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Weedy rice (Oryza spp.) is one of the most troublesome weeds affecting rice (Oryza sativa L.) production in many countries. Weedy rice control is difficult in rice fields, because the weed and crop are phenotypically and morphologically similar. Weedy rice can be a source of genetic diversity for cultivated rice. Thus, this study aimed to characterize the morphological diversity of weedy rice in southern Brazil. Qualitative and quantitative traits of 249 accessions from eight rice-growing mesoregions in Rio Grande do Sul (RS) and Santa Catarina (SC) states were analyzed. For each accession, 24 morphological descriptors (14 qualitative and 10 quantitative) were evaluated. All 249 accessions from RS and SC are of indica lineage. Considering all the phenotypic traits evaluated, the accessions separated into 14 distinct groups. One of the largest groups consisted of plants that were predominantly tall with green leaves, intermediate shattering, and variable flowering time. Distinct subgroups exist within larger clusters, showing discernible phenotypic diversity within the main clusters. The variability in flowering time was high (77 to 110 d after emergence), indicating high potential for flowering synchrony with rice cultivars and, consequently, gene flow. This indicates the need to remove escapes when planting herbicide-resistant rice. Thus, weedy rice populations in southern Brazil are highly diverse, and this diversity could result in variable response to weed management.

Weedy rice (WR) (Oryzaspp.) is the most troublesome weed infesting rice paddies in Brazil. Several changes have occurred in this region regarding crop management, especially WR control based on the Clearfield®(CL) rice production system launched in 2003. This survey’s objective was to evaluate the WR infestation status by assessing the producers’ perception and the management practices used in southern Brazil after 18 yr of CL use in Brazil. Rice consultants and extension agents distributed a questionnaire to 213 producers in the Rio Grande do Sul (RS) and Santa Catarina (SC) states in the 2018 to 2019 growing season. In RS, most farms are larger than 150 ha, and farmers have adopted the CL system for more than 2 yr and use minimal or conventional tillage, permanent flooding, clomazone PRE tank-mixed with glyphosate at the rice spiking stage, and crop rotation with soybean [Glycine max(L.) Merr.] or pasture. In SC, rice farms are small, averaging from 20 to 30 ha, farmers predominantly plant pre-germinated rice and do not rotate rice with other crops, and roguing is practiced. Comparing both states, the CL system is used in 99.5% and 69.3% of the total surveyed rice areas in RS and SC, respectively. Imidazolinone-resistant WR is present in 68.4% and 26.6% of rice farms in RS and SC, respectively. Rice cultivation in Brazil is currently coexisting with WR with minimal integration of control methods. However, integrated practices can control this weed and are fundamental to the sustainability of systems based on herbicide-resistant rice cultivars.

This study aimed to determine the growth and yield performance of five rice varieties under the different crop establishments and assess rice profitability as influenced by crop establishment under irrigated lowland conditions. The study was laid out in a split-plot arranged in an RCBD with three replications. Crop establishment was designated as the main plot while rice varieties as a subplot. Results revealed that the direct row seeding method significantly showed a significant advantage in agronomic and yield and yield component parameters over the transplanting method among rice varieties tested. Heirloom red rice significantly headed earlier (63.17 days) when planted in both crop establishments and obtained the tallest plant height, greater leaf area index, the heavier weight of 1,000 grains, and grain yield. There was a significant interaction effect on crop establishment and rice variety recorded from sowing to heading and maturity. Cost and return analysis revealed that the direct row seeding method achieved higher gross income (USD 2,012.00) and gross margin (USD 1,086.60) than the transplanting method. Heirloom red rice significantly achieved the highest grain yield (5.85 t ha-1), resulting in a higher gross income and gross margin of USD 2,340.00 and USD 1,352.45, respectively. Direct row seeding is applicable as an effective cost-reducing method of crop establishment for lowland rice production. Besides, it can shorten the time of crop establishment. Heirloom red rice with dual characteristics as an irrigated lowland and upland rice cultivar is feasible for direct row seeding and transplanting methods during the dry season.

Effects of genotype, environment and their interaction for grain yield and yield attributing characters in 20 advanced breeding lines of rice across six environments was investigated. Yield stability and adaptability of yield performance were analyzed by Eberhart and Russel model and (GGE) bi-plot. The AMMI analysis of variance indicated that mean squares due to genotypes, location and genotype location contributed per cent 59.08, 5.79 and 21.63, respectively for total variability in grain yield per hectare. Estimates of GGE bi-plot revealed that the lines G1, G3, G11, G13, G15, G12, G16, G7 and G10 were positioned near GGL bi-plot origin indicating wider adaptation for the trait grain yield per hectare. Eberhart and Russel Model and GGE biplot model showed the advanced breeding lines viz., JB 1-11-7 (G1) and JA 6-2 (G15) exhibited wider adaptability across the tested environments for number of productive tillers per plant and yield per hectare.

Upland rice has diverse agro-ecological attributes that can tolerate changes brought by climate change. Hence, this study aimed to determine the performance of upland rice cultivars under rainfed lowland conditions, assess the root growth of upland rice cultivars under rainfed lowland conditions, and evaluate the profitability of growing upland rice cultivars under rainfed lowland ecosystems. This was laid out in a Randomized Complete Block Design (RCBD) with three replications. Twelve rice cultivars were designated as treatments, however, only seven rice cultivars survived namely; Caimpas, Black rice, Red rice, Speaker, NSIC Rc192, PSB Rc18, and NSIC Rc27 that showed significant differences on agronomic characteristics, root and shoot parameters, yield, yield components, and harvest index. The five drought-tolerant upland rice cultivars such as Perya, Remolites, Kalinayan Monos, Tukoran, and Lebolebo showed permanent wilting due to non-adjustment of said cultivars to changes in growing conditions from sufficient irrigation water during early growth to low soil moisture and absence of precipitation during the reproductive growth phase. Improved upland rice variety NSIC Rc27 performed excellently under limited soil moisture through early heading and maturity, and high grain yield as mainly contributed by its heavier straw yield, an abundant number of productive tillers, higher filled spikelets, the heavier weight of seeds, high harvest index and adjustment of aforesaid cultivar to drought. Thus generated the highest gross margin of 1,823.16.00 USD. Therefore, it is recommended to grow NSIC Rc27 under rainfed lowland ecosystems even if this cultivar is experiencing limitations on soil moisture conditions.

Weedy rice (Oryza sativa f. spontanea Rosh.) is an emerging weed of California rice (Oryza sativa L.) that has potential to cause large yield losses. Early detection of weedy rice in the field is ideal to effectively control and prevent the spread of this weed. However, it is difficult to differentiate weedy rice from cultivated rice during early growth stages due to the close genetic and phenotypic relatedness of cultivated rice and weedy rice. The objective of this study is to examine phenotypic variation in weedy rice biotypes from California and to identify traits that could be used to visually identify weedy rice infestations at early growth stages for effective management. Greenhouse experiments were conducted in 2017 and 2018 using five phenotypically distinct biotypes of weedy rice found in California, along with diverse cultivated, weedy, and wild rice types in a randomized complete block design. We measured variation for 13 phenotypic traits associated with weedy rice and conducted principal component analysis and factor analysis to identify important weedy traits. Most weedy rice individuals within a biotype clustered together by phenotypic similarity. Pericarp color, hull color, chlorophyll content, grain length, plant height, leaf pubescence, collar color, and leaf sheath color account for most of the observed variation. California weedy rice biotypes are phenotypically distinct from wild rice and from weedy rice from the southern United States in their combinations of seed phenotypes and vegetative characteristics. In comparison with the locally grown temperate japonica cultivars, California weedy rice tends to be taller, with lower chlorophyll content and a red pericarp. Weedy rice biotypes vary in seed shattering and seed dormancy. For weedy rice management, plant height and chlorophyll content are distinct traits that could be used to differentiate weedy rice from the majority of cultivated rice varieties in California during vegetative stages of rice growth.

Weedy rice (Oryza spp.) is a worldwide weed of domesticated rice (O. sativa), considered particularly problematic due to its strong competition with the crop, which leads to reduction in yields and harvest quality. Several studies have established multiple independent origins for weedy rice populations in the United States and various parts of Asia; however, the origins of weedy rice in South America have not been examined in a global context. We evaluated the genetic variation of weedy rice populations in Colombia, as well as the contributions of local wild Oryza species, local cultivated varieties, and exotic Oryza groups to the weed, using polymorphism generated by genotyping by sequencing (GBS). We found no evidence for genomic contributions from local wild Oryza species (O. glumaepatula, O. grandiglumis, O. latifolia, and O. alta) to Colombian weedy rice. Instead, Colombian weedy rice has evolved from local indica cultivars and has also likely been inadvertently imported as an exotic pest from the United States. Additionally, weeds comprising de novo admixture between these distinct weedy populations now represent a large proportion of genomic backgrounds in Colombian weedy rice. Our results underscore the impressive ability of weedy rice to evolve through multiple evolutionary pathways, including in situ de‐domestication, range expansion, and hybridization.

This research aimed to examine growth and yield responses of various promising lines of upland red rice to different doses of P fertilizer and different levels of watering, by conducting pot experiment in a plastic house of the Faculty of Agriculture (University of Mataram), located in the experimental farm in Narmada, West Lombok, Indonesia. The experiment was designed according to Randomized Complete Block Design, consisting of three treatment factors, i.e. upland red rice genotypes (G1= M-G8; G2= M-G11; G3= M-G13; G4= M-G17); levels of watering (W1= 200 and W2= 300 ml/day); and doses of P fertilizer (P0= 0; P1= 100; P2= 200 kg/ha of SP-36 fertilizer). Each treatment combination was prepared in three blocks as the replicates grouped according to the different sources of the soil used to fill the pots. Results indicated levels of watering appears to have most dominant effects, in which the higher level of watering resulted in higher leaf number, panicle length, dry straw weight, filled grain number, and grain yield, but increasing P doses only increased plant height and grain yield, while genotypes were significantly different only in plant height, tiller number, panicle number and straw dry weight. Although both increased P doses and watering levels increased grain yield of red rice, there was a strong indication that increased P doses can increase grain yield only when level of watering is also increased, or vice versa.

Previous studies reported that intercropping rice with legume crops such as soybean, peanut, and mungbean increased nutrient uptake and yield of rice plants. This study aimed to examine the effects of relay-planting peanuts between double or triple rows of rice at different dates on growth, nitrogen content, and yield of red rice in aerobic irrigation systems on raised beds. The experiment was conducted in Narmada (West Lombok, Indonesia), arranged according to Split Plot design with two treatment factors, i.e. rice row patterns as the main plots (P1= double, P2= triple rows) and relay-planting dates of peanut as the subplots (T0= without peanut; T1= relay-planting peanut 1 week, T2= 2 weeks, T3= 3 weeks after seeding pre-germinated red rice seeds). Results indicated that between the treatment factors, relay-planting peanut at different dates resulted in significant effects on more variables compared with the patterns of rice rows. However, there were significant interaction effects between the treatment factors on tiller and panicle numbers per clump, and higher panicle number supported by higher leaf N content and higher harvest index resulted in significantly higher grain yield of the red rice intercropped with peanuts, especially when peanut was relay-planted at three or two weeks after seeding the pre-germinated rice seeds on raised-beds in aerobic irrigation systems. Although there was no significant effect of row patterns, the highest grain yield average (75.96 g/clump) was on T3 treatment under triple-row and the lowest average (33.29 g/clump) was on T0 treatment under double-row pattern.

Previous studies reported that intercropping rice with legume crops under aerobic systems increased growth and yield of rice compared with monocropped rice. This study aimed to examine the effects of rice cultivation techniques and patterns of rows on growth and yield of red rice with special objective to examine if intercropping red rice with soybean relay-planted between double or triple rows of rice on raised-beds under aerobic irrigation system can produce higher yield than the conventional one. The experiment was conducted in Narmada (West Lombok, Indonesia), arranged according to Split Plot design with two treatment factors, i.e. rice row patterns as the main plots (P1= double, P2= triple rows) and techniques of rice cultivation (Tc= conventional rice, T0= irrigated aerobic rice system (ARS) without intercropping; T1= relay-planting soybean 1 week, T2= 2 weeks, T3= 3 weeks after seeding the pre-germinated red rice seeds). Results indicated that between the two treatment factors, techniques of growing rice resulted in significant effects on more variables compared with the patterns of rice rows, but there were significant interaction effects on leaf number per clump at anthesis and grain yield per clump. Based on the main effects, tiller number, filled panicle number and grain yield per clump and harvest index were significantly higher on red rice plants grown in irrigated aerobic systems intercropped with soybean compared with those in aerobic monocropped or conventional systems, with the highest grain yield average of 53.76 g/clump in T3, 29.04 g/clump in T0 and only 17.45 g/clump in Tc treatment, and based on the interaction effects, the highest average of grain yield was on red rice plants in the T3 treatment under triple-row pattern (57.58 g/clump) and the lowest was on conventional plot (Tc) under double-row pattern (16.53 g/clump).

In recent years, wastes have been reprocessed into useful products, such as organic fertilizer. The application of organic fertilizers in farming practices can produce agricultural products that are safe for human health and the environment. The objective of this study was to investigate the effect of liquid organic fertilizer made from fish waste on the growth of Bali red rice seedlings. A Complete Randomized Design (CRD) consisted of 8 treatments with 5 replications was applied in this experiment. These included immersing of rice seeds in fish waste fertilizer with concentrations of 0.5% = P1, 1% = P2, 1.5% = P3, 2% = P4, 2.5% = P5 and 3% = P6 with volume/volume ratio (v/v), prior to soaking. Rice seeds without immersion in this fertilizer (C0) and those immersed in PGPR bacterial suspension only (C1) served as nil control and control treatments, respectively. The results showed that the application of 2.5% fish waste fertilizer produced the highest results, following measurement of parameters, including the percentage of germination (88.18%), plant height (28.78 cm), and root length (20, 74 cm) on day 15 after sowing.

Background Knowledge of the genetic diversity and spatial structure of Taiwan weedy red rice (WRR) populations, which adapted in a transplanting system, will facilitate the design of effective methods to control this weed by tracing its origins and dispersal patterns in a given region. Results Taiwan WRR is genetically most similar to Taiwan indica cultivars and landraces according to genetic distance. The inbreeding coefficient of the Taiwan WRR population is greater than 0.8, which is similar to the inbred cultivars. The ancestry coefficients map suggests a dispersal pattern of long-distance and seed-mediated contamination across Taiwan, often from warmer, earlier-planted regions to cooler, later-planted regions. Parentage analysis of Taiwan WRR revealed that mostly early indica landraces and indica cultivars were present in the genetic pool; in rare cases temperate japonica was present. Based on the above results, the phylogenetic origin of most Taiwan weedy rice appears to be from hybrid progenies of old cultivated red rice accessions crossed with 'DGWG'. The inbreeding coefficient trend of the six TWR clusters suggests a temporal shift from 'old' indica landraces with red bran (high inbreeding coefficient) to modern indica varieties (low inbreeding coefficient). Conclusion Although there were sustained efforts to remove these old red rice accessions from paddy fields before 1945, some farmers continued to use low purity seed. This practice, along with volunteer cultivation of these old varieties in the second cropping season, apparently has facilitated the long-distance, seed-mediated contamination of rice seed, and the increase in weedy rice seed in paddy soil. © 2019 Society of Chemical Industry.

BRS 901 and BRS 902 are red pericarp rice cultivars developed by Embrapa for irrigated and rainfed lowland production systems in Brazil. These cultivars have medium and early maturation cycles, respectively, and both have high grain yield potential, good lodging tolerance and short to medium length grains.

BackgroundThe element selenium (Se) deficiency is thought to be a global human health problem, which could disperse by daily-supplement from Se-rich food. Increasing the accumulation of Se in rice grain is an approach matched to these nutrient demands. Nonetheless, Se is shown to be essential but also toxic to plants, with a narrow margin between deficiency and toxicity. Notably, the regulatory mechanism balancing the accumulation and tolerance of Se in Se-rich rice plants remains unknown.ResultsIn this study, we investigated the phenotypical, physiological, and biochemical alterations of Se-rich rice in the exposure to a variety of Se applications. Results showed that the Se-rich rice was able to accumulate more abundance of Se from the root under a low Se environment comparing to the Se-free rice. Besides, excessive Se led to phytotoxic effects on Se-rich rice plants by inducing chlorosis and dwarfness, decreasing the contents of antioxidant, and exacerbating oxidative stresses. Furthermore, both phosphate transporterOsPT2and sulfate transportersOsSultr1;2may contribute to the uptake of selenate in rice.ConclusionsSe-rich red rice is more sensitive to exogenous application of Se, while and the most effective application of Se in roots of Se-rich rice was reached in 20 μM. Our findings present a direct way to evaluate the toxic effects of Se-rich rice in the Se contaminated field. Conclusively, some long-term field trial strategies are suggested to be included in the evaluation of risks and benefits within various field managements.

The present study was carried out at the Experimental Farm of Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt, during 2017 and 2018 rice growing seasons to study the behaviors of four rice genotypes under three dates of sowing. These rice genotypes were the new Egyptian red rice line NRL 54, Giza 177, Giza 178 and Black rice. The results showed that rice plants sown on May 1st or May 15th surpassed those sown on the late date of sowing (May 30th) in days to heading, plant height, number of tillers/plant, number of panicles/plant, panicle length, panicle weight and grain yield per hectare. While, rice plants sown on May 15th or May 1st surpassed those sown on the late date of sowing (May 30th) in thousand grain weight, number of filled grains/panicle and number of spikelets/panicle. Plants of promising line NRL 54 produced the highest grain yield in the two seasons. While, Black rice variety produced the lowest grain yield in the two seasons. It can be concluded that the first two dates of sowing (1st May and 15th May) were the most suitable dates of sowing. While, the promising rice line NRL 54 can be sown on May 30th without yield reduction. The line NRL 54 is more tolerant to delay in sowing date than Black rice variety. Generally, the rice line NRL 54 could be recommended to be sown from May 1st to May 30th. The tolerance of NRL 54 to late sowing gives it an advantage for time isolation.

Field experiments were initiated near Colt, AR, in the fall of 2016 and continued through the summer of 2018 to evaluate rice tolerance and weedy (or red) rice control after fall-applied very-long-chain fatty acid (VLCFA)-inhibiting herbicides. A split-plot design was used for the experiment, with the whole-plot factor being winter condition (flooded or non-flooded) and the split-plot factors being herbicide and rate. Herbicide treatments included acetochlor, dimethenamid-P, pethoxamid, pyroxasulfone, and S-metolachlor applied at 1,050, 525, 420, 205, and 1,070 g ai ha-1 and at 2,100, 1,050, 840, 410, and 2,140 g ha-1 for low rates and high rates, respectively. Herbicides were applied in the fall, then ‘CL172’ rice was drill seeded in the spring of the following calendar year. Weedy rice control differed between years, but acetochlor and pyroxasulfone consistently provided the greatest levels of control across rates and flood conditions. Consequently, herbicides that best controlled weedy rice also caused the greatest injury to cultivated rice. Rice injury did not exceed 13% regardless of herbicide treatment at 3 wk after planting (WAP). However, the high rate of pyroxasulfone caused 20% rice injury at 5 WAP in 2018. Although it was expected that winter condition may affect residual activity of the VLCFA-inhibiting herbicides, herbicide selection and application rate both had much greater effects on rice injury and on weedy rice control. Based on these results, rice injury would be minimal or nonexistent after fall applications of the tested VLCFA inhibitors, and intermediate levels of weedy rice control may be achieved. The implementation of VLCFA-inhibiting herbicides in rice production systems would offer a novel herbicide site of action and offer a degree of selective control of weedy rice.Nomenclature: Acetochlor; dimethenamid-P; pethoxamid; pyroxasulfone, S-metolachlor; red rice, Oryza sativa L. ORYSA; rice, Oryza sativa L.

Weedy rice (Oryza spp.) is considered one of the main weeds in cultivated rice (Oryza sativa L.) around the world, having a great impact on both yield and quality of crop rice. Recent studies have characterized the range of morphological and genetic diversity in weedy rice from different locations and have revealed that there is often great morphological diversity within growing regions. No systematic attempt to characterize phenotypic diversity of weedy rice in Colombia, where this group of weeds greatly affects rice production, has yet been carried out. This study seeks (1) to establish the range of variation in various morphological characters for weedy rice collected in the five production zones of Colombia and to compare these with commercial varieties and landraces sown in the country, (2) to determine the association between weedy rice morphotypes and rice production areas in the country, and (3) to assess whether any association exists between morphology and recently discovered genetic groupings for weedy rice in Colombia. Based on a sampling of rice production areas in Colombia and evaluation of 27 phenotypic traits, a two-step cluster analysis identified four morphological groups for weedy rice in Colombia. These groupings had some limited association with geography and the genetic ancestries of weedy rice. Clustering showed that awn and apiculus color and awn length and presence are the most important predictors in defining morphological groupings. Understanding and classifying the morphological diversity may be helpful in understanding weedy rice origins, evolution, and potential management practices.

This study aimed to examine the effect of application of a bio-fertilizer containing arbuscular mycorrhizal fungi (AMF) and additive intercropping with soybean relay-planted between double rows of rice on growth and yield components of various promising lines of red rice grown in aerobic irrigation systems on permanent raised-beds. The field experiment, carried out on farmers' riceland in Beleke village of Gerung district in West Lombok, Indonesia, from May to September 2018, was designed according to Split Split-Plot design with three blocks and three treatment factors, i.e. intercropping (T0= without; T1= with soybean) as the main plot factor, red rice promising lines with 4 genotypes (G1= MG4, G2= MG10, G3= AM4, G4= AM10) as the sub-plot factor, and AMF bio-fertilizer (M0= without; M1= with AMF) as the sub-sub-plot factor. The pre-germinated red rice seeds were planted on permanent raised-beds, with a base spacing of 25x20 cm, which was then modified into a double-row pattern of 20x20 cm within the double-row and 30 cm between double-rows. The results indicated that application of the bio-fertilizer “Technofert” containing AMF significantly increased growth and yield components of various promising lines of red rice, especially in relation to filled grain number and grain yield per clump, but significantly reduced percentage of unfilled grain number. Additive intercropping with soybean that was relay planted between double-rows of rice (one week after seeding rice) also significantly increased grain yield of the red rice genotypes. Among the four selected genotypes, grain yield of AM10 was the highest, especially when bio-fertilized with AMF and intercropped with soybean.

Rice yields under conventional techniques are very low without high doses of commercial fertilizer application, while intercropping with legumes can increase yields. This research aimed to examine the effect of relay-planting peanut between rice rows of different patterns on yield of red rice in aerobic irrigation systems, by conducting a field experiment designed according to Split Plot design with two treatment factors, i.e. intercropping as main plots (T0= without; T1= intercropping with peanuts), and rice row patterns as sub-plots (P1= normal or single-row; P2= double-row; P3= triple-row). In T1, one row of peanut was relay-planted (additive series) between single, double, or triple rows of red rice plants three weeks after seeding red rice on raised-beds. Results indicated that additive intercropping with peanut significantly increased clump size, dry straw weight, filled panicle number, panicle length, total biomass, filled grain number, grain yield per clump, and harvest index, and reduced percentage of unfilled grains of red rice , while patterns of rice rows only affected dry straw weight, percentage of panicle number, and weight of 100 grains. However, there were significant interactions between the treatment factors on dry straw weight and percentage of panicle number, which under single-row, they were low in monocropping but high and no differences between row patterns in intercropping system. Similarly, grain yield was lower in single or double row than triple row pattern under monocropping but significantly higher and no differences between row patterns under intercropping, indicating the highest benefits of intercropping under single row pattern.

Markus JER, Ndiwa ASS, Oematan SS, Mau YS. 2021. Variations of grain physical properties, amylose and anthocyanin of upland red rice cultivars from East Nusa Tenggara, Indonesia. Biodiversitas 22: 1345-1354. Red rice is becoming more popular nowadays due to the increasing awareness of rice consumers on its health benefits. The demands for red rice are increasing but the supply is limited, thus, local red rice cultivars can be used to fill this gap. Optimal use of local rice germplasm requires a comprehensive evaluation of their traits, and the genotypes having the most desirable traits can be selected for direct use. Several upland red rice cultivars from East Nusa Tenggara Province have been evaluated for various traits while their grain properties are still unrevealed. Information on grain properties is important, both for consumer preference and rice breeders. This study aimed to elucidate the grain physical properties, amylose, and anthocyanin of upland red rice germplasm from ENT Province, and to identify genotypes with the most desirable characters for further employment. Eighteen rice genotypes were used in this study. They were cultivated in the field, and the harvested grains were analyzed in the laboratory. Both ANOVA and descriptive statistics were used for data analysis. Substantial variations were observed on all variables, except the chalky grain percentage. The kernel length of tested genotypes was classified as long, medium, and short while the kernel shapes were slender, medium, and bold. Most tested genotypes had high head rice percentage and low to medium percentages of large and small broken kernels. Chalky grain was almost absent. Amylose content ranged from 1.0% to 28% while anthocyanin was about 1.0 - 20 mg/100 g. The evaluated genotypes were clustered into three main groups. Percentages of large and small broken kernels, and amylose content were mostly responsible for the observed variations among the rice genotypes. The red rice genotypes were diverse in the studied characters, thus, those with desirable grain characters are useful for further development and utilization.

Clearfield™ (CL) rice (Oryza sativa L.) is a weedy rice (Oryza spp.; synonym = red rice) control tool that has been used in Brazil since 2003. This system includes the use of an imidazolinone (IMI)-tolerant cultivar and the application of IMI herbicides. In this review article, Brazilian weed scientists evaluate the challenges and lessons learned over 18 yr of CL use. CL system benefits include selective weedy rice control, better crop establishment during the most advantageous period of the year, and more efficient fertilizer use. In Rio Grande do Sul state, the CL system, in conjunction with other improvements, has contributed to rice grain yield gains from 5,500 kg ha−1 before 2002 to around 8,400 kg ha−1 currently. In contrast, the main problem that has arisen over this period is the rapid evolution of IMI-resistant weedy rice, caused by gene flow from CL rice cultivars. The off-label use (rate and continuous use) of IMI herbicides has contributed to the evolution of resistance in Echinochloa spp. and other weeds. IMI herbicide carryover has also affected susceptible crops grown after CL rice. Crop rotation with soybean [Glycine max (L.) Merr.] is increasing, ensuring system sustainability. The importance of minimum tillage has also become apparent. Such cultivation includes applying nonselective herbicides before sowing or just before crop emergence (at the spiking stage to eliminate as much weedy rice as possible and other weeds at an early growth stage). It also includes the use of certified seeds free of weedy rice, following label instructions for IMI herbicides, applying the herbicide PRE followed by POST, and complementary weedy rice management practices, such as roguing of surviving weedy rice plants.

Weedy rice (Oryza sativa L.) is a troublesome rice (Oryza sativa L.) weed in Italy and in many other rice areas. The objective of this study was to correlate the O. sativa infestation level in northern Italy, the main European rice-growing area, with agricultural practices adopted by farmers by using data obtained from a farmer survey. In 2018 to 2019, a survey was carried out on 98 rice farms chosen to ensure different sizes, different cultivation practices, and variable degrees of O. sativa infestation. The following information was acquired: farm size; area cultivated with Clearfield® varieties; the most-adopted agronomic practices (type of tillage, crop rotation, type of sowing, water management, origin of seeds, adoption of stale seedbed, use of imazamox, presence of O. sativa resistant to imazamox); and level of O. sativa infestation: low (≤5 plants m−2), medium (>5 to 20 plants m−2), and high (>20 plants m−2). The data were analyzed through descriptive statistics and ordinal logistic regression to determine which agronomic practices influenced the level of O. sativa infestation. Farm clustering was also determined through two-step cluster analysis. Rice was cultivated as a monocrop and mainly sown in water, using purchased seeds, in plowed fields. More than half of the farms used the stale seedbed practice, and 63% adopted Clearfield® varieties, while about 45% of the farms reported imazamox-resistant O. sativa. The ordinal logistic regression underlined that use of a stale seedbed was correlated with the infestation level of O. sativa, and the two-step cluster analysis showed that the farms were mainly grouped based on the use of this technique. Most of the farms that used a stale seedbed had higher O. sativa infestation than those that did not use it, meaning that this practice was mainly applied in zones where O. sativa infestations were more serious.

The abundance of weedy rice (Oryza sativa L.) in the soil seedbank was estimated in 2011 in Italian rice (Oryza sativa L.) fields with different histories of imidazolinone-resistant Clearfield® rice varieties (CL), non-Clearfield® varieties (NCL), and planting methods. A model was used to predict weedy rice seedbank dynamics over time under different control strategies. Soil samples were taken from 50 rice fields cultivated with CL varieties consecutively for 0, 1, 2, or 3 yr, and weedy rice seedbank data were used in a model considering eight scenarios: (A) rice monoculture with CL and NCL varieties in alternate years; (B) 2 yr of CL, followed by 1 yr with NCL; (C) 3 yr of CL followed by 1 yr of NCL; (D) rice monoculture with only CL; (E) rice monoculture with only NCL; (F) 2 yr of CL followed by 1 yr of rotation with another crop (CR), and then by an additional year with NCL; (G) 1 yr of CR followed by 2 yr of CL, and then by 1 yr of NCL; (H) 2 yr of CR followed by 2 yr of CL. The weedy rice seedbank exceeded 1,000 seeds m−2 in the surveyed fields with no significant differences between rice planting methods. Highest densities were found in fields cultivated for 1 yr with CL varieties. Simulations indicated that where CL varieties were used in rice monoculture, the susceptible weedy rice seedbank was gradually reduced, producing a depletion after 17, 13, 11, and 9 yr in scenarios A, B, C, and D, respectively. The weedy rice seedbank increased in NCL monoculture (E) and declined significantly in crop rotation scenarios (F, G, H). The simulations indicated that the introduction of crop rotation is crucial for obtaining a relatively fast reduction of weedy rice seedbank and delaying the evolution of herbicide-resistant populations.

Drought is a complicated abiotic stress factor with severe effects on rice growth and production. Weedy rice is a valuable genetic resource that possesses a strong capacity for drought tolerance, cold tolerance, and salt tolerance, and is an excellent material for studying rice tolerance. Here, according to comprehensive tolerance to drought index D, accession WR16 was selected based on strong drought tolerance among 133 studied weedy red rice germplasms. WR16 was compared with Oryza sativa ssp. Japonica. cv. IAPAR-9, a reference genotype originating from Brazil. In addition, accession WR24 was classified as moderately tolerant to drought accessions. Transcriptomic and proteomic analyses were combined to identify 38 co-upregulated proteins related to drought tolerance, and targeted parallel reaction monitoring (PRM) was used to precisely quantify and verify nine proteins in the complex backgrounds. Result showed that six proteins were significantly (Fisher's exact P value

Weedy rice (Oryza spp.) is a problematic weed of cultivated rice (O. sativa) around the world. Recent studies have established multiple independent evolutionary origins of weedy rice, raising questions about the traits and genes that are essential for the evolution of this weed. Among world regions, South Asia stands out due to the heterogeneity of its weedy rice populations, which can be traced to at least three origins: two through de-domestication from distinct cultivated rice varieties, and one from local wild rice (O. rufipogon/O. nivara). Here we examine five traits considered typical of or advantageous to weedy rice in weedy, cultivated and wild rice samples from South Asia. We establish that convergence among all three weed groups occurs for easy seed shattering, red pericarp color, and compact plant architecture, suggesting that these traits are essential for weed success in the South Asian agricultural environment. A high degree of convergence for black hull color is also seen among weeds with wild ancestors and weeds evolved from the aus cultivated rice group. We also examine polymorphism in five known domestication candidate genes, and find that Rc and Bh4 are associated with weed seed pericarp color and hull color, respectively, and weedy alleles segregate in the ancestral populations, as do alleles for the seed dormancy-linked gene Sdr4. The presence of a domestication related allele at the seed shattering locus, sh4, in weedy rice populations with cultivated ancestry supports a de-domestication origin for these weedy groups, and raises questions about the reacquisition of the shattering trait in these weedy populations. Our characterization of weedy rice phenotypes in South Asia and their associated candidate genes contribute to the emerging understanding of the mechanisms by which weedy rice evolves worldwide, suggesting that standing ancestral variation is often the source of weedy traits in independently evolved groups, and highlighting the reservoir of genetic variation that is present in cultivated varieties as well as in wild rice, and its potential for phenotypic evolution.

The evolution of herbicide resistance is making it extremely difficult for US rice producers to use chemical control on weed species such as barnyardgrass and red rice. To combat herbicide resistance, it is imperative that alternative herbicide sites of action (SOAs) be incorporated into rice whenever possible. There are currently no very-long-chain fatty acid– inhibiting herbicides (WSSA Group 15) labeled for use in US rice; however, pethoxamid is one such herbicide currently under development. If appropriate rice tolerance and weed control can be established, pethoxamid would represent a unique herbicide SOA for use in US rice. We conducted field trials near Stuttgart, AR, in 2015 and near Colt and Lonoke, AR, in 2016 to assess selectivity of pethoxamid and weed control alone and in combination with other herbicides as a delayed preemergence (DPRE) application in drill-seeded rice. Pethoxamid was applied at 0, 420, or 560 g ai ha-1 alone and in combination with clomazone, imazethapyr, pendimethalin, and quinclorac. Minimal rice injury occurred with any treatment assessed. A reduction in rice shoot density and plant height compared to the nontreated control followed the use of pethoxamid; however, no decrease in yield resulted. The highest levels of barnyardgrass control followed the use of imazethapyr at 91% and quinclorac at 89% regardless of the presence of pethoxamid near Lonoke; however, pethoxamid applied at both rates in combination with clomazone and quinclorac increased barnyardgrass control compared to clomazone and quinclorac applied alone. Near Colt, barnyardgrass control of 92% and 96% resulted from pethoxamid alone, averaged over the high and low rates. Based on these data, rice can tolerate pethoxamid when applied DPRE, and adequate levels of barnyardgrass control can be achieved at the rates evaluated within a program; hence, pethoxamid appears to be a viable option for use in rice to allow for increased rotation of herbicide SOAs to combat herbicide-resistant and difficult-tocontrol weeds.Nomenclature: Pethoxamid; barnyardgrass, Echinochloa crus-galli (L.) Beauv.; red rice, Oryza spp..; rice, Oryza sativa L.

Herbicide resistance to several of the most common weed species in US rice production, such as barnyardgrass and red rice, has made weed control extremely difficult with available herbicide options. No very-long-chain fatty acid–inhibiting herbicides are labeled for use in US rice; however, pethoxamid is one such herbicide under development for soil-applied use to control grasses and small-seeded broadleaves in rice and various row crops. Field trials were conducted in 2015 and 2016 near Stuttgart, AR, for rice tolerance and in 2016 near Colt, AR, and Lonoke, AR, for weed control with the use of pethoxamid-containing rice herbicide programs. Pethoxamid was applied alone and in a program at 420 and 560 g ai ha-1 with other herbicides labeled in rice including clomazone, quinclorac, propanil, imazethapyr, and carfentrazone POST. Injury less than 10% was seen for all treatments 2 wk after application in 2015 and 2016, except for pethoxamid at 420 g ha-1 to clomazone to one-leaf rice. Rice injury dissipated to less than 5% following all treatments by 4 wk after flood establishment. Barnyardgrass was controlled 95% or more near Colt and 93% or more near Lonoke for herbicide programs including clomazone PRE followed by pethoxamid plus quinclorac or imazethapyr at three- to four-leaf stage rice. Considering the minimal injury and high levels of barnyardgrass control associated with pethoxamid-containing weed control programs, pethoxamid provides a unique and effective site of action for use in US rice production.Nomenclature: Carfentrazone; clomazone; imazethapyr; pethoxamid; propanil; quinclorac; barnyardgrass, Echinochloa crus-galli (L.) Beauv.; red rice, Oryza sativa var. sylvatica L.; rice, Oryza sativa L

Australian wild rices are genetically distinct from commercially cultivated rices and present new opportunities for the development of improved rice cultivars. Before use in rice breeding, the eating and cooking properties of Australian wild rice must first be understood as these are key factors in determining rice quality and consumer acceptance. Samples of Australian wild rice (taxa B) were collected and evaluated together with a commercial Canadian wild rice (Zizania aquatic L.), Oryza sativa L.cv. Nipponbare, and selected commercial rices including long grain, medium grain, basmati, red basmati, and red rice. Cooking profiles were established, physical traits were measured and conventional descriptive analysis techniques were used to compare the sensory properties of the unpolished rices. Twenty six descriptors, together with definitions, were developed with a panel of twelve experienced assessors including aroma, flavour, texture and aftertaste attributes. Results reveal that the Australian wild rice had a mild aroma and flavour similar to that of red rice and red basmati but without the lingering aftertaste. In terms of texture, the wild rice was firmer, and somewhat crunchy and chewy rather than soft and fluffy despite requiring a longer cooking time. The sensory, physical and cooking profiles indicate that Australian wild rice has a high potential for commercialization in itself and provides a suitable genetic source for breeding programs, particularly in the coloured rice market.

Upland rice is an important food crop in Indonesia, including in Southeast Sulawesi, and the productivity still low under the production potential. One of the causes of this low production is low soil fertility and limited nutrients for plants. One of the efforts is by providing liquid organic fertilizer derived from moringa. This study used a two-factor and arranged in a randomized block design (RBD). The first factor was organic fertilizer treatment from moringa, consisting of two levels, namely without treatment and 20 ml per liter. The second factor was the difference cultivars tested consisting of 4 cultivars, namely GS44-1, GS44-2, GS16-1, GS16-2, and Lipigo 4. The results showed that the treatment of liquid organic fertilizer made from moringa significantly effects on the on the plant height. number of leaves and number of tillers on upland red rice.

Red rice is an essential food and has nutritional content, but farmers’ production and interest in red rice cultivation are still relatively low. One effort to develop and increase brown rice production is planting superior varieties with selection efficiency. The purpose of this study was to determine the correlation between yield components and yields of the six promising lines of red rice in paddy fields and to know the yield components that were positively correlated very significantly to the results in paddy fields. The research design used was a randomized block design (RBD) consisting of 6 crosses, namely GS11-1, GS11-2, GS12-1, GS12-2, GS44-1, GS44-2, and one comparison variety, Trisakti. The results of the analysis show that there were two components of yield that were highly positively correlated with yields of red rice, which were positively correlated significantly, including the number of productive tillers with grain yield per clump (0.83 **) and the weight of 1000 grains with grain yield (0.57 **).

BACKGROUND Provisia™ rice (PV), a non-genetically engineered (GE) quizalofop-resistant rice, will provide growers with an additional option for weed management to use in conjunction with Clearfield® rice (CL) production. Modeling compared the impact of stacking resistance traits versus single traits in rice on introgression of the resistance trait to weedy rice (also called red rice). Common weed management practices were applied to 2-, 3-, and 4-year crop rotations and resistant and multiple-resistant weedy rice seeds, seedlings, and mature plants were tracked for 15 years. RESULTS Two-year crop rotations resulted in resistant weedy rice after two years with abundant populations (exceeding 0.4 weedy rice plants m-2) occurring after seven years. When stacked trait rice was rotated with soybeans in a 3-year rotation and with soybeans and CL in a 4-year rotation, multiple-resistance occurred after 2-5 years with abundant populations present in 4-9 years. When CL rice, PV rice, and soybeans were used in 3- and 4-year rotations, the median time of first appearance of multiple-resistance was 7-11 years and reached abundant levels in 10-15 years. CONCLUSION Maintaining separate CL and PV rice systems, in rotation with other crops and herbicides, minimized the evolution of multiple herbicide-resistant weedy rice through gene flow compared to stacking herbicide resistance traits.

A study was conducted at three locations in Louisiana to evaluate the interactions of imazamox at 44 g ai ha−1mixed with propanil, thiobencarb, or with a prepackaged mixture of propanil plus thiobencarb. A synergistic response was observed for red rice control for all treatments at 14 days after treatments (DAT); however, at 21 DAT a neutral response was observed for imazamox mixed with propanil or thiobencarb. A synergistic response occurred for red rice control when imazamox was mixed with propanil plus thiobencarb at 3360 g ai ha−1for all evaluation dates; however, imazamox mixed with propanil plus thiobencarb at 1680 g ha−1resulted in synergism at the same evaluations except at 35 DAT with neutral response. Synergism was observed for barnyardgrass control with imazamox mixed with propanil plus thiobencarb at 3360 g ha−1at 35 and 49 DAT. The only antagonism observed for barnyardgrass control was at 42 DAT with imazamox plus propanil at 840 and 1680 g ha−1or mixed with the prepackage mixture at 1680 g ha−1. Rice treated with imazamox mixed with propanil plus thiobencarb at 3360 g ha−1yielded 5770 kg ha−1.

Studies were conducted to determine the impact of introgression of crop alleles into weedy rice populations. Seeds of 89 weedy rice accessions collected from Arkansas fields in 11 counties, with a history of Clearfield™ rice production, were planted in 2011 and sprayed twice with imazethapyr (0.071 kg ai ha−1). Survivors were genotyped using an allele-specific PCR assay to detect the presence of resistance-endowing als mutations, S653N and G654E, in herbicide-resistant (HR) weedy rice that could have originated from Clearfield™ cultivars planted in the state. Hybridization between Clearfield™ rice and weedy rice was verified using four DNA markers RM 215, RM 220, and RM 234 microsatellites, and the and RID12 indel. Two to five HR plants, representing different plant types per accession per replication (698 plants total) were characterized for 16 morphological and biological traits. Seventy-nine percent of accessions were resistant to imazethapyr. The HR weedy rice plants carried the S653N mutation and were confirmed as outcrosses with Clearfield™ rice using DNA markers. Ten weedy rice accessions (nearly 25% of confirmed outcrosses) harbored multiple alleles from rice cultivars, indicating previous hybridization events with multiple cultivars or outcrossing with weedy rice. The majority of HR weedy rice accessions were similar to cultivated rice in height, culm angle, flag leaf length and width, days to flower, seed shattering and dormancy. Kernels of 20% of the parent weedy rice accessions were segregating for white and red bran color. Two of the parent weedy rice accessions with gold hull were homozygous for white bran and produced progenies with 100% white-bran kernels; thus, weedy rice was no longer exclusively red. Therefore, HR weedy rice outcrosses generally had acquired crop-like traits, which make it easier to deplete from the soil seedbank, but also difficult to scout.

This study investigated the physicochemical and antioxidant properties of rice bran oil (RBO) produced from the bran of three rice varities; Khao Dawk Mali 105 (white rice), Red Jasmine rice (red rice) and Hom-nin rice (black rice) using three extraction methods including cold-press extraction (CPE), solvent extraction (SE) and supercritical CO2 extraction (SC-CO2). Yields, color, acid value (AV), free fatty acid (FFA), peroxide value (PV), iodine value (IV), total phenolic compound (TPC), γ-oryzanol, α-tocopherol and fatty acid profile were analyzed. It was found that the yields obtained from SE, SC-CO2 and CPE extractions were 17.35-20.19%, 14.76-18.16% and 3.22-6.22%, respectively. The RBO from the bran of red and black rice samples exhibited high antioxidant activities. They also contained higher amount of γ-oryzanol and α-tocopherol than those of white rice sample. In terms of extraction methods, SC-CO2 provided better qualities of RBO as evidenced by their physicochemical and antioxidant properties. This study found that RBO produced from the bran of black rice samples using SC-CO2 extraction method showed the best physicochemical and antioxidant properties.

A field experiment was carried out at the Bagusala Farm, of M.S. Swaminathan School of Agriculture, Centurion University of Technology and Management, Paralakhemundi, Odisha during the kharif season of 2018. Four traditional rice varieties namely, V1, Red rice (kondo dano), V2, Manipuri black rice, V3, Balami and V4, Dudheshwar were taken into consideration and the treatments were laid out in Randomized Complete Block Design (RCBD) with four replications. The traditional rice variety Dudheshwar got highest values of growth attributing characteristics, yield attributes and yield of rice. The highest grain yield (6560.25 kg ha−1) and straw yield (10632 kg ha−1) were achieved by treatment V4-Dudheshwar. In terms of net return and benefit: cost ratio, the variety Manipuri black rice is resulted in higher profitability as compared to other traditional rice varieties.

The rice production system in Japan is changing due to the aging of rice farmers, shortage of labor, mechanization, and increase of large-scale rice fields and increased application of direct sowing, all of which contribute to the lack of sophisticated weed management practices. Because the changing production system has not improved and likely worsened weed management practices, weedy rice (Oryza sativa L.) has become a serious threat to rice production in Japan. We analyzed weedy rice accessions from Nagano, the central part of Japan, and other rice accessions to elucidate the origin of this weedy rice using a whole-genome single nucleotide polymorphism (SNP) array. For developing sustainable weedy rice management practices, the elucidation of the origin of re-emerging weedy rice is crucial. Population genetic analysis indicated that weedy rice in Nagano was phylogenetically independent from the local red rice cultivar with low genetic diversity. Past and recently re-emerging weedy rice ecotypes in Nagano shared a similar genetic background which implies the evolution of weedy rice by severe natural selection. Window-based FST and selection sweep analysis revealed the divergence of some of the known key domestication-related genes, such as shattering gene sh4 and qsh1, of weedy rice from domesticated rice cultivars.

The objective of this work was to evaluate the distribution of imidazolinone-resistant (IMI-R) red rice (Oryza sativa) populations, the frequency of alleles conferring resistance to IMI, and the adoption of agronomic practices applied to red rice control, across growing seasons and production regions of the state of Rio Grande do Sul (RS), Brazil. In the experiment, 1,008 red rice populations were screened for resistance to IMI, 760 IMI-R red rice plants were genotyped for the acetolactate synthase (ALS) alleles conferring resistance to IMI, and 40 'Clearfield' rice growers were surveyed. IMI-R red rice populations were widespread throughout RS since the 2006/2007 growing season, with a higher initial frequency in the Depressão Central and Fronteira Sul production regions. The occurrence of IMI-R red rice ranged from 1.6 to 3.5 years after 'Clearfield' rice release. Gly654Glu was the most frequent ALS mutation in IMI-R red rice populations, which shows a gene flow from the most used 'Clearfield' rice cultivars to the red rice plants. Crop rotation systems and certified seed were used by only 30% of the surveyed growers of 'Clearfield' rice, with lower percentages in the production regions where IMI-R red rice appeared faster. Resumo: O objetivo deste trabalho foi avaliar a distribuição de populações de arroz-vermelho (Oryza sativa) resistente às imidazolinonas (R-IMI), a frequência dos alelos que conferem resistência às IMI, e a adoção de práticas agronômicas aplicadas ao controle do arroz-vermelho, em estações de cultivo e regiões produtoras de arroz do Estado do Rio Grande do Sul (RS), Brasil. No experimento, 1.008 populações de arroz-vermelho foram avaliadas quanto à resistência às IMI, 760 plantas de arroz-vermelho R-IMI foram genotipadas quanto aos alelos da acetolactato sintase (ALS) que conferem resistência às IMI, e 40 produtores de arroz 'Clearfield' foram entrevistados. As populações de arroz-vermelho R-IMI estavam amplamente distribuídas no RS, desde a época de cultivo em 2006/2007, com maior frequência inicial nas regiões orizícolas da Depressão Central e da Fronteira Oeste. A ocorrência de arroz-vermelho R-IMI variou de 1,6 a 3,5 anos após o lançamento do arroz 'Clearfield'. A mutação Gly654Glu da ALS foi mais frequente nas populações de arroz-vermelho R-IMI, o que indica a ocorrência de fluxo gênico da cultivar de arroz 'Clearfield' para as plantas de arroz-vermelho. A rotação de culturas e o uso de sementes certificadas foram adotados por apenas 30% dos produtores de arroz 'Clearfield' entrevistados, com menores percentagens nas regiões em que o arroz-vermelho R-IMI apareceu mais rápido.