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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]

For rice breeders to identify the ideal breeding lines for potential varietal releases it is critical to have a yield trial under the most representative soil types and environmental conditions. To bridge the gap between the single location, 2-3 replication preliminary yield trials with over 1,400 breeding lines and the multi-state Cooperative Uniform Regional Rice Nursery (URRN) and/or the multi-location statewide Arkansas Rice Variety Advancement Trials (ARVAT), which only accommodate a very limited number of entries, an advanced elite line yield trial (AYT) was initiated in 2015. The trial is conducted at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC), near Stuttgart, Ark.; the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS), near Colt, Ark.; and the University of Arkansas System Division of Agriculture's Northeast Research and Extension Center (NEREC), in Keiser, Ark. This trial will help us to select the best and the most uniform breeding lines for advancement into the URRN and/or ARVAT trials, and ultimately will improve the quality of those yield trials. [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 Arkansas Long Grain and Aromatic Rice breeding program is actively developing and improving rice varieties that are widely adopted in the U.S. Mid-South. Strict evaluations on desirable characteristics are conducted in different phases of the breeding program. Characteristics that are important include high grain yield potential, excellent milling yields, good plant stature, pest and disease resistance, and superior grain quality (i.e., low percent chalk, cooking, processing and eating). We conducted an advanced yield trial of conventional, herbicide-tolerant Clearfield and conventional aromatic long grains at four locations in Arkansas to identify potential lines to be advanced and possibly released as varieties in the future. We have identified several lines that are comparable or better in grain yield, milling yield, and other agronomic characteristics than existing checks in some or all four locations. These lines will be advanced to another multi-location yield test in the following year to confirm stability across years and locations. [ABSTRACT FROM AUTHOR]

Efforts in 2022 were made by the University of Arkansas System Division of Agriculture's (UADA) Rice and Research Extension Center's (RREC) hybrid rice breeding program in developing hybrid rice (Oryza sativa L.) varieties; which include developing environmentally sensitive male sterile (EGMS) lines, cytoplasmic male sterile (A) lines, maintainer (B) lines, and restorer (R) lines. As parental line development was being attempted, test crosses were also made to evaluate both parents and the experimental hybrids. Parents were planted as panicle rows to select based on phenotypes, while simultaneously being crossed with other parental lines to produce test crosses to be evaluated in 2023. Efforts for hybrid variety development with Provisia® and Clearfield® herbicide technologies were also attempted. Lastly, successful hybrid seed (F1) production of 13 hybrid combinations was achieved, which enables us to test these new hybrids in the Advanced Elite Line Yield Trials (AYT) and/or Arkansas Rice Variety Advancement Trials (ARVAT) across the state in 2023. [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]

For rice breeders to identify the ideal breeding lines for potential varietal releases, it is critical to have a yield trial under the most representative soil types and environmental conditions. To bridge the gap between the single location, 2-3 replication preliminary yield trials and the multi-state Cooperative Uniform Regional Rice Nursery (URRN) and/or the multi-location statewide Arkansas Rice Variety Advancement Trials (ARVAT), which only accommodate a very limited number of entries, and an advanced elite line yield trial (AYT) were initiated in 2015. The trial is conducted at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC), near Stuttgart, Ark.; the Pine Tree Research Station (PTRS), near Colt, Ark.; and the Northeast Research and Extension Center (NEREC), in Keiser, Ark. This trial will help us to select the best and the most uniform breeding lines for advancement into the URRN and/or ARVAT trials, and ultimately will improve the quality of those yield trials. [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]

Two-line hybrid rice (Oryza sativa L.) production requires an environment-sensitive genetic male-sterile (EGMS) line in which sterility is induced by high temperatures (TGMS), long photoperiod (PGMS), or both (PTGMS). Later in the ricegrowing season, temperatures will lower, and TGMS lines can produce late tillers, which could form fertile panicles (self-pollination). This would reduce hybrid seed purity. The seeding rate of the EGMS line could minimize this issue because the higher the seed rate, the higher the plant density, which would reduce the number of late tillers. Two Arkansas TGMS lines, 801s and 811s, were tested with four different seeding rates (20, 30, 40, and 60 lb/ac). Plots were planted in a randomized block design with three replications at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) near Stuttgart, Ark. Tillers were counted from the three centermost rows of each 7-row plot to avoid border effects. The number of tillers was categorized as late tillers (no panicles exerted) and mature tillers (panicles exerted). The results showed that there is no significant difference in the number of late tillers among the seeding rates; thus, seeding rate does not significantly reduce late tillers for hybrid seed purification. There was a significant difference in the number of mature tillers between the 20 and 60 lb/ac rates. An optimum seed rate of 30 lb/ac is recommended for an ample number of panicles for hybrid seed production because there is no significant gain of mature tillers using the higher seeding rates. This could help reduce hybrid seed costs by avoiding over-seeding the EGMS lines while maximizing hybrid seed production yields. [ABSTRACT FROM AUTHOR]

Overall rice acreage in the United States is declining while imports have been rising since the 1980s. Rice imports are mainly driven by the consumption of Jasmine type "aromatic" rice. The aromatic rice breeding program at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) is actively developing aromatic varieties that not only have good cooking quality and aroma but also have improved agronomic performance and adaptation to the climatic conditions in the mid-South. In 2021, 20 out of 68 entries had a significantly higher yield than the check varieties in the Stuttgart Initial Test. In the Advanced Yield Trial conducted at the RREC, 23 out of 40 entries had a significantly higher yield over the check varieties. The top 3 entries in both trials had a yield advantage of 50 bu./ac or more over Jazzman 2 or ARoma 17. Furthermore, the Uniform Regional Rice Nursery (URRN) conducted in Arkansas showed the three new aromatic lines also out-yielded the check ARoma 17. Our results showed our current selections of the top elite lines have improved the agronomic performance and can be further tested in multi-environment trials. [ABSTRACT FROM AUTHOR]

The long-grain rice breeding program in the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) has a long history of successfully developing long- and medium-grain as well as specialty rice cultivars for the Arkansas rice producers and the mid-South. Selections and evaluations are strictly conducted based on the desirable characteristics that need to be improved. These important characteristics include high rough rice yield potential, high milling yields, disease resistance, abiotic tolerance, good plant stature, and superior grain quality (i.e., low chalk, processing, cooking, and eating qualities). In 2021, a total of 1,204 entries entered the yield trials of both initial and advance tests for a total of more than 4,000 yield plots, including plots for seed increases. This report presents the overall results of the 2021 breeding program that includes lines from both initial and advance tests as well as potential lines in the pipeline. [ABSTRACT FROM AUTHOR]