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The rice cultivar by seeding rate study objective is to evaluate the response of new cultivars to selected seeding rates to determine the most effective seeding rate throughout the diversity of the rice-growing environmental conditions in Arkansas. These cultivars were seeded at 3 University of Arkansas System Division of Agriculture locations in Arkansas: the Rice Research and Extension Center (Stuttgart; silt loam soil), the Pine Tree Research Station (Colt; silt loam soil), and the Northeast Research and Extension Center (Keiser, clay soil). The pure-line varieties evaluated in 2022 were Ozark, Taurus, PVL03, DG263L, and RTv7231 MA seeded at 5, 10, 20, 30, and 40 seed/ft2; and the hybrids evaluated were RT 7321 FP, RT 7331 MA, RT 7421 FP, and RT 7302 seeded at 4, 6, 8, 10, and 12 seed/ft2. Results suggest that seeding rates lower than currently recommended are capable of producing optimal yields for the cultivars evaluated. [ABSTRACT FROM AUTHOR]

Hybrid rice (Oryza sativa L.) accounts for over 50% of Arkansas rice acres annually. The objective of this research is to determine the optimal nitrogen (N) fertilizer rates for new hybrids across different soils and environments in the Arkansas rice production region. The hybrids RT 7302, RT 7321 FP, and RT 7421 FP were evaluated at a range of preflood N rates. Previous studies have found that a 2-way split application (preflood and boot) increases grain and milling yields combined with reduced lodging. Therefore, a boot N application was made to all treatments. However, to reevaluate the benefits of the boot N application, 2 additional treatments were included to compare with and without boot N. The results of this single year of study suggest that all the hybrids evaluated achieve near-optimal yields at 90-120 lb N/ac. However, additional years of study are needed to make this recommendation which differs from past research. [ABSTRACT FROM AUTHOR]

The purposes of the cultivar x nitrogen (N) studies are the observation, collection, and analysis of the growth and yield response of new rice (Oryza sativa L.) cultivars to N fertilization. The collection of this data is used to determine the optimal N fertilizer rates across the range of soils and environments in which rice is grown in Arkansas. Eight cultivars were studied in 2022: Addi Jo, Avant, CLL18, DG263L, Diamond, Ozark, PVL03, and Taurus at 4 locations: the University of Arkansas System Division of Agriculture's Northeast Research and Extension Center (NEREC), the Northeast Rice Research and Extension Center (NERREC) the Pine Tree Research Station (PTRS), and the Rice Research and Extension Center (RREC). Seed treatment and seeding rates followed current recommendations and production practices. The grain yields were fair to good for all cultivars studied at the 4 locations in 2021 with little to no lodging reported for all cultivars across all locations. The 2022 season was the first year the cultivars Addi Jo, Avant, CLL18, Ozark, and Taurus were included and the second year of inclusion for the cultivar PVL03; therefore, there is insufficient data to make a N rate recommendation at this time, and hence the response to N reported here can serve as a guide while more data is collected in subsequent years. Three years of results for DG263L provide evidence that this cultivar should have excellent yields with minimal to no lodging if 135 pounds (lb) of N/ac is applied in a 2-way split of 90 lb N/ac at the preflood timing followed by 45 lb N/ac at midseason when grown on silt loam soils and 165 lb N/ac in a 2-way split of 120 lb N/ac at the preflood timing followed by 45 lb N/ac applied at midseason when grown on clay soils. [ABSTRACT FROM AUTHOR]

The Degree-Day 50 (DD50) computer program is one of the most successful management aids developed by the University of Arkansas System Division of Agriculture. This program predicts critical growth stages that assist in increasing the effectiveness of crop management operations. In order to maintain its relevance, the computer program must be updated continually as new rice cultivars become available to growers. In order to accomplish this goal, studies are conducted in a controlled research environment where developmental data and DD50 thermal unit thresholds for current and new cultivars are determined. Throughout the 2022 season, DD50 thermal unit accumulation, developmental data, and the effect of seeding date (SD) on grain and milling yield potential for 21 cultivars were evaluated over 6 SDs under a dry-seeded, delayed-flood management system commonly used in southern U.S. rice production. Significant differences in grain yield were observed for all 21 cultivars at each location. [ABSTRACT FROM AUTHOR]

Use of on-farm commercial fields and research stations provides the opportunity to evaluate cultivar performance across a wide range of environmental conditions and management situations. The Arkansas Rice Performance Trials (ARPT) utilize experiment stations and commercial fields throughout the rice-producing regions of Arkansas to evaluate the performance of commercial rice cultivars. These trials provide information on agronomic factors of cultivars such as disease resistance, lodging, plant stand, plant height, grain yield, and milling yield across a range of environmental conditions, growing practices, and soil types. Choosing a cultivar is a critical decision annually for producers. Studies in 2022 were in grower fields in Clay, Desha, Greene, Jackson, Lawrence, and Lonoke counties, and on research stations in Arkansas, Mississippi, Poinsett, and St. Francis counties. The average grain yield across all 10 trials was 176 bu./ac with the highest average yielding location being Arkansas County at 191 bu./ac. Cultivars that had the highest average grain yield across all locations include RT XP780, RT 7521 FP, RT 7401, RT XP753, RT 7302, RT 7331 MA, Ozark, and DG263L. The average milling yield across all cultivars was 56/70 (%HR/%TR), with Addi Jo, Jupiter, Leland, DGL2065, and CLM04 producing the highest average milling yields. [ABSTRACT FROM AUTHOR]

In a flooded Arkansas rice system, producers and consultants identified the most problematic weed they face is barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.]. Due to the evolution of herbicide resistance and the overall hardiness of the weed, other control measures are needed for barnyardgrass in rice. The objective of this study was to evaluate the influence of rice cultivars and the manipulation of drill row width for barnyardgrass control in rice. Field experiments were conducted at the University of Arkansas System Division of Agriculture's Pine Bluff Small Farm Outreach Center, near Lonoke, Arkansas, Pine Tree Research Station, near Colt, Arkansas, and the Rohwer Research Station, near Watson, Arkansas in 2021 and 2022. The experiments were designed as randomized complete block split-plot designs (16 treatments) replicated 4 times with 4 nontreated controls for each drill width spacing. Each trial consisted of a whole plot factor of 4 drill row width spacings: 5, 7.5, 10, and 15 in. The subplot factor consisted of 4 cultivars: medium-grain inbred (CLM04), long-grain inbred (CLL16), long-grain hybrid (RT 7301), and FullPage long-grain hybrid (RT 7521 FP). Results indicated no interaction of drill row width spacing and rice cultivar for any response variables. A decrease in barnyardgrass density was observed for the 7.5-in. spacing compared to the 15-in. spacing across site-years for the 5- to 6-leaf (preflood) and preharvest rice stages. A 43% decrease in barnyardgrass density was observed for the hybrid cultivars compared to the inbred at the preharvest timing. Based on small unmanned aerial system (sUAS) imagery at panicle differentiation, there was a 20 percentage point decrease in canopy coverage from the 7.5 in. drill row width to the 15 in. width. This research provides insights on alternative weed management efforts through more precise drill row width spacing and cultivar selection in an Arkansas flooded rice system. [ABSTRACT FROM AUTHOR]

Furrow-irrigated rice (Oryza sativa L.), or row rice, has increased in acreage in Arkansas in the past few years. This practice allows growers to potentially grow rice on steeper ground that would require a vast number of levees that is labor and time intensive. However, this non-traditional rice growing method has a weed management drawback. The removal of the flood as a means of weed control places additional pressure on other weed management strategies and potentially different herbicide programs. Therefore, the objectives of this research were to determine if the manipulation of drill row spacing and bed width would influence season-long weed control. Two studies were seeded with hybrid rice RT7521 FP in 2021 and 2022 at Lonoke and Pine Tree, Ark. to evaluate treatments that consisted of three bed widths (30-, 38-, and 60-in.) and four drill row spacings (5-, 7.5-, 10-, and 15-in.). Barnyardgrass [Echinochloa crus galli (L.) P. Beauv.] density was assessed at the 5- to 6-leaf rice stage and preharvest. Canopy closure was captured with aerial digital images from a small, unmanned aircraft system (sUAS) collected at the 3-6 leaf and panicle differentiation rice stages. Rough rice yield was harvested with a plot combine and adjusted to 13% moisture. In general, barnyardgrass densities were lower across narrower drill row spacings (=7.5-in.) and bed widths (30-in.) early in the season; however, little differences were seen at the later preharvest timing. Canopy closure responded similarly as narrower drill row spacing and bed width had greater canopy closure. Rough rice yield was impacted less by drill row spacing and bed width, but narrower drill row spacing and bed width had a slightly higher numerical yield increase. Early findings suggest that a grower choosing this method of rice management should choose the narrowest drill row spacing allowed by their equipment and the narrowest bed widths that they can obtain to maximize weed management efforts. [ABSTRACT FROM AUTHOR]

Reflecting recent changes of the Arkansas rice industry and streamlining the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include conventional, Clearfield®, and Provisia® medium-grain and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins, will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. To improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as genomic selection are vigorously pursued. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Variety Advancement Trials (ARVAT) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program compared to commercially available cultivars from public and private breeding programs. ARVATs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARVATs were conducted at 6 locations during 2022. Averaged across locations, among conventional long-grains grain yields were highest for RU2201020 at 191 bu./ac compared to the commercial checks RT XP753 (205 bu./ac), Ozark (188 bu./ac), DG263L (188 bu./ac), and Diamond (172 bu./ac). Among Clearfield long-grains grain yields were highest for 21CL1054 at 189 bu./ac, RU1801101 at 186 bu./ac, and RU2101177 at 186 bu./ac compared to the commercial checks RT 7321 FP (190 bu./ac), CLL18 (178 bu./ac), and CLL16 (173 bu./ac). Among conventional and Clearfield medium-grains, grain yields were highest for 21AR1217 at 190 bu./ac and 21AR1222 at 190 bu./ac compared to the commercial checks Taurus (181 bu./ac), Titan (161 bu./ac), and CLM04 (154 bu./ac). Among longgrain aromatics, grain yields were highest for RU2101109 at 174 bu./ac compared to the commercial check ARoma 17 (139 bu./ac). Among Provisia long-grains, grain yields were highest for 22AR2106 at 177 bu./ac compared to the commercial check PVL03 (172 bu./ac). [ABSTRACT FROM AUTHOR]

The 2022 Rice Research Verification Program (RRVP) was conducted on 9 commercial rice fields across Arkansas. Counties participating in the program included Arkansas, Crittenden, Drew, Jefferson, Lonoke, Mississippi, Monroe, Phillips, St. Francis for a total of 421 acres. Grain yield in the 2022 RRVP averaged 176 bu./ac, ranging from 145 to 218 bu./ac. The 2022 RRVP average yield was 11 bu./ac greater than the estimated Arkansas state average of 165 bu./ac. The highestyielding field was Mississippi County with a yield of 218 bu./ac. The lowest-yielding field was Arkansas tied with St. Francis County and produced 145 bu./ac. Milling quality in the RRVP averaged 50/67 (% head rice/% total milled rice). The Mississippi Co. field had the greatest returns to operating costs of $747.46/ac while the St. Francis Co. field had the lowest returns to operating costs of $199.60/ac. [ABSTRACT FROM AUTHOR]

Arkansas is the leading rice producer in the United States. The state represents 50.1% of total U.S. rice production and 49.8% of the total acres planted to rice in 2022. Rice cultural practices vary across the state and across the U.S. However, these practices are also dynamic and continue to evolve in response to changing political, environmental, and economic times. This survey was initiated in 2002 to monitor and record changes in the way Arkansas rice producers approach their livelihood. The survey was conducted by polling county extension agents in each of the counties in Arkansas that produce rice. Questions included topics such as tillage practices, water sources and irrigation methods, seeding methods, and precision leveling. Information from the University of Arkansas System Division of Agriculture DD50 Rice Management Program was included to summarize variety acreage distribution across Arkansas. Other data were obtained from the USDA National Agricultural Statistics Service. [ABSTRACT FROM AUTHOR]

The timing of rice planting, the type of cultivar planted, and weather can greatly affect the profitability of rice production. Earlier studies focused on the impacts of rice planting timing on grain yields and/or milling yields and concentrated almost exclusively on public pure-line rice cultivars. The earlier studies also did not evaluate the impacts of planting timing on rice profitability. The impacts of weather outcomes on the profitability of rice planting timing have also not been evaluated. This study uses a payoff matrix approach to evaluate the economic impacts of different planting windows and cultivar types on rice profitability during dry, wet, and normal growing seasons. The results indicate that expected monetary payoffs are greatest in dry and normal growing seasons when all rice cultivar types are planted early (11 March-14 April) but are greatest in wet growing seasons for long-grain pure-lines and hybrids when planted in the middle planting window (15 April-14 May). Monetary payoffs by planting window are smallest for herbicide-tolerant non-hybrids relative to all other rice cultivar types regardless of the weather outcome faced during the growing season. [ABSTRACT FROM AUTHOR]

The timing of rice planting can greatly affect the profitability of rice production. Planting too early or too late can result in significant yield reductions and can, thus, reduce economic returns. Earlier studies primarily focused on the impacts of planting timing on public pure-line rice cultivars and did not evaluate the impacts of planting timing on rice profitability. The effects of planting timing on rice return variability have also not been considered. This study uses a safety-first approach to incorporate risk considerations into the economic analysis of rice planting and timing decisions in east-central Arkansas. Expected net returns and lower confidence limits on returns are evaluated for risk-neutral and risk-averse rice producers, respectively. The results indicate that all rice cultivar types produce the largest expected net returns and the largest lower confidence limits when planted early (11 March--14 April). Hybrid rice cultivars result in the largest expected net returns and the largest lower confidence limits, while herbicide-tolerant non-hybrid cultivars result in the lowest expected net returns and the lowest lower confidence limits across all planting windows examined in the study. [ABSTRACT FROM AUTHOR]

The Degree-Day 50 (DD50) computer program is one of the most successful management aids developed by the University of Arkansas System Division of Agriculture. This program predicts critical growth stages that assist in increasing the effectiveness of crop management operations. In order to maintain its relevance, the computer program must be updated continually as new rice cultivars become available to growers. In order to accomplish this goal, studies are conducted in a controlled research environment where developmental data and DD50 thermal unit thresholds for current and new cultivars are determined. Throughout the 2021 season, DD50 thermal unit accumulation, developmental data, and the effect of seeding date (SD) on grain and milling yield potential for 22 cultivars were evaluated over 6 SDs under a dry-seeded, delayed-flood management system commonly used in southern U.S. rice production. Significant differences in grain and milling yield were observed for all 22 cultivars at each location. [ABSTRACT FROM AUTHOR]

The purpose of the cultivar by nitrogen (N) studies is the observation and analysis of the response of new rice (Oryza sativa L.) cultivars to N fertilization in order to determine the optimal N fertilizer rates across an array of soils and environments in which rice is grown in Arkansas. Twelve cultivars were studied in 2021 and included: ARoma17, CLL16, CLL17, CLM04, DG263L, DGL274, Diamond, Jewel, Lynx, ProGold1, ProGold2, and PVL03 at 3 University of Arkansas System Division of Agriculture locations: the Northeast Research and Extension Center (NEREC), the Pine Tree Research Station (PTRS), and the Rice Research and Extension Center (RREC). Seed treatment and seeding rates followed current recommendations and production practices. The grain yields were fair to good for most cultivars studied at the 3 locations in 2021, with lodging ranging from mild to none, with a few plots severely damaged at the PTRS location. The 2021 season was the first year the cultivars DGL274 and PVL03 were included, and the second year for DGL263L, ProGold1, and ProGold2; therefore, there is insufficient data to make an N rate recommendation at this time, and hence the response to N reported here can serve as a guide while more data is collected in subsequent years. Multiple years of results for ARoma17, Diamond, CLL16, CLM04, Jewel, and Lynx provide evidence that these cultivars should have good yields with minimal to no lodging if 150 pounds (lb) of N/ac is applied in a two-way split of 105 lb N/ac at the preflood timing followed by 45 lb N/ac at midseason when grown on silt loam soils and 180 lb N/ac in a two-way split of 135 lb N/ac at the preflood timing followed by 45 lb N/ac applied at midseason when grown on clay soils. [ABSTRACT FROM AUTHOR]

The use of on-farm commercial fields and research stations provides the opportunity to evaluate cultivar performance across a wide range of environmental conditions and management situations. The Arkansas Rice Performance Trials (ARPT) utilize experiment stations and commercial fields throughout the rice-producing regions of Arkansas to evaluate the performance of commercial rice cultivars. These trials provide information on agronomic factors of cultivars such as disease resistance, lodging, plant stand, plant height, grain yield, and milling yield across a range of environmental conditions, growing practices, and soil types. Choosing a cultivar is a critical decision annually for producers. Studies in 2021 were in grower fields in Clay, Desha, Greene, Jackson, Lawrence, and Phillips counties and on research stations in Arkansas, Mississippi, Poinsett, and St. Francis counties. The average grain yield across all 11 trials was 206 bu./ac, with the highest average yielding location being Mississippi County at 227 bu./ac (Table 2). Cultivars that had the highest average grain yield across all locations include RT XP753, RT 7321 FP, RT 7401, RT 7301, RT 7521 FP, DG263L, Taurus, and Ozark. The average milling yield across all cultivars was 58/70 (%HR/%TR), with Jupiter, CLM04, Lynx, PVL02, and Taurus displaying the highest average milling yields. [ABSTRACT FROM AUTHOR]

Arkansas rice producers have noticed an increase of resilient barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] becoming increasingly difficult to control. Cultural methods of drill width spacing manipulation and nozzle selection aid in controlling this hardy weed. The objective of this study was to evaluate the influence of nozzle type and rice drill width spacing on spray coverage and weed control in rice. Experiments were conducted at the University of Arkansas at the Pine Bluff Small Farm Outreach Center near Lonoke, Arkansas and the University of Arkansas System Division of Agriculture's Pine Tree Research Station near Colt, Arkansas, in 2021. Each plot was drill-seeded with four drill width spacings: 5, 7.5, 10, and 15 inches. Two herbicide applications were made with commonly used rice herbicides with 5 types of nozzles: XR, AIXR, TTI, TTI60, and AITTJ60, of which, the TTI60 and AITTJ60 were dual-fan nozzles. Barnyardgrass density counts were assessed at the 3-leaf rice stage and prior to harvest. Water-sensitive cards were placed and sprayed at the preflood stage to assess the percent spray coverage of each nozzle type. Both experiments showed no differences between the interaction of drill width spacing and nozzle types for any response variables. At the Lonoke location, barnyardgrass density was greater at 15-in. spacing than the 5-, 7.5-, and 10-in. spacing at the 3-leaf rice stage. The smaller droplet-sized nozzles (XR, AITTJ60, AIXR) produced a greater percent spray coverage than the larger droplet-sized nozzles (TTI60 and TTI), but no increase in coverage was observed from dual-fan nozzles. This research provided insights on a more precise drill width spacing and nozzle type selection to be used in rice standard practices. [ABSTRACT FROM AUTHOR]

Weeds compete with rice for resources, and suboptimal management can result in significant yield losses. Proper weed seedling identification with adequate herbicide application timeliness are required to develop effective weed control strategies. With a gradually decreasing barrier to entry, stakeholders are gaining interest in using drone remote sensing to facilitate scouting and optimize strategic planning. However, remote rice weed detection presents unique challenges, and rice growers will only fully benefit from available technologies if provided with decision-support systems that meet their specific needs. Often, assumptions are made on the type and quality of information that can be extracted from drone images without proof that such data can, in fact, be collected. The objective of this study was to determine if rice weed seedlings could be identified in raw drone images collected before flood. Remote sensing and ground-truth data were collected in 6 locations with different weed species, rice growth stages, and weed seedling sizes. Weed seedlings were counted in the field and in drone images collected at different flight altitudes. Data were analyzed to compare the number of weed seedlings seen in the drone images to the number of weed seedlings found in the field. Results demonstrated that it was not always possible to distinguish all rice weed seedlings in the collected images independently from image resolution. When possible, drone images needed to be collected at a very low altitude (less than 5 ft) using typical prosumer drone remote sensing equipment. The findings provided a better understanding of the possibilities and limitations of drone remote rice weed seedling detection. [ABSTRACT FROM AUTHOR]

Reflecting recent changes in the Arkansas rice industry and streamlining the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include conventional, Clearfield®, and Provisia® medium-grain and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins, will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. In order to improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as genomic selection are vigorously pursued. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Variety Advancement Trials (ARVAT) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program compared to commercially available cultivars from public and private breeding programs. The ARVATs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARVATs were conducted at 6 locations during 2021. Averaged across locations, grain yields were highest for the conventional long-grain hybrid RT XP753, the FullPage long-grain hybrid RT 7521 FP, the conventional medium-grain RU1901033, the MaxAce long-grain RTv7231 MA, the Clearfield medium-grain RU2101234, the Clearfield long-grain RU2001093, the conventional long-grain RU2001185, and the conventional long-grain RU2001125. [ABSTRACT FROM AUTHOR]

The 2021 Rice Research Verification Program (RRVP) was conducted on 8 commercial rice fields across Arkansas. Counties participating in the program included Arkansas, Chicot, Desha, Drew, Jefferson, Lonoke, Mississippi, and Monroe, for a total of 462 acres. Grain yield in the 2021 RRVP averaged 206 bu./ac, ranging from 172 to 243 bu./ac. The 2021 RRVP average yield was 36.4 bu./ac greater than the estimated Arkansas state average of 169.6 bu./ac. The highest yielding field was the furrow-irrigated rice field in Desha Co., with a grain yield of 243 bu./ac. The lowest yielding field was in Jefferson County and produced 172 bu./ac. Milling quality in the RRVP averaged 53/69 (% head rice/% total milled rice). The Mississippi Co. field had the greatest returns to operating costs of $725.13/ac, while the Lonoke Co. field had the lowest returns to operating costs of $468.12/ac. [ABSTRACT FROM AUTHOR]

Arkansas is the leading rice producer in the United States. The state represents 47.5% of total U.S. rice production and 47.8% of the total acres planted to rice in 2021. Rice cultural practices vary across the state and across the U.S. However, these practices are also dynamic and continue to evolve in response to changing political, environmental, and economic times. This survey was initiated in 2002 to monitor and record changes in the way Arkansas rice producers approach their livelihood. The survey was conducted by polling county extension agents in each of the counties in Arkansas that produce rice. Questions included topics such as tillage practices, water sources and irrigation methods, seeding methods, and precision leveling. Information from the University of Arkansas System Division of Agriculture's Degree-Day 50 (DD50) Rice Management Program was included to summarize variety acreage distribution across Arkansas. Other data were obtained from the USDA National Agricultural Statistics Service. [ABSTRACT FROM AUTHOR]

Furrow-irrigated rice (FIR) acreage is rapidly increasing across Arkansas. Acreage has risen from approximately 10,000 acres in 2015 to over 240,000 acres in 2020. The rapid increase in FIR acres has also resulted in a wide range of practices used to implement FIR. Therefore, a study was designed to assess 4 different methods of seeding and/or seedbed preparation for FIR. Treatments include 1) drilling seed into flat soil followed by creating water furrows post-seeding, 2) forming beds/furrows followed by drilling seed into the previously formed beds, 3) drilling seed into flat soil followed by forming beds/furrows post-seeding over the top of seed, and 4) broadcasting seed on the soil surface followed by forming beds post-seeding. Trials were conducted on both a silt loam and clay soil. At the silt loam site, broadcasting seed followed by forming beds produced significantly higher grain yields compared to drilling flat followed by water furrows and forming beds followed by drilling. Drilling flat followed by forming beds performed similarly to the broadcast treatment. At the clay site, drilling flat followed by water furrows resulted in significantly higher grain yields compared to all other treatments. Differences between sites could be related to soil type and/or equipment available to perform operations, but further study is needed to quantify these differences. [ABSTRACT FROM AUTHOR]

In 2021, the Rice Grower Research and Demonstration Experiment (GRADE) Program was located in Arkansas County near Stuttgart, Ark., Craighead County near Harrisburg, Ark., and Lee County near Moro, Ark. Trials consisted of replicated, large-block demonstrations evaluating the rice varieties Diamond, CLL15, CLL16, and Jewel. The University of Arkansas System Division of Agriculture and the Arkansas Rice Research and Promotion Board first initiated this program in 2017 to conduct replicated large block field trials consisting of replicated plots of approximately one-half acre or larger on grower farms to bridge information between small plot research trials and grower field experiences. It is a collaborative effort between growers, consultants, county extension agents, extension specialists, and researchers. [ABSTRACT FROM AUTHOR]

In the last several years, there has been increasing interest in furrow-irrigated rice (FIR) (Oryza sativa L.) production. Cultivar selection recommendations have been general and primarily based on anecdotal evidence to date. In 2021, a small-plot rice cultivar performance trial was established at Jackson Co. on a Dundee silt loam soil. A split-plot design was utilized with the whole-plot factor being the location within the field (top and bottom) and the split-plot factor being cultivar, of which there were 12 evaluated. In 2021, the bottom area of the field had significantly higher yields than the top area of the field. In general, the hybrid cultivars RT XP753, RT 7521 FP, and RT 7401 had significantly higher grain yields than the other entries in the trials at both top and bottom areas of the fields. Jupiter, Lynx, and CLL17 had greater head rice yields than all other entries at the top of the field. Jupiter and Lynx also had the highest head rice yields at the bottom of the field. As plot areas were uniformly managed, additional research is necessary to determine whether varieties can be more competitive with the hybrids when cultivar-specific management practices are implemented. [ABSTRACT FROM AUTHOR]

Cultivar by seeding rate studies assist in developing production recommendations for new rice (Oryza sativa, L.) cultivars to determine necessary seeding rates that cover a range of Arkansas production/growing conditions. The 2021 study examined 5 rice cultivars, CLL16, CLL17, DG263L, Jewel, and Lynx. Seeding rates of 10, 20, 30, 40, and 50 seed/ft² were used for each cultivar. Current production recommendations were utilized at each location, and all seed received insecticide and fungicide seed treatments. Studies were seeded at 3 research station locations across eastern Arkansas. Differences were observed for stand density among seeding rates; however, there were few grain yield differences and no differences in milling yields. In 2021, even the lowest seeding rates produced stand densities at or near the recommended stand density range to produce optimal grain yields. The possibility of reduced stand density and grain yield should be noted if seed treatments for insecticides and fungicides are not used. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Performance Trials (ARPTs) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program and commercially available cultivars from public and private breeding programs. The ARPTs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARPTs were conducted at 4 locations during 2019. Averaged across locations, grain yields were highest for the commercial cultivars RT 7301, RT XP753, RT 7501, RT 7521 FP, DGL263, RT Gemini 214 CL, RT 7321 FP, Jupiter, Titan, and RT CLXL745. Cultivars with the highest overall milling yields during 2019 included: PVL02, CLJ01, Jazzman-2, ARoma 17, Jupiter, CL151, CL153, and CLM04. [ABSTRACT FROM AUTHOR]

In 2019, the Rice Grower Research and Demonstration Experiment (GRADE) Program was conducted in commercial rice fields at 8 locations across Arkansas. Trials consisted of replicated, large-block demonstrations evaluating varieties, nitrogen management, and seeding rates. The University of Arkansas System Division of Agriculture and the Arkansas Rice Research and Promotion Board first initiated this program in 2017 to conduct large block replicated field trials on grower farms to bridge information between small plot research trials and grower field experiences. It is a collaborative effort between growers, consultants, county extension agents, extension specialists, and researchers using large block plots of approximately one-half acre or larger within a grower's field to achieve program goals. [ABSTRACT FROM AUTHOR]

On-farm cultivar testing provides the ability to evaluate performance in commercial fields with more unpredictable environments than those at traditional research stations. The Producer Rice Evaluation Program (PREP) utilizes commercial fields throughout the state of Arkansas to evaluate 25 different rice cultivars, including experimental and commercial lines. These on-farm tests are used to analyze different agronomic aspects of cultivars such as disease, lodging, plant stand, plant height, grain yield, and milling yield in diverse environmental conditions, soil types, and growing practices. The most important decision for a producer can be the cultivar that will provide the maximum yield potential for each field. On-farm testing can indicate the cultivars that are best suited for a particular growing situation. Studies were located in grower fields in Craighead, Greene, Lee, Lonoke, Poinsett, Prairie, and Woodruff counties for the 2019 season. The average grain yield across all six locations was 199 bu./ac, and the location with the highest average grain yield average was Woodruff County at 223 bu./ac. The cultivars with the highest average grain yield across all locations were RT XP753, RT Gemini 214 CL, RT 7301, RT 7521 FP, CLL16, RT 7501, Jupiter, RT 7321 FP, Titan, and Diamond. Cultivars with the highest head rice yields were PVL02, CLM04, Jupiter, CLJ01, CL151, CL153, Jazzman-2, ARoma 17, Jewel, Lynx, and PVL01. [ABSTRACT FROM AUTHOR]

The Degree-Day 50 (DD50) computer program is one of the most successful management aids developed by the University of Arkansas System Division of Agriculture. This program predicts critical growth stages that assist in increasing the effectiveness of crop management operations. In order to maintain its relevance, the computer program must be updated continually as new rice cultivars become available to growers. To accomplish this goal, studies are conducted in a controlled research environment where developmental data and DD50 thermal unit thresholds for current and new cultivars are determined. Throughout the 2019 season, DD50 thermal unit accumulation, developmental data, and the effect of seeding date (SD) on grain and milling yield potential for 20 cultivars were evaluated over six SDs under a dry-seeded, delayed-flood management system commonly used in southern U.S. rice production. Significant differences in grain and milling yield were observed for all 20 cultivars at each location. [ABSTRACT FROM AUTHOR]

Furrow-irrigated rice (FIR) (Oryza sativa L.) acreage has steadily increased over the past several growing seasons, and it appears this trend will continue. One issue that is likely to be common in FIR is the possible loss of nitrogen (N) via nitrification-denitrification sequences in the alternating aerobic-anaerobic soil conditions. Trials were established in 2019 at 1 commercial site, Almyra, on a Dewitt silt loam and at 2 University of Arkansas System Division of Agriculture research stations, the Pine Tree Research Station (PTRS) on a Calloway silt loam and the Rice Research and Extension Center (RREC) on a Dewitt silt loam. Factors included location within the field (top and bottom), N source [urea + n-butyl thiophosphoric triamide (NBPT) and SuperU®], and N management regime, of which there were six variations of rate and time combinations. The use of SuperU® increased yield at the PTRS by 17.7 bu./ac at the bottom of the field compared to urea + NBPT, but did not affect yield at the top of the field nor did it have an effect at the other two sites. The major yield discrepancy was at Almyra, where the bottom of the field yielded 57.6 bu./ac greater than the top of the field, most likely due to drought stress at the top of the field. Nitrogen source did not affect head rice yield or total white rice yield at any of the locations. Considering current pricing and trial results, urea + NBPT appears to be the optimum N source for furrowirrigated rice production in Arkansas. [ABSTRACT FROM AUTHOR]

Hybrid rice (Oryza sativa L.) has accounted for nearly 50% of Arkansas' total rice acres harvested during the last decade. Previous research conducted on the current recommendation of applying 30 lb nitrogen (N)/ac to hybrid rice cultivars at the late-boot growth stage indicated an increase in both grain and milling yields. The conclusions from previous research suggested that significant increases in grain and milling yields were due to the addition of a late-season N application; however, more research is needed to determine if the late-season N application is necessary due to inconsistent results. A study was initiated to examine grain and milling yields on hybrid rice when implementing a late-season N application across varying preflood N application rates. The RiceTec (RT) hybrids, RT Gemini 214 CL and RT XP753, were used in this study and are the most common hybrid rice cultivars grown in Arkansas. These two cultivars were planted at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Arkansas, on a silt loam soil, and the Rohwer Research Station (RRS) near Rohwer, Arkansas on a clay soil. Results indicate that there is a positive impact from the late-season N application on both grain and milling yields from both cultivars at each of the locations. When lateseason N was applied, there was an increase of 11 to 16 bu./ac across the two locations. Also, the late-season N application resulted in a significant increase in head rice milling yield from 1% to 5% across both locations but showed no significant difference in total rice. When observing head rice yields from various plant components (main stem vs. tillers) within the same plots, there is a significant increase in head rice yield when applying the late-season N that is equal across both main steams and tillers. It is apparent that the late-season N application results in significant increases in both grain and milling yields. Further research is needed to better understand the relationship contributing to increased grain yield and milling yields when late-season N is applied to hybrid rice and define the physiological mechanism for this response and help predict when and where it will occur. [ABSTRACT FROM AUTHOR]

The objective of the cultivar × nitrogen (N) studies is to determine the optimal N fertilizer rates for new rice (Oryza sativa L.) cultivars across the array of soils and environments encountered in the Arkansas rice-growing region. The eleven cultivars studied in 2019 were: ARoma 17, CLJ01, CLL15, CLL16, CLM04, Jewel, Lynx, PVL01, PVL02, the experimental line ARX7-1084, and Diamond. Seed treatment and seeding rates were determined following current recommendations and production practices. The grain yields were good to excellent for all the cultivars studied at the three locations in 2019: University of Arkansas System Division of Agriculture's Northeast Research and Extension Center (NEREC), Keiser, Arkansas, on a Sharkey Clay (Vertic Haplaquepts) soil; the Pine Tree Research Station (PTRS) near Colt, Arkansas, on a Calloway silt loam (Glossaquic Fragiudalfs) soil series; and the Rice Research and Extension Center (RREC), near Stuttgart, Arkansas, on a Dewitt silt loam (Typic Albaqualfs) soil. This is the first year the cultivars ARoma 17, CLJ01, CLL15, CLL16, CLM04, Jewel, Lynx, and PVL02 are included in the cultivar × N rate study; therefore there is insufficient data to make a recommendation at this time. Multiple years of results for PVL01 indicate this cultivar should have good yields with minimal to no lodging if 150 pounds (lb) of N/ac is applied in a two-way split of 105 lb N/ac at the preflood timing followed by 45 lb N/ac at midseason when grown on silt loam soils and 180 lb N/ac in a two way split of 135 lb N/ac at the preflood timing followed by 45 lb N/ac applied at midseason when grown on clay soils. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) acres utilizing alternative irrigation practices have increased tremendously over the past several growing seasons, mainly in the form of furrow-irrigated rice (FIR) due in part to its water saving capability and reduced labor requirement. Because this is a new concept for many producers, there is little guidance on producing rice under the FIR and alternate wetting and drying (AWD) systems. A study was initiated in 2018 and continued in 2019 to define the optimum soil moisture threshold for rice produced using furrow-irrigation and AWD production strategies. Large, production-scale trials in both FIR and AWD were conducted at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Arkansas on a Calloway silt loam and the Northeast Research and Extension Center (NEREC) near Keiser, Arkansas on a Sharkey silty clay. The timing of irrigation within the FIR treatments was determined based on a soil moisture threshold of either -15, -30, or -45 centibars (cb), while AWD trials utilized the same thresholds but only between 3 weeks after the initial flood establishment and 50% heading. Data from the 2019 growing season suggested that the irrigation threshold did not have a significant influence on rice grain yield under FIR production. However, the control performed better than all FIR at the PTRS, while all FIR performed better than the control at the NEREC. Alternate wetting and drying rice performed equally to the control at the PTRS, but AWD rice with a -15 or -30 cb threshold actually performed better than the -45 cb threshold and the control at the NEREC. The -45 cb threshold also resulted in significant irrigation water savings--17.2% and 34.1% savings in FIR and 17.7% and 73.0% savings in AWD when compared to the control at the PTRS and the NEREC, respectively. These studies suggest that utilizing a -45 cb threshold under alternative irrigation strategies allows for significant water savings while maintaining rice yield and quality. [ABSTRACT FROM AUTHOR]

Arkansas is the leading rice producer in the United States. The state represents 45.6% of total U.S. rice production and 47.1% of the total acres planted to rice in 2019. Rice cultural practices vary across the state and across the U.S. However, these practices are also dynamic and continue to evolve in response to changing political, environmental, and economic times. This survey was initiated in 2002 to monitor and record changes in the way Arkansas rice producers approach their livelihood. The survey was conducted by polling county extension agents in each of the counties in Arkansas that produce rice. Questions included topics such as tillage practices, water sources and irrigation methods, seeding methods, and precision leveling. Information from the University of Arkansas System Division of Agriculture's Degree-Day 50 (DD50) Rice Management Program was included to summarize variety acreage distribution across Arkansas. Other data were obtained from the USDA National Agricultural Statistics Service. [ABSTRACT FROM AUTHOR]

The 2019 Rice Research Verification Program (RRVP) was conducted on 15 commercial rice fields across Arkansas. Counties participating in the program included Arkansas, Chicot, Craighead, Crittenden, Desha, Jackson, Jefferson, Lawrence, Lee, Lincoln, Lonoke, Monroe, Randolph, White and Woodruff for a total of 830 acres. Grain yield in the 2019 RRVP averaged 183 bu./ac, ranging from 164 to 214 bu./ac. The 2019 RRVP average yield was 17 bu./ac greater than the estimated Arkansas state average of 166 bu./ac. The highest yielding field was in Craighead County with a grain yield of 214 bu./ac. The lowest yielding field was in Desha County and produced 164 bu./ac. Milling quality in the RRVP averaged 57/70 (% head rice/% total milled rice). [ABSTRACT FROM AUTHOR]

To reflect the recent changes of the Arkansas rice industry and streamline the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include both conventional and Clearfield medium- and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. To improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as molecular marker-assisted selection (MAS) are rigorously pursued. [ABSTRACT FROM AUTHOR]

Hybrid rice cultivars have accounted for approximately 40% of harvested rice acres in Arkansas in recent years. The current University of Arkansas System Division of Agriculture's Cooperative Extension Service recommendation for hybrid cultivars, in addition to preflood nitrogen (N) fertilizer, is for 30 lb N/ac, termed late-boot N fertilizer, to be applied between late boot and beginning heading in order to reduce lodging and enhance grain and milling yields. To determine the validity of this recommendation on current hybrid cultivars, a study was initiated to examine the effects of the lateboot N application on the grain yield, milling yield, and lodging of two new hybrids. The RiceTec (RT) hybrids most commonly grown in Arkansas, RT CLXL745 and RT XP753, were seeded at three University of Arkansas System Division of Agriculture experiment centers/stations. Results of this study suggest that the late-boot N application has a positive impact, relative to rice receiving no boot N, on milling yields of RT CLXL745 and RT XP753, often significantly increasing percent head rice. Percent total white rice was less impacted by the late-boot N application. Substantial lodging of RT CLXL745 occurred at two locations, while lodging of RT XP753 was minor and only at one location. Lodging was reduced numerically by the late-boot N application in all cases, but only significantly for RT CLXL745 at one location. Relative to no boot N, the late-boot N application significantly increased the grain yields of both cultivars at two locations by 9 to 17 bu./ac, while smaller, non-significant increases occurred at the other location. The potential benefits of a 30 lb N/ac late-boot N application to hybrids are apparent, but it will be important to collect more data to further understand and clarify the statistical relationship of the late-boot N application on lodging, milling yields, and grain yields of current hybrid rice cultivars. [ABSTRACT FROM AUTHOR]

Irrigation water is a significant input in Arkansas agricultural production, and rice requires more water than any other field crop grown in the state. Rice is also a high-cost crop relative to other field crops. This study measures the technical efficiency of irrigation water and other important inputs in rice production using Data Envelopment Analysis and data from 142 fields enrolled in the University of Arkansas System Division of Agriculture's Rice Research Verification Program for the period 2005 to 2017. Average irrigation water technical efficiency for all 142 fields is 0.627, indicating irrigation water is over-applied on average by 37.3% across all 142 fields. A large portion of fields in the analysis (60 out of 142 fields or 42.3% of the fields evaluated) have irrigation water efficiencies less than 0.5, indicating many fields are over-applying irrigation water by over 50%. Irrigation water efficiency has a high positive correlation with both diesel and labor efficiency, providing evidence that good irrigation water management can also lead to better management of these key production inputs and improved profit margins for rice producers. [ABSTRACT FROM AUTHOR]

Groundwater from the Mississippi River Valley alluvial aquifer is the major source of irrigation water in Arkansas. Significant downward pressure is being placed on this economically important water source, and rice accounts for a significant portion of the groundwater withdrawn. An earlier study by Watkins et al. (2019) was conducted to evaluate the technical efficiency of irrigation water and other rice production inputs using data from the University of Arkansas System Division of Agriculture's Rice Research Verification Program. This study found average irrigation water efficiency for all 142 fields to be 0.627, indicating irrigation water is over-applied on average by 37.3% across all 142 fields. The present study uses data from the former study to investigate the impacts of specific field characteristics on irrigation water efficiency using Tobit regression analysis. The results indicate that multiple-inlet rice irrigation (MIRI) and precision land grading (straight levees; zero-grade) significantly improve irrigation water efficiency on rice fields. [ABSTRACT FROM AUTHOR]

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is becoming an increasingly frequent pest of rice grown in the mid-southern United States. The current action threshold for fall armyworm in Arkansas is based on the number of larvae per square foot, which is often difficult to determine in rice due to thick stands, large plants, and flooded conditions. A new action threshold based on level of defoliation would help growers and consultants with determining the amount of damage present in the field versus larval counts per square foot. The objective of this study was to evaluate the impact of damage caused by the FAW at different growth stages of rice using both live infestation studies and mechanical defoliation. In greenhouse studies, larvae were infested on rice plants grown in the greenhouse at the 2- to 3-leaf, second-third tiller, and heading growth stages. Greenhouse research also included rice that was mechanically defoliated to simulate feeding of FAW by defoliating 25%, 50%, and 100% at the same growth stages. Rice plants in field plots were mechanically defoliated at 0%, 33%, 66%, and 100% with a weed eater at the 2- to 3-leaf, early tiller, late tiller, and panicle internode elongation (PIE) growth stages. Yield was impacted at the 2- to 3-leaf growth stage when defoliated 100% in the larval infestations. When 2- to 3-leaf rice was mechanically defoliated in the greenhouse to 100%, a yield reduction was observed compared to the untreated control. Yield loss was also observed from mechanical defoliation in the field trial at the late tiller growth stage when defoliation reached 66%, and 100%, and again at the PIE stage when defoliation reached 33%, 66%, and 100% in the field. These studies will be helpful in developing a defoliation threshold for fall armyworm in rice. [ABSTRACT FROM AUTHOR]

This study sought to determine the grain maturity level at which rice, Oryza sativa L., is no longer susceptible to damage from rice stink bug, Oebalus pugnax (F.), feeding. Data from this study indicates that rice is susceptible to damage through 60% hard dough, and that rice stink bug damage is significantly reduced between 80-100% hard dough. If threshold levels of rice stink bug are not observed at 60% hard dough, monitoring and control for this pest are no longer warranted. [ABSTRACT FROM AUTHOR]

A study was conducted at the University of Arkansas System Division of Agriculture's Northeast Research and Extension Center, Pine Tree Research Station, and Rice Research and Extension Center in 2018 to examine the influence of midseason nitrogen (N) fertilizer application timing on the grain yield of conventional, pure-line rice (Oryza sativa L.) cultivars from Louisiana and Arkansas. The conventional rice cultivars chosen for the study were the Horizon Ag semidwarf, long-grain CL153 and the Arkansas short-stature, long-grain Diamond. There were two preflood N fertilizer rates at each location and five weekly midseason N application timings from beginning internode elongation (BIE) to BIE + 28 days. There was also a control, or no midseason N application, and an optimum single preflood N application treatment. At the lower preflood N rate, midseason N timing significantly impacted grain yield at all locations while midseason N timing at the greater preflood N rate only impacted grain yield at two of the locations. At the lower preflood N rate, with exception of the latest midseason N application timing (BIE + 28 days) at two locations, all midseason N application timings produced grain yields that did not differ from the optimum single preflood N application, but were generally greater than yields where no midseason N was applied. The midseason N application window appeared to span multiple weeks in this study. Although midseason N applied at BIE+28 days generally seemed too late to impact grain yields, applications from BIE to BIE + 21 days often did not result in different grain yields from numerical maximums that occurred at BIE + 7, BIE + 14, or BIE + 21 days. Results from this and previous studies have led to the new recommendation that the midseason N application should be applied no earlier than BIE and at least 3 weeks and at times 4 weeks after the preflood N application; both of these conditions must be met to obtain the full grain-yield benefit from the midseason N application. [ABSTRACT FROM AUTHOR]

On-farm testing provides researchers the opportunity to evaluate cultivars in a more unpredictable environment than that of the research station or traditional test plots. The Producer Rice Evaluation Program (PREP) utilizes commercial rice fields throughout the state to evaluate experimental lines and various commercial cultivars for disease, lodging, grain yield potential, and milling yield in diverse growing conditions, soil types and farming practices. For producers, knowing the optimum cultivar for each field is their biggest and most important tool. On-farm testing can indicate which cultivars are suited for a particular growing situation. Field studies were located in Craighead, Crittenden, Randolph, Lonoke, Prairie, Perry, Poinsett, St Francis, White and Woodruff counties during the 2018 growing season. Twenty-five cultivars were selected for evaluation in the on-farm tests. The average grain yield across all locations was 211 bu./ac and the mean milling yield or percent head rice/percent total white rice (%HR/%TR) was 59/70. The cultivars with the highest grain yields averaged across locations were RT XP753, RT 7311 CL, RT 7801, RT XP760, RT Gemini 214 CL, RT 7321 FP, and RT 7521 FP. Cultivars with the highest milling yields included CL172, ARoma 17, CL153, CLL15, and PVL01. [ABSTRACT FROM AUTHOR]