Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Limin Kung, Jr., Dept. of Animal and Food Sciences. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-92).

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-80).

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Master of Science / Department of Agronomy / Romulo P. Lollato / Winter wheat (Triticum aestivum L.) water limited yield potential in Kansas averages 5.2 Mg ha⁻¹; however, state-level yields rarely surpassed 3.4 Mg ha⁻¹. Our objective was to quantify the contribution of individual management practices to reduce wheat yield gaps (YG) economically. An incomplete factorial treatment structure established in a randomized complete block design with six replications was used to evaluate 14 treatments during two years in Manhattan, Belleville, and Hutchinson Kansas. Sites were combined based on tillage practice, growing region in Kansas, and disease pressure. Thus, Manhattan had low disease pressure, was no-tilled, and in eastern Kansas for 2015-16 and 2016-17 (two site years). Meanwhile, Belleville and Hutchinson had high disease pressure, were conventionally tilled, and in central Kansas for 2015-16 and 2016-17 (four site years). We individually added six treatments to a farmer’s practice control (FP) or removed from a water-limited yield control (Y[subscript]w), which received all treatments. Practices were additional split-nitrogen (N), sulfur (S), chloride (Cl), increased plant population, foliar fungicide, and plant growth regulator (PGR). Percent YG was calculated by block and site-year using the Y[subscript]w as reference for potential yield. Orthogonal contrasts indicated yield under no-till which had low disease pressure increased from the FP by the full Y[subscript]w (+0.37 Mg ha⁻¹), but also by the individual practices split-N (+0.28 Mg ha⁻¹), S (+0.26 Mg ha⁻¹), increased plant population (+0.36 Mg ha⁻¹), and fungicide (+0.18 Mg ha⁻¹). In the conventional till which had high disease pressure, wheat yield was increased by 1.18 Mg ha⁻¹ from the Y[subscript]w and by 1.44 Mg ha⁻¹ from the fungicide. The Y[subscript]w and split-N increased grain protein concentration in no-till and conventional-till on average by 9 g kg-1 and 12 g kg-1, respectively. Across all inputs, orthogonal contrasts indicated that the FP yield gap was 8% in no-till which had low disease pressure. Likewise, the orthogonal contrasts indicated that across individual treatments the YG was reduced by split-N (6%), S (5%), Cl (3%), increased plant population (8%), and fungicide (4%). Meanwhile, orthogonal contrasts indicated that the FP yield gap was 20% across all inputs and across individual inputs reduced to 5% from fungicide under conventional-till which had high disease pressure. Fungicide increased net return (+$106.57 ha⁻¹) under conventional-till which had high disease pressure, and increased plant population under no-till which had low disease pressure (+$36.65 ha⁻¹). While a high-cost input (i.e. fungicide) only economically reduced YG greater than 20%; however, a low-cost input (i.e. increased plant population) economically reduced YG less than 20%.

Master of Agribusiness / Department of Agricultural Economics / Christine Wilson / Risk management is critical in crop production as the challenges farmers face on a year to year basis are quite variable due to Mother Nature. There are many tools a farmer can utilize to help manage risk such as crop insurance and forward contracting or hedging. In recent years with lower prices, these tools have been more heavily used than they were a few years ago when corn and soybean prices were $8 and $15 per bushel, respectively. Margins in crop production are tight when market prices are low and input prices are high relative to market prices, and due to land cost. In order for farmers to produce greater profit, they must find ways to lower expenses or produce more bushels to increase their revenue. As margins tighten, farmers typically try to lower expenses to be more profitable rather than trying to increase bushels that would ultimately increase their revenue. When farmers try to reduce expenses, agricultural retailers experience lower revenues holding all else equal; distributors have lower revenues because the retailer is not selling as much, and the manufacturers experience lower revenues because the retailer and distributor are not moving the inventory compared to when farmer margins are larger. This thesis examines how yield protection for grain corn can be utilized as a risk management tool for crop production farmers. This thesis explores how increasing bushels and ultimately increasing revenue by protecting the bushels the crop is physically able to produce, can help manage producer risk. This thesis uses yield protection as a tool alongside crop insurance and marketing, rather than as a tool to replace crop insurance or marketing. Data used for yield protection is replicated fungicide, fungicide with an adjuvant, and fungicide with insecticide, that were evaluated against the untreated check over multiple locations and years across the Midwestern United States. Fungicide data were chosen because it is truly the definition of yield protection, protecting the crop against disease. Fungicides are usually the first products cut from a farmer’s crop production program to help reduce expenses and maintain profitability as margins tighten. The results found in this study are consistent with work conducted at Iowa State University. Results exhibited an increase in corn yield, but were not consistently statistical significant across treatments and location. In conclusion, the average yield increase was not enough over multiple years to pay for itself, and it lacked sufficient evidence. Yield protection does not fit a risk management strategy annually. However, yield protection should be utilized when specific thresholds on disease or insects are present to warrant this strategy.

10 pp. / Forage sorghum yields have been should to increase with narrow row spacing of 20 inches or less. The purpose of this research is to determine the effect of narrow row spacing on forage sorghum yield and quality in Arizona. Two row spacing (20 and 40 inch) and two forage sorghum hybrids (Great Scott and Silo 700D BMR) were evaluated in a study conducted at the University of Arizona Maricopa Agricultural Center in 2015. Row spacing had no effect on forage yield, moisture, plant height, or maturity even though light interception was greater for the closer row spacing. The only feed quality parameter affected by row spacing was lactic acid which increased with row spacing. Hybrid by row spacing interactions was detected for a few feed quality parameters. Decreasing forage sorghum row spacing from 40 to 20 inches does not appear to have an advantage based on the results of this study.

Typescript (photocopy).

MSc (Horticulture) / Department of Horticultural Sciences / Grafting is the process of combining two parts of plants to form a single plant. Grafting is a common technique in trees and vine crops and is becoming popular in annual vegetable production in order to control biotic and abiotic stresses, improve fruit yield and quality. The objectives of the study were to determine the (a) compatibility of the tomato scion x rootstocks combinations (b) effect of rootstocks on vegetative growth parameters (c) effect of tomato rootstocks on fruit quality and yield of tomato. The experiments were conducted under a protected environment (in a high tunnel) at the University of Venda, Thohoyandou, South Africa. Four tomato rootstocks (‘Powapak’, ‘Everest’, ‘Matterhorn’ and ‘Golf’) and two scion cultivars (‘Money Maker’ and ‘Rodade’) were used to develop 10 scion x rootstock combinations. The tube grafting method was used. Seedlings were transplanted in the polyethylene bags inside the high tunnel. Growth parameters, including plant height, stem diameter, number of leaves per cluster as well as yield attributes were measured. In addition, the chemical fruit quality parameters including the total soluble solids and pH were determined. A randomized complete block design with four replications was used for the study. Quantitative data sets of the variables were subjected to analysis of variance. There was a high plant survival rate and the number of clusters per plant showed marked improvement in some grafting combinations particularly in ‘Rodade x Everest’ and ‘Money Maker x Everest’. A few individual stunted plants were observed in the tunnel. A significant seasonal effect was observed on some of the growth and productivity attributes. The pH showed a narrow range of values and there was significant interaction between sampling time and genotype. The results demonstrated the viability of producing grafted tomatoes under tunnel conditions. / NRF

Companies are no longer judged on financial performance alone, but rather on their “Triple-Bottom Line”, which accounts for social and environmental measures as well. This leads companies to investigate the sustainability of their operations and their products. Between the increasing cost of virgin raw materials and customers demanding post-consumer product content, manufacturers have begun looking at recycled material options. This paper addresses a procurement issue facing a polystyrene packaging manufacturer considering its optimal purchasing strategies between two suppliers – one providing virgin material, the other offering recycled material. A single-period scenario is modeled where each supplier sells product with a known yield distribution at market pricing. The manufacturer must choose whether to sole-source or dual-source, as well as determine how much material to purchase from each supplier to meet deterministic demand. Our results indicate that there is a range of prices from the recycled material supplier where dual-sourcing will lead to higher manufacturer profits compared to sole-sourcing. We show, based on the procurement strategy, the optimal quantities to purchase to maximize manufacturer’s expected profit. We then investigate the area of supplier development and how the manufacturer can improve their expected profit by investing in their supplier’s quality improvement effort. The questions addressed are how much the manufacturer would be willing to invest and how they ensure the proper return on their investment. This paper determines the expected increase in profit for the manufacturer from yield improvement projects at a supplier, which therefore becomes the upper threshold for investment. We also find that a company can err in their project acceptance criteria if they have an approval process that views project acceptance myopically rather than holistically. Lastly, we develop a systematic and comprehensive approach to the supplier selection process. We utilize the fundamental concepts behind W. Edwards Deming’s Plan-Do-Study-Act improvement cycle and apply them to the supplier selection process. We also present analytic and numerical study results that can be used in conjunction with contractual mechanisms to not only overcome issues such as free riding, but to also incentivize suppliers to engage in supplier development projects they may not have otherwise undertaken.