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.
Effect of zinc foliar spray and soil application of mixed bio-fertilizer on growth and yield of kharif rice in red and lateritic soils of West Bengal
The acidic, low-humus, and nutrient-deficient soils of the red and lateritic zone often exhibit poor nutrient retention and micronutrient deficiencies, leading to reduced rice productivity. A field experiment was conducted during the kharif season of 2022 at the Institutional Farm of Seacom Skills University, Birbhum, West Bengal, to evaluate the effect of chelated zinc foliar application at different growth stages in combination with the recommended dose of fertilizers (RDF) and mixed biofertilizer (Azotobacter, phosphate-solubilizing bacteria, and Trichoderma) on the growth, yield, and economics of rice cv. MTU 1010. The experiment was laid out in a Randomized Complete Block Design (RCBD) with eight treatment combinations and three replications. Results showed the tallest plants (122.4 cm) with more dry matter production (760.5 g m-2) and highest root length, root volume and root dry weight in RDF + @ 0.5 % Zn foliar spray at 15 DAB (nursery stage) + Soil application of mixed biofertilizer treated plots. The same treatment also recored the highest number of effective tiller m-2(315), panicle length (26.1 cm), panicle weight (6.17 g), filled grains panicle-1(215.3), test weight (22.57 g) and grain yield (5.95 t ha-1) followed by RDF + @ 0.5% Zn foliar spray at 15 DAT + Soil application of mixed biofertilizer. Yield increase was to the tune of 11.63% over control. The gross returns, net returns and benefit: cost ratio followed the similar trend. Therefore, integrating RDF with 0.5% chelated Zn foliar spray at 15 DAB and mixed biofertilizer application can be recommended as a sustainable nutrient management strategy for enhancing rice productivity and profitability in the red and lateritic soils of West Bengal.
Copyright (c) 2026 ORYZA-An International Journal of Rice http://creativecommons.org/licenses/by/4.0
Naphthalene Acetic Acid Mitigates the Adverse Effects of Climate Change on Rice Productivity and Grain Quality under Different Nitrogen Fertilizer Levels
Rice productivity in Egypt is increasingly constrained by rising temperatures, limited resources, and the need to improve nitrogen-use efficiency (NUE). Although 1-naphthaleneacetic acid (NAA) can enhance crop growth and nutrient utilization, its interaction with nitrogen fertilization in newly released Egyptian rice cultivars remains poorly understood. Therefore, a field experiment was conducted to evaluate the effects of nitrogen fertilization and foliar NAA application on productivity, grain quality, nutrient accumulation, and NUE of the rice cultivar Giza 184 under transplanted conditions following barley. The experiment was arranged in a split-plot design with four replications, comprising four nitrogen rates (0, 55, 110, and 165 kg N ha-1) and four NAA concentrations (0, 5, 10, and 15 ppm). NAA was sprayed at 25 and 55 days after transplanting. Nitrogen and NAA significantly improved growth, yield attributes, grain quality, and nutrient concentrations (N, P, K, and Zn) in grain and straw. The combined application of 165 kg N ha-1 and 15 ppm NAA produced the highest grain yields (11.61 and 11.80 t ha-1) and straw yields (17.83 and 17.92 t ha-1) during 2024 and 2025, respectively. This treatment also enhanced milling quality and nutrient accumulation, with grain phosphorus concentration reaching 0.214% and 0.213% and straw potassium concentration reaching 2.41% and 2.63% in the respective years. However, the highest NUE was achieved at 110 kg N ha-1 combined with 10-15 ppm NAA. Integrating NAA with nitrogen fertilization can therefore improve rice productivity, grain quality, nutrient enrichment, and NUE, contributing to more sustainable rice production in Egypt.
The oligosaccharides of alginate and chitosan influence the growth, metabolism and physiological processes in rice seedling
Natural biostimulants such as alginate and chitosan oligosaccharides have emerged as promising tools for improving plant growth and stress tolerance. The study was undertaken to evaluate the effects of irradiated alginate and chitosan oligosaccharides on the growth, physiological attributes, and enzymatic activities of young rice plants. Seven-day-old rice seedlings were treated with different concentrations of alginate and chitosan oligosaccharides generated through gamma irradiation at varying doses. Among the treatments, alginate oligosaccharide produced at 500 kGy and applied at 200 ppm (A/500/200) proved most effective in enhancing biomass accumulation, photosynthetic performance, leaf water status, and the activities of enzymes associated with carbon metabolism and plant defence. Likewise, chitosan oligosaccharide produced at 200 kGy and applied at 400 ppm (C/200/400) significantly improved biomass production and enhanced seedling water relations. The yield improvement may be mediated through enhanced carbon assimilation, metabolic activity, and activation of defence-related enzymes. These findings highlight the potential of irradiated alginate and chitosan oligosaccharides as sustainable biostimulants for improving early-stage rice growth, physiological
Post-harvest losses and productive efficiency in rice farming systems of Bunkeya, Democratic Republic of the Congo
This study analyzed the relationship between post-harvest losses, technical efficiency, and rice productivity in farming systems in Bunkeya, a rural rice-producing area in south-eastern Democratic Republic of Congo. Data were collected from 240 rice producers from November 2023 to June 2024 across six villages. Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), regression models, and Stochastic Frontier Analysis (SFA) were used to establish farm typologies and assess productive efficiency. Three farm categories were identified: small-scale, intermediate, and large-scale producers. Smallholders achieved the highest field yield per hectare (966.8 kg ha-1) but also recorded the highest cumulative post-harvest losses (44.5%). Large-scale producers showed lower harvest losses (11.3%) and the highest technical efficiency score (0.91), although processing losses remained high (30.3%). Intermediate producers exhibited transitional inefficiencies and moderate technical efficiency (0.89). Overall post-harvest losses exceeded 40% across all farm categories. The average technical efficiency score was 0.87, suggesting that rice output could increase by approximately 13% without additional input use if existing inefficiencies were reduced. Regression results further indicated that harvest losses significantly and negatively affected final marketable rice output. These findings suggest that productive efficiency is associated not only with agronomic intensification and farm size, but also with effective post-harvest management and operational coordination throughout the rice value chain.
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
Nutritional quality and growth attributes of naturally growing floating rice in Tal lands of Ballia district, Uttar Pradesh
Floating rice is a unique ecotype adapted to deep-water and flood-prone ecosystems, and plays an important role in sustainable wetland agriculture. Information on the growth performance and nutritional quality of naturally occurring floating rice in the Tal ecosystems of eastern Uttar Pradesh is limited. Therefore, the present study was conducted in the Suraha Tal and Dah Tal regions of Ballia district to evaluate the growth, yield, and nutritional characteristics of naturally growing floating rice. Two sampling spots were selected at each location, resulting in a total of 24 sampling sites. Growth and yield attributes were recorded from 20 to 160 days of crop duration. After harvest, grain and straw samples were analyzed for nutrient composition and grain quality parameters. Grain and straw nutrient contents ranged from 1.51-2.10% and 1.05-1.79% N, 0.73-1.07% and 0.27-0.65% P, 0.41-0.99% and 0.94-1.83% K, and 0.28-0.52% and 0.12-0.28% S, respectively. Micronutrient concentrations in grain and straw were 0.056-0.081% and 0.071-0.095% Fe, 0.011-0.025% and 0.165-0.379% Cu, 0.009-0.024% and 0.020-0.036% Zn, and 0.020-0.035% and 0.033-0.060% Mn, respectively. Grain quality parameters varied from 9.60-13.22% crude protein, 0.51-0.88% crude fibre, 21.08-23.75% amylose, and 14.42-19.37% oil content. Floating rice grown in Suraha Tal soils exhibited superior nutritional quality compared with that grown in Dah Tal soils. These findings highlight the nutritional value and ecological significance of naturally occurring floating rice in sustaining wetland agroecosystems and enhancing food security.
Floating rice, nutritional quality, plant analysis, soil fertility and Tal lands.
Use of machine learning techniques to detect and classify selected fungal diseases in rice crop using hyperspectral imaging
Fungal diseases cause significant yield losses in rice, making early detection and accurate classification essential for effective disease management. In this study, hyperspectral imaging technique was used to acquire the spectral signatures of three major fungal diseases viz., brown spot, blast and sheath blight in rice. The acquired hyperspectral images were pre-processed using Standard Normal Variate (SNV) transformation and Savitzky-Golay filtering, followed by pixel-wise spectral data extraction. Principal Component Analysis (PCA) was used to investigate spectral variability among healthy and diseased leaf samples. Subsequently, machine learning models including artificial neural networks (ANN), support vector machines (SVM) and random forests (RF) were employed to classify these diseases based on the acquired and pre-processed spectral signature data. The results indicated that the ANN model outperform the others, achieving an accuracy of 98%, followed by SVM at 94%, and RF at 88%. Among the three models, the ANN exhibited the highest accuracy, precision and recall, making it the most effective model for disease detection and classification. Hyperspectral imaging, combined with machine learning, offers an affordable and efficient solution for large-scale detection and assessment of fungal diseases in rice crops.
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.
Productivity, profitability and energetics of direct seeded rice under different nutrient and tillage management practices
A field experiment was conducted during the kharif season of 2024 at the Agricultural Research Station, SOA University, Bhubaneswar, Odisha, to evaluate the effect of nutrient management practices under different tillage systems on the productivity and profitability of direct-seeded rice (DSR). The experiment was laid out in a split-plot design with three tillage practices in the main plots: conventional tillage, minimum tillage with dhaincha brown manuring at 50% seed rate, and minimum tillage with dhaincha brown manuring at 100% seed rate. Four nutrient management options, namely control, inorganic recommended dose of nitrogen (RDN) @ 60 kg ha-1,organic nutrient management, and integrated nutrient management (INM; 25% organic + 75% inorganic), were assigned to the subplots and replicated thrice. Results revealed that minimum tillage with dhaincha brown manuring at 100% seed rate significantly improved growth and yield attributes, resulting in the highest grain yield (2194 kg ha-1) and straw yield (2761 kg ha-1). Among nutrient management practices, INM recorded the maximum tiller density (263.7 m-2), grain yield (2280 kg ha-1), and straw yield (2780 kg ha-1). Economic analysis indicated that minimum tillage with dhaincha brown manuring at 100% seed rate generated the highest net return (Rs.16,750 ha-1) and benefit-cost ratio (1.45), whereas inorganic RDN exhibited the highest economic efficiency (Rs.192.6 ha-1 day-1). The study suggests that integrating minimum tillage with dhaincha brown manuring at 100% seed rate and INM can enhance productivity, profitability, and sustainability of direct-seeded rice cultivation.
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.
Assessment of drum seeding technology of rice cultivation through on farm trials and front-line demonstration
In the majority of countries, rice is the staple crop and the cultivation is a labour-intensive and expensive process. Farmers are experiencing difficulty in the adoption of transplanting due to the shortage of labour and high labour wages and the delay in release of water from canals or the low availability of water during early kharif. In order to overcome the problems, farmers are looking for new and simple technologies. Krishi Vigyan Kendra (KVK) scientists also searched for the simplest and most effective technology based on initial feedback from the farmers. We finally determined that drum seeding technique is quite simple, requires awareness and training to adopt the technology. To evaluate the technology, KVK, Ramagirikhilla, has introduced the drum seeding technology in Peddapalli district of Telangana in the year 2012-13 and continued its assessment through On Farm Trials (OFT) and Front Line Demonstration (FLD) for seven years from 2012-13 to 2018-19 covering an area of 23.20 ha in 16 locations. The results revealed that there was an increase of 14.74 % yield (58.97 q ha-1) compared to farmer's practice (51.57 q ha-1). Overall data on seven years' assessment showed an extension gap of 7.4 q ha-1, a technology gap of 16.03 q ha-1, and a technology index of 21.37%. Drum seeding technology resulted in better net returns and an increase of Rs. 11,895.71 ha-1 over farmers' practice and achieved higher benefit cost ratio (2.88) than farmers' practices (2.32). The adoption of drum seeding technology increased from negligible to 343.30% with an overall adoption level of 182.41% and a horizontal spread from 0 ha to 1387 ha during the study period.
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.