing defects like chalky kernels-often more severely than high day-time temperatures. Despite this, yield declines are often attributed solely to night heat, overlooking broader effects of asymmetric warming. Given the variability in temperature patterns across time and regions, there is an urgent need for targeted strategies, such as breeding high-temperature-tolerant rice varieties, reducing heat-induced yield losses, and safeguarding future food security.
Genetic diversity in aromatic rice (Oryza sativa L.)
Aromatic rice represents a valuable genetic resource, yet comprehensive diversity assessments of non-Basmati landraces from eastern India remain limited. In this study, 36 aromatic rice genotypes-including local landraces, released varieties, and mutants-were evaluated using 32 agro-morphological and quality traits alongside seven SSR markers to assess genetic variability and identify superior genotypes for breeding. Cluster analysis grouped the genotypes into seven distinct clusters, with Cluster I being the largest, while Clusters V, VI, and VII were monogenotypic, reflecting unique genetic backgrounds. Cluster III exhibited the highest intra-cluster variability, and the greatest inter-cluster distance was observed between Clusters VII and V, indicating potential for selecting genetically diverse parents. Cluster mean analysis revealed trait-specific superiority: Cluster II excelled in yield and nutritional traits, Cluster III in grain quality traits, and Cluster VII in both yield and iron content. SSR analysis indicated moderate polymorphism (PIC 0.204 - 0.405), with RM 5474 and RM 72 being highly informative. Unweighted pair group method with arithmetic mean (UPGMA) clustering further confirmed broad genetic diversity, highlighting the value of integrating phenotypic and molecular data for strategic hybridization and the development of improved aromatic rice cultivars.
Morphological, aromatic rice, genetic diversity, genetic base, markers
Effect of selenium on physiological responses in black gram and rice seedlings under cadmium and lead stress: A comparative study
The present study evaluates the physiological, biochemical, and antioxidative responses of (Vigna mungo (L.) Hepper, cv. Ujala) and rice (Oryza sativa L.cv. Arnapurna) seedlings under cadmium (Cd) and lead (Pb) stress, and examines the ameliorative potential of selenium (Se) supplementation (10 mg L-¹). Cd and Pb exposure significantly inhibited growth and biomass in a dose-dependent manner. In black gram, shoot and root length decreased by up to 27.27% and 25.01% under Cd stress (T3), and by 31.82% and 35.70% under Pb stress (T6), respectively. Similarly, shoot and root biomass declined by 23.30% and 49.28% (Cd), and by 22.15% and 53.62% (Pb). Rice exhibited shoot length reductions of 19.64% and root length reductions of 23.3% under Cd stress. Photosynthetic pigments were also reduced, with chlorophyll-a, total chlorophyll, and carotenoids decreasing by up to 29.22%, 24.27%, and 21.3% in black gram, and 29.2%, 27.15%, and 33.3% in rice, respectively. Biochemically, Cd and Pb caused declines in protein (up to 17.65%), sugar (up to 25.64%), and sharp increases in proline levels up to 925.0% in black gram and 760.0% in rice. Antioxidant enzyme activities (POX, CAT, SOD) increased 2.4-3.1fold under stress, indicating elevated oxidative damage. Selenium supplementation significantly alleviated these effects. In Cd-stressed black gram, Se increased shoot and root lengths by 22.7% and 28.6%, and in rice by 10.7% and 20.0%, respectively, compared to controls. Pigment content recovered markedly, with chlorophyll-a increasing by 75.9% (black gram) and 50.8% (rice) over Cd-only treatments. Protein and sugar content also improved (up to 36.84% and 41.54%), while proline remained elevated, further increasing by up to 153.3%. Antioxidant enzymes were further enhanced by Se, with POX, CAT, and SOD activities increasing by 3.5-, 3.3-, and 2.7-fold in rice shoots, and similar trends observed in roots. The findings confirm that selenium plays a crucial role in mitigating Cd and Pb toxicity by enhancing growth, stabilizing cellular metabolism, and strengthening antioxidant defenses in both crops.
Comparative study of chromium stress in pot-cultured wheat and rice seedlings: role of DTPA and EDTA chelation in bioaccumulation and antioxidant responses
Chromium (Cr+6) is a highly toxic heavy metal that adversely affects plant growth and physiology. This study aimed to evaluate the effects of Cr+6 stress on biomass accumulation, metal bioaccumulation, and antioxidant defense responses in 20-day-old wheat (Triticum aestivum L. cv. HD-2894) and rice (Oryza sativa L. cv. Sabita) seedlings grown under pot culture conditions. Seedlings were exposed to increasing Cr concentrations (20-80 mg L-¹), with or without chelating agents diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) at 20 mg L-¹. Chromium exposure significantly reduced shoot and root biomass in a dose-dependent manner, with wheat showing up to 54.8% and 51.6% reductions in shoot and root biomass, respectively, and rice exhibiting reductions of 29.8% and 47.8%. Cr accumulation was higher in roots than shoots, suggesting limited translocation. Chelator application notably enhanced growth and reduced shoot Cr accumulation. DTPA and EDTA improved shoot biomass by up to 154% (wheat) and 37.2% (rice), and reduced Cr content in shoots by 11-31%. Bioconcentration factor (BCF) and total accumulation rate (TAR) increased under chelator treatments, while transportation index (Ti) was moderated, indicating greater root retention of Cr. Antioxidant enzymes-peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) were significantly upregulated under Cr stress, with the highest fold increases observed in root tissues. Combined Cr + EDTA (T12) and Cr + DTPA (T8) treatments led to maximum antioxidant activation, suggesting enhanced oxidative stress tolerance. Overall, the study demonstrates that Cr+6 impairs plant biomass and induces oxidative damage, while DTPA and EDTA alleviate toxicity through reduced metal bioavailability and stimulation of antioxidant defenses. EDTA was slightly more effective than DTPA, highlighting its potential in phytoremediation strategies for Cr-contaminated soils.
Growth and yield of late sown rice varieties under various nitrogen management practices
Late sowing in rice cultivation reduces the effective growing window, adversely affecting crop performance and nitrogen use efficiency (NUE). Adopting short-duration varieties along with efficient nitrogen management practices can mitigate these effects. A field experiment was conducted during kharif 2021 at ICAR-Indian Institute of Rice Research, Hyderabad, to evaluate the performance of short-duration rice varieties under late-sown conditions and identify suitable nitrogen management strategies. The experiment was laid out in a split-plot design with three replications. The main plot treatments included three short-duration rice varieties: DRR Dhan-44, MTU 1010, and MTU 1156. The subplot treatments comprised four nitrogen management strategies: recommended dose of nitrogen (RDN) @ 120 kg N ha-1, slow-release silicon-coated urea (SRSCU) @ 90 kg N ha-1, Leaf Colour Chart (LCC)-based application @ 105 kg N ha-1, and Soil Test Crop Response (STCR)-based application @ 114.5 kg N ha-1. Among the varieties, MTU 1156 recorded the highest grain yield (5.71 t ha-1), dry matter accumulation (12.43 t ha-1), leaf area index (4.12), and productive tillers (285 m-²). Among nitrogen treatments, LCC-based application @ 105 kg N ha-1 resulted in the highest grain yield (5.76 t ha-1) and was statistically at par with RDN. SRSCU recorded the lowest yield. The highest partial factor productivity of N (PFPN), was observed in MTU 1156 (55 kg grain kg-1 N). The study concludes that MTU 1156 combined with LCC-based nitrogen management is an effective strategy for sustaining rice productivity under late-sown conditions.
Comparative effects of urea and nano-urea on growth and yield performance of transplanted rice in the inner Terai Region of Nepal
Efficient nitrogen management is essential for enhancing rice productivity and nitrogen use efficiency. Overdependence on conventional urea often leads to suboptimal crop response and significant nitrogen losses to the environment. To address this, a field experiment was conducted during the 2023 rainy season in the Inner Terai region of Deukhuri, Dang, Nepal, to assess the effect of integrating conventional granular urea with nano-urea on the growth and yield of transplanted rice (Oryza sativa L., variety Hardinath-6). The study included eight treatments: a control, 100% recommended dose of nitrogen recommended dose of nitrogen (RDN) using ures, and six combinations of 75% or 50% RDN with nano-urea applied at vegetative and/or booting stages. Growth and yield parameters such as plant height, tiller number, panicle length, thousand-grain weight, grain and straw yield, filled grains per panicle, and sterility percentage were measured. The highest grain yield (4.38 t ha-1) was obtained under 100% RDN, while the treatment with 75% RDN + 25% nano-urea applied at the vegetative stage produced a statistically comparable yield (4.16 t ha-1). This treatment also recorded higher straw yield (7.07 t ha-1), longer panicles (23.96 cm), and more filled grains per panicle (198.67). In contrast, treatments with nano-urea alone resulted in lower yields, despite slightly reducing sterility. Overall, the findings indicate that partial substitution of urea with nano-urea, particularly at 25% applied at the vegetative stage, can sustain rice yield and thereby offering a more resource-efficient nitrogen management strategy.
Methane emissions from paddy fields: a root-to-shoot perspective on rice plant traits
Methane (CH4) emissions from flooded rice paddies are a major source of global greenhouse gases (GHGs), especially in rice-dominant countries such as India and China. With rising global rice demand, it is critical to adopt sustainable cultivation practices that reduce environmental impacts while safeguarding food security. This review highlights the morpho-physiological traits regulating CH4 formation and transport from soil to atmosphere, focusing on root and shoot anatomical features, carbon allocation patterns, aerenchyma-mediated gas flow, root exudate composition, and the indirect influence of panicle architecture on carbon partitioning. Key traits such as restricted aerenchyma development, optimized radial oxygen loss (ROL), improved shoot sink strength, and modified root exudation profiles emerge as promising targets for mitigation. The review also explores the interplay between microbial methanogenesis, plant anatomy, and gas exchange. Integrating these biological insights with agronomic best practices can accelerate the development of climate-smart, high-yielding rice cultivars that contribute to low-carbon agriculture.
Measurement of reactive nitrogen loss in lowland rice and associated uncertainties: A Review
Nitrogen (N) is a critical macronutrient for rice production, particularly in lowland flooded systems where crop productivity depends heavily on external nitrogen inputs. Global fertilizer-use projections indicate that nitrogen application may reach 130-150 million metric tons annually by 2050, with rice-based systems accounting for a substantial share. In lowland rice, native soil nitrogen is insufficient to meet crop demand, making fertilizer inputs essential for sustaining yields and improving grain nutritional quality. Despite decades of research aimed at enhancing nitrogen use efficiency, effective nitrogen management within the soil-plant-atmosphere continuum remains a major challenge due to inherently high losses of reactive nitrogen under flooded conditions. Processes such as ammonia volatilization, denitrification, and leaching lead to low fertilizer recovery and contribute to environmental and human health impacts, including eutrophication, nitrogen pollution, greenhouse gas emissions, and climate change. This review synthesizes current knowledge on nitrogen loss pathways in lowland rice systems, highlights key methodological challenges and uncertainties in measuring and quantifying reactive nitrogen losses, and examines recent advances in monitoring, modeling, and upscaling approaches. The paper further identifies critical research gaps and discusses implications for mitigation strategies and policy interventions aimed at improving nitrogen use efficiency and promoting the sustainability of lowland rice production.
Nitrogen transformation, nitrogen use efficiency, nitrogen measurement, nitrate leaching, nitrification, nitrous oxide emission, volatilization
Genetic diversity and population structure analysis of aromatic rice germplasm using SSR markers
Aromatic rice landraces represent a unique and valuable genetic resource due to their traditional, nutritional, and commercial significance. In the present study, 48 aromatic rice germplasm were evaluated for population structure and genetic diversity using 23 polymorphic simple sequence repeat (SSR) markers. The SSR markers revealed high levels of polymorphism, with polymorphic information content (PIC) values ranging from 0.47 to 0.88 (mean = 0.72) and gene diversity values ranging from 0.52 to 0.89 (mean = 0.75). Major allele frequencies ranged from 0.21 to 0.65. Population structure analysis grouped the germplasms into three distinct subpopulations (SP1, SP2, SP3), with five germplasms identified as admixtures. Cluster analysis using the UPGMA method further classified the germplasms into two major clusters and four subclusters. A clear geographic pattern was observed in the clustering: all eight germplasms from Punjab grouped closely within a single major cluster, while most germplasms from Chhattisgarh, Odisha, and Assam clustered together along with several Southeast Asian germplasm. Analysis of molecular variance showed that 84% of the total genetic variation existed among individuals within populations, while 16% was due to variation among populations. These results confirm the presence of substantial genetic diversity within aromatic rice germplasm and demonstrate the effectiveness of SSR markers in characterizing population structure. The findings provide a valuable genetic foundation for the selection of diverse parental lines, and conservation strategies aimed at improving and utilizing aromatic rice in crop improvement programs.
Assessing genetic potential of direct seeded rice for yield and its component traits in upland conditions of Western Himalayas
Direct seeded rice (DSR) offers a sustainable alternative to conventional transplanted rice due to its potential to enhance environmental health, improve resource efficiency and suitability for climate resilience. Genetic improvement for direct seeded rice requires identification of genotypes with rapid early vigour, stress resilience and stable yield expression under rainfed conditions. This study focused on dissecting the combining ability and heterosis patterns under direct seeded rainfed conditions. Thirteen lines, three testers and thirty nine F1 hybrids were evaluated using line × tester mating design to identify promising parents and hybrid combinations performing well under DSR systems. Among the parents, lines HPR 2872, HPR 2877, HPR 2888 and tester, HPR 2656 were identified as good general combiners, underscoring their utility as elite donors for enhancing genetic architecture under direct seeded conditions. Among the F1 hybrids, HPR 2872 × HPR 1156, HPR 2873 × HPR 2656, HPR 2875 × HPR 2795, HPR 2902 × HPR 2656 demonstrated outstanding Specific Combining Ability (SCA) effects, heterobeltiosis and standard heterosis, indicating strong role of non-additive genetic control and suitability for heterosis exploitation. By using DSR-adapted genetic material, this study focuses on identifying elite parents and F1 crosses that can accelerate development of climate resilient, resource efficient rice cultivars.
Direct seeded rice (DSR), upland, general combing ability (GCA), specific combining ability (SCA), heterosis, gene action.
Effects of fluoride and aluminium stress on antioxidant defense, biochemical responses, and soil properties in rice
Fluoride is naturally present in water, soil, gases, and dust, and elevated concentrations can impose physiological stress on plants. Aluminium (Al³+) toxicity is a major constraint to crop growth, as it disrupts root development, nutrient uptake, and cellular regulatory processes. This study evaluated the effects of varying fluoride ion concentrations (0, 1, 2, 5, 10, 50, and 100 mg L-1), applied alone or in combination with aluminium (Al³+), on rice (Oryza sativa L. cv. Deluxe Ponni). The responses were assessed through changes in the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR), which were monitored on a monthly basis. Post-harvest analyses determined carbohydrate and protein contents in rice grains and evaluated soil pH, electrical conductivity, and microbial population. Fluoride-aluminium stress enhanced antioxidant enzyme activities, indicating the activation of defense mechanisms to mitigate oxidative damage. Fluoride alone increased soil pH by reducing acidity, whereas combined fluoride-aluminium treatments resulted in a moderate pH increase, likely due to aluminium hydroxide formation and associated proton dynamics. This slight increase in soil pH promoted microbial activity, and overall, the combined fluoride-aluminium treatment elicited favorable physiological responses in rice and improved soil quality.
Aluminium, Antioxidant enzymes, Electrical conductance, Glutathione reductase, Glutothione peroxidase, Microbial count.
Growth and instability of Chhattisgarh's non-basmati rice
The "Rice Bowl of India," Chhattisgarh, contributes substantially to the country's Non-Basmati rice production, yet remains underrepresented in export markets. This paper examines the growth performance, instability, and trade dynamics of Non-Basmati rice in Chhattisgarh from 2012-13 to 2023-24. The findings indicate a notable increase in production and yield, particularly during 2020-2023. Although the area under cultivation expanded only marginally (CAGR: 1.02%), there were statistically significant increases in production (3.89%) and yield (2.84%). Export performance showed high volatility, with 2023 recording the highest export value (` 2,846.59 million). To translate Chhattisgarh's strong production base into sustainable export gains, targeted policy interventions are required. Strengthening post-harvest handling and milling infrastructure is critical to ensure export-grade quality and reduce losses. Establishing specialized export clusters and logistics hubs in major rice-producing regions can enhance market connectivity. Improving SPS compliance, quality testing facilities, and certification systems will support adherence to international standards. Additionally, capacity building for farmers, FPOs, and millers on export protocols and value addition is essential for enhancing global competitiveness.
Zinc-iron interactions in submerged rice soils: Effects on nutrient availability and plant uptake
Zinc (Zn) and iron (Fe) are essential micronutrients for rice and play a critical role in improving human nutrition. A laboratory incubation study followed by a pot experiment was conducted during the rabi season of 2019-20 to evaluate the interaction between Zn and Fe in soil and rice plants under submerged conditions. Application of Zn at 10 kg ha-1 significantly increased available Zn in both incubation and pot soils, whereas increasing Fe application reduced Zn availability. Submergence further decreased Zn availability but enhanced Fe concentration in soil. The highest Fe availability was observed in the treatment without Zn but with 10 kg ha-¹ Fe, which was 27.94% higher than the control. A negative correlation between available Zn and Fe in soil was observed across different rice growth stages (r = -0.026 to -0.438*). Increasing Fe levels reduced Zn concentration in rice tissues, while higher Zn application decreased Fe concentration, indicating antagonistic interaction. Grain Zn showed strong positive correlations with root Zn (r = 0.887**) and straw Zn (r = 0.894**). Soil Zn was strongly correlated with plant Zn (R² = 0.80-0.98**), whereas soil Fe showed weak and non-significant relationships. The highest grain Zn (35.88 mg kg-1) was recorded in the treatment receiving 10 kg ha-1 Zn without Fe, while the highest grain Fe (30.5 mg kg-1) was observed with 10 kg ha-¹ Fe without Zn, confirming antagonistic Zn-Fe interactions in the soil-plant system.
A novel diamide-mesoionic combination insecticide, (Chlorantraniliprole 0.5% + Triflumezopyrim 0.45%) (GR) against stem borer and leaf folder in rice
Field experiments were conducted during the kharif 2020 and rabi 2020-2021 seasons at the Regional Agricultural Research Station, Pattambi, Palakkad, to evaluate the efficacy of diamide and mesoionic insecticide combinations against major insect pests of rice. The treatments included a new combination insecticide, chlorantraniliprole 0.5% + triflumezopyrim 0.45%, applied at 76, 85.5, 95, and 104.5 g a.i. ha-1, along with chlorantraniliprole 0.4% GR @ 40 g a.i. ha-1, triflumezopyrim 10.6% SC @ 25 g a.i. ha-1, and chlorantraniliprole (0.5%) + thiamethoxam (1.0%) GR @ 90 g a.i. ha-1 as standard checks, with an untreated control. Pooled analysis of both seasons revealed that chlorantraniliprole + triflumezopyrim applied at 95 and 104.5 g a.i. ha-1 was most effective in managing yellow stem borer (Scirpophaga incertulas), recording 91.03% and 90.73% reduction in dead heart incidence, respectively, over the control. The same treatments also significantly suppressed leaf folder (Cnaphalocrocis medinalis), with 97.94% and 96.51% reduction in leaf damage. Correspondingly, these treatments resulted in the highest grain yield, with yield increases of 56.00% and 54.14% over the untreated control. The study demonstrates the superior efficacy of the chlorantraniliprole + triflumezopyrim combination for effective pest management and yield enhancement in rice.
Morpho-physiological responses of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) to chromium stress
Hexavalent chromium (Cr+6) contamination poses a severe threat to crop productivity by impairing plant physiological and biochemical functions. This study investigated the impact of increasing Cr concentrations (20-80 mg l-1) on shoot and root growth, biomass accumulation, pigment content, and antioxidant responses in hydroponically grown wheat (Triticum aestivum L. cv. HD-2894) and rice (Oryza sativa L.cv. Sabita) seedlings, along with the mitigating roles of chelating agents, diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA). Chromium stress significantly reduced shoot and root length (up to ~40%), biomass (up to ~61%), and photosynthetic pigments (chlorophylls and carotenoids by ~35-59%) in both crops. Protein content declined by ~15%, while proline increased up to 10.4-fold in wheat and 8.7-fold in rice, indicating strong oxidative stress. Chelator application reversed these effects: DTPA at 20 mg L-1 Cr enhanced wheat shoot biomass by 1.20-fold and rice shoot length by 1.18-fold over control, while EDTA provided comparable improvements. Antioxidant enzyme activities (peroxidase, catalase, superoxide dismutase) increased significantly under Cr exposure, with maximum SOD activity reaching 36.25 unit g-1 of the fresh weight in rice root (8.06-fold over control) under EDTA. DTPA and EDTA improved antioxidant defense, nutrient uptake, and growth recovery, with DTPA slightly more effective for growth restoration and EDTA for enzymatic stimulation. These findings highlight the protective roles of DTPA and EDTA in mitigating Cr+6-induced stress and suggest their potential use in enhancing metal tolerance and phytoremediation efficiency in wheat and rice.
Effect of selenium on heavy metal bioaccumulation and antioxidant responses in black gram and rice seedlings under cadmium and lead stress: A comparative study
Heavy metal stress from cadmium (Cd) and lead (Pb) is a major constraint on crop productivity, impairing biomass accumulation and inducing oxidative damage. This study investigates the comparative impact of Cd and Pb toxicity on black gram (Vigna mungo (L.) Hepper, cv. Ujala) and rice (Oryza sativa cv. Arnapurna) seedlings, with a focus on selenium (Se) supplementation as a mitigating agent. Results demonstrated that both metals significantly reduced biomass, particularly in roots up to 55.22% in rice and 60% in black gram, under Pb stress. Co-application of Se alleviated metal-induced growth inhibition, improving shoot biomass by up to 18.15%, 9.34% and root biomass by up to 31.11%, 20.89% respectively in black gram followed by rice. Metal accumulation was higher in roots than in shoots, but Se co-treatment significantly reduced Cd and Pb uptake, reflected in lowered Bioconcentration Factor (BCF) values. Enhanced Translocation Factor (TAR), Translocation Index (Ti), and Tolerance Index (TI) under Se treatment indicated improved metal translocation and physiological tolerance. Additionally, Cd and Pb stress elevated activities of antioxidant enzymes, peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) by more than two-fold, particularly in shoot tissues. Se supplementation further amplified antioxidant enzyme activities (up to 3-fold), suggesting enhanced reactive oxygen species (ROS) scavenging and reduced oxidative stress. These findings highlight selenium's potential as an effective ameliorant for Cd and Pb toxicity in black gram and rice by reducing metal uptake, improving stress tolerance, and enhancing antioxidative defense mechanisms.
Field evaluation of yellow stem borer, Scirpophaga incertulas (Walker) incidence in selected rice genotypes
An evaluation of 26 local landraces and ten popular cultivars for resistance to paddy yellow stem borer (YSB), Scirpophaga incertulas (Walker), was conducted at the College of Agriculture, V.C. Farm, Mandya, during the kharif 2022 and Summer 2023 seasons. The percentage of YSB damage across various genotypes was assessed at 30, 60, and 90 days after transplanting (DAT). Based on the mean percentage of infestation, the genotypes were classified into different resistance categories according to the Standard Evaluation System for Rice (SES) developed by IRRI. Among the 26 local landraces, five genotypes demonstrated resistance with a damage score of 1, nine were moderately resistant with a score of 3, eight genotypes were moderately susceptible with a score of 5, and four genotypes were classified as susceptible with a score of 7 across both seasons, showing varied infestations. Of the popular cultivars evaluated, four genotypes showed resistance, four were moderately resistant, one was moderately susceptible, and one was susceptible during Summer 2023. No genotypes, either local landraces or popular cultivars, displayed high resistance or high susceptibility to YSB.
Evaluation of energy, economics and performance of weeding methods in rice cultivation
Weeds pose a major constraint in paddy cultivation, and effective weeding is crucial. Traditional hand weeding is costly, labor-intensive, and time-consuming, whereas mechanical and chemical methods require less labor, time, and cost compared to the traditional approach. Field performance evaluation of different weeding methods revealed that the highest field capacity was observed for the NRRI two-row self-propelled weeder (0.067 ha·h-1), while the lowest was for the finger weeder (0.002 ha·h-1). Similarly, the highest labor requirement was recorded for hand weeding (910 man·h·ha-1), and the lowest for chemical weeding (221.5 man·h·ha-1). The maximum machine energy was required by the NRRI single-row self-propelled weeder (83.27 MJ·ha-1), while hand weeding required the highest total input energy (1439.33 MJ·ha-1). The highest operational cost was associated with the NRRI single-row self-propelled weeder (` 12,533 ha-1), whereas the lowest weeding cost was observed for the commercial power weeder (` 3,328.37 ha-1). The study suggests that traditional weed control methods demand more labor and incur higher costs compared to modern mechanical and chemical alternatives.
Genetic variability and trait relationships in M2F2 rice population derived from combined chemical mutagenesis
This study investigated genetic variability and trait associations in M2F2 rice populations developed through combined chemical mutagenesis of the commercial hybrid DPS-Virat with Colchicine, EMS and Sodium azide along with dimethyl sulfoxide. The experiment was conducted at Rice Research Farm, BAU, Kanke, Ranchi during the Kharif 2023 and 2024. Data on eleven quantitative traits were collected from 100 M2F2 plants. Descriptive statistical analysis revealed substantial phenotypic variation across grain traits, with high standard deviation observed for number of grains per panicle, number of unfilled grains per panicle, and spikelet fertility. Principal component analysis identified four significant components explaining 68.18% of the total variance. Principal component 1 (22.01%) was primarily influenced by chaff percentage and spikelet fertility, PC2 (20.65%) by grain number and primary branches, PC3 (14.21%) by plant height and panicle length, and PC4 (11.30%) by 1000-grain weight and grain yield per plant. Correlation analysis revealed significant positive associations between plant height and panicle length (r = 0.715), productive tillers and secondary branches (r = 0.611), and grain number and spikelet fertility (r = 0.741), while an inverse relationship was observed between chaff percentage and spikelet fertility (r = -0.787). The observed phenotypic diversity and trait associations provide valuable insights for developing targeted selection strategies in mutation breeding programs. These findings demonstrate the effectiveness of induced mutagenesis in creating genetic variability for yield-related traits and highlight the complex, multifactorial nature of yield determination in rice.
Characterization of South Indian rice accessions for physico-chemical properties, starch digestibility and antioxidant properties
Pigmented rice accessions are renowned for their unique colour characteristics and therapeutic applications. This study aims to characterize five popular pigmented rice accessions from South India-Matta (brown), Rakthasali, Njavara, Mappilai samba (red), and Kavuni (black)-by evaluating their physicochemical properties, starch digestibility, and antioxidant properties. The investigation included a detailed analysis of phytochemical concentrations, such as total phenolic content (TPC), total flavonoid content (TFC), and anthocyanins. Antioxidant activities were assessed using the 2,2-Diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging assay, 2,2-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging assay, and ferric reducing antioxidant potential (FRAP) assay. In terms of starch digestibility and glycemic potential, all rice accessions exhibited an intermediate glycemic index (GI) ranging from 55 to 60. Kavuni rice, with a GI value of 60, showed the highest glycemic potential, likely due to its low amylose concentration (6%). All accessions demonstrated significant phytochemical concentrations and notable antioxidant potential. Specifically, Kavuni rice exhibited high levels of TPC (1.4 mg GAE/g), TFC (9.6 mg QE/g), and anthocyanins (0.7 mg CE/g). The high antioxidant activities observed in Kavuni (DPPH - 86.8%; ABTS - 91%; FRAP - 0.5 mg AAE/g) are attributed to its elevated bioactive compound levels. The findings underscore the health-promoting potential of pigmented rice, especially in managing diabetes and related disorders. Future research should explore the molecular mechanisms underlying the health benefits of pigmented rice, particularly in metabolic disorder management. Additionally, breeding programs could aim to enhance specific phytochemical profiles to maximize therapeutic potential.
Genetic diversity and mutual relationships through principal component analysis in F2 generation of aus rice (Oryza sativa L.)
The present study was carried out to enumerate the extent of genetic diversity for yield components in 15 different F2 segregating populations with their 10 parents of Aus rice using principal component analysis (PCA), clustering and linkage analysis. In the correlation matrix, 14 characters of 25 genotypes generated14 principal components without changing their relative positions and the first four PCs explained 42.1%, 15.5%, 12.2% and 7.5% of total variation towards genetic diversity. In two cluster condition, 25 genotypes were grouped into two clusters having 7 genotypes (P2 x P1, P2 x P5, P2 x P6, P1, P2, P8, P10) in cluster 1 and 18 genotypes cluster 2. In the three cluster condition, there were 4, 6, 15 individuals in cluster 1, 2 and 3, respectively. In four cluster condition, clusters consisted of 4, 14, 3, 4 genotypes, respectively. Cluster means for the days to maturity, number of non-effective tillers per plant, empty grains per plant showed the lowest values in cluster 1. On the other hand, number of tillers per plant, effective tillers per plant, panicle length, filled grains per panicle, grain length and thousand seed weight showed maximum cluster means in cluster 4. The dendrogram revealed that six genotypes (P8 x P3, P7, P3, P7 x P3, P3 x P4, P11) having more distance as compared to rest (19 genotypes) of the genotypes. In complete linkage, 25 genotypes were grouped into two major clusters. Cluster 1 containing seven genotypes and cluster 2 containing 18 genotypes; among the two clusters, there was maximum cluster distance than the sub-clusters. Cluster 1 showed two sub clusters where four genotypes (P1, P2 x P1, P2 x P5, P2) were in one cluster and three genotypes (P11, P8 and P10) in another cluster. Cluster 2 also contains two sub-clusters in which three genotypes remain in one sub-cluster and 15 genotypes in another sub-cluster. In average linkage, 25 genotypes were also grouped into two major clusters. The first cluster contains three genotypes (P7, P3 x P4, P7 x P3) and the second cluster divided into two sub-clusters which contain rest of the genotypes (22 genotypes). It can be concluded that, there were more distance where cluster number was less and the distance was less where the cluster number was more.
Evaluation of insecticides at different stages of plant growth for management of major pests in rice
An experiment was conducted under the All India Rice Improvement Project during the kharif seasons of 2021, 2022, and 2023 to assess the effectiveness of various insecticide application methods against major insect pests in rice. Thirteen treatments, including different combinations of seed treatment, nursery drenching, and main field applications of granular insecticides at 25 and 60 days after transplanting (DAT), were evaluated along with an untreated control, using a randomized block design with three replications. The pooled results over three seasons indicated that stem borer (dead heart) incidence was lowest with main field application of cartap hydrochloride (mean damage 1.60%), followed by seed treatment with thiamethoxam combined with main field application of cartap hydrochloride (2.08%), resulting in 83.88% and 79.05% reduction over control, respectively. White ear incidence was minimum with seed treatment using thiamethoxam plus main field application of cartap hydrochloride (17.31%), followed by main field application of cartap hydrochloride alone (19.83%), reducing damage by 48.59% and 41.10% over control, respectively. Nursery application of fipronil a week before transplanting recorded the lowest gall midge incidence (19.40%), followed by seed treatment plus main field application of fipronil (20.95%), with reductions of 43.02% and 38.47% over control. Whorl maggot and leaf folder incidences were also effectively reduced by seed treatment with main field application of cartap hydrochloride. The highest grain yield (3704 kg ha-1) was achieved with main field application of chlorantraniliprole, followed by fipronil nursery treatment combined with chlorantraniliprole, yielding 3568 kg/ha, with 18.38% and 14.03% increases over control, respectively. These findings demonstrate that integrated insecticide application strategies significantly minimize pest incidence and enhance rice productivity.
Evaluating productivity and sustainability of linseed through conservation agricultural practices under rice based cropping system
The rice-linseed cropping system holds promise for enhancing sustainability and resource use efficiency in Chhattisgarh, India. Conservation agriculture (CA) practices like zero tillage and integrated nutrient management are potential strategies to optimize productivity and soil health in such systems. The study aimed to evaluate the productivity, resource-use efficiency, and sustainability of linseed under different conservation agricultural practices in a rice-based cropping system. The experiment was conducted at the Research-cum-Instructional Farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh over three years (2018-2021) across kharif and rabi seasons. A randomized block design (RBD) was used during the kharif season (rice), and a split-split plot design was employed in the rabi season (linseed). Treatments included combinations of tillage (conventional and zero tillage) and nutrient management (RDF, RDF + FYM, and integrated RDF) for both rice and linseed. Significant residual effects of rice management practices were observed on linseed growth and yield attributes. The combination of conventional tillage-direct seeded rice (CT-DSR) with 100% RDF + 2 t ha-1 FYM yielded the highest system productivity, nutrient uptake and economic returns in linseed. Zero tillage with residue retention using a happy seeder improved soil organic carbon and nutrient content, while conventional tillage increased bulk density and nutrient uptake. Among nutrient applications in linseed, 100% RDF + FYM proved most effective for growth, yield and profitability. Conservation agriculture practices, particularly CT-DSR with integrated nutrient management, significantly enhanced the productivity, profitability, and sustainability of the rice-linseed system. The residual effects of preceding rice practices and appropriate nutrient strategies are crucial for optimizing linseed performance under conservation agriculture.