Master of Science, The Ohio State University, 2023, Horticulture and Crop Science

Over the last two decades, Ohio has seen a consistent decrease in harvested hectares of soft red winter wheat (SRWW) [Triticum aestivum L.]. Low profitability compared to large scale corn and soybean production is the main contributing factor. Management decisions play a pivotal role in deciding wheat profitability. Alterations to current wheat management package can have severe implications on grain yield and quality, thereby affecting farmer profitability. Hence, it is imperative to optimize management strategies that can have a positive impact on grain yield and quality, as a measure of improving farmer profitability. Planting date and harvest stage are two key management decisions that can have severe implications on grain yield and quality. The first goal of this study was to re-evaluate wheat seeding rate recommendations under a range of plating dates expanding across early, timely and late planting scenarios to improve yield, economic return, and end-use quality. During the 2021-2022 and 2022-2023 growing seasons at two locations in western and northwest Ohio, multiple plating dates were evaluated under five seeding rates using a split-plot randomized complete block design with four replications. Grain yield, grain protein, test weight and Fusarium head blight (FHB) incidents were measured. Agronomic optimum seeding rates (AOSR) for early, timely and late planted wheat were 6.05, 3.14 and 4.66 million seeds ha-1, respectively. Economic optimum seeding rates were 51.4% and 13.7% lower compared to their respective AOSRs at early and late plantings. For timely planted wheat, AOSR and EOSR were similar. When planted late, grain protein decreased with increasing seeding rates and for early plantings, it increased with higher seeding rates. Test weights decreased with increasing seeding rates. FHB incidents were significantly higher for early planted wheat. Results suggest the possibility of lowering seeding rates for early and timely planted wheat with a foliar fu (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Byung-Kee Baik (Committee Member); Paul Pierce (Committee Member) Subjects: Agriculture; Agronomy; Food Science

Master of Science, The Ohio State University, 2021, Horticulture and Crop Science

Many farmers typically regard wheat as a “low input” crop and expect low yields and low returns. Conversely, some farmers intensively manage wheat with many inputs and expect high yields and returns. The objective of this research was to identify inputs that improve wheat grain yield, straw yield, and economic return and reduce deoxynivalenol (DON) concentration in the grain. An incomplete factorial, omission trial was established at two locations in Ohio (South Charleston and Custar) during the 2019-2020 and 2020-2021 growing seasons. Treatments consisted of intensive management (IM) which received all inputs, a traditional management (TM), and the individual addition or removal each input from the TM or IM, respectively. The inputs were a high seeding rate, a high N rate, a split application of N, a spring sulfur application, a fungicide application at Feekes 9, and a fungicide application at Feekes 10.5.1. Intensive management increased grain yield at three of the site-years during this study by an average of 0.83 Mg ha-1. At the South Charleston location, in general, the use of a fungicide at either timing proved to be important for protecting yield. The addition of a fungicide at Feekes 10.5.1 to the TM significantly protected yield both years by an average of 0.66 Mg ha-1 and the removal of this fungicide from the IM significantly decreased yield by 0.63 Mg ha-1 in 2021. Additionally, at the same location the addition of a fungicide at Feekes 9 to the TM and the removal of a fungicide from the IM significantly changed yield in 2020 by 0.81 and -0.71 Mg ha-1. At Custar, only one treatment significantly changed yield in either year. In 2021, the removal of split N from the IM significantly reduced grain yield by 0.44 Mg ha-1. Straw yield was not consistently affected by any treatment in this study. DON concentration was significantly reduced by the IM at South Charleston both years due to the addition of a fungicide at Feekes 10.5.1. Intensive management did not (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Pierce Paul (Committee Member); Tim Haab (Committee Member) Subjects: Agricultural Economics; Agriculture; Agronomy

Master of Science, The Ohio State University, 2023, Horticulture and Crop Science

Winter rye (Secale cereale L.) is a popular cover crop in the U.S. due to its winter hardiness, ease of establishment, and positive contributions to soil conservation, but research on winter hybrid rye grain production for human consumption and animal feed is severely lacking. Niche markets in distilling, bread and baking products, and livestock feed are currently available and in demand in the U.S. For farmers to integrate winter hybrid rye into their cropping systems to supply these markets, they need basic agronomic information on planting dates, seeding rates, and potential grain yield and quality. Study objective was to determine the influence of planting date and seeding rate on winter hybrid rye grain yield in five locations (OH, KY, and WI, and two in MN) over two years (2021-2022 & 2022-2023). The experimental design was a split-plot randomized complete block design with four replications. Whole plot factor was planting date (ranging from September to November) and sub-plot factor was seeding rate (0.4, 0.6, 0.8, 1.0, 1.2 million seeds/acre). Maximum grain yields of >100 bu/acre were obtained for all locations in the 2021-2022 season, while yields of >120 bu/acre were harvested from all locations except Crookston, MN, as the Crookston 2022-2023 site-year was deemed unharvestable due to drought. Agronomic optimum planting dates and agronomic optimum seeding rates (AOSR) varied among locations, but no recommendation of 0.4 million seeds/acre was given for any planting date across locations. Recommended AOSR for all locations was generally 0.8 million seeds/acre or higher, though Lexington, KY, had an AOSR of 0.6 – 0.8 million seeds/acre for the week before the fly-free date, and Arlington, WI, had a recommended AOSR of 1.0 million seeds or less. Overall, optimal planting dates fell within the two weeks following the established fly-free date across locations. Growing hybrid rye was possible in many environments across the Midwestern U.S., and excellent yields (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Pierce Paul (Committee Member); Alexander Lindsey (Committee Member) Subjects: Agriculture; Agronomy

Master of Science, The Ohio State University, 2022, Horticulture and Crop Science

Planting soybean early (late April through early May) is recommended to achieve high grain yields. However, unfavorable conditions can limit farmers' ability to plant during the recommended period, and thus, an increase in the seeding rate may be necessary. Also, weather conditions can affect seed quality, and choosing an adequate planting date can mitigate the impacts of unfavorable weather on the seed. Thus, the objectives of this study were to (1) measure the effect of planting date and seeding rate on stand loss over the growing season, (2) measure the effect of soybean seeding rate and planting date on grain yield, (3) identify the agronomic optimum soybean seeding rate (AOSR) and the partial economic return for the lowest and highest soybean price, and (4) measure the effect of soybean planting date and seeding rate on harvested seed mass, seed germination, and seedling vigor. For these objectives, a field study was conducted for two growing seasons at two locations in Ohio: Western (WARS) and Northwest (NWARS) Agricultural Research Stations. The experimental design used was a split-plot randomized complete block with four replications. The main plot factor was four planting dates ranging from 25 April through 10 July, and the split-plot factor was five seeding rates ranging from 123,500 to 618,000 seeds ha-1. At WARS-2020, planting soybeans in April through early June had a similar grain yield (5,090-5,285 kg ha-1), while there was a reduction in grain yield when soybean was planted in late June (4,216 kg ha-1). In contrast, in WARS-2021, planting dates did not statically influence grain yield. At NWARS-2020, a small amount of rainfall during the pod-setting growth stages (R3-R4 stages) impacted and reduced the grain yield for soybeans planted in April (3,113 kg ha-1) and May (2,909 kg ha-1) when compared to soybean planted on early-June (3,595 kg ha-1). The AOSR changed among site-years. For soybean grown under normal weather conditions, the AOSR needed to b (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Alexander Lindsey (Committee Member); David Barker (Committee Member) Subjects: Agriculture; Agronomy; Plant Sciences

Master of Science, The Ohio State University, 2021, Horticulture and Crop Science

Over 80 million acres of soybean were planted in the United States in 2020. The cost of soybean seed has increased by 65% from 2000 to 2019, making the average cost of seed per acre $56.10 in 2019. The increasing cost of seed, along with recent studies suggesting that lower seeding rates achieve similar yields and provide a higher return on investment, has prompted interest in optimizing seeding rate. There is often a discrepancy between soybean seeding rate and final soybean stand that is attributed to both abiotic and biotic factors. In other crops, plant competition as a result of population density can result in variations in aboveground and fine-root biomass, nutrient composition, and yield. The objectives of this research were to 1) determine how soybean seeding rate impacts biomass accumulation and nutrient composition, 2) determine how seeding rate and stand evenness influences soybean yield and 3) determine when soybean is most susceptible to stand reduction. For these objectives, six on-farm trials were established in 2019 and 2020. Treatments included seeding rate (from 80,000 seeds/acre to 250,000 seeds/acre). Soybean population, spatial variability, and growth stage were recorded every 14-21 days. Aboveground biomass, belowground fine-root biomass, and yield were collected at physiological maturity. Aboveground biomass, belowground fine-root biomass, and yield were collected at physiological maturity. There were minimal differences in aboveground biomass among the seeding rate treatments, aligning with other research that suggests soybean is highly plastic in its ability to compensate for lower seeding rates. Fine-root production was not impacted by population density, but biomass did vary from year-to-year.. Yield improvements from increased seeding rates occurred at three of six site-years and resulted in yield advantages of 4.2-9.3 bu/ac. At four site-years, lower seeding rates (80,000-120,000) resulted in a higher stand reduction compared to higher (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Anne Dorrance (Committee Member); Christine Sprunger (Committee Member); Elizabeth Hawkins (Committee Member) Subjects: Agriculture; Agronomy; Plant Biology; Plant Pathology; Plant Sciences; Soil Sciences

Master of Science, The Ohio State University, 2019, Horticulture and Crop Science

Soybean [Glycine max (L.) Merr] inputs are continually increasing, and with market values decreasing, producers are forced to find ways to maintain profitability. To address these challenges, soybean producers are interested in reducing seeding rates. However, due to within field variability, it may not be possible to lower seeding rates throughout an entire field uniformly and still achieve the same soybean yield. Variable rate seeding (VRS) of soybean allows producers to adjust seeding rates according to the variability in their fields. However, little is known regarding the accuracy of farmers' VRS prescriptions. The objectives of this research were to 1) determine the agronomic optimum seeding rate (AOSR) and the economic optimum seeding rate (EOSR) in predetermined management zones, 2) compare the calculated AOSR and EOSR to each producer's VRS prescription, 3) determine the impact of final plant stand on yield within management zones, 4) identify how soybean plant architecture maintains yield across multiple seeding rates, and 5) determine how plant population impacts harvest, especially combine fuel use and harvest grain loss. In 2017 and 2018, eight on-farm trials were conducted across Ohio. The trials consisted of three uniform seeding rates of 247,000, 346,000, 445,000 seeds ha-1, and a variable rate strip determined by the producers ranging from 198,000 to 445,000 seeds ha-1. The AOSR (yield maximizing) and EOSR (profit maximizing) were calculated from regression analyses for each management zone and field. Agronomic and economic optimum seeding rates ranged from <247,000 to iii >445,000 seeds ha-1 depending on the site-year. Final plant stands varied across site- years, but the calculated agronomic optimum final stand (AOFS) were similar to the recommended AOFS of 247,000 to 297,000 plants ha-1. At lower final stands, soybean yield was maintained by the plants' ability to grow lateral branches that produced pods. In 2017 and 2018, two management zones (open full item for complete abstract)

Committee: Laura Lindsey (Advisor) Subjects: Agriculture; Agronomy

Master of Science, The Ohio State University, 2017, Horticulture and Crop Science

Ohio is an important source of soft red winter wheat (SRWW) [Triticum aestivum L.] for the milling industry, but is typically a low profitability crop for grain producers. Ohio wheat producers are concerned about a lack of consistency in both grain quality and yield, a perspective that is reflected in decreasing harvested hectares. The first objective was to reassess wheat seeding rate recommendations using four cultivars planted at seeding rates of 1.85, 2.47, 4.94, and 6.18 million seeds ha-1, the second was to determine the best economic seeding rates, and the third was to examine the impact of seeding rate and cultivar on grain quality. An experiment was conducted consisting of four site-years at the Northwestern Agricultural Research Station (NWARS) and the Western Agricultural Research Station (WARS) during the 2015/2016 and 2016/2017 growing seasons. The design was a split-plot randomized complete block design with cultivar as the whole plot factor and seeding rate as the subplot factor. Wheat quality tests were performed at the USDA-ARS Soft Wheat Quality Lab (SWQL) in Wooster, OH. Significant cultivar by seeding rate interactions were observed. Agronomic optimum seeding rates ranged from 5.19 to 5.54 million seeds ha-1, and economic optimum seeding rates ranged from 4.27 to 4.72 million seeds ha-1 depending on cultivar. Effect of seeding rate was significant for test weight and sodium carbonate solvent retention capacity. Test weight increased and damaged starch decreased as seeding rate increased. Cultivar selection impacted test weight, softness equivalency, kernel weight, glutenin strength, and starch damage. Cultivar by seeding rate interactions were significant for flour yield and protein. Generally, flour yield increased and flour protein decreased as seeding rate increased. Overall, a seeding rate of 4.94 million seeds ha-1 was suggested to produce the best combination of yield and grain quality. Differences between area of land planted to wheat a (open full item for complete abstract)

Committee: Laura Lindsey Dr. (Advisor); Kent Harrison Dr. (Committee Member); Pierce Paul Dr. (Committee Member) Subjects: Agriculture; Agronomy