Biostimulants offer an innovative approach to potentially improve crop yield and quality under abiotic stresses. Particularly, plant-derived protein hydrolysates (PH), a mixture of amino acids and soluble peptides from enzymatic or chemical hydrolysis of agricultural waste, are gaining global interest due to their sustainability and positive effects on crops. However, a functional role of the PH in crop yield and quality remains uncertain and is proposed to be associated with its phytohormone-like activities or serve as an additional nitrogen (N) source. Besides, the effects of PH on crop yield and quality are limited in intensive production systems such as greenhouse facilities. The purposes of this research are to examine the effects and mechanisms of PH on crops and to assess the potential of PH application to reduce fertilizer use in crop production. The specific objectives were to; 1) elucidate the hormone-like activities of PH in the adventitious rooting formation of cuttings, 2) evaluate the effects of different PH application methods on greenhouse crop yield and quality under different N levels when plants are grown with a commercial growing medium, and 3) examine the effects of PH application methods on yield and quality of hydroponically grown lettuce under different N levels and forms. Three conclusions were that 1) <a>the hormonal effects of PH are attributed to brassinosteroid-mediated processes, and PH has overlapping functions with auxin during adventitious rooting of cuttings in a plant species-specific manner</a>, 2) root application of PH (PH-R) effectively improves nutrient uptake compared to foliar spray of PH (PH-F), subsequently, increases the lettuce and tomato yield and quality regardless of N levels while PH-R did not change the chemical properties of growing media, and 3) PH-R effectively increases root growth, and subsequently, improving shoot yield and quality with significant PH × N levels and PH × NO₃:NH₄ratios interactions. Also, PH-R counteracted the negative effects of low NO₃:NH₄ratios on lettuce yield. The outcomes provide the optimization of PH and N fertilization in modern sustainable greenhouse production and the development of a new strategy for producing high-quality greenhouse crops with improved nutrient use efficiency.

<p>This thesis aims to evaluate a Modular Manufacturing (MM) technical approach to Controlled Environment Agriculture (CEA) for cultivating plant food crops in a repurposed urban space. The specific approach was to fit a modular hydroponic CEA system into an insulated cooler box with environmental control to act as a micro plant factory. The feasibility of the approach was evaluated and a benchmark comparison between repurposed urban space and controlled lab environments was produced.</p><p>Possessing accessibility and affordability to desired quantitatively and nutritious food is a pillar for a healthy lifestyle, yet food insecurity is a growing problem worldwide, in industrial as well as industrializing nations. Food insecurity is defined as “lacking the ability to meet nutritional needs at one or multiple times during the year.” [1] Though Developing countries tend to score poorly on the Food Security Index [2], the issue is common in developed countries as well, where countries like the U.S. Possess a household food insecurity rate of above 10% [1]. Especially, subgroups of the urban population and university students in developed countries are represented at a higher rate concerning food insecurity [3], due to food insecurity’s dependence on socioeconomic factors such as purchasing power and local accessibility.</p><p>Bringing production close to the consumers or to the Point-of-Need (PoN) would be a valuable tool for supplementing traditional food crop production and increasing access to high-quality food for groups exposed to food insecurity. This is especially attractive in densely populated areas and college campuses, where real estate is prime. Bringing production to the PoN does however carry certain challenges, such as severe resource restrictions, which are not present in traditional agricultural production in rural areas where there is vast access to land, water, and plenty of sunlight. Pushing the boundaries of CEA research, technology, and application areas will be crucial for the utilization of nontraditional agricultural land, agricultural resource optimization, and food security improvements in difficult-to-farm environments to facilitate delivery to PoN.</p><p><br></p><p><b>Salient outcomes:</b> The salient outcomes of this research were that a MM platform was proven to be feasible for CEA cultivation of food crops in a repurposed urban space as well as a controlled location. Specimens cultivated in a repurposed urban space were shown to have a lower growth rate compared to a controlled location, but the important comparison is to the currently nonexistent productivity in such spaces.</p><p><b>Intellectual merit:</b> The MM CEA platform was designed, prototyped, and tested using components-of-the-shelf (COTS) as recommended by frugal engineering methodology [4]. This manufacturing platform was engineered for a case study for repurposing unused “garage space” on the college campus at Purdue University. The platform was further used for a set of studies to evaluate the feasibility of the MM platform and the production efficiency of the platform not only in a repurposed urban space but also across harsh environments across winter-spring seasons. Romaine lettuce cultivars were used as a sample plant for winter and spring studies due to their property as a popular consumable, nutritious, and relatively short growth time for better productivity. The following research issues were addressed by this research: (1) design of a modular manufacturing module; (2) testing of the module in the indoor controlled lab environment; (3) advancing design based on findings in no.2; (4) CEA testing of the integration of multiple modules (two and water supply) in the Purdue University garage (living lab) and the indoor lab environment.</p><p><b>Broader Impact:</b> The results from this research could serve as a proof-of-concept to validate the feasibility of functional modules and their integration in scaled-up urban food crop production using repurposed space. This case study especially could open opportunities for college campuses across the US (and the world), to repurpose multi-storied garage spaces for healthy food production at PoN, for example, accessible to students’ dorms and cafeterias. This MM model could further be extended to other forms of urban areas for food security and production in communities in the vicinity of garages and similar spaces in form. Utilizing unrecognized space resources in an otherwise resource-restricted environment could be the supplemental production needed to fight food desertification and insecurity in urban locations. Bringing food production to the PoN would increase the accessibility of high-quality and nutritious fresh produce, improving conditions for localized food insecurity problems.</p>

<p dir="ltr">Controlled environment agriculture (CEA) is a practice of food production under optimized conditions to intensify production yield, and thus has potential for addressing food security for a growing population. Aquaculture and aquaponics are two types of CEA that can produce aquatic animals along with plants using non-arable lands and lower inputs of water and nutrients. However, their operations have high energy consumption and generate considerable nutrient-rich sludge and wastewater, making their environmental performance an emerging research focus. This thesis quantitively analyzed the environmental sustainability of aquaponics and aquaculture production using life cycle assessment (LCA).</p><p dir="ltr">The LCA on aquaponics evaluated a marine aquaponics production system that grew shrimp, red orache, minutina and okahajiki, and analyzed the effect of salinity, C/N ratio, and shrimp-to-plant stocking density. The grow-out stage accounted for over 90% of total environmental impacts with electricity use as the predominant contributor. The marine aquaponic production exhibited best environmental performance when operated at low salinity (10 ppt), and high C/N ratio (15) and stocking density (5:1), which can be further improved by 95–99% via the use of wind power as electricity source. Additionally, variation in the prices of aquaponic products was found to improve the system’s environmental impacts by up to 8%.</p><p dir="ltr">The aquaculture LCA focused on shrimp recirculating aquaculture systems (RAS) and evaluated the environmental feasibility of microalgae-based wastewater treatment. Microalgae treatment effectively removed 74% of phosphate in RAS wastewater and thus reduced the freshwater eutrophication potential by 55%. However, its remediation performance was inferior to activated sludge treatment due to different operation scales. Electricity was the principal hotspot of microalgae treatment and made up over 99% of all the environmental impacts, which can be considerably decreased by reducing coal use in the electricity supply. Three utilization pathways for algal biomass (feed ingredient, biodiesel and biogas) were investigated; however, only biogas production was found to show environmental benefits to marine eutrophication remediation owing to the low biomass quantity produced.</p><p dir="ltr">While <a href="" target="_blank">aquaculture and aquaponics</a> play important roles in meeting the globally growing demand for seafood, this thesis provides valuable life cycle inventory data for these fields. Moreover, the LCA models developed in this thesis are useful decision-making tools for aquaculture and aquaponic producers to adapt farming practices with lower environmental footprint.</p>