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Resource-poor areas with moisture deficit lands following aerobic and direct seeded rice (DSR) methods of cultivation face severe problems of iron deficiency. In this study, Bengal and Assam Aus rice panel was phenotyped at the seedling stage using an iron-deprived hydroponic medium for various shoot and root traits. A novel iron deficiency scoring scale was used to classify the tolerance reaction and could range anywhere between 0 and 9, indicating the most tolerant and susceptible, respectively. The GWAS results identified four putative candidate genes; OsFLA for number of leaves and shoot length, OsBIDK1 for root traits; average diameter, volume, biomass, projected area, and surface area, OsHPL3 for chlorophyll index of the third leaf and AKR2B (XBOS252) was for Fe score, (which was earlier reported in relation to Xa21). The nsSNP (nsSNPs) variations in these gene sequences were used to group the panel and identify superior haplotypes and donors. BR16 was identified as a superior donor, with higher chlorophyll index and shoot length than RA23, also higher values for root traits like root average diameter, root volume, root projected area and root surface area followed by Shete Bhado. The impact of identified nsSNPs on protein structure and stability was investigated. The conserved domains detected in the mutated proteins of the superior haplotypes are very informative, highlighting that natural selection favors abiotic stress tolerant variants in resource poor areas. Thus, justifying our choice of Aus landraces for association mapping of Fe deficiency tolerant genes in rice. [ABSTRACT FROM AUTHOR]

The sustainability of rice production continues to be a subject of uncertainty and inquiry attributed to shifts in climatic conditions. In light of the impending climate change crisis and the high labor and water costs accompanying it, direct-seeded rice (DSR) is unquestionably one of the most practical solutions. Despite its resource and climate-friendly advantages, early maturing rice faces weed competitiveness and seedling establishment challenges. Resolving these issues is crucial for promoting its wider adoption among farmers, presenting it as a more effective sustainable rice cultivation method globally. Diverse traditional and contemporary breeding methods are employed to mitigate the limitations of the DSR approach, leveraging advanced techniques such as speed breeding and genome editing. Focusing on key traits like mesocotyl length elongation, early seedling vigor, root system architecture, and weed competitiveness holds promise for transformative improvements in DSR adaptation at a broader scale within farming communities. This review aims to summarize how these features contribute to increased crop production in DSR conditions and explore the research efforts focusing on enhancing DSR adaptation through these traits. Emphasizing the pivotal role of these game-changing traits in DSR adaptation, our analysis sheds light on their potential transformative impact and offers valuable insights for advancing DSR practices.

The objectives of this study were to explore the mechanism of stem mechanical strength in direct-seeded rice (DSR) as affected by paclobutrazol, especially its related endogenous hormone and cell wall component changes in culm tissue and response to the application of paclobutrazol. Field experiments were conducted in Changchun County, Jilin Province, China, by using two japonica rice varieties, Jiyujing and Jijing305, with soaking seeds in paclobutrazol at concentrations of (0 mg L−1, S0; 50 mg L−1; S1; 100 mg L−1; S2; 150 mg L−1, S3; 200 mg L−1, S4) in 2021 and 2022. The results suggest that the application of paclobutrazol increased the grain yield and reduced the lodging rate of DSR. Compared with the S0 treatments, soaking the seeds in paclobutrazol treatments rapidly shortened the length of the basal internode by decreasing the endogenous indole acetic acid (IAA) and gibberellin A3 (GA3) contents in culm tissue. The larger breaking strength (M) was attributed to a higher section modulus (SM) and bending stress (BS). The higher mechanical tissue thickness in culm tissue under paclobutrazol treatments, which was raised by higher endogenous zeatin and zeatin riboside (Z+ZR) content in culm tissue, increased the culm diameter, culm wall thickness, and section modulus (SM) of the internode. Compared with the S0 treatments, soaking the seeds in paclobutrazol treatments increased the cellulose content, lignin content, activities of lignin-related enzymes, and expression of key genes in lignin biosynthesis, as well as resulted in a higher bending stress (BS) to enhance the culm breaking strength (M). [ABSTRACT FROM AUTHOR]

The sustainability of rice production continues to be a subject of uncertainty and inquiry attributed to shifts in climatic conditions. In light of the impending climate change crisis and the high labor and water costs accompanying it, direct-seeded rice (DSR) is unquestionably one of the most practical solutions. Despite its resource and climate-friendly advantages, early maturing rice faces weed competitiveness and seedling establishment challenges. Resolving these issues is crucial for promoting its wider adoption among farmers, presenting it as a more effective sustainable rice cultivation method globally. Diverse traditional and contemporary breeding methods are employed to mitigate the limitations of the DSR approach, leveraging advanced techniques such as speed breeding and genome editing. Focusing on key traits like mesocotyl length elongation, early seedling vigor, root system architecture, and weed competitiveness holds promise for transformative improvements in DSR adaptation at a broader scale within farming communities. This review aims to summarize how these features contribute to increased crop production in DSR conditions and explore the research efforts focusing on enhancing DSR adaptation through these traits. Emphasizing the pivotal role of these game-changing traits in DSR adaptation, our analysis sheds light on their potential transformative impact and offers valuable insights for advancing DSR practices. [ABSTRACT FROM AUTHOR]

The use of allelopathic bacteria to combat weed infestation in crops is regarded as an effective technology for sustainable agriculture and environment. In this regard, six bacterial strains from the genus Pseudomonas were selected for their ability to inhibit the germination and growth of Leptochloa chinensis (L.) and Dactyloctenium aegyptium (L.) while promoting the growth of rice. These strains were applied to the target weeds and rice using different application methods viz. seed priming, liquid application, and foliar application. The results showed that all strains possessed herbicidal activity and significantly reduced growth of L. chinensis. Shoot length, root length, and fresh biomass of D. aegyptium were also significantly reduced in all strains by 60, 55, and 76%, respectively, with the exception of R15-4. Additionally, the growth suppression of both weed species was more prominent in the liquid application. The selected allelopathic strains also demonstrated plant growth-promoting traits and improved the growth and physiological parameters of rice in all three application methods, with the best results achieved with liquid and foliar applications. The survival efficiency of the bacterial strains was also tested using four different carrier materials, where the press mud was found the best carrier for controlling L. chinensis and D. aegyptium. [ABSTRACT FROM AUTHOR]

In Punjab, Pakistan, wheat production within the rice-wheat cropping system is frequently undermined by soil degradation and nutrient depletion, exacerbated by traditional agricultural practices. Addressing these challenges, this study evaluates the impact of green manuring and tillage practices on wheat productivity in rice-wheat cropping system, using a randomized complete block design (RCBD) with three replicates. The study examined twelve treatments combining green manuring (no green manuring, Sesbania, or Cluster bean) with rice cultivation methods (direct-seeded or transplanted) and tillage practices (zero or plough tillage). Wheat was sown following rice at a rate of 125 kg ha-1, with fertilizers applied in split applications. The analysis revealed significant differences across treatments. The highest number of fertile tillers (429 m-2 in 2020, 441 m2 in 2021) was recorded in Treatment 5 (Sesbania green manuring, direct-seeded rice, zero tillage wheat), while the lowest (322 m-2 in 2020, 329 m-2 in 2021) was in Treatment 4 (No green manuring, transplanted rice, plough tillage wheat). Similar trends were observed for spikelets per spike, grains per spike, and thousand grain weight, with Treatment 5 consistently performing the best. Biological yield was highest in Treatment 5 (13.12 t ha-1 in 2020, 13.42 t ha-1 in 2021), and grain yield peaked at 4.10 t ha-1 (2020) and 4.50 t ha-1 (2021) in Treatments 5 and 6. These findings underscore the benefits of integrating Sesbania green manuring with zero tillage and direct seeding of rice, significantly enhancing soil moisture retention and structure, which leads to improved wheat yields. [ABSTRACT FROM AUTHOR]

This study was carried out in Amritsar, Punjab, to find out how efficiently nutrients were used and how much energy was employed in direct-seeded rice (DSR) production. In this study, four levels of nitrogen (0, 40, 50, and 60 kg N ha−1) and three levels of phosphorus (0, 37.5, and 45 kg P2O5 ha−1) were tested. In a rice production system, the energy indices of various inputs and outputs were evaluated through the application of energy equivalency. The nutrient-use efficiencies in rice were assessed using different efficiency indices. The maximum grain yields of 38.9 q ha−1 and 36.9 q ha −1 were recorded at 50 kg N ha−1 and 45 kg P2O5 ha−1, respectively. On the other hand, application of nitrogen at 60 kg N ha−1 and phosphorus at 45 kg P2O5 ha−1 resulted in maximum straw yield of 57.1 q ha−1 and 51.1 q ha−1, respectively. In comparison with the control, application of 60 and 50 kg N ha−1 resulted in 161.9% and 151.0% higher grain yield, respectively. On the other hand, with applications of 45 kg P2O5 ha−1 and 37.5 kg P2O5 ha−1, an increase in the grain yield of 17.3 and 28.6%, respectively, over the control was recorded. Moving further towards nutrient-use efficiencies (NUEs), the highest values of partial factor productivity of nitrogen (PFPN), agronomic efficiency of nitrogen (AEN), partial nutrient balance of nitrogen (PNBN), and recovery efficiency of nitrogen (REN) were 89.1, 50.4, 1.78 and 0.72, respectively, which were obtained at 40 kg N ha−1, after which the values started decreasing steadily. In the case of phosphorus, the partial factor productivity (PFPP) of 88.6 was the maximum at 37.5 kg P2O5 ha−1, but partial nutrient balance (PNBP) of 0.36 and recovery efficiency (REP) of 0.08 were highest at 45 kg P2O5 ha−1. The main results revealed that the farmer field had an excessive amount of non-renewable energy inputs. The experimental field depicted greater energy-usage efficiency (EUE) of 4.5, energy productivity (EP) of 0.14, and energy profitability (EP1) of 3.5. These results were primarily ascribed to a significant drop in energy inputs under direct-seeded rice (DSR). In the case of non-renewable energy inputs, fertilizer made the maximum contribution to energy input (47.9%) in the farmer's field. We conclude that nutrient-use efficiencies and energy-use efficiency were highest at 50 kg N and 45 kg P2O5 ha−1. This recommendation is beneficial for farmers because lower inputs and higher outputs are the main objective of every farmer. [ABSTRACT FROM AUTHOR]

Pre-harvest yield prediction of direct-seeded rice is critical for guiding crop interventions and food security assessment in precision agriculture. Technology advances in unmanned aerial vehicle (UAV)-based remote sensing has provided an unprecedented opportunity to efficiently retrieve crop growth parameters instead of labor-intensive ground measurements. This study is aiming to evaluate the feasibility of fusing multi-temporal UAV-derived features collected at critical phenological stages in forecasting direct-seeded rice yield across different cultivars and nitrogen (N) management. The results showed that RGB sensor-derived canopy volume, canopy coverage, and spectral features including RBRI, WI etc., were identified to be most sensitive to the differences in aboveground biomass and grain yield. Heading stage was the suitable time for estimating yield performance (R2 = 0.75) for mono-temporal UAV observation. By contrast, multi-temporal features fusion could remarkably enhance the yield prediction accuracy. Moreover, the yield prediction accuracy can be further improved by integrating UAV features collected at panicle initiation and heading stages (i.e., rice reproductive phase) compared to multi-temporal features fusion (R2 increased from 0.82 to 0.85 and RMSE decreased from 35.1 to 31.5 g m−2). This can be attributed to the fact that the biomass accumulation during the reproductive phase was closely associated to the total spikelets and final yield. By using this proposed approach, the predicted yield showed a good spatial consistency with the measured yield across different cultivars and N management, and yield prediction error in the most of the plots (114 of 128 plots) was less than 45 g m−2. In summary, this study highlights that the reproductive phase is the optimal time window for UAV observing, which provides an effective method for accurate pre-harvest yield prediction of direct-seeded rice in precision agriculture. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adjusting nitrogen (N) input based on actual seedling density (ASD) and plant N status is a practical approach for improving the yield stability of direct‐seeded rice. However, the adjustment of topdressing N rates has been empirical in the past. This study aimed to establish a quantitative approach for determining N topdressing rates during tillering (Ntil) and panicle development (NPI) based on ASD and crop N status in direct‐seeded rice. Field experiments were conducted involving 12 treatments, consisting of four Ntil and three seeding rates in 2017, and eight treatments combining seeding rate, Ntil, and NPI in 2020. RESULTS: Linear regression analysis revealed that the tiller number at panicle initiation (TILPI) was predominantly influenced by ASD and Ntil. The determination coefficients (R2) of the regression models ranged from 0.887 to 0.936 across the four‐season experiments. The results indicated that Ntil could be determined accurately using ASD and the target maximum tiller number. Similarly, grain yield was influenced significantly by the N uptake at panicle initiation (NUPPI) and NPI, with R2 of 0.814 and 0.783 in the early and late seasons of 2020, respectively. This suggested that NPI could be calculated based on NUPPI and the target grain yield. CONCLUSION: The findings offer a quantitative method for establishing N topdressing rates for tillering and panicle development, relying on the monitoring of actual seedling density and plant N status in direct‐seeded rice production. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Weeds are a major obstacle in the widespread implementation of direct seeding of rice (DSR). Traditional weed control methods have raised serious environmental and health concerns. In this study rhizobacterial strains were assessed for the growth inhibition of Leptochloa chinensis, Dactyloctenium aegyptium, and promotion of rice. For initial screening, hydrogen cyanide (HCN) and Escherichia coli (E. coli) was employed. After screening, plant growth-promoting traits were assessed, and two in vitro growth reduction and growth promotion trials were conducted on weeds and rice. Based on 16S ribosomal RNA (16S rRNA) gene sequencing, all selected rhizobacteria belonged to Pseudomonas spp. The results of the laboratory experiment showed that strains R4-1 (Pseudomonas plecoglossicida) and R16-10 (Pseudomonas fluorescens) exhibited significant ability to inhibit the growth of selected weeds, while potential to enhance the growth of rice. Further evaluation in pot trial under ambient light and temperature conditions showed that the selected strains significantly reduced weed growth and yield parameters of both weeds compared to the control. Strains R16-10 and R4-1 decreased the biomass of Leptochloa chinensis and Dactyloctenium aegyptium by 20% and 15%, respectively. The trial confirmed that strain R16-10 significantly increased DSR growth traits infested with Leptochloa chinensis and Dactyloctenium aegyptium, including grain yield (10% and 12%) and photosynthetic rate (9% and 7%). Furthermore, strain R4-1 was also effective in promoting the growth, yield, and physiological attributes of DSR. These results suggest that the strain R16-10 and R4-1 can reduce Leptochloa chinensis and Dactyloctenium aegyptium growth while promoting DSR growth. [ABSTRACT FROM AUTHOR]

In Northeast China, transplanted rice cultivation has been adopted to extend the rice growing season and boost yields, responding to the limitations of the cumulative temperature zone and high food demand. However, direct-seeded rice offers advantages in water conservation and labour efficiency. The precise and timely monitoring of the distribution of different rice planting types is key to ensuring food security and promoting sustainable regional development. This study explores the feasibility of mapping various rice planting types using only early-stage satellite data from the rice growing season. We focused on Daxing Farm in Fujin City, Jiamusi City, Heilongjiang Province, for cropland plot extraction using Planet satellite imagery. Utilizing Sentinel-2 satellite imagery, we analysed the differences in rice's modified normalized difference water index (MNDWI) during specific phenological periods. A multitemporal Gaussian mixture model (GMM) was developed, integrated with the maximum expectation algorithm, to produce binarized classification outcomes. These results were employed to detect surface changes and map the corresponding rice cultivation types. The probability of various rice cultivation types within arable plots was quantified, yielding a plot-level rice-cultivation-type mapping product. The mapping achieved an overall accuracy of 91.46% in classifying rice planting types, with a Kappa coefficient of 0.89. The area extraction based on arable land parcels showed a higher R2 by 0.1109 compared to pixel-based area extraction and a lower RMSE by 0.468, indicating more accurate results aligned with real statistics and surveys, thus validating our study's method. This approach, not requiring labelled samples or many predefined parameters, offers a new method for rapid and feasible mapping, especially suitable for direct-seeded rice areas in Northeast China. It fills the gap in mapping rice distribution for different planting types, supporting water management in rice fields and policies for planting-method changes. [ABSTRACT FROM AUTHOR]

Direct-seeded rice (Oryza sativa) (DSR) is gaining increasing acceptance worldwide because it saves both time and labor. A covering treatment is a simple method to improve early plant growth under direct-seeding conditions. Herein, field experiments were conducted to study the effects of different powdered organic covering materials, i.e., organic fertilizer, seedling substrate, nutrient soil A, and nutrient soil B. In addition, the effects of different covering thicknesses were studied, including 5, 10, 15, and 20 mm, on the germination and early growth of DSR varieties. The two rice varieties Wufengyou 286 and Zhongjiazao 17 were used for this study. The seedling substrate at 15 mm and nutrient soil A at 5 mm covering thickness significantly increased the rate of germination of Wufengyou 286 by 43.93% and 40.26%, respectively, compared to the control treatment. Organic fertilizer, seedling substrate, and nutrient soil A at covering thicknesses of 5 mm significantly increased the germination rate by 42.57%, 38.62%, and 40.10%, respectively, compared to the control. Notably, all the treatments increased the emergence rate, with Wufengyou 286 exhibiting the most pronounced effect. The seedling substrate at 10 mm covering thickness significantly increased the rate of emergence of Wufengyou286 by 15.42% compared to the control. Similarly, the seedling substrate at 10 mm covering thickness gave the best results by increasing the rate of emergence of Zhongjiazao 17 by 10.85% compared to the control. On average, the rate of emergence of Wufengyou 286 and Zhongjiazao 17 under the experimental treatment increased by 11.81% and 6.45%, respectively, compared to the control. The appropriate cover treatment enhanced the early growth of DSR by improving its morphological attributes, such as plant height and dry weight, and regulating the physio-biochemical responses, such as the production of antioxidants and photosynthetic pigments. The seedling growth rate of both varieties decreased as the thickness increased. This study elucidated the effects of different covering materials on the early growth of DSR, which can further guide their actual production. [ABSTRACT FROM AUTHOR]

The objectives of this study were to explore the mechanism of stem mechanical strength in direct-seeded rice (DSR) as affected by paclobutrazol, especially its related endogenous hormone and cell wall component changes in culm tissue and response to the application of paclobutrazol. Field experiments were conducted in Changchun County, Jilin Province, China, by using two japonica rice varieties, Jiyujing and Jijing305, with soaking seeds in paclobutrazol at concentrations of (0 mg L−1, S0; 50 mg L−1; S1; 100 mg L−1; S2; 150 mg L−1, S3; 200 mg L−1, S4) in 2021 and 2022. The results suggest that the application of paclobutrazol increased the grain yield and reduced the lodging rate of DSR. Compared with the S0 treatments, soaking the seeds in paclobutrazol treatments rapidly shortened the length of the basal internode by decreasing the endogenous indole acetic acid (IAA) and gibberellin A3 (GA3) contents in culm tissue. The larger breaking strength (M) was attributed to a higher section modulus (SM) and bending stress (BS). The higher mechanical tissue thickness in culm tissue under paclobutrazol treatments, which was raised by higher endogenous zeatin and zeatin riboside (Z+ZR) content in culm tissue, increased the culm diameter, culm wall thickness, and section modulus (SM) of the internode. Compared with the S0 treatments, soaking the seeds in paclobutrazol treatments increased the cellulose content, lignin content, activities of lignin-related enzymes, and expression of key genes in lignin biosynthesis, as well as resulted in a higher bending stress (BS) to enhance the culm breaking strength (M).

Breeding for "weed competitive" cultivars is a prioritized goal under direct seeded rice (DSR) conditions for achieving higher grain yields. Early seedling vigour (ESV) is an imperative trait that imparts weed competitiveness through initial rapid growth and uniform crop establishment. African rice species Oryza glaberrima has been recognised as potential donors for weed competitive traits due to their early vegetative vigour. In the present study, 29 accessions of O. glaberrima were evaluated for early seedling vigour traits under laboratory and DSR conditions. Seedling vigour index-I and II estimated from the paper roll method under laboratory condition revealed that six O. glaberrima accessions (EC861796, EC861801, EC861804, EC861814, EC861819 and EC861820) had higher/similar seedling vigour indices than high vigour check Sabita. In addition, during Kharif 2017 and Rabi 2018, O. glaberrima accessions were phenotyped for nine ESV traits, e.g. seedling height, number of leaves/tillers, leaf area, shoot fresh/dry weight, absolute growth rate, specific leaf area and crop growth rate under DSR condition. Significant genetic variation and genotype × environment interaction was observed for ESV traits under DSR condition. The heritability estimates for ESV traits were ranging from low to high, indicating complex inheritance of the trait. The study identified six accessions of O. glaberrima (EC861787, EC861790, EC861792, EC861795, EC861819 and EC861820) as promising accessions with early seedling vigour based on mean performance in both seasons under direct seeded rice condition. Thus, our study demonstrated inherent nature of early seedling vigour in O. glaberrima and these promising accessions could be exploited for breeding weed-competitive rice cultivars. [ABSTRACT FROM AUTHOR]

Lodging is an important factor that limits rice yield and the large‐scale promotion of direct‐seeded rice (DSR). The objective of this study was to clarify the relationship between the characteristics of basal internodes and lodging and the physiological mechanism underlying this process in DSR. A field study was conducted in Changchun, Jilin Province, China, using a japonica rice variety Jiyujing with two direct seeding cultivation methods, including dry DSR (DDSR), wet DSR (WDSR) and conventional‐transplanted rice (CTSR) as a control in 2019 and 2020. Lodging‐related physical parameters, morphological characteristics and carbohydrate components of basal internodes were investigated at heading stage (HS) and 30 days after heading stage (HS30). The results showed that WDSR increased lodging index (LI) and lodging rate compared with CTSR and DDSR. LI increased rapidly from HS to HS30, primarily because of the significant reduction in the breaking strength (M). Correlation analysis revealed that the M of N4 internode was significantly positively correlated with culm plumpness and structural carbohydrate proportions at HS30. Culm plumpness decreased significantly, due to a decrease in nonstructural carbohydrate (NSC) content then primarily the decrease in starch proportions and content. Compared with CTSR and DDSR, WDSR decreased culm wall thickness, dry weight per centimetre of the culm and leaf sheaths, and the proportions and contents of cellulose, lignin and starch of internode, resulting in the decrease in internode breaking strength. Thus, it was concluded that the DSR reduced internode strength by reducing internode plumpness and carbohydrate content, thus decreasing lodging resistance. [ABSTRACT FROM AUTHOR]

Rice is one of the strategic crops in Egypt and the world. Therefore, the main objective of the research was to modify and develop the seed drill to suit the cultivation of rice and add the digger to make a path for the cultivation area to direct the irrigation water. The modification and development were done in the workshop of the Rice Mechanization Center (RMC) in Kafr El-Sheikh Governorate, and field experiments were carried out on the rice variety "Sakha Super 300" with the planting seasons 2021 and 2022. The field experiments were carried out using the modified hill seed drill under four different planting forward speeds, namely, 2.55, 4.01, 6.11, and 8.38 km/h.; three different hills spacing between within the row, namely, 12.5, 15.5 and 17.5 cm; and three different cell volumes of feeding rollers namely, 354, 428 and 509 mm³ with a fixed depth of 6 mm. The results showed that when the forward speed of cultivation increased, the field capacity increased and power requirements, and a decrement percentage in field efficiency and energy consumption at any given load for modified hill drill. The minimum values of grain yield (3.45, 3.41, and 2.94 Mg/fed) were obtained at planting forward speed of 8.38 km/h., for grain cell volume of 354 mm³ under 12.5, 15, 17.5 cm hill spacing, respectively. However, the maximum values of grain yield (4.79, 4.74, and 4.34 Mg/fed) were obtained at planting forward speed 2.55 km/h., and grain cell volume of 509 mm³ under 12.5, 15, and 17.5 cm hill spacing, respectively. [ABSTRACT FROM AUTHOR]

Background: Enhancing grain yield and nitrogen use efficiency (NUE) of rice is of great importance for sustainable agricultural development. Little effort has been made to increase grain yield and NUE of direct‐seeded rice under the double‐cropping system in South China. Field trials were conducted during 2018–2020 with four treatments, including nitrogen‐free, farmers' fertilization practice (FP), 'three controls' nutrient management (TC), and simplified and nitrogen‐reduced practice (SNRP). Results: Grain yield under SNRP averaged 6.46 t ha−1 during the three years and was 23.0% higher than that of FP but comparable to that of TC. Recovery efficiency (REN), agronomic efficiency (AEN), and partial factor productivity (PFPN) of nitrogen under SNRP increased by 12.0–22.7%, 159.3–295.0% and 94.6–112.5% respectively compared with FP. Harvest index and sink capacity increased by 7.3–10.8% and 14.9–21.3% respectively. Percentage of productive tillers (PPT) and biomass after heading increased by 24.0% and 104.5% respectively. Leaf nitrogen concentration at heading and nitrogen accumulation after heading increased by 16.3% and 842.0% respectively. Grain yield was positively correlated with PPT, sink capacity, harvest index, biomass and nitrogen accumulation after heading, REN, AEN, and PFPN. Conclusion: Grain yield and NUE under SNRP were superior to those under FP and comparable to those under TC. Increase in sink capacity, higher PPT, more biomass and nitrogen accumulation after heading, and greater harvest index were responsible for high grain yield and NUE in SNRP with reduced nitrogen fertilizer and labor input. SNRP is a feasible approach for direct‐seeded rice under a double‐cropping system in South China. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A growing population, changing climate, scarcity of resources, and the urgent need to achieve sustainable development goals makes it imperative to reimagine agriculture in a way that makes it economically profitable, climate-resilient, resource-efficient. Traditional rice production technology involving puddling and transplanting has often been criticized for its inefficient resource utilization, high cost of production, and emission of greenhouse gases such as methane. Direct-seeded rice (DSR), promoted for its climate-resilient nature, is often utilized by farmers in three different ways: broadcasting, line sowing, and zero tillage. However, these establishment methods have certain advantages and limitations, as perceived by farmers. The present study attempts to closely study the crop performance of rice under the abovementioned crop establishment methods. The study was conducted in farmers' fields in a way where both the farmers' freedom and research conditions were equally taken care of. The study aims to analyze crop performance while emphasizing farmers' field-based knowledge to ensure a lab-land-lab loop for understanding the scope of refinement in agronomic as well extension strategies. The results of this study reveal the superiority of zero tillage over broadcasting and line sowing in terms of crop performance and economic performance in the northwest alluvial plain zone of Bihar. The study has also identified the constraints associated with adoption of line sowing and zero tillage. [ABSTRACT FROM AUTHOR]

BACKGROUND: Direct‐seeded rice has been developed rapidly because of labor savings. Changes in rice cultivation methods put forward new requirements for nitrogen (N) fertilizer management practices. Field experiments with five different fertilizer ratios of basal, tillering and panicle fertilizer, namely N1 (10:0:0), N2 (6:2:2), N3 (4:3:3), N4 (2:4:4) and N5 (0:5:5), were conducted to investigate the effects of different N fertilizer management practices on yield formation, N uptakes, and ammonia (NH3) volatilization from paddy fields in direct‐seeded rice. RESULTS: The results showed that the N4 treatment improved grain yield by 5.1% while decreasing NH3 volatilization by 20.4% compared with that of conventional fertilizer treatment (N2). The panicle number per unit area was the key factor to determine the yield of direct‐seeded rice (72%). Excessive N application of basal fertilizer (N1) reduced seedling emergence, N use efficiency, and yield by 45.3%, 160.6%, and 6.9% respectively and increased NH3 volatilization by 28.1% compared with that of the N4 treatment. Removal of basal N fertilizer (N5) N reduced spike number and yield by 13.0% and 6.9% respectively, minimizing NH3 volatilization while affecting the construction of high‐yielding populations compared with that of the N4 treatment. CONCLUSION: Optimized N fertilizer management achieved delayed senescence (maintenance of higher leaf Soil Plant Analysis Development meter values in late reproduction), higher canopy photoassimilation (suitable leaf area), higher N fertilizer use efficiency, and less N loss (lower cumulative NH3 volatilization). © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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To explore the effects of different types of nitrogen fertilizers and different tillering ratios on runoff nitrogen loss, ammonia volatilization, and nitrogen fertilizer use efficiency in direct-seeded rice fields, seven nitrogen application treatments were arranged in field plot experiments with three replicates, including the blank control (CK) without nitrogen fertilizer, common compound fertilizer (base fertilizer), and urea (tiller fertilizer) at ratios of 4∶6 (U40) and 6∶4 (U60), controlled-release blended fertilizer (base fertilizer) and urea (tiller fertilizer) at ratios of 7∶3 (C70) and 10∶0 (C100), and seaweed polysaccharide urea at ratios of 4∶6 (H40) and 6∶4 (H60) . The results showed that runoff N loss mainly occurred after basal fertilizer application and was dominated by ammonium nitrogen (NH+ 4-N) . Compared with the U60 treatment, Total N loss in the C100, H60, U40, C70, and H40 treatments decreased by 7.20%, 13.36%, 24.30%, 26.41%, and 35.92%, respectively. The order of the amount and rate of ammonia volatilization loss between different N fertilizers was as follows： treatment of common compound fertilizer with urea > treatment of seaweed polysaccharide urea > treatment of controlled-release blended fertilizer with urea. Compared with the U60 treatment, the total ammonia volatilization loss in the U40, H60, H40, C70, and C100 treatments decreased by 7.89%, 20.81%, 27.84%, 42.08%, and 47.00%, respectively, with significant differences between the C70 and C100 treatments (P<0.05) . The total N losses from runoff were reduced by 24.30%, 20.70%, and 26.04% for U40, C70, and H40 treatments compared with U60, C100, and H60 treatments, respectively. N fertilizer setback reduced runoff N loss and ammonia volatilization loss in the U40, C70, and H40 treatments, with no yield loss. The maximum yield of 9 116.67 kg·hm-2 and the highest N fertilizer agronomic utilization of 29.64 kg·kg-1 occurred in the C70 treatment, and the apparent N fertilizer utilization was 41.99%. The study suggested that the C70 and C100 treatments both significantly reduced runoff N loss and ammonia volatilization loss in direct-seeded rice fields, while improving N fertilizer utilization efficiency and yield. The ratio of 7∶3 between controlled-release blended fertilizer (base fertilizer) and urea (tiller fertilizer) at the base tiller fertilizer ratio is worth pursuing for productivity and environmental protection. [ABSTRACT FROM AUTHOR]

Direct-seeded rice has been widely adopted in Asia in recent years. However, its low and unstable yields severely limit the increase in rice production and directly affect food security. The aim of this research was to investigate the effects of different concentrations of paclobutrazol seed soaking on the biomass production and yield formation of direct-seeded rice and to find the optimal concentrations to provide a theoretical basis for the high-yielding cultivation of direct-seeded rice. Two rice varieties, Jiyujing and Jijing305, were used in this experiment, and the seeds were soaked in paclobutrazol at concentrations of 0, 50, 100, 150, and 200 mg L−1. The appropriate concentration of paclobutrazol seed soaking increased the yield of direct-seeded rice; this was attributed to the increase in the spikelet per unit area and the seed setting rate. However, the too-high paclobutrazol concentration was not conducive to a yield increase. Regression analysis showed that the appropriate concentration of paclobutrazol seed soaking was 100–105 mg L−1. The appropriate concentration of paclobutrazol for seed soaking ensured the seedling emergence rate; improved the seedling quality, stem tillers, and productive tillers; increased the efficient leaf area, chlorophyll content, and net photosynthetic rate, resulting in an increase in dry matter accumulation; coordinated the source-sink relationship and dry matter distribution; and promoted the material translocation from the "source" to the "sink". In conclusion, using the appropriate concentration of paclobutrazol for seed soaking is an effective means of obtaining high yields of direct-seeded rice. [ABSTRACT FROM AUTHOR]

Direct-seeded rice (DSR) has received much attention because of its advantages in having low labor costs compared to the traditional transplanted rice (TPR). Investigating the differences in evapotranspiration (ET) partitioning and crop coefficients (Kc) between DSR and TPR is essential in understanding how agricultural water demand is affected by crop rotation. In this study, the water fluxes of two-year (2017–2018) growing seasons were collected from a pair of eddy covariance (EC) towers for DSR and TPR in the Poyang Lake Basin, Southern China. This study aims to compare the seasonal characteristics of the ET components (evaporation, E, and transpiration, T) and dual crop coefficients (basal crop coefficient, Ks·Kcb, and soil/water crop coefficient, Ke) of DSR with those of TPR. The ET values for the 2017 and 2018 growing seasons were 374 mm and 436 mm for the DSR, respectively, and 309 mm and 342 mm for the TPR. The seasonal T/ET values in 2017 and 2018 were 0.40 and 0.46 for the DSR, respectively, and 0.49 and 0.52 for the TPR, indicating that the higher ET values for the DSR can be mostly attributed to E. The DSR had overall higher Kc values than the TPR because of free water evaporation during the initial stage and a higher plant density. Our results enrich the Kc dataset for DSR and have great implications for the sustainable irrigation of the Poyang Lake Basin in the future. [ABSTRACT FROM AUTHOR]

Ammannia auriculata Willd. (eared redstem) has become one of the most troublesome weeds in paddy rice in China. Resistance to bensulfuron-methyl (BSM) has spread extensively in this species. Greenhouse and field experiments were conducted to determine how the eared redstem biotype and density affect competition against rice. In the greenhouse experiment, five treatments were tested: a BSM-susceptible biotype at low density (58 plants m−2, SL), a BSM-susceptible biotype at high density (288 plants m−2, SH), a BSM-resistant biotype at low density (RL), a BSM-resistant biotype at high density (RH), and a control without eared redstem (CK). Eared redstem grew slowly until 15 days after sowing (DAS); however, growth accelerated after 20 DAS, and the eared redstem plants were taller than the rice from 55 DAS on. The SH and RH treatments were associated with greater intraspecific competition: eared redstem plants in the SH and RH treatments had fewer branches, fewer capsules, and less shoot dry weight per individual plant relative to the SL and RL treatments. The SH and RH treatments also caused greater reductions in the rice yield. The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK. At 141 DAS, BSM-resistant plants were smaller than BSM-susceptible plants, suggesting a fitness cost of herbicide resistance in the absence of a herbicide. In the field study, eared redstem densities as low as 5 plants m−2 reduced the rice yield by 22%. A density of 50 eared redstem plants m−2 reduced the rice yield by 70%. Overall, these findings demonstrate that eared redstem is a highly aggressive weed species and threatens the rice yield even at a low density. However, the findings also demonstrate that BSM-resistant populations are less competitive. There is an urgent need to develop integrated management programs for this aggressive weed, which may include tactics to shift competitive dynamics in favor of rice. Additionally, this research provides the theoretical basis for the damage level, resistance risk evaluation, and management strategy of eared redstem in rice cropping systems. [ABSTRACT FROM AUTHOR]

Conventional tillage practices coupled with irrational use of fertilizer in the rice-wheat cropping system (RWCS) often leads to poor productivity, low nutrient use efficiency, and cause environmental pollution. Conservation tillage with surface residue retention in combination with intelligent nutrient management might improve productivity and use efficiency of water as well as nutrients in zero-till direct-seeded rice (ZTDSR). Keeping this in mind, during the kharif season of 2018 and 2019, a trial was carried out at the ICAR-IARI in New Delhi to investigate the varying nutrient management approaches following a precise manner in DSR. The treatments consisted of soil-test-based NPK (STB-NPK) and Nutrient Expert® (+LCCN) based NPK (NE-NPK) applications, Fertilizer applied at the recommended dose (RDF) [120-60-40 kg/ha NPK], the state recommended NPK (110-50-40 kg/ha) and omission plot technique of NPK [i.e., STB (N0PK, NP0K & NPK0); SR (N0PK, NP0K & NPK0) and NE-(N0PK, NP0K & NPK0)]. The results indicated that STB NPK application led to a 12% higher grain yield over RDF. However, NE-NPK resulted in a 7% and 35% increase in N (AEN) agronomic efficiency and P (AEP) over the STB-NPK application respectively. In contrast, AEk was 24% higher in STB-NPK over NE-NPK treatment. The comparison of two years' results that the first year performed better than the succeeding year in these respect (productivity and AE) except in the case of AEk. The N2O emission in NE-NPK treatment was also significantly reduced (49%) over the control (no N). STB-NPK treatment also improved profitability by 22% over RDF. Precision nutrient management (PNM) increased the crop yield, income, and use efficiency of nutrients and water and reduced greenhouse gas (GHG) emissions of DSR in Southeast Asia. [ABSTRACT FROM AUTHOR]

This study was carried out in Amritsar, Punjab, to find out how efficiently nutrients were used and how much energy was employed in direct-seeded rice (DSR) production. In this study, four levels of nitrogen (0, 40, 50, and 60 kg N ha−1) and three levels of phosphorus (0, 37.5, and 45 kg P2O5 ha−1) were tested. In a rice production system, the energy indices of various inputs and outputs were evaluated through the application of energy equivalency. The nutrient-use efficiencies in rice were assessed using different efficiency indices. The maximum grain yields of 38.9 q ha−1 and 36.9 q ha −1 were recorded at 50 kg N ha−1 and 45 kg P2O5 ha−1, respectively. On the other hand, application of nitrogen at 60 kg N ha−1 and phosphorus at 45 kg P2O5 ha−1 resulted in maximum straw yield of 57.1 q ha−1 and 51.1 q ha−1, respectively. In comparison with the control, application of 60 and 50 kg N ha−1 resulted in 161.9% and 151.0% higher grain yield, respectively. On the other hand, with applications of 45 kg P2O5 ha−1 and 37.5 kg P2O5 ha−1, an increase in the grain yield of 17.3 and 28.6%, respectively, over the control was recorded. Moving further towards nutrient-use efficiencies (NUEs), the highest values of partial factor productivity of nitrogen (PFPN), agronomic efficiency of nitrogen (AEN), partial nutrient balance of nitrogen (PNBN), and recovery efficiency of nitrogen (REN) were 89.1, 50.4, 1.78 and 0.72, respectively, which were obtained at 40 kg N ha−1, after which the values started decreasing steadily. In the case of phosphorus, the partial factor productivity (PFPP) of 88.6 was the maximum at 37.5 kg P2O5 ha−1, but partial nutrient balance (PNBP) of 0.36 and recovery efficiency (REP) of 0.08 were highest at 45 kg P2O5 ha−1. The main results revealed that the farmer field had an excessive amount of non-renewable energy inputs. The experimental field depicted greater energy-usage efficiency (EUE) of 4.5, energy productivity (EP) of 0.14, and energy profitability (EP1) of 3.5. These results were primarily ascribed to a significant drop in energy inputs under direct-seeded rice (DSR). In the case of non-renewable energy inputs, fertilizer made the maximum contribution to energy input (47.9%) in the farmer’s field. We conclude that nutrient-use efficiencies and energy-use efficiency were highest at 50 kg N and 45 kg P2O5 ha−1. This recommendation is beneficial for farmers because lower inputs and higher outputs are the main objective of every farmer.

In Northeast China, transplanted rice cultivation has been adopted to extend the rice growing season and boost yields, responding to the limitations of the cumulative temperature zone and high food demand. However, direct-seeded rice offers advantages in water conservation and labour efficiency. The precise and timely monitoring of the distribution of different rice planting types is key to ensuring food security and promoting sustainable regional development. This study explores the feasibility of mapping various rice planting types using only early-stage satellite data from the rice growing season. We focused on Daxing Farm in Fujin City, Jiamusi City, Heilongjiang Province, for cropland plot extraction using Planet satellite imagery. Utilizing Sentinel-2 satellite imagery, we analysed the differences in rice’s modified normalized difference water index (MNDWI) during specific phenological periods. A multitemporal Gaussian mixture model (GMM) was developed, integrated with the maximum expectation algorithm, to produce binarized classification outcomes. These results were employed to detect surface changes and map the corresponding rice cultivation types. The probability of various rice cultivation types within arable plots was quantified, yielding a plot-level rice-cultivation-type mapping product. The mapping achieved an overall accuracy of 91.46% in classifying rice planting types, with a Kappa coefficient of 0.89. The area extraction based on arable land parcels showed a higher R2 by 0.1109 compared to pixel-based area extraction and a lower RMSE by 0.468, indicating more accurate results aligned with real statistics and surveys, thus validating our study’s method. This approach, not requiring labelled samples or many predefined parameters, offers a new method for rapid and feasible mapping, especially suitable for direct-seeded rice areas in Northeast China. It fills the gap in mapping rice distribution for different planting types, supporting water management in rice fields and policies for planting-method changes.

The rice-wheat rotation system is an important planting system in the middle and lower reaches of the Yangtze River. Studies on the effects of different rice planting methods on the water, energy, and carbon footprints of subsequent wheat have rarely been reported. In this study, the effects of different rice cultivation practices on the water, energy, and carbon footprints of subsequent wheat were investigated among different rice-wheat rotation systems including dry direct-seeded rice (DSR)-wheat rotation, wet direct-seeded rice (WSR)-wheat rotation and transplanted rice(TPR)-wheat rotation. Results showed that the yield of wheat after DSR was 8,552 kg ha−1, which was 14.61 and 4.72% higher than the yields after WSR and TPR, respectively. In addition, the water and carbon footprints of wheat after DSR were lower than those after WSR and TPR, while its energy and carbon production efficiencies and net ecosystem economic benefits were higher than those after WSR and TPR. Notably, the use of fertilizers and fuel are the two major contributors to the high energy inputs and greenhouse gas emissions in wheat production. In summary, wheat after DSR has higher ecological and economic benefits, and we recommend that it be promoted as the preferred wheat planting model in rice-wheat rotation areas.

Introduction/Background: Direct-seeded rice is exceptionally vulnerable to chilling stress, especially at the seed germination and seedling growth stages in the early season of the double cropping system. Methods: Therefore, we conducted two experiments to evaluate the role of various seed primings and their different concentrations of plant growth regulators [experiment 1--abscisic acid (ABA), gibberellin (GA3), salicylic acid (SA), brassinolide (BR), paclobutrazol, uniconazole (UN), melatonin (MT), and jasmonic acid (JA)] and osmopriming substances (chitosan, polyethylene glycol 6000 (PEG6000), and CaCl2) and experiment 2--GA, BR (two best), CaCl2 (worst), and control (CK)] on rice seedlings under low temperature condition. Results: Results showed that the maximum germination rate of 98% was recorded in GA3 (10 mgL-1) and BR (0.3 mgL-1) among treatments. Compared to CK, root and shoot length were improved in ABA (0.5 mgL-1) and GA3 (100 mgL-1) by 64% and 68%, respectively. At the same time, root and shoot weights (fresh and dry) were enhanced in Paclobutrazol (300 mgL-1) and GA3 among treatments. Furthermore, the average root volume, average root diameter, and total root surface area were increased by 27%, 38%, and 33% in Paclobutrazol (300 mgL-1), Paclobutrazol (200 mgL-1) and JA (1 mgL-1) treatments, respectively compared to CK. In the second experiment, a respective increase of 26%, 19%, 38%, and 59% was noted in SOD, POD, CAT, and APX enzyme activities in GA treatment compared to CK. Similarly, proline, soluble sugar, soluble protein, and GA content were also improved by 42%, 25.74%, 27%, and 19%, respectively, in GA treatment compared to CK. However, a respective reduction of 21% and 18% was noted in MDA and ABA content in GA treatment compared to CK. Our finding highlighted that better germination of primed-rice seedlings was associated with fresh and dry weights of the roots and shoots and the average root volume of the seedlings. Discussion: Our results suggested that GA3 (10 mg L-1) and BR (0.3 mg L-1) seed priming prevent rice seedlings from chilling-induced oxidative stress by regulating antioxidant enzyme activities and maintaining ABA, GA, MDA, soluble sugar, and protein content. However, further studies (transcriptome and proteome) are needed to explore the molecular mechanisms involved in seed priming-induced chilling tolerance under field conditions. [ABSTRACT FROM AUTHOR]

Weed menace is the major biotic constraint in direct-seeded rice (DSR) cultivation as they cause higher yield loss. Hence, exploring different weed management options along with intercropping could be promising practice for improving crop productivity. Keeping this in view, an experiment was conducted at Pantnagar, Uttarakhand, India in 2015 and 2016 to evaluate the effect of different weed management practices in the DSR + Brahmi intercropping system for providing farmers with a practical and economically viable weed control solution. Two intercropping ratios along with four weed management practices in sole rice and sole Brahmi as control were evaluated. The results revealed the significant effect of weed management and intercropping on weed control efficiency (WCE) and different competition indices. The highest WCE (73.3 and 83.3%) was recorded with pendimethalin (pre-emergence) + cyhalofop-butyl (post-emergence) + 1 HW (hand weeding) at 45 DAS (days after sowing) in 2:1 ratio treatment. Similarly, significantly minimum density and weed biomass were also recorded under the same treatment. However, significantly higher values of relative yield total, aggressivity, relative crowding coefficient, and competition ratio were recorded in a 1:1 ratio of DSR + Brahmi. In conclusion, using Brahmi as an intercrop with DSR can help with weed management, reduces the use of pesticides, and increases profitability. [ABSTRACT FROM AUTHOR]

Compared with the standard method of manual fertilizer broadcasting (MFB), mechanized hill-drilling direct-seeding with deep application of slow-release nitrogen fertilizer (MHDDF) is an efficient method to integrate both fertilization and seeding. However, there are few studies that combine the use of slow-release fertilizer with MHDDF. We sought to explore the combined effect of MHDDF with slow-release fertilizer on rice yield and nitrogen, phosphorus, and potassium utilization, compared to MFB. We compared three different MHDDF methods (D30: 450 kg ha−1, D40: 600 kg ha−1, D50: 750 kg ha−1), with one MFB method (B50: 750 kg ha−1), and one control (CK: 0 kg ha−1). We found that the yield of all MHDDF method was higher than that of both the MFB method. Yield was the highest in the D50 treatment and was 14.14–46.03% higher than that in B50 treatment. Biomass accumulation, nutrient accumulation, and nutrient use efficiency were similarly higher in MHDDF method than both MFB and CK. Compared to B50, the D50 treatment increased nitrogen recovery efficiency by 170.53–231.50%, phosphorus recovery efficiency by 480.00–724.25%, and potassium recovery efficiency by 201.55–169.59%. Overall, we found that combining MHDDF with slow-release fertilizer was an effective method to increase rice yield and nutrient use efficiency compared with MFB. [ABSTRACT FROM AUTHOR]