Rice producers battle herbicide-resistant weeds worldwide while producing rice for ≥50% of the world’s population. Oxyfluorfen can provide rice producers with an alternative site of action for barnyardgrass control, as there are no documented cases of grass weeds being resistant to the herbicide in the mid-southern United States. Oxyfluorfen is anticipated to be labeled in the Roxy Rice Production System and may be sold as a clomazone/oxyfluorfen premixture; hence, experiments were conducted in 2021 and 2022 to evaluate preemergence-applied clomazone/oxyfluorfen ratios compared to clomazone alone on silt loam and clay soils. All ratios of the herbicides caused less than 7% injury to rice in two of four site-years on silt loam soils, whereas, in the two other site-years, the mixtures caused 10% to 40% rice injury at all observation timings. All combinations of the two herbicides provided at least 73% barnyardgrass control 5 wk after rice emergence (WAE) in three of the four site-years on silt loam soils. In at least two of four site-years at 1 and 3 WAE, barnyardgrass control was improved when oxyfluorfen was added to clomazone compared to clomazone alone. On clay soil, barnyardgrass control in both site-years was ≥77% at 5 WAE for all clomazone and oxyfluorfen ratios. Injury to rice ranged from 13% to 30% for all treatments containing clomazone and oxyfluorfen in one of two site-years on clay soil at all observation timings. At 7 WAE, contrasts indicated that the 1:3 ratio of clomazone to oxyfluorfen provided greater barnyardgrass control than the 1:1.5 and 1:2 ratios in one of two site-years. Based on these findings, oxyfluorfen would improve the consistency of barnyardgrass control over clomazone alone in some instances. However, there is an increased risk of injury to rice with the addition of oxyfluorfen.

Off-target movement of herbicides is a concern in California rice production, where sensitive crops are often grown nearby. Florpyrauxifen-benzyl and triclopyr are auxin mimics that are commonly used in rice systems. To steward florpyrauxifen-benzyl around the time of its initial registration in the state, research was conducted to compare the onset of foliar symptoms from simulated florpyrauxifen-benzyl and triclopyr drift onto grapevine, peach, and plum. The use rates on rice were 1/200×, 1/100×, 1/33×, and 1/10× of 29.4 g ai ha–1 florpyrauxifen-benzyl; and 1/200×, 1/100×, and 1/33× of 420.3 g ae ha–1 triclopyr. Herbicides were applied on one side of 1- to 2-year-old peach and plum trees and one side of established grapevines in 2020 and 2021. The general symptoms from applications of florpyrauxifen-benzyl and triclopyr were similar and included chlorosis, leaf curling, leaf distortion, leaf malformation, leaf crinkling, and necrosis. The symptoms from herbicides were observed on both sides of the grapevine canopy, whereas florpyrauxifen-benzyl symptoms on peach and plum were mostly observed on the treated side of the tree. Florpyrauxifen-benzyl and triclopyr symptoms were observed 3 d after treatment (DAT) for grapevines and 7 DAT for peach and plum. In all crops, most symptoms persisted through 42 DAT. Some grape clusters showed deformation and dropping of berries. All treated crops gradually recovered during the season regardless of application rates. Because symptoms in peach and plum were relatively minor, this research suggests that application precautions to reduce off-site drift are likely to minimize the occurrence of significant injury. However, grapevines were more sensitive and showed injury symptoms of up to 71% at 14 DAT with a simulated drift rate of 1/10× florpyrauxifen-benzyl. Therefore, extra precautions, such as using drift-management agents and closely monitoring wind speed conditions at the time of florpyrauxifen-benzyl applications may be necessary if vineyards are nearby.

Commercialization of florpyrauxifen-benzyl as Loyant® in 2018 as a synthetic auxin herbicide in rice was followed by soybean injury due to off-target movement of spray applications in the mid-southern United States. Concerns surrounding off-target movement led to the exploration of an alternative application method to help alleviate the issue. Field experiments were conducted in 2020 and 2021 to explore the likelihood of a reduction in soybean injury following applications of florpyrauxifen-benzyl coated on urea in narrow- and wide-row soybean systems and to determine the likelihood of volatilization from this novel application method. Florpyrauxifen-benzyl spray-applied at 0.18 g ai ha−1 caused greater than 60% injury, whereas coating the herbicide on urea at 5.63 g ai ha−1 never exceeded 30% injury in narrow-row soybean. Similarly, florpyrauxifen-benzyl spray-applied at 0.18 g ai ha−1 caused greater than 50% injury, whereas coating the herbicide on urea at 5.63 g ai ha−1 never exceeded 30% injury in wide-row soybean. As soybean injury increased, relative yield decreased in both narrow- and wide-row soybean. Spray-applied florpyrauxifen-benzyl decreased relative soybean groundcover, yield components, and soybean survival rate as the herbicide rate increased, whereas coating the herbicide on urea resulted in little to no decrease in both narrow- and wide-row soybean assessments. No negative impacts on relative yield and yield components of soybean from florpyrauxifen-benzyl coated on urea indicates that even though visible injury may persist, there is a low likelihood of any yield losses associated with the herbicide exposure using this application method. Additionally, coating the florpyrauxifen-benzyl on urea did not increase the likelihood of volatilization under any of the evaluated soil moisture conditions. Overall, applying florpyrauxifen-benzyl coated on urea is likely to be a safer application method and can reduce soybean injury compared to spray-applying the herbicide when favorable off-target movement conditions exist.

Complaints regarding the sensitivity of rice to florpyrauxifen-benzyl and off-target movement of the herbicide occurred following its commercial launch in 2018 in the midsouthern United States. These two concerns encouraged the exploration of an alternative application method for florpyrauxifen-benzyl in rice. A field study was conducted in 2020 and 2021 to determine if coating florpyrauxifen-benzyl on urea would reduce negative impacts of the herbicide to rice. Five commercial rice lines were evaluated: ‘Diamond’, ‘Titan’, ‘RT7321 FP’, ‘RT7521 FP’, and ‘XP753’. Florpyrauxifen-benzyl coated on urea at a 2× rate (60 g ai ha–1) reduced rice injury in one of five commercial rice lines in 2020 and four of five commercial rice lines in 2021, compared to spray applications at the same rate. In 2020, ‘RT7521 FP’ exhibited a 17-percentage point injury reduction when coating florpyrauxifen-benzyl on urea at a 2× rate vs. the same rate sprayed. In 2021, rice injury was reduced by 26, 10, and 27 percentage points in the commercial rice lines ‘Diamond’, ‘Titan’, and ‘XP753’, respectively, following coated urea vs. spray applications at 4 wk after treatment (WAT). ‘XP753’ exhibited reduced injury (15 percentage points) by coating florpyrauxifen-benzyl at a 1× rate (30 g ai ha–1) 4 WAT in 2021, and another, ‘Diamond’, had comparable groundcover to nontreated plots when florpyrauxifen-benzyl was coated on urea at a 1× rate rather than the reductions observed from the spray application at a 2× rate. Yield differences were a function of urea rate rather than application method, where in six out of ten instances greater rough rice grain yield occurred at the higher rate. Findings from this experiment indicate that coating florpyrauxifen-benzyl on urea can reduce the amount of injury observed, especially in areas of overlap where you would have a 2× rate.

Early morning flowering (EMF) is a desirable trait in rice to avoid heat stress as temperatures in early morning hours are low compared to afternoon and flowering is the most sensitive stage to heat exposure. Cultivated rice accessions including both Oryza glaberrima and O. sativa were phenotyped for an EMF trait in 2016–2018 in two locations viz. Cotonou in Benin Republic and Ibadan in Nigeria. The initial screening was done in Cotonou in three phases in 2016 dry season, 2017 wet season and 2017 dry season, respectively. The 2093 accessions used in initial screening were subdivided into three groups based on flowering duration ensuring that each accession was grown under conditions which were best suited to their flowering duration. Further screening was done in Ibadan in 2018 dry season and 2018 wet season. Out of 2093 accessions taken in the initial screening only 1754 accessions germinated out of which only 64 accessions exhibited EMF phenotype consistently across the cultivated years, seasons and locations. Among the 64 accessions exhibiting EMF phenotype, 15 accessions also showed an early peak in spikelet opening time (EPSOT) trait, more than 80% flowering before 09:00 h. We conclude that 15 O. glaberrima accessions identified possessing both the EMF and EPSOT traits are suitable donors for use in breeding for heat escape in rice.

In Japan, the discipline of food culture studies has developed since the 1970s under the initiative of Naomichi Ishige. Ishige's works have been referenced widely, but no one has attempted a critical reading of his writings. Therefore, the objective of this paper was to trace his life and contributions to the development of Asian food culture studies. Ishige's first contribution was to identify the commonality in Asian food cultures, tightly connected to rice and umami. Second, Ishige greatly contributed to institutionalising an interdisciplinary dialogue on food cultures in Japan and Asia. In fact, food culture studies are a product of food modernity because their disciplinary development has been conditioned by an increasing globalisation of food systems and the collapse of modern family systems since the 1970s and 1980s. Third, this paper analyses Ishige's food philosophy. Unlike Asian food culture studies in general, which mainly focuses on the genealogy of specific foods and dietary practices before modernisation, Ishige was also a careful observer of food modernity. His food philosophy, backed by long-term civilisational perspectives, was full of balanced ideas about how to cope with the loss of family meals, economic inequalities, and the rise of nutritional sciences during his period.

Understanding the yield attributes of rice crops grown at super high-yielding sites is useful for identifying how to achieve super high yield in rice. In this study, field experiments were conducted in 2021 and 2022 to compare grain yield and yield attributes of ten high-yielding hybrid rice varieties between Xingyi (a super high-yielding site) and Hengyang (a site with typical yields). Results showed that Xingyi produced an average grain yield of 13.4 t ha−1 in 2021 and 14.0 t ha−1 in 2022, which were, respectively, 20% and 44% higher than those at Hengyang. Higher panicles per m2 and higher grain weight were responsible for the higher grain yield at Xingyi compared to Hengyang. The higher values of panicles per m2 and grain weight at Xingyi compared to Hengyang were due to greater source capacity resulting from improved pre-heading biomass production. This study suggests that simultaneously increasing panicle number and grain weight through improving pre-heading biomass production is a potential way to achieve super high yield in rice.

Molybdenum (Mo) is an essential micronutrient for plants. However, Mo status in Sri Lankan paddy fields as affected by climate and soil is not known. This study was conducted to (i) determine the distribution of exchangeable Mo concentration, and (ii) examine the interactive effects of the agro-climatic zone (ACZ), soil order, water source, and their interactions in determining exchangeable Mo concentration in lowland paddy fields of Sri Lanka. A total of 3,719 soil samples representing six ACZs, six soil orders, and three water sources were collected using a stratified random sampling approach. Exchangeable Mo concentration was determined after extracting in 0.01 M CaCl2 solution and detected using inductively coupled plasma-mass spectrometry. Soil Mo concentration varied in the range of 0.01 to 245 µg kg−1 with a mean of 25.9 µg kg−1. Samples collected from the Wet zone, particularly Wet zone Low country, had higher Mo concentrations than those reported in other ACZs. Among the soil orders tested, Histosols had a higher Mo concentration while that in other soil orders was similar. Rainfed paddy fields had more Mo than supplementary irrigated paddy fields. Spatial maps were generated to visualise the geographical variation in soil Mo concentration. Due to the presence of a spatial heterogeneity of exchangeable Mo concentration, it is important to implement ACZ, soil, and water source-based strategies to improve Mo status in Sri Lankan paddy fields.

Tiafenacil is a new nonselective protoporphyrinogen IX oxidase–inhibiting herbicide with both grass and broadleaf activity labeled for preplant application to corn, cotton, soybean, and wheat. Early season rice emergence and growth often coincide in the mid-southern United States with applications of preplant herbicides to cotton and soybean, thereby increasing the opportunity for off-target herbicide movement from adjacent fields. Field studies were conducted to identify any deleterious effects of reduced rates of tiafenacil (12.5% to 0.4% of the lowest labeled application rate of 24.64 g ai ha−1) applied to 1- or 3-leaf rice. Visual injury 1 wk after treatment (WAT) for the 1- and 3-leaf growth stages ranged from 50% to 7% and 20% to 2%, respectively, whereas at 2 WAT these respective ranges were 13% to 2%, and no injury was observed. Tiafenacil applied at those rates had no negative season-long effect because observed early season injury was not manifested as a reduction in rice height 2 WAT or rough rice yield. Application of tiafenacil to crops directly adjacent to rice in its early vegetative stages of growth should be avoided because visual injury will occur. When off-target movement does occur, however, the affected rice should be expected to fully recover with no effect on growth or yield, assuming adequate growing conditions and agronomic/pest management are provided.

Bearded sprangletop is a problematic native grass weed in California’s rice fields. The widespread and extensive use of acetyl-CoA carboxylase (ACCase)–inhibiting herbicides, such as cyhalofop-p-butyl (cyhalofop), has led to speculation that biotypes of bearded sprangletop have developed herbicide resistance to ACCase. The aim of this study was to evaluate suspected resistant bearded sprangletop biotypes, R1, R2, R3, and the susceptible biotype, S1, in terms of their levels of resistance to three ACCase-inhibiting herbicides and to characterize the molecular mechanisms of resistance. Dose–response experiments suggested that the biotype R1, R2, and R3 had high-level resistance to cyhalofop and to quizalofop-p-ethyl (quizalofop), but not clethodim. The study determined that the resistance to ACCase inhibitors was a target-site mechanism resulting from nucleotide substitution. The carboxyl transferase (CT) domain of the ACCase gene’s sequence analysis revealed the substitutions Trp-2027-Cys for R1 and R2 biotypes and Ile-2041-Asn for the R3 biotype. This study revealed the presence of target-site resistance to cyhalofop and quizalofop in at least two mutation points in representative biotypes of bearded sprangletop in California. This research highlights the significance of careful herbicide selection due to weed species responding quite rapidly to selection pressure, so as to aid in managing bearded sprangletop in rice fields.

Two separate field studies were conducted at two locations near Crowley, Louisiana, to evaluate early season applications of florpyrauxifen and a prepackaged mixture of halosulfuron plus prosulfuron in water-seeded rice production. In each study, florpyrauxifen and halosulfuron plus prosulfuron were applied at two rates and either applied to the soil surface 48 h before the seeding flooding and seeding, directly onto the pregerminated seed 24 h following seeding and immediately after removal of the seeding flood (SEED), and at pegging. Data suggest that both florpyrauxifen and halosulfuron plus prosulfuron have a role to play in water-seeded rice production. Crop injury of 19% was observed from applications of florpyrauxifen applied directly to pregerminated SEED. Additionally, 28% crop injury was observed when halosulfuron plus prosulfuron was applied directly to SEED. Due to crop injury observations, both herbicides should be avoided when the pregerminated seed is exposed to the soil surface after removing the seeding flood. These data suggest that florpyrauxifen may be a better option for postemergence application, whereas halosulfuron plus prosulfuron may be a better preemergence option in water-seeded rice production. Overall, the findings show that both herbicide technologies will provide adequate early-season weed control in water-seeded rice production.

Florpyrauxifen-benzyl has generated complaints and concerns around rice injury and off-target movement to soybean since its commercial launch in 2018. Developing a precise method for applying florpyrauxifen-benzyl was imperative for its continued use. Experiments were conducted in 2020 and 2021 to evaluate rice weed control as influenced by preflood application interval and flood loss following florpyrauxifen-benzyl at 30 g ai ha−1 applied as a spray or coated on urea. In a preflood application experiment, coating florpyrauxifen-benzyl on urea and applying it the day of flood establishment and 5 and 10 d prior to flooding (DPTF) resulted in lower yellow nutsedge, broadleaf signalgrass, and barnyardgrass control than when the herbicide was spray at 3 and 5 wk after final treatment (WAFT). Coating florpyrauxifen-benzyl onto urea provided only 61% to 63% yellow nutsedge control at 3 and 5 WAFT, which was 35 to 37 percentage points lower than when the spray was applied at 5 or 10 DPTF. Likewise, rice yields following applications of florpyrauxifen-benzyl coated onto urea were 1,200 kg ha−1 less than yields following spray applications. Florpyrauxifen-benzyl coated onto urea and clomazone provided lower levels of weed control than spraying the herbicide alone, suggesting an explanation for the yield losses. The timing of flood loss experiment suggested that when florpyrauxifen-benzyl coated onto urea at 30 g ai ha−1 was applied preflood and flood was relinquished at 2 h, 24 h, and 7 d after flood establishment, hemp sesbania and yellow nutsedge control were not affected. However, loss of floodwater 2 h after flood establishment resulted in lower barnyardgrass control than when the flood was lost 24 h and 7 d after flooding. Generally, the period between a herbicide application and flooding completion should be minimized to aid in weed control. These results indicate the importance of maintaining a flood for weed control and nutrient management.

The objective of the research was to assess diversity among 50 rice genotypes for ratooning and perennation which refers to ability of a plant to regrow from stubble remaining after harvesting. Results showed that 30 genotypes exhibited different degree of ratoon production and ratoon yield. Diversity analysis revealed that all the ratooning genotypes could be assigned to ten clusters. Clusters III (Binadhan-11 and Sayjihari) and VI (IR-64, DRR-44) were the best performing for ratoon yield. Maximum inter-cluster distance was observed between genotypes falling under clusters III and X followed by genotypes under clusters III and II indicating wider genetic diversity between these genotypes. Thus, these genotypes may be useful for future breeding to develop superior varieties with respect to ratooning ability and ratoon yield.

Dates from recently excavated Gangetic site of Sakas in Bihar, India, place it at ca.1800–1100 BC. The ceramic and lithic chronologies have been interpreted as Early Farming, Transitional and Chalcolithic/Developed Farming in date. However, depending on where in the Ganges Plains is studied, the time frame of Early, Developed and Advanced Farming periods varies widely, from 7th millennium to 2nd millennium BC and beyond, making the chronological framing of absolute dates within a regional scheme highly complex. In this paper we report the new radiocarbon results from Sakas and note how while these are critical for cementing the absolute dating of the site, until such time as a more stable periodization linked not only to relative and absolute dates but also human lifeways within the different zones of the Ganges plains is created, there remains difficulties in understanding how Sakas and other sites of similar date fit into the changing social, cultural and economic systems in this region.

By examining the econometric interrelationships of rice export prices of India, Thailand, Vietnam, Pakistan, the U.S., Argentina, Brazil, and Uruguay, this study examines the most influential rice-exporting countries in the international rice export market. The sampled countries are the source of more than 80% of the global rice exports. In the process, this study relies on online data portals of the United Nations and country-level sources for aromatic and non-aromatic rice export price information from India, Pakistan, and Thailand. This study employed the Prais-Winsten and Autoregressive Distributive Lag (ARDL) estimation processes with the error correction procedure. Combining the findings from both models, this study concludes that in terms of interactions, the non-aromatic long-grain rice price of the U.S., and the aromatic rice price of Pakistan are the most correlated prices in the international rice market. Considering the number of countries influenced by the price of a given country, our results indicate that Vietnam is the price leader in the non-aromatic long-grain market, followed by Argentina, Brazil, and India. India, the largest exporter, is the fourth top price leader. In the case of aromatic rice, Thailand is the absolute leader. Many countries in Asia and Africa rely on rice imports to meet domestic demand, where the food security situation is already precarious. Based on the findings, this study suggests closely monitoring rice production and export trends of Vietnam, Argentina, Brazil, India and Thailand to provide early warning when necessary to better manage supply shocks in the international rice market.

The domestication of rice increases the divergence between cultivated rice and its wild progenitor because of artificial selection. However, it remains unknown whether highly diverged loci in rice can be explained by neutral demographic scenarios alone. In this study, we genotyped 45 InDels (insertion/deletion) in two subspecies of Asian cultivated rice (Oryza sativa ssp. japonica and Oryza sativa ssp. indica) and their wild progenitor (O. rufipogon/O. nivara). Among them, 17 loci are highly diverged (FST > 0.4) between rice cultivars and their ancestor. We performed coalescent-based simulations on neutral demographic scenarios and found that neutral demography alone could explain the polymorphic profiles on those highly diverged loci between cultivated and wild rice. Therefore, more signatures of selection should be considered when detecting artificial selection in rice.

Late-season weed emergence in California rice fields complicates decisions concerning the timing of control measures. The objective of this study was to predict the emergence of three problematic weed species in rice using thermal time models. Smallflower umbrella sedge, barnyardgrass, and bearded sprangletop seedlings were counted and removed daily at three locations across the Sacramento Valley rice-growing region in 2018. The accumulation of thermal time (growing degree days; GDD) commenced with the initial flooding of the fields at each location, utilizing the specific base temperatures corresponding to each species. The pattern of emergence as a function of GDD was modeled with a Weibull function. Root-mean-square values for comparing actual and model-predicted cumulative emergence values were 6% to 23%. Percent cumulative emergence initially increased rapidly for smallflower umbrella sedge and reached 90% emergence with accumulation of 13 GDD. Barnyardgrass emerged after smallflower umbrella sedge and reached 90% emergence with an accumulation of 124 GDD. Bearded sprangletop had a delay of 64 GDD compared to barnyardgrass to reach first emergence and reached 90% emergence at 215 GDD. The period of weed emergence at all field sites differed across the three species and led to a continuous spectrum of weed emergence over time. This study characterizes the emergence of three economically important rice weeds and provides useful information for the timing of weed management. Typical herbicide applications on the day of seeding may have less efficacy on the late-emerging weeds, causing reduced weed control. Delayed herbicide application, overlay of residual herbicides, or use of herbicides with longer residual activity are suggested to control late-emerging weeds.

The evolutionary relationship between domesticated Oryza species and their wild relatives in North East India is not well understood. To improve the understanding of the evolutionary relationship, this study investigates the genetic diversity of 68 indigenous rice landraces from North East India, ten O. rufipogon genotypes, and nine O. nivara genotypes using chloroplast variable repeat markers which, due to non-recombination and uniparental inheritance, enable better phylogenetic inference. Reference genotypes IR64 (indica) and Nipponbare (japonica) were included to characterize various phylogenetic clusters. Using distance-based hierarchical clustering, model-based structuring and principal component analysis, selected landraces from the three North Eastern Indian states of Assam, Manipur and Arunachal Pradesh were grouped into two phylogenetically different clusters that represented the IR64 and Nipponbare groupings. Interestingly, despite the fact that a cluster analysis combining North East landraces and wild relatives likewise produced two separate clusters (cluster I: Nipponbare, cluster II: IR64), the majority of the wild relatives were only clustered in the IR64 cluster. This suggests that the two distinct evolutionary histories of the rice landraces in North East India are distinguished by their genetic affinity for wild relatives and their variation in the indica and japonica pools. These results highlight chloroplast divergence influencing the genetic diversity of North East landraces with wild relatives. Further, these findings will enable in-depth studies on the functional significance of chloroplast diversity on trait adaptation in rice landraces.