Rice Production Systems Research Articles

Registration of ‘CLL17’ rice

Abstract‘CLL17’ (Reg. no. CV‐160; PI 693941), a high‐yielding long‐grain rice (Oryza sativa L.) cultivar, was developed by the Louisiana State University Agricultural Center at the H. Rouse Caffey Rice Research Station near Crowley, LA, and approved for release in 2020. CLL17 contains the herbicide‐resistant gene for use in the Clearfield rice production system. The Clearfield rice production system is defined as the brand of rice cultivars that are tolerant to imidazolinone herbicides. CLL17 was derived from the cross ‘CL131’/‘Trenasse’. It showed good yield potential and favorable agronomic characteristics in the 2015 Clearfield Preliminary Yield Trial. In 2016, it was evaluated in the uniform regional rice nursery trial across four southern states. From 2017 to 2022, CLL17 was evaluated in 50 replicated trials across 10 locations in Louisiana. Three high‐yielding commercial cultivars were included as checks: ‘Cheniere’, ‘CL153’, and ‘CL111’. The grain yield of CLL17 was 9.0 t ha−1 compared with 8.9 t ha−1 for CL153, 8.3 t ha−1 for CL111, and 8.2 t ha−1 for Cheniere across 25 commercial advanced trials from 2017 to 2020. CLL17 had a similar plant height to CL111, 2‐cm taller than CL153, and 5‐cm taller than Cheniere. It exhibits typical US long‐grain rice cooking quality with intermediate amylose and gel temperature. CLL17 is susceptible to sheath blight [caused by Rhizoctonia solani Kuhn ], resistant to Cercospora spp., leaf blast [caused by Magnaporthe grisea (T.T. Hebert)], and neck blast, and moderately susceptible to bacterial panicle blight (caused by Burkholderia glumae).

Ergonomic Evaluation Of Farm Women’s Drudgery In Rice Production System: Current Research Trends

Women are the backbone of agricultural workforce but worldwide her hard work has mostly been unpaid. She does the most tedious and back-breaking tasks in agriculture, animal husbandry and homes. Farmwomen’s participation was crucial in various operations such a sowing/transplanting (86%), weeding (84%), storage of grains (78%), land preparation (72%), cleaning seed for sowing (70%), gap filling (68%), manure and fertilizer application (68%), harvesting (64%), and threshing and winnowing (62%).During the peak season of sowing and harvesting rural women spend 8-9 hours in the field. Women’s contribution to the operations related to wheat and rice cultivation is significantly higher than that of men in terms of man days of work done. All of these activities contribute to anincrease in the physiological costs and physical loads to a great extent. It also causes unbalancing of the body with heavy workloads. Musculoskeletal disorders are common among farm workers especially lower and upper back disorders due to bending and squatting body posture in manual rice transplanting and uprooting activity. Considering the above facts and point of view, it was proposed to investigate changes in the physiological responses and perceived exertion due to heavy workloads and body postures in rice production system. to better understand how the manual rice production system activity perform, identify potential health risk factors, and gain insight into the health effects of the task.

Agronomic assessment of rice genotypes (Oryza sativa) under different levels of fertilizer application: A review

The current rice production system, centered around the high-input green revolution methods, tends to favour affluent farmers, leaving lower-income farmers unable to fully embrace modern agricultural techniques due to soaring input prices. In India, shrinking cultivable land and a growing population have led to intensified agronomic practices like heavy chemical fertilizer usage mainly impacting soil health and crops productivity especially rice. This trend has discouraged poorer farmers from rice cultivation due to diminishing factor productivity and profitability amidst rising input expenses, posing significant concerns about sustainability and economic viability. In this context, the review aims to assess how rice (Oryza sativa L.) genotypes perform when exposed to varying levels of fertilizer application, providing valuable insights into their adaptability and potential for increased productivity and soil fertility. It was investigated how different fertilizer levels, specifically nitrogen, phosphorus, and potassium, affects important agronomic practices, yield-related parameters, and grain quality in various rice genotypes. A diverse set of genotypes represent a broad spectrum of genetic background and adaptation strategies, including those known for their efficiency in using nutrients. Highlighting how the robustness of certain genotypes under conditions with limited nutrients maintained satisfactory yields and grain quality. In contrast, some genotypes demonstrated superior performance under higher fertility conditions, resulting in significant yield increases, larger grain sizes, and improved nutritional profiles. These approaches optimize fertilizer application, reduce the environmental impacts associated with excessive nutrient use, and ultimately enhance overall rice production.

The Identification, Characterization, and Functional Analysis of the Sugar Transporter Gene Family of the Rice False Smut Pathogen, Villosiclava virens.

False smut, caused by Villosiclava virens, is becoming increasingly serious in modern rice production systems, leading to yield losses and quality declines. Successful infection requires efficient acquisition of sucrose, abundant in rice panicles, as well as other sugars. Sugar transporters (STPs) may play an important role in this process. STPs belong to a major facilitator superfamily, which consists of large multigenic families necessary to partition sugars between fungal pathogens and their hosts. This study identified and characterized the STP family of V. viren, and further analyzed their gene functions to uncover their roles in interactions with rice. Through genome-wide and systematic bioinformatics analyses, 35 STPs were identified from V.virens and named from VvSTP1 to VvSTP35. Transmembrane domains, gene structures, and conserved motifs of VvSTPs have been identified and characterized through the bioinformatic analysis. In addition, a phylogenetic analysis revealed relationship between VvSTPs and STPs from the other three reference fungi. According to a qRT-PCR and RNA-sequencing analysis, VvSTP expression responded differently to different sole carbon sources and H2O2 treatments, and changed during the pathogenic process, suggesting that these proteins are involved in interactions with rice and potentially functional in pathogenesis. In total, 12 representative VvSTPs were knocked out through genetic recombination in order to analyze their roles in pathogenicity of V. virens. The knock-out mutants of VvSTPs showed little difference in mycelia growth and conidiation, indicating a single gene in this family cannot influence vegetative growth of V. virens. It is clear, however, that these mutants result in a change in infection efficiency in a different way, indicating that VvSTPs play an important role in the pathogenicity of virens. This study is expected to contribute to a better understanding of how host-derived sugars contribute to V. virens pathogenicity.

Profitability differentials between broadcasting and transplanting system of rice production in Southeast, Nigeria

The study examined the profitability differentials between the broadcasting and transplanting systems of rice production in the Southeast, A multi-stage sampling method was used to randomly select 384 (192 broadcasters and 192 transplanters). Data collected were analyzed using descriptive statistics, budgetary method, and inferential statistics of paired t-tests. The study found that the mean age of farmers under the broadcasting system and transplanting system were 50yrs and 43yrs respectively. Result on profitability level showed that the Net Returns were ₦1,569,053.11 and ₦5,628,752.33 for farmers under broadcasting and those under transplanting system, the return on investment (ROI) was 0.72 or 72.0% and 1.92 respectively, with a profitability index of 45.5% for broadcasting system and 68.9% for transplanting system respectively. The null hypothesis was rejected because there was a (6.59)*** substantial difference in the profit margin of the production systems. The study identified the following constraints; high cost of labour, poor quality seedlings, climatic changes, inadequate storage facilities and high cost of equipment among others. Policymakers are recommended to proactively address these challenges to enhance the effectiveness and efficiency of these farmers.

Does Demographic Backgrounds Affect Agricultural Drone Technology in Granary Areas?

The adoption of technology in paddy sector appears to have coincided with the advancement of the country’s development, as the agricultural sector is likewise undergoing the Industrial Revolution 4. Over the years, the Malaysian rice production system has faced a number of challenges, including extreme weather conditions, poor soil fertility and nutrient management, farmers’ lack of awareness and knowledge, reluctance to use genetically modified planting materials, and poor technology deployment. Despite the adoption of drone in the paddy farming is seem gradually increasing, the factor effecting the adoption remains unclear. Thus, this study investigates the association between socio-demographic profiles and their adoption towards drone technology in selected granary areas. A cross-sectional study was conducted among 384 paddy farmers using a self-administered questionnaire, selected through cluster random sampling. Result found that there are no association between age, education level, experience, farm size and income. The finding recommend that government should provide opportunities for all paddy farmers regardless their background in adopting drone technology to improve the modernization in paddy industry.

Higher rice yield and lower greenhouse gas emissions with cattle manure amendment is achieved by alternate wetting and drying

ABSTRACT Climate change and water scarcity threaten the sustainability of rice production systems. Alternate wetting and drying (AWD) is a promising option to reduce methane (CH4) emission from irrigated paddy fields. However, its effect on rice yield remains to be clarified. Organic amendment can increase rice yield but may also increase CH4 emission. We therefore hypothesized that the combination of AWD with organic amendment could both increase rice yield and decrease CH4 emission. We carried out field experiments in six consecutive rice seasons during 2019 − 2022 in Central Java, Indonesia. We examined the effect of water management (continuous flooding [CF] and AWD) with (+M) and without (−M) the amendment of cattle manure as a locally available organic matter on rice growth and yield and the emissions of CH4 and nitrous oxide (N2O). AWD significantly (p < 0.05) decreased CH4 emission by 29% but marginally (p < 0.1) increased N2O emission by 10% relative to CF. There was no significant effect of AWD alone on rice yield. AWD significantly increased water productivity (the ratio of rice yield to irrigated water volume) by 50%. Cattle manure amendment significantly increased CH4 emission by 12% and rice yield by 5% but did not affect N2O emission. The combination effect of AWD+M relative to CF−M (control) was additive and resulted in a 7% increase in rice yield, a 19% decrease in the global warming potential (GWP) of CH4 + N2O emissions during both growing and fallow periods, and a 24% decrease in yield-scaled GWP. Our results indicated that the combination of AWD with cattle manure amendment would be a promising means to increase rice yield while reducing total soil greenhouse gas emission from irrigated rice paddies.

Multifunctionality of Rice Production Systems in Asia a Synoptic Review &lt;br&gt;

Multifunctionality of Rice Production Systems in Asia a Synoptic Review &lt;br&gt;

Unravelling spatial drivers of topsoil total carbon variability in tropical paddy soils of Sri Lanka

This study aimed to map and identify the spatial drivers of total carbon (TC) concentration in topsoil (0–15 cm) across paddy-growing regions in tropical climates using Sri Lanka as a case study. For model calibration, a total of 888 sampling locations were sampled using the conditioned Latin Hypercube sampling approach with a sample density of one sample per 11 km2. Additionally, 99 sampling sites were selected using a design-based (probabilistic) stratified random strategy for independent evaluation of the developed models. Two distinct spatial random forest (RF) models were developed using a variety of environmental covariates: Model 1: using all environmental covariates without variable selection; Model 2: only incorporated covariates selected based on the forward selection process. Evaluation of model quality using fully independent validation sites revealed that both Model 1 and Model 2 performed similarly. Based on the spatial estimates of Model 1 across the paddy-growing regions of Sri Lanka, the predicted TC concentration varied from 0.89% to 13.15%. The highest predicted TC concentration range was in the Wet zone (2.06% to 13.15%), followed by the Intermediate zone (1.18% to 7.23%), and the lowest was reported in the Dry zone (0.86% to 4.30%). In the spatial estimates of Model 2, the predicted values varied between 0.86% and 13.29% and were similar to Model 1. The highest predicted TC concentration range was in the Wet zone (2.09% to 13.29%), followed by the Intermediate zone (1.08% to 6.99%), and the lowest was reported in the Dry zone (0.86% to 4.30%) following the similar pattern to Model 1. In fact, this clearly showed the importance of mean annual rainfall on the dynamics of TC in tropical rice production systems. Furthermore, the variable importance plot of the RF models revealed that out of all considered environmental covariates, the mean annual rainfall was identified as being the most important variable in the developed spatial prediction function. Moreover, we deployed an area of applicability (AOA) calculation to quantify and identify regions where prediction is less reliable and quantified the prediction uncertainty using a bootstrapping approach. Additionally, we assessed the influence of increasing the number of calibration sites on model prediction quality and reliability using user defined sequence of calibration sites. Independent evaluations of each model indicated that model performance quality indices were improved up to n = 400 and thereafter stagnated. For AOA results, an improvement in model reliability is observed for Wet and Intermediate zones when models are developed using 400 calibration sites. Derived estimates of TC can be used for regional-scale planning to enhance the soil carbon and provide a baseline for designing a future land-based carbon accounting system for Sri Lanka.

Climate Smart Irrigation Practices for Improving Water Productivity in India: A Comprehensive Review

India, supporting 17% of the global population, from limited land (2.4% of the world's total) and freshwater resources (4%), faces severe water scarcity issues. The country experiences heightened challenges due to a monsoon climate leading to floods and droughts. Irrigation efficiency in India is 35-40% and irrigated area ~48.9%. To meet the demands of a large or growing population in limited land and water resources, climate-smart irrigation practices (CSIPs) are imperative. These practices not only increase yield but also precisely supply water, reduce water application volume, and enhance soil health under changing climate conditions. Precision water management technologies includes; advanced agro-techniques, micro-irrigation, conservation agriculture, crop diversification, integrated farming systems, and water harvesting. Micro-irrigation, encompassing drip and sprinkler systems, emerges as a critical solution for efficient water use. Techniques like Surface Drip Irrigation and Sub-surface Drip Irrigation (SSDI) not only save water but also enhance nutrient transport and reduce labor costs. The automation of micro-irrigation through sensors and wireless communication revolutionizes traditional practices, ensuring precise water management and boosting agricultural productivity. In addition, advanced agro-techniques, including laser land leveling, furrow-irrigated raised beds, aerobic rice cultivation, system of rice intensification, ground cover cum rice production system and Saguna rice technique have good potential to save water and improve water productivity. Implementing these advanced agro-techniques not only conserves water but also contributes to sustainable agriculture by improving overall water productivity, reducing environmental impact, and enhancing crop productivity. The integration of conservation agriculture (minimum soil disturbance, crop residue cover and crop diversification), integrated farming systems (combine diverse agricultural activities synergistically), and water harvesting is imperative for sustainable water management. This review paper systematically compiles climate-smart irrigation practices, including precision water management, combined with conservation agriculture, crop diversification, integrated farming systems, and water harvesting. This review paper offers researchers a comprehensive understanding of different CSIPs, assessing their impact on water conservation, increased crop and water productivity, and sustainability amid climate change. Farmers can gain practical understandings of CSIPs, while policymakers obtain essential information for addressing national water mission goals.

Recycling potassium from cow manure compost can replace potassium fertilizers in paddy rice production systems

The prevalence of K deficiency and negative K balance in rice production increases the demand for K fertilizer. However, the primary source of K fertilizer, potash rock, is limited. Recycling K from cow manure compost (CMC) is a sustainable solution. Nevertheless, the effects of substituting K fertilizer with CMC on rice yield, soil K fertility, and partial K balance (PKB) are not well understood. Therefore, a field experiment with four treatments (control - unfertilized, MNP K - CMC plus NPK fertilizer, MNP ½ K - CMC plus NP and 50 % K fertilizer, and MNP - CMC plus NP fertilizer) was conducted from 2020 to 2022 to study the effects of replacing K fertilizer with K from CMC on rice growth, yield, plant K uptake, soil K fertility, and PKB. The results indicated that K input from CMC exceeded the recommended K fertilizer level, sufficient for optimal rice growth and yield over three growing seasons and plant K uptake in the last two seasons. Plant K uptake increased with total K input and reached a plateau when total K input approached the maximum plant K uptake. In the MNP treatment, PKB was negative in the first two seasons but became positive in the last season, owing to the equivalence between K input from CMC and plant K uptake. Key factors influencing PKB in this treatment were K input from CMC and plant K uptake. Increasing the CMC application rate during the first two seasons could lead to a positive PKB. In this treatment, soil exchangeable K changed correspondingly with PKB, decreasing in the first two seasons but increasing in the last season. Overall, determining the appropriate amount of CMC application for a positive PKB is vital for the sustainability of substituting K fertilizer with K from CMC in paddy rice systems.

Sustaining rice productivity through weather-resilient agricultural practices.

Enhancing productivity and profitability and reducing climatic risk are the major challenges for sustaining rice production. Extreme weather can have significant and varied effects on crops, influencing agricultural productivity, crop yields and food security. In this study, a comparative evaluation of two crop management systems was performed involving farmers adopting a weather forecast-based advisory service (WFBAS) and usual farmers' practice (FP). WFBAS crop management followed the generated weather forecast-based advice whereas the control farmers (FP) did not receive any weather forecast-based advice, rather following their usual rice cultivation practices. The results of the experiments revealed that WFBAS farmers had a significant yield advantage over FP farmers. With the WFBAS technology, the farmers used inputs judiciously, utilized the benefit of favorable weather and minimized the risk resulting from extreme weather events. As a result, besides the yield enhancement, WFBAS provided a scope to protect the environment with the minimum residual effect of fertilizer and pesticides. It also reduced the pressure on groundwater by ensuring efficient water management. Finally, the farmers benefited from higher income through yield enhancement, reduction of the costs of production and reduction of risk. A successful and extensive implementation of WFBAS in the rice production system would assist Bangladesh in achieving Sustainable Development Goal 2.4, which focuses on rice productivity and profitability of farmers as well as long-term food security of the country. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A Comprehensive Step-by-Step Guide to Using Data Science Tools in the Gestion of Epidemiological and Climatological Data in Rice Production Systems

The application of data science (DS) techniques has become increasingly essential in various fields, including epidemiology and climatology in agricultural production systems. In this sector, traditionally large amounts of data are acquired, but not well-managed and -analyzed as a basis for evidence-based decision-making processes. Here, we present a comprehensive step-by-step guide that explores the use of DS in managing epidemiological and climatological data within rice production systems under tropical conditions. Our work focuses on using the multi-temporal dataset associated with the monitoring of diseases and climate variables in rice in Colombia during eight years (2012–2019). The study comprises four main phases: (I) data cleaning and organization to ensure the integrity and consistency of the dataset; (II) data management involving web-scraping techniques to acquire climate information from free databases, like WordClim and Chelsa, validation against in situ weather stations, and bias removal to enrich the dataset; (III) data visualization techniques to effectively represent the gathered information, and (IV) a basic analysis related to the clustering and climatic characterization of rice-producing areas in Colombia. In our work, a process of evaluation and the validation of climate data are conducted based on errors (r, R2, MAE, RSME) and bias evaluation metrics. In addition, in phase II, climate clustering was conducted based on a PCA and K-means algorithm. Understanding the association of climatic and epidemiological data is pivotal in predicting and mitigating disease outbreaks in rice production areas. Our research underscores the significance of DS in managing epidemiological and climatological data for rice production systems. By applying a protocol responsible for DS tools, our study provides a solid foundation for further research into disease dynamics and climate interactions in rice-producing regions and other crops, ultimately contributing to more informed decision-making processes in agriculture.

Unlocking the Energy-Water-Carbon Nexus in Rice Cultivation: A Comprehensive Review

Rice cultivation, as a cornerstone of global food security, holds significant environmental implications due to its carbon, water, and energy footprints. Energy, carbon and water footprint assessments can be powerful tools to guide sustainable food production systems. Due to higher water losses in conventional rice culture, the irrigation water footprint associated with rice cultivation increases, thereby elevating the energy and carbon footprint. Improper use of resources like fertilizers, pesticides, labour and fuel may lead to higher energy consumption. Several alternative rice production systems like Direct Seeded Rice (DSR), Alternate Wetting and Drying (AWD), System of Rice Intensification (SRI) as well as better nutrient management practices have been developed and refined to reduce energy, carbon and water footprint associated with rice cultivation. This review presents a comprehensive analysis of the intricate interplay between these footprints, highlighting potential trade-offs and synergies that warrant attention within the context of rice cultivation. Moreover, this review discusses in detail the significance of selecting appropriate rice cultivation techniques, such as direct seeded rice, SRI and alternate wetting and drying suitable for different ecologies in comparison to transplanted method of rice cultivation.

Ground Cover Rice Production System Affects Soil Water, Nitrogen Dynamics and Crop Growth Differentially with or without Climate Stress.

The ground cover rice production system (GCRPS) has been proposed as a potential solution to alleviate seasonal drought and early low-temperature stress in hilly mountainous areas; clarifying its impact on crop growth is crucial to enhance rice productivity in these areas. A two-year (2021-2022) field experiment was conducted in the hilly mountains of southwest China to compare the effects of the traditional flooding paddy (Paddy) and GCRPS under three different nitrogen (N) management practices (N1, zero-N fertilizer; N2, 135 kg N ha-1 as a urea-based fertilizer; and N3, 135 kg N ha-1 with a 3:2 base-topdressing ratio as urea fertilizer for the Paddy or a 1:1 basal application ratio as urea and manure for GCRPS) on soil water storage, soil mineral N content and crop growth parameters, including plant height, tiller numbers, the leaf area index (LAI), aboveground dry matter (DM) dynamics and crop yield. The results showed that there was a significant difference in rainfall between the two growth periods, with 906 mm and 291 mm in 2021 and 2022, respectively. While GCRPS did not significantly affect soil water storage, soil mineral N content, and plant height, it led to a reduction in partial tiller numbers (1.1% to 31.6%), LAI (0.6% to 20.4%), DM (4.4% to 18.8%), and crop yield (7.4% to 22.0%) in 2021 (wet year) compared to the Paddy. However, in 2022 (dry year), GCRPS led to an increase in tiller numbers (13.7% to 115.4%), LAI (17.3% to 81.0%), DM (9.0% to 62.6%), and crop yield (2.9% to 9.2%) compared to the Paddy. Structural equation modeling indicated that GCRPS significantly affected tiller numbers, plant height, LAI, DM, and productive tiller numbers, which indirectly influenced crop yield by significantly affecting tiller numbers and productive tiller numbers in 2022. Overall, the effects of GCRPS on soil water and N dynamics were not significant. In 2021, with high rainfall, no drought, and no early, low-temperature stress, the GCRPS suppressed crop growth and reduced yield, while in 2022, with drought and early low-temperature stress and low rainfall, the GCRPS promoted crop growth and increased yield, with tiller numbers and productive tiller numbers being the key factors affecting crop yield.

Effectiveness of preemergence- and postemergence-applied oxyfluorfen in rice compared to current standards

Abstract Control of barnyardgrass is becoming increasingly difficult as plants evolve resistance to herbicides. ROXY oxyfluorfen-resistant rice (ROXY® Rice Production System) has been developed to provide an alternative mode of action for controlling barnyardgrass and other weeds. In 2021 and 2022, field trials were conducted at the Pine Tree Research Station near Colt, AR; the Northeast Research and Extension Center in Keiser, AR; and the University of Arkansas Pine Bluff Small Farm Research Center near Lonoke, AR, to determine the level of weed control and crop tolerance following oxyfluorfen applied preemergence (PRE) or postemergence (POST) relative to herbicides currently labeled for use in rice crops. When applied post-plant PRE on silt loam soil, oxyfluorfen alone at 1,120 and 1,680 g ai ha−1 resulted in barnyardgrass control comparable to that of clomazone applied alone at 336 g ha−1. Still, injury to rice was often greater than with clomazone, ranging from 20% to 45%. On clay soil, oxyfluorfen applied at 1,680 g ha−1 resulted in barnyardgrass control that was comparable to that of clomazone alone in both site-years at 3 wk after emergence but caused up to 18% injury to rice. When oxyfluorfen was applied at 560 to 1,680 g ha−1 at the 2-leaf rice growth stage, barnyardgrass control was ≥85% in three of four site-years 1 wk after treatment. However, injury to rice ranged from 38% to 73% for the rates evaluated. Propanil caused the greatest injury by a herbicide currently labeled for use in rice at 34%. Oxyfluorfen should be used as a post-plant PRE herbicide rather than a POST herbicide due to the injury that occurred after a POST application. The data indicate that if used as a PRE herbicide, oxyfluorfen should be applied at 560 g ha−1 to reduce the injury that occurred on silt loam and clay soils.

The relative infection potential of Meloidogyne incognita and M. graminicola in the basmati rice cultivar PB1121

AbstractRoot‐knot nematodes, Meloidogyne spp., are considered one of the major biotic constraints for global rice production. Although the role of Meloidogyne graminicola in root‐knot disease progression is well investigated, negligible research has been performed to understand the damaging potential of M. incognita in rice. In this study, the comparative infection biology of M. incognita and M. graminicola was investigated in the basmati rice cultivar PB1121 growing in Pluronic gel medium and soil. Intriguingly, M. incognita laid eggs outside the galled root, whereas M. graminicola egg masses were deposited inside the galled root. This differential egg‐laying pattern can be correlated with their specific adaptations in irrigated and upland rice production systems. Although M. incognita induced a greater number of galls than M. graminicola, M. graminicola gall sizes were comparatively larger than those of M. incognita. The greater reproductive success of M. graminicola than M. incognita did not cause any difference in their yield reduction potential in PB1121. PB1121 was equally vulnerable to M. incognita and M. graminicola in terms of reduction in plant height, tiller numbers per plant and grain yield per plant. Our research suggests that M. incognita also causes economic damage to rice, and nematode management tactics must consider the damaging potential of both nematode species.

Optimizing Nitrogen Fertilization to Enhance Productivity and Profitability of Upland Rice Using CSM-CERES-Rice.

Nitrogen (N) deficiency can limit rice productivity, whereas the over- and underapplication of N results in agronomic and economic losses. Process-based crop models are useful tools and could assist in optimizing N management, enhancing the production efficiency and profitability of upland rice production systems. The study evaluated the ability of CSM-CERES-Rice to determine optimal N fertilization rate for different sowing dates of upland rice. Field experimental data from two growing seasons (2018-2019 and 2019-2020) were used to simulate rice responses to four N fertilization rates (N30, N60, N90 and a control-N0) applied under three different sowing windows (SD1, SD2 and SD3). Cultivar coefficients were calibrated with data from N90 under all sowing windows in both seasons and the remaining treatments were used for model validation. Following model validation, simulations were extended up to N240 to identify the sowing date's specific economic optimum N fertilization rate (EONFR). Results indicated that CSM-CERES-Rice performed well both in calibration and validation, in simulating rice performance under different N fertilization rates. The d-index and nRMSE values for grain yield (0.90 and 16%), aboveground dry matter (0.93 and 13%), harvest index (0.86 and 7%), grain N contents (0.95 and 18%), total crop N uptake (0.97 and 15%) and N use efficiencies (0.94-0.97 and 11-15%) during model validation indicated good agreement between simulated and observed data. Extended simulations indicated that upland rice yield was responsive to N fertilization up to 180 kg N ha-1 (N180), where the yield plateau was observed. Fertilization rates of 140, 170 and 130 kg N ha-1 were identified as the EONFR for SD1, SD2 and SD3, respectively, based on the computed profitability, marginal net returns and N utilization. The model results suggested that N fertilization rate should be adjusted for different sowing windows rather than recommending a uniform N rate across sowing windows. In summary, CSM-CERES-Rice can be used as a decision support tool for determining EONFR for seasonal sowing windows to maximize the productivity and profitability of upland rice production.

Assessment on the Level of Mechanization in the Rice Production and Post-Production Systems in Surigao Del Sur

Assessment on the Level of Mechanization in the Rice Production and Post-Production Systems in Surigao Del Sur

Evaluating topsoil salinity via geophysical methods in rice production systems in the Vietnam Mekong Delta

AbstractThe Vietnam Mekong Delta (VMD) is threatened by increasing saltwater intrusion due to diminishing freshwater availability, land subsidence, and climate change induced sea level rise. Through irrigation, saltwater can accumulate in the rice fields and decrease rice production. The study aims at evaluating topsoil salinity and examining a potential link between topsoil salinity and rice production systems in a case study in the Tra Vinh province of the VMD. For this, we applied two geophysical methods, namely, 3D electrical resistivity tomography (ARES II) and electromagnetic induction (EM38‐MK2). 3D ARES II measurements with different electrode spacings were compared with EM38‐MK2 topsoil measurements to evaluate their respective potential for monitoring topsoil salinity on an agricultural scale and the relationship between land‐use types and topsoil salinity. Results show that EM38‐MK2 is a rapid and powerful tool for obtaining high‐resolution topsoil salinity maps for rice fields. With ARES II data, 3D maps up to 40 m depth can be created, but compared with EM38‐MK2 topsoil maps, topsoil salinity was underestimated due to limitations in resolution. Salt contamination of above 300 mS m−1 was found in some double‐cropped rice fields, whereas in triple‐cropped rice fields salinity was below 200 mS m−1. Results clearly show a relation between topsoil salinity and proximity to the saline water sources; however, a clear link between rice production and topsoil salinity could not be established. The study proved that geophysical methods are useful tools for assessing and monitoring topsoil salinity at agricultural fields scale in the VMD.