Rice Varieties Research Articles

Residual Effect of Microbial-Inoculated Biochar with Nitrogen on Rice Growth and Salinity Reduction in Paddy Soil.

Increasing soil and water salinity threatens global agriculture, particularly affecting rice. This study investigated the residual effects of microbial biochar and nitrogen fertilizer in mitigating salt stress in paddy soil and regulating the biochemical characteristics of rice plants. Two rice varieties, Shuang Liang You 138 (SLY138), a salt-tolerant, and Jing Liang You 534 (JLY534), a salt-sensitive, were grown under 0.4 ds/m EC (S0) and 6.84 ds/m EC (S1) in a glass house under controlled conditions. Three types of biochar-rice straw biochar (BC), fungal biochar (BF), and bacterial biochar (BB)-were applied alongside two nitrogen (N) fertilizer rates (60 kg ha-1 and 120 kg ha-1) in a previous study. The required salinity levels were maintained in respective pots through the application of saline irrigation water. Results showed that residual effects of microbial biochars (BF and BB) had higher salt mitigation efficiency than sole BC. The combination of BB and N fertilizer (BB + N120) significantly decreased soil pH by 23.45% and Na+ levels by 46.85%, creating a more conducive environment for rice growth by enhancing beneficial microbial abundance and decreasing pathogenic fungi in saline soil. Microbial biochars (BF and BB) positively improved soil properties (physicochemical) and biochemical and physiological properties of plants, ultimately rice growth. SLY138 significantly had a less severe response to salt stress compared to JLY534. The mitigation effects of BB + N120 kg ha-1 were particularly favorable for SLY138. In summary, the combined residual effect of BF and BB with N120 kg ha-1, especially bacterial biochar (BB), played a positive role in alleviating salt stress on rice growth, suggesting its potential utility for enhancing rice yield in paddy fields.

Screening of Arsenic toxicity in Oryza sativa L. (rice) and assessment of variation in growth, ROS, and antioxidant responses in tolerant and sensitive rice cultivars

ABSTRACT Arsenic (As) in rice plants has toxic effects on their quality and human health. In the present study, 100 rice cultivars have been screened in hydroponics to analyze As toxicity and select As-tolerant and sensitive rice cultivars. The findings showed that rice cultivars responded differently to As stress at varying levels of effect. As treatments significantly changed morphological traits, the arsenic tolerance index (ATI %), pigments, and H2O2 concentrations. The rice cultivars Luit and Swarna demonstrated remarkable results (tolerant and sensitive) in terms of growth, as well as in terms of ATI, chlorophyll content, H2O2 content, and enzymatic and non-enzymatic antioxidants. Arsenic-induced pigment degradation and antioxidant content reduction were greater in Swarna than in Luit. Moreover, the results of biochemical analysis correlated with the morphological parameters. The selected As-tolerant and sensitive cultivars may be used to explore the tolerance mechanism in greater depth, which will require further molecular investigations.

Cadmium absorption and translocation in rice plants are influenced by lower air temperatures during grain filling stage

The increasing frequency and severity of low temperatures, and soil cadmium (Cd) pollution threaten food security. However, the interactive effects of Cd exposure and low temperatures on rice yield and quality, as well as the mechanisms of Cd absorption and translocation, remain unclear. In this study, two rice varieties were cultivated in soils with two Cd contamination levels (Cdhigh and Cdlow) and exposed to control (CT25) or lower temperatures of 20 °C (LT20) and 17 °C (LT17) during grain-filling stage. Results showed significant decreases in seed setting rate and grain weight, reduced head rice yield, and increased chalkiness due to low temperatures, particularly in Cdhigh soils. Compared to CT25, LT17 and LT20 increased Cd concentration by 37.6 % and accumulation by 14.8 % in grains grown in Cdhigh soils. Enhanced root activity and upregulation of OsNramp1 and OsNramp5 under both low-temperatures increased Cd levels in roots. Lower temperatures also decreased phytochelatins (PCs) and increased expression of OsHMA2 and OsCAL1, facilitating Cd transport and raising Cd levels in stems. Furthermore, upregulated OsHMA2, OsLCT1, and OsZIP7 in stems under low-temperatures promoted Cd transport to panicles. Overall, low temperatures during grain filling increased Cd uptake and translocation into rice grains, especially in high Cd contaminated soils, raising health risks. The study highlights the need to address climate change's impact on cadmium hazards in rice.

Critical yield components for achieving high annual grain yield in ratoon rice.

Ratoon rice is considered an eco-friendly and resource-efficient method for rice cultivation, providing innovative strategies to mitigate the global food crisis. To clarify the critical yield components for achieving high annual grain yield in ratoon rice, data from 136 widely cultivated rice cultivars were collected through a six-year field experiment. The study analyzed the correlations between yield components and yields for both the main season and the ratoon season, indicating that main yields vary between 5.9 and 10.9 Mg ha-1, exhibiting a highly significant positive correlation with spikelets per panicle; ratoon yields range from 1.8 to 7.1 Mg ha-1, showing a highly significant positive correlation with panicles per m2, grain filling rate, and 1000-grain weight. Path analysis reveals that, in terms of contributing to ratoon yield, the grain filling rate is the most influential component, followed by panicles per m2, and 1000-grain weight. Therefore, by selecting large-panicle cultivars in the main season and enhancing panicles per m2, grain filling rate, and grain weight in the ratoon season, high annual yield in ratoon rice can be realized.

The effect of the Fitostemin-WP® biostimulator on yield and quality characteristics of rice (Oryza sativa L.)

In order to avoid yield and quality reduction of rice, it is essential to provide nutrition rice plants require. Therefore, a field experiment was conducted at the research area of the Institute of Agriculture - Skopje, Department of Field Crops, Ss. Cyril and Methodius University in Skopje, Republic of Macedonia, in Kochani, a rice production region. The experiment was set up to determine the effects of the Fitostemin-WP® biostimulator on some yield and quality properties of an Italian rice variety Opale during the vegetative seasons in 2020 and 2021. Standard agrotechnical methods for crop production were applied. Fitostemin-WP® is an herbal product in the form of powder and it consists of herbal extracts and minerals. It is used for increasing crop yield. The field experiment was arranged in a Zade method with a Fitostemin-WP® treatment and a control one in 3 replications. Only basic fertilizers (350kg/ha NPK and 200kg/ha Urea (46% N)) were applied on the control plot, while the treatment plot, besides basic fertilization, was also treated with Fitostemin-WP® with 100 g/ha dosage once during the vegetation period (tillering stage). The following parameters were examined in this study, namely the biological, grain and straw yield, the number of productive tillers/m2, panicle weight, and milling fractions. Results were analyzed with the ANOVA and LSD test. According to the results from this study, statistically significant differences were not found in these two years of field experiments for the examined parameters. However, the values for the brokens have shown some significant differences between the years, but not between the treatment and the control. This can result from the environmental impact during the vegetative period. More frequent usage of Fitostemin-WP® during the vegetation period of the rice plant may show more significant results.

Classification of Northern Thai Rice Varieties Using Random Forest (RF) and Support Vector Machine (SVM) on Google Earth Engine with Sentinel Imagery: A Case Study in Buak Khang Subdistrict, San Kamphaeng District, Chiang Mai Province

Classification of Northern Thai Rice Varieties Using Random Forest (RF) and Support Vector Machine (SVM) on Google Earth Engine with Sentinel Imagery: A Case Study in Buak Khang Subdistrict, San Kamphaeng District, Chiang Mai Province

Effect of Grain Thickness on Appearance and Cooked Rice Quality of Paddy Rice Variety “Hitomebore” and Effect of Temperature at Ripening Stage

Effect of Grain Thickness on Appearance and Cooked Rice Quality of Paddy Rice Variety “Hitomebore” and Effect of Temperature at Ripening Stage

Elevated O3 has stronger effects than CO2 on soil nematode abundances but jointly inhibits their diversity in paddy soils

Anthropogenic activities have resulted in rising atmospheric concentrations of carbon dioxide (CO2) and ozone (O3), exerting substantial direct and indirect impacts on soil biodiversity within agroecosystems. Despite the considerable attention given to the individual impacts of elevated CO2 and O3 levels, the combined effects on soil nematode communities have not been extensively explored. In this study, we investigated the interactive effects of elevated CO2 (+200 ppm, eCO2) and O3 (+40 ppb, eO3) levels on the abundance, diversity, and trophic composition of soil nematode communities associated with two rice cultivars (Nanjing 5055, NJ5055 and Wuyujing 3, WYJ3). Our findings revealed that soil nematodes had greater abundances under eO3, whereas eCO2 had no significant impacts. Conversely, both eCO2 and eO3, and their combination led to significant reductions in nematode generic richness, accompanied by a decline in the diversity particularly associated with the WYJ3 cultivar. Moreover, eCO2 and eO3 influenced nematode community composition and environmental factors, particularly for the WYJ3 cultivar. Both eCO2 and eO3 significantly increased soil nitrate levels. The changes in nematode community composition were related to soil nitrate levels, as well as nitrogen and carbon concentrations in rice plant roots. Furthermore, interactions between eCO2 and eO3 significantly impacted soil nematode abundance and trophic composition, revealing intricate consequences for soil nematode communities that transcend predictions based on single-factor experiments. This study unveils the potential impacts posed by eCO2 and eO3 on soil biodiversity mediated by rice cultivars, plant functional characteristics and soil feedback mechanisms, thereby underscoring the complex and interactive outcomes arising from concurrent drivers of climate change within the soil food web.

Regulation of eating quality, sensory aroma and 2-acetyl-1-pyrroline biosynthesis in fragrant rice through foliage application of aromatic compounds

The experiment was conducted at the research area of Sher-e-Bangla Agricultural University from 15 June 2022, to 25 November 2022 (Aman season) to evaluate the impact of aromatic compound application on fragrant rice. The experiment included two factors: factor 1 comprised four rice varieties (BRRI dhan34, BRRI dhan70, BRRI dhan80, and Tulshimala), and factor 2 comprised application of four aromatic compounds (L-proline, α-ketoglutaric acid, γ-aminobutyric acid, and sodium selenite). A randomized complete block design was employed with three replications. Results revealed significant effects of aromatic compound applications and/or rice varieties on grain eating qualities, sensory aroma and 2-acetyl-1-pyrroline, which were superior in Tulshimala and BRRI dhan34. α-Ketoglutaric acid and sodium selenite application improved water uptake ratio, amylose and amylopectin content, alkali spreading value, gel consistency, protein content, sensory aroma score, and kernel stickiness and tenderness of fragrant rice. Moreover, α-ketoglutaric acid application led to enhanced 2-acetyl-1-pyrroline content in Tulshimala and BRRI dhan34. Several eating quality and fragrance parameters were found either positively or negatively correlated. Apparent amylose content exhibited a negative correlation with stickiness of kernel. Sensory aroma and grain 2-AP content were also positively correlated.

Maroon Rice Genomic Diversity Reflects 350 Years of Colonial History.

Maroons in Suriname and French Guiana descend from enslaved Africans who escaped the plantations during colonial times. Maroon farmers still cultivate a large diversity of rice, their oldest staple crop. The oral history and written records of Maroons by colonial authorities provide contrasting perspectives on the origins of Maroon rice. Here, we analyzed the genomic ancestry of 136 newly sequenced Maroon rice varieties and found seven genomic groups that differ in their geographical associations. We interpreted these findings in light of ethnobotanical and archival investigations to reconstruct the historical contexts associated with the introduction of rice varieties to the Guianas. We found that two rice groups trace to West Africa, which we propose are linked to the transatlantic slave trade (c. 1526 to 1825). We posit that the Maroon rice stock additionally contains varieties that derive from rice introduced by indentured laborers from Java (1890 onwards), USA rice breeders (1932 onwards), and Hmong refugees who fled the Vietnam War (1991). Furthermore, on the Maroon fields, we found rice types never documented before that were derived from crosses. Overall, our results demonstrate that the Maroon farmers prioritize maintenance of a high stock diversity, which we posit reflects the expertise they inherited from their (African) ancestors. Ignored by agricultural modernization initiatives, Maroon farmers today are custodians of a unique cultural heritage. Notably, the genomic findings underline many Maroon stories about their past. We anticipate that a similar study approach can be applied to other heirloom crops of (Indigenous) communities that may have preserved their history on their farms to reconstruct, acknowledge, and honor the past.

A phenological-knowledge-independent method for automatic paddy rice mapping with time series of polarimetric SAR images

Paddy rice, which sustains more than half of the global population, requires accurate and efficient mapping to ensure food security. Synthetic aperture radar (SAR) has become indispensable in this process due to its remarkable ability to operate effectively in adverse weather conditions and its sensitivity to paddy rice growth. Phenological-knowledge-based (PKB) methods have been commonly employed in conjunction with time series of SAR images for paddy rice mapping, primarily because they eliminate the need for training datasets. However, PKB methods possess inherent limitations, primarily stemming from their reliance on precise phenological information regarding paddy rice growth. This information varies across regions and paddy rice varieties, making it challenging to use PKB methods effectively on a large spatial scale, such as the national or global scale, where collecting comprehensive phenological data becomes impractical. Moreover, variations in farming practices and field conditions can lead to differences in paddy rice growth stages even within the same region. Using a generalized set of phenological knowledge in PKB methods may not be suitable for all paddy fields, potentially resulting in errors in paddy rice extraction. To address the challenges posed by PKB methods, this study proposed an innovative approach known as the phenological-knowledge-independent (PKI) method for mapping paddy rice using time series of Sentinel-1 SAR images. The central innovation of the PKI method lies in its capability to map paddy rice without relying on specific knowledge of paddy rice phenology or the need for a training dataset. This was made possible by the incorporation of three novel metrics: VH and VV normalized maximum temporal changes (NMTC) and VH temporal mean, derived from the distinctions between paddy rice and other land cover types in time series of SAR images. The PKI method was rigorously evaluated across three regions in China, each featuring different paddy rice varieties. Additionally, the PKI method was compared with two prevalent phenological-knowledge-based techniques: the automated paddy rice mapping method using SAR flooding signals (ARM-SARFS) and the manual interpretation of unsupervised clustering results (MI-UCR). The PKI method achieved an average overall accuracy of 97.99%, surpassing the ARM-SARFS, which recorded an accuracy of 89.65% due to errors stemming from phenological disparities among different paddy fields. Furthermore, the PKI method delivered results on par with the MI-UCR, which relied on the fusion of SAR and optical image time series, achieving an accuracy of 97.71%. As demonstrated by these findings, the PKI method proves highly effective in mapping paddy rice across diverse regions, all without the need for phenological knowledge or a training dataset. Consequently, it holds substantial promise for efficiently mapping paddy rice on a large spatial scale. The source code used in this study is available at https://code.earthengine.google.com/f82cf10cad64fa3f971ae99027001a6e.

TKM 15 -A High Yielding, Short Duration Rice Variety Suitable for Direct Sown Water Limited Areas of Tamil Nadu, India

TKM 15 -A High Yielding, Short Duration Rice Variety Suitable for Direct Sown Water Limited Areas of Tamil Nadu, India

Ecology and diversity of arbuscular mycorrhizal fungi (AMF) in rice (Oryza sativa L.) in South India: an ecological analysis of factors influencing AMF in rice fields.

This study examined the diversity of arbuscular mycorrhizal fungi (AMF), mean spore density (MSD), and root colonization in relation to factors such as agroclimatic zones, rice varieties and soil types in paddy fields of South India. The aim was to understand how these factors influence AMF association in rice, facilitating their effective use as a biological tool in paddy cultivation. AMF were identified through light microscopy of spores, while MSD and percentage-root-length colonization (PRLC) were measured using standard methods. Correlation and principal component analyses were performed to explore the interrelationships between AMF characteristics and various environmental, soil, and plant variables. Sixteen AMF species were identified across 29 rice varieties from three agroclimatic zones, 6 soil orders, and 18 soil series over 2 seasons. Notably, 70% of chemicalized rice fields lacked AMF spores, and only 50% exhibited root colonization. This study offers new insights into the role of AMF in rice cultivation. The AMF diversity and root colonization in relation to environmental variables underscore their significant impact on AMF in particular crop fields.

Dynamic alterations and ecological implications of rice rhizosphere bacterial communities induced by an insect-transmitted reovirus across space and time

BackgroundCereal diseases caused by insect-transmitted viruses are challenging to forecast and control because of their intermittent outbreak patterns, which are usually attributed to increased population densities of vector insects due to cereal crop rotations and indiscriminate use of pesticides, and lack of resistance in commercial varieties. Root microbiomes are known to significantly affect plant health, but there are significant knowledge gaps concerning epidemics of cereal virus diseases at the microbiome-wide scale under a variety of environmental and biological factors.ResultsHere, we characterize the diversity and composition of rice (Oryza sativa) root-associated bacterial communities after infection by an insect-transmitted reovirus, rice black-streaked dwarf virus (RBSDV, genus Fijivirus, family Spinareoviridae), by sequencing the bacterial 16S rRNA gene amplified fragments from 1240 samples collected at a consecutive 3-year field experiment. The disease incidences gradually decreased from 2017 to 2019 in both Langfang (LF) and Kaifeng (KF). BRSDV infection significantly impacted the bacterial community in the rice rhizosphere, but this effect was highly susceptible to both the rice-intrinsic and external conditions. A greater correlation between the bacterial community in the rice rhizosphere and those in the root endosphere was found after virus infection, implying a potential relationship between the rice-intrinsic conditions and the rhizosphere bacterial community. The discrepant metabolites in rhizosphere soil were strongly and significantly correlated with the variation of rhizosphere bacterial communities. Glycerophosphates, amino acids, steroid esters, and triterpenoids were the metabolites most closely associated with the bacterial communities, and they mainly linked to the taxa of Proteobacteria, especially Rhodocyclaceae, Burkholderiaceae, and Xanthomonadales. In addition, the greenhouse pot experiments demonstrated that bulk soil microbiota significantly influenced the rhizosphere and endosphere communities and also regulated the RBSDV-mediated variation of rhizosphere bacterial communities.ConclusionsOverall, this study reveals unprecedented spatiotemporal dynamics in rhizosphere bacterial communities triggered by RBSDV infection with potential implications for disease intermittent outbreaks. The finding has promising implications for future studies exploring virus-mediated plant-microbiome interactions.2AL1xEb7k2nunVBmbuNCsVVideo

Use of rice flour to produce plant-based yogurt alternatives.

Plant-based yogurt alternatives (YAs) are in demand due to the societal prevalence of milk sensitivities and allergies and some consumers abstaining from animal-derived products. Producing rice flour YAs has considerable potential because rice flour is hypoallergenic, more economical compared to plant milks, and there are no commercial rice-based YAs. A new higher protein variety of rice was developed, Frontière, which is sold as both brown and white rice. Therefore, the overall goals of this study were (1) to compare physicochemical properties of YAs from Frontière brown (Frontière brown rice flour [FBRF]) and white (Frontière white rice flour [FWRF]) high-protein rice flours to regular protein level rice flours and (2) to evaluate the sensory quality of Frontière YAs compared to commercial plant-based oat yogurt. Rice flours were fermented with Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lacticaseibacillus rhamnosus (a probiotic) to produce FBRF- and FWRF-YAs. A consumer study was conducted to compare FBRF- and FWRF-YAs to a commercially available oat-based YA. Consumers rated the YAs using 9-point hedonic and just-about-right (JAR) scales. Protein, fat, and ash levels were greater, whereas starch levels and peak viscosities were lower for BRFs than for WRFs. The use of BRF resulted in longer fermentation times but higher bacteria counts for YAs. FWRF-YA was preferred in terms of overall flavor and liking, sweetness, and tartness. Purchase intent (PI) for FWRF-YA increased 2.6 times after providing a health claim. This research showed that rice flour can be used to produce YAs with probiotic counts above the minimum recommended, which provides added health benefits for consumers. PRACTICAL APPLICATION: This research provides a possible new use of Frontière high-protein rice flour to produce plant-based yogurts. This will help the rice industry by adding value, and those who are vegan, allergic to casein, or lactose-intolerant will have another option for a plant-based yogurt. Moreover, the greater levels of probiotic bacteria found in the brown rice flour YAs can potentially provide greater health benefits, making brown rice flour a better choice for making rice-based YAs.

Retraction Note: Salt acclimation differentially regulates the metabolites commonly involved in stress tolerance and aroma synthesis in indica rice cultivars

Retraction Note: Salt acclimation differentially regulates the metabolites commonly involved in stress tolerance and aroma synthesis in indica rice cultivars

Involvement of plasma membrane H+-ATPase in the nitrate-nutrition uptake and utilization in indica rice

Utilization of nitrogen by crops is essential for sustainable agriculture. The transport of nitrate (NO3−) across the plasma membrane is a critical gateway for N uptake and subsequent utilization. This process requires proton (H+) coupled cotransport, which is driven by proton motive force, provided by plasma membrane (PM) H+-ATPase. In this report, two indica rice varieties [Meixiangzhan 2 (MXZ) and Jifengyou 1002 (JFY)] in South China were selected and cultivated in hydroponic solution with 0.5 mM or 2.0 mM NO3− as the N source. The JFY exhibited stronger growth with higher biomass than MXZ under both 0.5 mM and 2.0 mM NO3−. PM H+-ATPase activity of JFY roots was significantly higher than that of MXZ. The higher PM H+-ATPase activity in JFY was consistent with a higher abundance of PM H+-ATPase protein and higher transcription levels of OSAs, such as OSA2, OSA7 and OSA8 in roots, OSA3, OSA7 and OSA8 in leaves. The expression of nitrate transporters (OsNRT1;1b, OsNRT2.1, OsNRT2.2, and OsNAR2.1) were also higher in roots or shoots of JFY than those in MXZ. Under 0.5 mM and 2.0 mM NO3−, the NO3− absorption and translocation rate, nitrate content, as well as nitrate reductase (NR) activity were all significantly higher in JFY, as compared to those in MXZ. Taken together, in JFY and MXZ, a higher level of PM H+-ATPase protein and higher activity coupled with greater efficiency in nitrate uptake, translocation and assimilation, suggesting the existence of a close correlation between PM H+-ATPase and nitrate utilization in indica rice. PM H+-ATPase may one of the elite genes that can contribute to nitrate use efficiency in rice.

Self-correcting deep learning for estimating rice leaf nitrogen concentration with mobile phone images

As a pivotal role in crop development, the application of nitrogen fertilizers enhances yields, while excessive use poses environmental risks. Precision nitrogen management requires rapid crop nitrogen assessment in field conditions and mobile phone images can be a promising approach. However, few studies have investigated how arbitrary white balance and exposure value settings affect crop nitrogen diagnosis using phone photos. Therefore, a new deep learning framework: self-correcting leaf nitrogen concentration estimation network (SCLNC-Net), was proposed to explore the potential of mobile phone images for non-destructive nitrogen status monitoring. Imperfect camera metering and incorrect user operations were addressed through attention U-Net for automatic white balance and exposure correction. Then a lightweight deep learning algorithm MobileNetV3 was utilized to estimate rice leaf nitrogen concentration based on the self-corrected images. Compared with most deep learning models, SCLNC-Net has fewer parameters and higher computational efficiency, which is better suited for deployment on mobile platforms. The results revealed that SCLNC-Net enhanced image quality and acquired high accuracy in the estimation of rice leaf nitrogen concentration (R2 = 0.84, RMSE = 0.39 %, RRMSE = 13 %). Moreover, the robustness and effectiveness of the proposed SCLNC-Net remained excellent across various shooting angles, mobile phone types, and rice varieties. This study provides insights into rapid and cost-efficient nutrient assessment and precision nitrogen management.

Genome-wide investigation and analysis of U-box E3 ubiquitin-protein ligase gene family in kiwifruit (Actinidia chinensis) in response to the yeast antagonist, Wickerhamomyces anomalus

ABSTRACT Although the ubiquitin ligase U-box protein family is a vital component of plant development and stress response, the exact role of kiwifruit U-box genes family is not known. The study identified 73 putative U-box genes from the kiwifruit genome. Chromosomal localisation, phylogenetic analysis, physicochemical properties, gene structure, motifs, and promoters of these genes were analysed. Distribution of Actinidia chinensis PUB (AcPUB) genes exhibited varying densities across 27 chromosomes. The study found that U-box clusters were classified into groups I–VII in phylogenetic analyses of a variety of plants, including kiwifruit, Arabidopsis thaliana, and rice, with most of the genes in kiwifruit being related to rice. The conserved motif analyses revealed that all the AcPUB genes have typical U-box structural domains. Analysis of the cis-acting elements suggested that AcPUBs expression may be responsive to several hormones and stresses. RNA-Seq analysis showed that six kiwifruit U-box genes were differentially expressed after induction by Wickerhamomyces anomalus, suggesting a potential involvement of these U-box genes in the kiwifruit's response to W. anomalus, which might include mechanisms related to resistance. Overall, our findings provide valuable insights into the function and structure of U-box genes that will help develop new genomic technologies and study plant resistance.

Effect of chemical weed management on growth, yield and economics of drum seeded rice (Oryza sativa)

Field experiment was conducted at Periyanarkunam, Bhuvanagiri Taluk, Cuddalore District during Kuruvai 2021 and 2022 to study the effect of different herbicidal weed management on growth, yield and economics of drum seeded rice (Oryza sativa L.) variety ‘ASD 16’. The experiment was conducted in randomized block design with four replications. The treatments comprised of six weed management practices and are made up of a combination of herbicides (pre-emergence, early-post and post-emergence herbicides) with hand weeding, which was com- pared with unweeded control and twice hand weeding on 25 and 45 DAS. Application of bensulfuron methyl 0.6% + pretilachlor 6% GR @ 660 g a.i./ha PE fb metsulfuron methyl 10% + chlorimuron ethyl 10% WP @ 4 g a.i./ha PoE on 25 DAS fb hand weeding on 45 DAS recorded the highest weed control efficiency of 77.55 and 74.23% during Kuruvai 2021 and 2022 respectively, growth attributes at 60 DAS viz., plant height (96.82 and 91.79 cm), tillers/m2 (367 and 343) and dry matter production (8.01 and 7.78 t/ha), yield attributes like productive tillers/m2 (319 and 312), filled grains/panicle (100.64 and 98.42), grain yield (6.19 and 6.11 t/ha) and benefit cost ratio (2.78 and 2.49) during Kuruvai 2021 and 2022, respectively over bispyribac sodium 10% SC @ 25 g a.i./ha PoE on 20 DAS fb hand weeding on 45 DAS (farmers practice). Hence, it is an efficient weed management practice and an economically feasible method for achieving the maximum growth, yield and economics of drum seeded rice.