Agriculture Commons^™

Investigating The Mechanisms Of Freeze Tolerance In Lemna Minor, Tamara Bouchard

Honors Theses and Capstones

Freezing presents a significant abiotic stress to aquatic plants, yet little is known about the mechanisms by which species like Lemna minor (duckweed) survive subzero temperatures in nature. This study investigates whether L. minor employs freeze-avoidance or freeze-tolerance strategies and explores the potential role of its microbiome in enhancing cold resilience. Using both field-collected fronds from naturally frozen ponds and controlled freezing experiments in the lab, I assessed survival through viability staining and post-thaw survival. Results showed that L. minor can survive natural ice encasement and that prior cold acclimation significantly improves tissue survival under induced freezing. Trypan blue staining …

Parting The Corn Rows: Nikita Khrushchev’S Visit To Iowa, 1959, Jordan Stiles

Dissertations and Theses @ UNI

On September 23, 1959, Soviet leader Nikita Khrushchev visited Roswell Garst to inspect US hybrid corn and agricultural methods. Khrushchev’s initial reforms are discussed to show why Khrushchev sought agricultural knowledge abroad. The details of Khrushchev’s and Garst’s life regarding their work in agriculture are explored up to the visit. The visit would leave an indelible mark on the USSR and Iowa. Khrushchev and his successors would use Garst’s model for hybrid corn farming as the template for Soviet farming. Garst would use his limelight to catapult his corn diplomacy into action around the world. Lastly, the legacy of Khrushchev’s …

Effects Of Round-Up On The Environment, Sandra J. Marcu

Journal of Earth and Life Science

Many people around the world have used and still currently use Roundup but are unaware of the effects it has on the environment. Roundup is a spray on application weedkiller that is widely used around the world today both residentially and commercially. It enables its user to grow a garden or a field of crops with a no-tilling approach to eliminate weeds. It is a well-known and popular choice for killing weeds that has been around since the mid 1970’s (Oca, 2017). John Franz, a Monsanto scientist discovered that glyphosate (main ingredient in Roundup) was an herbicide or weedkiller, and …

The Effectiveness Of The Minnesota Buffer Law And Its Impacts On People, Ellen P. Isakson

Journal of Earth and Life Science

In January 2015, the then-governor of Minnesota Mark Dayton announced new legislation that would require 50-foot vegetation buffers along all waterways in Minnesota; this legislation would come to be known as the Minnesota buffer law, exact requirements being “perennial vegetative buffers of up to 50 feet along lakes, rivers, and streams and buffers of 16.5 feet along ditches” (Albert, 2017; MN Board of Water and Soil Resources [MN BWSR] 4 ). A buffer in the context of vegetation and natural resource management is a strip of vegetation around a body of water “designed to intercept stormwater runoff and minimize soil …

A Mystery Of Microecology: Revealing The Ecological Relationship Between Allorhizobium Vitis And Missouri Native Grape Species, Hunter White

Graduate Theses/Dissertations

Crown gall disease can be very detrimental to grape and wine producers around the world by reducing vine vigor and yield. It is caused by the bacteria Allorhizobium vitis (A. Vitis) carrying a tumor inducing (Ti) plasmid. The A. vitis bacteria have been found in soil and cane tissues in vineyards around the world, and infect all cultivated grapes. However, there have been no reports of crown gall on native wild grapevines, and very little is known about the ecology of A. vitis in native ecosystems. I have sampled cambium tissues from three native wild grape species of …

A Study Of Collegiate Equine Team Funding, Expenditures, And Recruitment Strategies, Sydni Marie Nilles

Graduate Theses/Dissertations

Collegiate equine teams (including horse judging, equestrian, ranch horse teams) have been recognized for their contributions to students' personal and professional development for post- graduation success. Teams have been used to provide opportunities, a sense of belonging and allow for experiences students may not have elsewhere. However, there is a notable gap in knowledge as to where funding comes from and how much teams may be able to budget for expenditures. Recruitment tactical knowledge provides other teams with knowledge of potential areas they may be lacking or unaware of. I used an online survey to understand current ranges of support …

Identification Of A Stable Qtl For Juice Color In A Vitis Interspecific Hybrid ‘Chambourcin’- Based Population, Qiuni Yang

Graduate Theses/Dissertations

Berry juice color is one of the key factors influencing grape and wine quality, consumer preference, and marketability. While most previous studies on berry color have focused on the skin, research on juice color remains limited. This study investigated the genetic basis of berry juice color in a hybrid population derived from the Vitis interspecific hybrid ‘Chambourcin’ and V. vinifera ‘Cabernet Sauvignon’. A new nine-category visual scoring system was developed to assess juice color based on OIV 225. To achieve comprehensive precision and quantitative analysis, CIELAB parameters (L*, a*, b*), Hue, and Chroma were extracted from image-based measurements. Using berries …

The Effects Of Calcium Availability On Growth And Calcium Content Of Hydroponic Daikon Radish Microgreens, Cory Michael Reichmuth

Graduate Theses/Dissertations

Microgreens are young, edible seedlings harvested upon emergence of the first true leaf. Their popularity is growing as a nutritionally dense food source that can be grown quickly in space-efficient systems. However, little is known about optimal cultivation practices and the effects of fertilization on growth and nutrition of microgreens. This study investigates the role of calcium (Ca) fertilization in optimizing the growth, yield, and nutrient content of daikon radish (Raphanus sativus) microgreens. A hydroponic system was designed to consistently deliver nutrient solution to microgreens grown in a closed-environment chamber. This study tested different Ca fertilization rates of 0, 5, …

Next In Line: Exploring Owner, Business, And Family Characteristics And Farm Succession Planning, Tucker Lane Bittick

Graduate Theses/Dissertations

The growing average age of the American farmer raises concerns about who will be involved in the future agricultural economy. Efficient succession in family farms keeps farm values high, and farms that plan for succession have an incentive to invest more resources into the farm. Knowing what factors on family farms are common when succession occurs could help encourage earlier succession planning. The research questions were: “Are family, business, and owner characteristics significantly related to the presence of a farm succession plan on farms in the Midwest?” and “Are family, business, and owner characteristics significantly related to principal operators’ preference …

Inoculating Soybean Plants At Different Growth Stages: Selecting Bradyrhizobium, Sinorhizobium, Or Both, Matthew R. Knoll

Graduate Theses/Dissertations

Soybean plants rely on nitrogen for growth, however atmospheric nitrogen (N2) is not a usable form and needs to be converted into different forms that are available to the plant. Nitrogen fixing bacteria such as rhizobia form symbiotic relationships with Soybeans in exchange for shelter and excess plant sugars. As a result, the plant can get the nitrogen it needs. There are four main genera of rhizobia that can form root nodules on Soybean including Bradyrhizobium, Sinorhizobium, Mesorhizobium, and Rhizobium. At this point, the effect that age of the host plant has on the selection of …

In-Season Nitrogen Mmanagement: Leveraging Data Visualization For Precision Agriculture, Chathurika Harshani Narayana

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Effective nitrogen management is vital for sustainable agriculture, impacting both crop yield and environmental health. Traditional methods often use fixed application rates set before planting, which do not adapt to changing crop needs during the season. This can lead to over- or under-application, reducing efficiency and sustainability. While modern tools like sensors, satellites, and UAVs provide valuable real-time data on crop and field conditions, integrating and using this data to guide timely nitrogen decisions remains a major challenge. In-season nitrogen management offers a solution by allowing for dynamic adjustments to nitrogen applications, addressing crop needs as they arise. This approach …

Native Bee Utilization Of Sorghum And Community Richness In Western Kansas Agricultural System, Katelyn M. Strack

Master's Theses or Doctor of Nursing Practice

In recent years, biologists have documented numerous threats facing native bee populations globally. Current agricultural practices have significant and often negative effects on native bee populations. It is imperative that we understand how these practices affect native bees. Sorghum (Sorghum bicolor (L.) Moench) is cultivated heavily in western Kansas as a grain crop. There is some evidence that native bees can utilize sorghum pollen in other systems. This study investigates whether native bees utilize pollen from sorghum and whether the presence of sorghum in the landscape influences the structure of native bee communities. We conducted observations of sorghum …

Location Intelligence Unveils Seasonal Spatiotemporal Pattern Shifts Of Habitat Use And Selection By Cattle Across A South Texas Coastal Landscape Infested With Rhipicephalus Microplus, Taylor G. Donaldson, Brian T. Rich, Miranda R. Peterson, Hsiao-Hsuan Wang, William E. Grant, Donald B. Thomas, Kimberly H. Lohmeyer, Adalberto Á. Pérez De León, Pete D. Teel

Biological Sciences Faculty Publications

Knowledge gaps on the dynamics of cattle fever tick-cattle-habitat-climate interactions in South Texas and their influence on the efficacy of treatments to eliminate infestations with the Rhipicephalus (Boophilus) microplus prevent optimal interventions by the Cattle Fever Tick Eradication Program (CFTEP). The CFTEP has been operating in the USA since 1907. This study applied the concept of location intelligence to examine movement, habitat use and selection by cattle in a highly heterogeneous coastal landscape infested with R. microplus. Cattle interface with white-tailed deer and nilgai, which are alternate wildlife hosts of R. microplus, in this unique South …

Resilience Of Food Sovereignty Organizations To The Covid-19 Pandemic, Rachel M. Brice

Antioch University Dissertations & Theses

This sequential explanatory mixed methods study explored the organizational resilience of food sovereignty organizations (FSOs) in the northeastern United States during the COVID-19 pandemic. Using a novel “open structural learning approach” that integrates structural contingency theory, open systems theory, and organizational learning theory, this research examined how FSOs’ structural attributes, resource flows, and organizational culture shaped their ability to navigate crisis. The study engaged FSO leaders through surveys (n = 13) and in-depth interviews (n = 7), supplemented by archival data analysis, to explore factors that strengthened or diminished FSO resilience. Findings revealed that FSOs navigated COVID-19 with multiple concurrent …

El Maíz Del Abuelo: Fidel Márquez Sanchez’S Legacy And Mexico’S Historical Maize Agriculture, Lucia Marquez-Uppman

Scripps Senior Theses

The Green Revolution was an era of scientific development in productive agricultural methods and technologies in the mid-twentieth century. High-yielding seed varieties, artificial fertilizers, irrigation infrastructure, pesticides, and herbicides all developed from this period. Texcoco, Mexico was the center of much of the Green Revolution's education and research from the 1940s onward at the Autonomous University of Chapingo, a prestigious agricultural school, with funding from the US-based philanthropic Rockefeller Foundation. Powerful consequences in the globe's agriculture emerged from the Green Revolution, including the production of maize, a staple crop in Mexico, especially for Indigenous and campesino populations. My abuelo, Fidel …

Management Adaptations To Sustainably Increase Soybean Yield And Water Productivity Through Field Studies And Crop Modeling, Mounica Talasila

Theses and Dissertations--Plant and Soil Sciences

Soybean (Glycine max [L.] Merr.), a major crop in the upper U.S. Mid-South, is predominantly cultivated under rainfed conditions, where variable precipitation frequently induces water stress and limits yield potential. Consequently, irrigation adoption has been increasing across this region. Determining the optimal cultivar maturity group (MG) and planting date (PD) for both rainfed and irrigated systems is essential for maximizing yield and improving water use metrics. Evaluating crop water use efficiency (WUE; yield per unit of seasonal evapotranspiration) and total water productivity (WP; yield per unit of total water input from precipitation and irrigation) is critical to developing such …

Cultivation Of Winged Kelp (Alaria Marginata) In Humboldt Bay, Evan C. Simpson

Cal Poly Humboldt theses and projects

The cultivation potential of the winged kelp (Alaria marginata) was evaluated in Humboldt Bay, California, to further develop sustainable aquaculture in the region. Seasonality, depth, and system design were evaluated in regard to harvest biomass and quality. Results suggested that single-longline configurations at shallow depths (< 2 m) produced greater total biomass than a multi-longline system, suggesting enhanced water flow and reduced self-shading improved growth. Kelp grew best with a winter outplanting period (December-April), most likely due to environmental conditions (e.g., temperature, nutrients, and salinity) being within the kelp’s tolerable range, with as much as 2.24 kg/meter of kelp being harvested. These findings demonstrate that while the estuarine system has more variable conditions than predicted, A. marginata can be successfully cultivated in Humboldt Bay and highlight its potential as a viable crop for northern California’s emerging seaweed industry. Future work targeting the optimization of single-longline design and deployment timing may further improve yield and support regional goals for sustainable aquaculture and food security.

An Economic And Production Analysis Of Seaweed Farms In California And The Pacific Northwest, Brian Donovan

Cal Poly Humboldt theses and projects

Since the early 2010s, the seaweed aquaculture industry has steadily expanded in the United States, with states like Alaska, Maine, Hawaii, and Connecticut leading the way in the development of this emerging sector. However, information gaps remain concerning certain aspects of the domestic seaweed aquaculture industry. The purpose of this study was to examine the status of the seaweed aquaculture industry along the West Coast of the United States; specifically in the states of California, Oregon, and Washington. Seaweed farmers in these states were invited to voluntarily complete surveys asking important production, economic, and commercial questions regarding their operations. Data …

Eggplant Variety Demonstration Results For West-Central Indiana, 2024, Petrus Langenhoven, Lizeth Sofia Catucuamba Tuquerrez

Midwest Vegetable Trial Reports

A non-replicated demonstration of eggplant varieties was conducted at Purdue University's Meigs Horticulture Facility to evaluate eight varieties, including four Italian-type and four Asian-type varieties, under Indiana growing conditions. Plants were transplanted on May 14, 2024, with 30 plants per variety in 180-foot rows. Weekly harvests occurred from weeks 8 to 18 after transplanting. Italian varieties consistently produced higher marketable yields than Asian types, with Nigral achieving the highest yield at 55,446 pounds per acre (17.7 fruits per plant, averaging 11.2 ounces per fruit). Rolandia produced the heaviest individual fruits, with an average weight of 12.3 ounces. Among Asian varieties, …

Colored Sweet Bell And Tapered Pepper Cultivar Evaluation For High Tunnel Production In West-Central Indiana, 2025, Petrus Langenhoven

Midwest Vegetable Trial Reports

Colored sweet bell-shaped and tapered peppers remain an important summer crop for small and medium-sized farming operations across Indiana. These crops can be produced in open-field systems or under protective structures, with high tunnels offering notable advantages for sweet pepper production. The moderated environment of a high tunnel allows planting 2–4 weeks earlier in the spring and extends harvest into the fall until the first hard freeze. Despite the crop’s regional importance, performance data for pepper varieties adapted to Indiana conditions have been limited. Our ongoing work aims to address this gap. To date, more than forty pepper cultivars have …

Eggplant Cultivar Demonstration Results For West-Central Indiana, 2025, Petrus Langenhoven, Alexandria Catherine Snabes

Midwest Vegetable Trial Reports

An eggplant cultivar demonstration at Purdue University's Meigs Horticulture Facility evaluated ten cultivars during the 2025 growing season to support evidence-based variety selection for Indiana growers. Eggplant production in Indiana totaled 34 acres in 2022, representing part of a national industry where 88.9% of 7,261 operations cultivate less than one acre. This demonstration provided performance data under Indiana conditions while offering hands-on learning for horticulture students. Results inform cultivar recommendations for small to medium-scale Midwest producers supplying diverse markets, including restaurants, farmers' markets, and ethnic food retailers seeking this Solanaceae crop for Asian, Mediterranean, and Middle Eastern cuisines.

2025 Standard-Sized Seedless Watermelon Cultivar Evaluation In Indiana, Wenjing Guan, Dennis Nowaskie, Cesar Escalante

Midwest Vegetable Trial Reports

Indiana ranked fifth in watermelon production in the United States. In 2024, Indiana growers planted approximately 8,100 acres of watermelons. Watermelon cultivar evaluation trials have been conducted annually at the Southwest Purdue Agricultural Center (SWPAC) in Vincennes, IN, for over 30 years. In 2025, 25 standard-sized seedless watermelons were evaluated, and yield and fruit quality parameters were assessed.

2025 Personal-Sized Seedless Watermelon Cultivar Evaluation In Indiana, Wenjing Guan, Dennis Nowaskie, Cesar Escalante

Midwest Vegetable Trial Reports

Indiana ranks fifth in the United States for watermelon production in 2024. Most of the state’s production consists of red-flesh seedless cultivars with fruit weighing 9 lbs and above. A small portion of watermelon production devoted to mini seedless types. Meanwhile, interest in watermelon production among small and diversified vegetable farms is increasing, where smaller-sized watermelons are likely fit better at these farms. In this report, we summarize the performance of 12 personal-sized watermelon cultivars evaluated at the Southwest Purdue Agricultural Center (SWPAC) in Vincennes, IN, during the 2025 season.

Cost-Effective Strategies For Feral Swine Control: Exploring Trapping Equipment Cooperatives, Phil Kenkel, Riza Radmehr, Rodney Holcomb, Mckenzie Boyce

Human–Wildlife Interactions

Feral swine (Sus scrofa) in the United States have become a growing concern, with a population of ≥6 million and causing annual damages of ≥$1.5 billion USD. Because of their high reproductive capacity, effective control methods are crucial to reducing or slowing their population growth. While remotely monitored and triggered traps have proven to be an effective control strategy, the cost of sophisticated trapping equipment, which can cost ≥$7,000 USD, is often cost prohibitive for many landowners. Despite the pressing need to address the challenge of making effective feral swine control methods more affordable, there are few studies …

Citrus Gall Wasp Control, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity factsheets

Citrus gall wasp (Bruchophagus fellis) is an Australian native insect from northern NSW and Queensland and is now established in most Perth suburbs. It affects all citrus species, particularly lemons and grapefruit, and will be an ongoing pest to manage for Perth gardeners, like other common pests. It has not been found in commercial citrus orchards in Western Australia yet.

“Fixing” Settler Capitalism: Un/Sustainability In The Former Fort Ord, Clare M. Beer, Sara Salazar Hughes

Urban and Environmental Studies Faculty Works

California's former Fort Ord Army Base is located on the unceded Indigenous territory of the Ohlone Costanoan Esselen Nation. After seven decades as a training ground for foreign wars, the decommissioning of the base triggered an economic, demographic, and cultural crisis for greater Monterey. The solution to this crisis, the Fort Ord Base Reuse Plan, promised sustainable development in the form of local environmental protection, public higher education, and economic growth. We argue that the Fort Ord Base Reuse Plan illustrates a settler sustainability fix, which the state deploys to secure settler capitalist futurity on the Monterey Peninsula at the …

Estimating The Carbon Footprint Of Sheep Production In Western Australia, Tafesse Estifanos, Christophe D'Abbadie, Johnny Machon, Amir Abadi Abadi Ghadim, Gus Manatsa, Paul Mattingley, Ross Kingwell, Kevin Foster

Farm Systems and Economics published reports

Western Australia’s broadacre mixed farming systems combine cropping and sheep production and are the largest component of the state’s agricultural sector. The south west Western Australia (WA) agricultural area hosts about 98% of the state's sheep flock. The sheep industry contributed $1.5 billion to the state’s economy in 2021-22 and accounts for about a quarter of on-farm greenhouse gas (GHG) emissions. Most sheep industry emissions (over 80%) come from methane produced by the sheep. Despite this environmental impact, only 9.9% of Australian sheep producers have estimated their emissions, which limits the industry's ability to monitor and manage carbon footprints effectively. …

Skeleton Weed In Western Australia: 2025 Management Guide, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity bulletins

Skeleton weed can reduce crop yields by competing for moisture and nutrients (mainly nitrogen).

This guide helps you manage and eradicate skeleton weed infestations on your property, and helps to stop the spread across WA.

Without the coordinated program aimed at controlling the spread, skeleton weed would now be much more abundant and widely established throughout cereal growing areas.

If you find skeleton weed on your property, we can help you get rid of it.

Skeleton weed is unpredictable and can spread over long distances due to wind dispersal, but once identified it can be managed effectively and eradicated

Skeleton Weed In Western Australia: Control Program 2024–2025, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity bulletins

Key program changes

Winter eradication program

New herbicide recommendations for control in crops, legume based annual pastures, plantations and glyphosate tolerant canola.

• The minimum size of ‘squares’ (infested areas) has been reduced from 40 m x 40 m (0.16 ha) to 20 m x 20 m (0.04 ha) to help reduce the winter treatment area.
• Landholders will need to consult with DPIRD/LAG officers to assess the degree of infestation before working or cultivating through squares in Code 1 paddocks.
• Clopyralid (LontrelTM) herbicide will no longer be provided for treatment on heavily infested paddocks. Landholders will still be required to undertake …

Characterizing Agroecosystem Effects Of Industrial Hemp On A Rotational Row Cropping System And Microbial Communities, Kent D. Pham

Theses and Dissertations--Plant and Soil Sciences

The implementation of crop rotation on a farm can have many benefits for agroecosystem health and production. This practice can potentially reduce nutrient amendments, disrupt pest and disease cycles, and increase crop yields. In Kentucky, one common rotation consists of either corn or soybean grown the first year, followed by the other crop, repeated every two years. Industrial hemp, grown for fiber or grain, is an emerging crop that has shown promise as a rotation alternative, although not much is known about its effects on soil health, agroecosystem functioning, and microbial communities. To better characterize hemp’s role within American agriculture, …