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>  </p> <p>With the rapid growth in population and urbanization, an increased supply of fresh, nutritious, and safe food in urban areas is required. Relying solely on conventional agriculture for food production can be risky due to climate change and decreasing natural resources (i.e., water, and arable land). Vertical farming (VF) involves growing food crops (primarily leafy greens and small-statured fruits) at multiple levels in controlled environments with less land and water inputs. However, high operational costs have resulted in low-profit margins in VF, which are challenging the economic sustainability of the VF industry. With the present VF technology, it may be difficult to significantly reduce the operational costs. Therefore, maximizing the wholesale value of produce, which is determined by the total yield and sale price per unit quantity (or crop value), is critical for increasing profits in VF. In this research, the overall goal is to increase lettuce growth, nutritional quality, and food safety by optimizing the light quality of light-emitting diodes (LED) in VF to increase the whole value of produce and thus increase the VF profits. The objectives of the research were to (i) study the independent and interactive effects of monochromatic wavebands of light from UV-A (365 nm) to far-red (750 nm) on lettuce growth and nutritional quality; (ii) identify the effects of substituting moderate proportions of UV-A and a high proportion of UV-A coupled with far-red light in growth lighting on lettuce growth and nutritional quality; (iii) study the effects of lettuce cultivars and UV LED light on the survival of <em>E. coli</em> O157:H7 on lettuce in VF production.</p> <p>In the first study, we investigated the effects of different wavebands of light ranging from UV-A (370 nm) to far-red (733 nm), both independently and in combination with commercial growth lighting on lettuce growth, incident light-use efficiency (LUEinc), and levels of phytochemicals. Results showed that the monochromatic wavebands 389 and 733 nm had positive interactions with the growth lighting on lettuce. In addition, results also indicated that UV-A light at a peak wavelength of 389 nm could potentially increase phytochemical concentrations. In the second study, the effects of 40% UV-A (UV 389 nm) and 60% UV-A (UV 389 nm) plus 10% far-red (FR 733 nm) light for growth light during the plant stationary growth stage on lettuce biomass and biosynthesis of phytochemicals were examined. Results showed that substituting UV-A for 40% growth lighting during the plant stationary growth stage for seven days resulted in significantly increased levels of beta-carotene and phylloquinone in lettuce while slightly lowering lettuce growth. And the addition of far-red light to UV-A did not result in the expected increase in vegetative growth, while the levels of phytochemicals were not affected. In the third study, we first investigated the effects of four lettuce cultivars, including oakleaf, romaine, butterhead, and leaf lettuce on the survival of <em>E. coli</em> O157:H7 gfp+. Results showed that leaf lettuce had the lowest while oakleaf and romaine had the highest concentrations of <em>E. coli</em> O157:H7 gfp+ when sampled on days 2 and 7 after the inoculation, and on day 7 after harvest and storage at 4 °C. Then we examined the feasibility of supplementing UV-A, UV A+B, and UV A+C during plant growth stages to reduce <em>E. coli</em> O157:H7 gfp+ contamination on lettuce. Our results indicated that only the UV A+C light at an intensity of 54.4 μmol·m-2·s-1 for 15 minutes per day after inoculation reduced <em>E. coli</em> O157:H7 gfp+ contamination by 0.33 log CFU·g-1 without affecting plant growth and levels of phytochemicals.</p> <p>The outcomes from our research suggested that the interactive effects of monochromatic wavebands should be considered in developing light recipes. In addition, VF growers who are interested in improving the nutritional phytochemical levels such as beta-carotene and phylloquinone in lettuce while maintaining growth should consider adding a moderate proportion (< 40%) of near-blue UV-A (i.e., 389 nm) radiation during the plant stationary growth phase to growth lighting. However, shorter wavelengths of UV-A radiation are not recommended due to their negative effects on plant growth and high economic cost. For growers who are at high risk of <em>E. coli</em> O157:H7 contamination, it is suggested that growing leaf lettuce and supplementation of UV A+C LED light during the plant-growth period should be considered to reduce the <em>E. coli</em> O157:H7 contamination levels.</p>

<p>Vertical farming (VF) as a newer sector of controlled-environment agriculture (CEA) is proliferating as demand for year-round, local, fresh produce is rising. However, there are concerns regarding the high capital expenses and significant operational expenses that contribute to fragile profitability of the VF industry. Enhancing resource-use efficiency is a strategy to improve profitability of the VF industry, and different approaches are proposed in the three chapters of this dissertation. LEDs are used for sole-source lighting in VF, and although they recently have significantly improved electrical efficiency and photon efficacy, the Lambertian design of the illumination pattern leads to significant loss of obliquely emitted photons beyond cropping areas. In chapter 1, close-canopy lighting (CCL) is proposed as one effective energy-saving strategy, through which unique physical properties of LEDs were leveraged, and two CCL strategies (energy efficiency and yield enhancement) were characterized at four different separation distances between light-emitting and light-absorbing surfaces. Dimming to the same light intensity at all separation distances resulted in the same biomass production while significant energy savings occurred at closer distances. Significantly higher light intensity and yield were achieved under closer separation distances in the yield-enhancement strategy for the same energy input. The energy-utilization efficiency (g fresh/dry biomass per kWh of energy) was doubled in both scenarios when the separation distance between LED emitting surface and crop surface was reduced maximally. At reduced separation distances, the chance of photon escape from growth areas is less, and canopy photon capture efficiency is improved.</p><p>Optimizing environmental conditions for indoor plant production also helps improve resource-use efficiency for the nascent vertical-farming industry. Although significant technical advancements of LEDs have been made, use of efficient far-red (FR) LEDs has yet to be exploited. As a recent proposed extension to traditional photosynthetically active radiation (PAR, 400-700 nm), FR radiation (700-750 nm) contributes to photosynthesis as well as photomorphogenesis when added to shorter wavelengths of traditional PAR. However, the interaction of FR with other environmental parameters such as CO2 is less studied. In chapter 2, the interaction effect of four FR fluxes (as substitution for red) in combination with three different CO2 concentrations were investigated at three distinctive stages of young-lettuce production. The highest biomass achieved at all stages occurred at 800 mmol mol-1 CO2 compared to 400 and 1600 mmol mol-1. A photomorphogenic effect of FR to promote leaf length was pronounced at the earliest stages of development, at which FR did not contribute to higher biomass accumulation. At more developed stages, 20 mmol m-2 s-1 of FR substituting for red contributed to biomass accumulation similar to shorter wavelengths of traditional PAR, whereas higher fluxes of FR in the light recipe resulted in undesirable quality attributes such as longer leaves.</p><p>Optimizing environmental conditions for indoor production with emphasis on light intensity and CO2 concentration at four distinctive stages of lettuce production was investigated in chapter 3. Utilizing the Minitron III gas-exchange system, light and CO2 dose-response profiles were characterized at four distinctive crop-development stages through instantaneous gas-exchange measurements at crop level. At all developmental stages, as CO2 concentration increased, photosynthesis increased up to 500 mmol mol-1, above which the incremental rate of photosynthesis was reduced. Light-dose response profiles were characterized at 400 or 800 mmol mol-1 CO2, and as light intensity increased, photosynthesis increased up to 650 mmol m-2 s-1. However, when instantaneous power (Watts) consumed for lighting was taken into consideration, power-use efficiency as the ratio of output photosynthesis increment to input power increment (to increase light intensity), decreased at higher light intensities. Vertical farming as a nascent and growing industry is facing limitations including marginal and even elusive profitability. Optimizing environmental conditions for indoor plant production such as these will help improve resource-use efficiency and profitability of the vertical farming industry.</p>

No description available.

<p>  </p> <p>Kentucky bluegrass is the most common cool-season turfgrass grown in the northern US. <br> The fact that Kentucky bluegrass requires s high quantity of fertilizers, pesticides, and irrigation to produce high quality turf has led to environmental concerns among policymakers, researchers, and consumers. To address this concern, turfgrass breeders have developed improved cultivars of low-input turfgrass species that aim to improve the sustainability of US lawns (Ghimire et al., 2019). For instance, tall fescue [(<em>Festuca arundinacea </em>Schreb.; syn. <em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.] and fine fescues (<em>Festuca </em>spp.) may represent viable options for residential and commercial buildings due to their outstanding performance under lower amounts of inputs such as irrigation, pesticides, and fertilizers (Watkins et al., 2011). Thus, adopting improved cultivars of low-input species may be a step towards reducing the use of inputs in landscapes (Simmons et al., 2011; Pooya et al., 2013). Yet, the production of low-input turfgrasses in the northern US is slow and limited, which leads to marketing and education obstacles that support their adoption. Thus, understanding factors that influence sod buyers to purchase low-input turfgrasses is imperative to increase the market share and the adoption of these turfgrasses. </p> <p>This study investigated the factors influencing sod buyers to purchase low-input turfgrass in the northern US, using tall fescue and fine fescue as low-input sod species. Using a logistic regression model, we assessed the determinants of low-input turfgrass purchase among sod buyers (i.e., athletic facilities, landscape contractors, garden centers, general contractors, lawn care, golf courses, and municipal parks). The logit model assumed the adoption decision to be driven by the buyers’ perception of the utility of buying low-input turfgrass species. Thus, the dependent binary variable Y equals 1 if the firm purchased tall or fine fescue in 2020, and 0 otherwise. The adoption is then expressed as a function of determinants, including the firm’s characteristics, supplier characteristics, sod attributes, and buyer’s perceptions. </p> <p>Data for this study came from a 2021 web-based survey of sod buyers located in 19 states of the Northern US. A total of 200 buyers completed the survey, including landscape contractors, golf courses, general contractors, lawn care services, and landscape maintenance firms who have purchased sod in 2020. The significant mean comparisons between adopters and non-adopters showed that adopters of low-input turfgrasses purchased most of their sod through contract agreements. The main suppliers of adopters were located at a closer distance to on-site delivery than the non-adopters. The logit regression results showed that low-input turfgrass adoption was positively influenced by the number of sod suppliers and managerial experience of the sod buyer. Landscapers were more likely to purchase tall fescue and fine fescue compared to golf courses and municipal parks. We found that distance from sod supplier to on-site delivery negatively impacted the purchase of low-input turfgrasses. Similarly, Kentucky bluegrass buyers were less likely to purchase low-input turfgrass species.</p>

<p> Fruit size is a polygenic trait controlled by multiple genomic regions each with small effect. The complex nature of fruit size regulation makes it challenging to dissect individual genes responsible for phenotypic variation. Though recent advances in high-throughput genome sequencing technology in conjunction with improved statistical and computational methods empowered science to explicitly understand the genetic basis underlying multiple fruit quality traits, much of the work that has been done through classical quantitative trait loci (QTL) approach resulted in reduced resolution and instability when evaluating in different genetic backgrounds and different environments. To increase the precision and improve the stability of QTL analyses and to identify genes controlling fruit size, we performed a set of multiple quantitative and molecular genetic analyses to elucidate the underlying genetic architecture of fruit mass. A total of nine genomic regions associated with fruit mass were identified, two of which are novel to this study; markers Md14_26050918 and Md14_26050904. Detected QTLs explained ~ 42% of the total genetic variation of which ~ 20% is explained by the two novel QTLs. Regions responsible for fruit mass variation appear to be under strong additive and epistatic genetic control. These regions exhibited high stability across-family as well as across-years and showed accurate genomic prediction across-family. Additionally, we identified the apple gene family of putative fw2.2 orthologs, naming them Cell Number Regulators (CNRs) genes (MdCNRs). Three CNRs (MdCNR1-3) showed increased expression at early fruit growth in small-fruited crabapple, associating with reduced relative cell production rate (RCPR), suggesting that alteration in cell number that leads to a subsequent reduction in fruit size is probably due to reduced cell division most likely due to changes in CNRs regulation. Furthermore, our study revealed that reduced fruit size is partially due to the shortened cell expansion period after which cell expansion ceases in the small-fruited crabapple species. Together, these data will advance our understanding of dissecting fruit mass genetic architecture and have high potential to be deployed for marker-assisted selection and further breeding approaches. </p>

<p>Sustainable food production is about producing more and better with less.As an emerging CEA system, aquaponics integrates recirculating aquaculture systems and hydroponics and can achieve the three SDGs mentioned above. However, challenges in sustainable aquaponics commercialization remains and my thesis addresses the following three layers of sustainable aquaponics  development:  sustainability  assessment,  sustainable  system  design  and management, understanding biological mechanisms for scalability.</p> <p>I conducted acradle-to-gate life cycle assessment (LCA)and compared the environmental performance, on an economic basis, of aquaponics andhydroponics withidentical system design in Indiana, US. Aquaponics produced 45% lower endpoint environmental impact than hydroponics.Electricity use for greenhouse heating and lighting, and water pumping and heating contributed to themajority of the environmental impacts of both systems, which was followed by the production of fishfeed and fertilizers. However, changing the energy source from coal to wind power could make thehydroponic system more environment-friendly than the aquaponic system. This LCA study can provideCEA farmers with the groundwork to reduce the environmental cost of their production.</p> <p>Aquaponics uses bacterial processes and plant nutrient uptake to recover nutrient from aquaculture wastewater. However, little is known which wastewater management strategy, autotrophic or heterotrophic, is best suited for the four objectives: nutrient recovery, system reliability, and growth and physiological welfare of fish and plants. In this study, I found that pH6 had the highest nitrogen (N) use efficiency (NUE) (assimilated by fish and plants, 65.5%) and the lowest N loss as gas (34.5%), followed by pH6M (55.5% and 44.5%,respectively), suggesting that lower pH and less organic carbon in aquaponics could enhance NUE and reduce N loss. pH6M had the highest phosphorus (P) use efficiency (PUE) (assimilated by fish and plants, 65.0%) suggesting that lower pH and organic carbonaddition could facilitate P recovery from wastewater. </p> <p>Reverse osmosis (RO) water enables aquaculture to expand in places where natural water is not desirable and reduces uncertainty in the operation. However, high K+environment of RO in  aquaponics  couldinduce  physiological  stress,  but  adaptation  mechanism  is  unknown. Proteomic analysis revealed up-regulation of stress response proteins and down-regulation of V-type H+-ATPase and other ion transporters, suggesting cellular adaptation of fish to RO water stress. In conclusion, fish was able to accommodate to the RO environment and the benefits of efficient ammonia excretion and increased feed consumption outweighed the stress caused by RO. RO water could be a standardized water source for better animal welfare, reduce uncertainty in production and assist scaling up aquaponics industry.</p>

<p dir="ltr">New cultivars of compact tomato (<i>Solanum lycopersicum</i>) and pepper (<i>Capsicum annuum</i>) plants are available to consumers, creating niche market opportunities for greenhouse growers who produce vegetable bedding plants for spring sale. However, production guidelines for these crops are limited. We conducted two experiments to evaluate non-chemical means of height control for these plants. In the first experiment, we treated ‘Siam’ tomato and ‘Basket of Fire’ pepper plants with 0, 50, 100, 150, or 200 mg·L^–1 nitrogen (N) during the “production” phase and used a similar or higher N concentration during the “fruiting” phase. Our results show that although height of these plants can be controlled with lower fertilizer concentration, their yield will likely be affected by limiting fertilizer availability. In addition, our findings suggest that these plants can be grown without the addition of fertilizer during production, provided that the substrate has a starter fertilizer charge, and that sufficient fertilizer is applied during the fruiting phase. In the second experiment, we characterized the effects of fertilizer use and substrate volumetric water content (VWC) during production using the same compact plants, and evaluated post-production carryover effects on growth and yield. Plants either received water-soluble fertilizer (100 mg·L^–1 N) once a week, or were irrigated with tap water only, relying on the starter fertilizer charge in the substrate. In addition, plants were irrigated when the substrate VWC reached 0.15, 0.30, 0.45, or 0.60 m³·m^–3. Overall, our results show that substrate VWC had minimal effects on growth and yield, but plants that were not fertilized were shorter, had less biomass, and produced less fruit than those treated with fertilizer. These findings suggest that growth and yield of these compact tomato and pepper plants are affected to a larger extent by fertilizer use than by substrate VWC.</p><p dir="ltr">In effort to better understand consumer preferences for these new compact plants, we used a citizen-science approach in another experiment. Approx. 300 participants from three states in the USA (IN, IA, and TN) compared three compact tomato cultivars (Red Robin, Cocoa, and Micro Tom) started from seed or as transplants. In addition, we compared pre- and post-experiment survey responses to assess potential changes in behaviors, beliefs, and attitudes towards gardening as a result of the experiment. Cocoa was the preferred cultivar, closely followed by Red Robin. Our results indicate participants valued plant appearance, fruit yield, and fruit taste when making these preference choices. Approximately 70% of participants preferred plants started as transplants compared to those from seed, regardless of cultivar. Most participants reported they would be willing to pay between $1.00 to $7.49 more for a transplant of their favorite cultivar compared to tomato plants available at local nurseries. Results for dietary behaviors show that participants increased their consumption frequency of fruit, lettuce salad, vegetables, and food mixed with vegetables at the end of the experiment, but few differences were measured for beliefs and attitudes towards gardening, likely due to previous positive biases towards gardening among project participants. In conclusion, results from our experiments show that growth and yield of compact tomato and pepper plants can be controlled by adjusting fertilizer management practices. In addition, citizen science was shown to be an effective research method to assess plant-performance and consumer-preference data, and to measure potential changes in behavior of project participants.</p>

<p dir="ltr"><a href="" target="_blank">Watermelon [<i>Citrullus lanatus </i>(Thunb.) Matsum. & Nakai] is one of the world's top three most consumed fruits.</a> Indiana cultivates approximately 7,000 acres of watermelons every year, ranking 6^th in the nation. More than 70% of this production is concentrated in and around Knox County, making Southern Indiana a key region for watermelon production in the States. Despite its significance, watermelon production faces many challenges, including erratic rainfall patterns exacerbated by climate change. Enhanced irrigation management has emerged as a critical strategy in mitigating negative environmental effects and in optimizing fertilizer applications.</p><p dir="ltr">Currently, Southern Indiana farmers have incorporated different irrigation and fertilization practices into watermelon production, yet the effects on production outcomes remain poorly understood. To bridge this gap in knowledge, this study aims to explore the effects of existing practices on watermelon yield and develop irrigation guidelines for optimal production in the region. The experiment was conducted at Southwest Purdue Agricultural Center, Vincennes, Indiana, in 2022 and 2023. Four treatments were applied: High Irrigation, Low Irrigation, No Irrigation, and Fertigation. Fertigation treatment received the same water application as the High Irrigation treatment. Fertilizers were applied pre-plant in the High, Low, and No irrigation treatments, while frequent fertigation was applied to the Fertigation Treatment. Soil moisture sensors measuring volumetric water content were used for irrigation decisions. In 2022, the irrigation thresholds were set at 15% water depletion at 1-ft depth for High Irrigation and Fertigation treatment, and 2-ft depth for Low Irrigation. In 2023, the irrigation threshold for Low Irrigation was adjusted to 40% water depletion at 1-ft depth.</p><p dir="ltr">While soil moisture levels in the bed at the different depths varied notably among treatments, no significant differences in yield by weight were observed. The minimal impact of irrigation on watermelon yield suggests that rainfall provides sufficient water, preventing yield-reducing stress. However, the Fertigation and High Irrigation treatments yielded more fruit than the Low Irrigation and No Irrigation treatments. The dry periods in both years coincided with the watermelon fruit setting stages that may have contributed to the lower fruit set in the Low Irrigation and No Irrigation treatments. Fertigation showed a higher early yield than the other treatments in 2022. Analysis of soil and tissue nitrogen levels indicated that sole nitrogen application before planting could result in excessive soil nitrogen levels during vegetative growth. This excess nitrogen might delay flowering and harvest. This project offers insights into enhancing irrigation and fertilization practices for watermelon production in southern Indiana.</p>

<p> Brown patch (caused by various <em>Rhizoctonia </em>and <em>Rhizoctonia-</em>like species) is one of the major summer diseases of tall fescue [<em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.]. Fungicides are available to suppress brown patch; however, there is increasing interest to reduce lawn pesticide inputs. Excessive summer nitrogen (N) applications and extended periods of leaf wetness have been suggested to enhance brown patch. Five projects were conducted from 2020 to 2022 to evaluate individual and various combinations of cultural management practices to improve brown patch management strategies through reducing chemical inputs and promoting environmentally sound integrated pest management (IPM) practices. Brown patch host resistance of 15 tall fescue cultivars was evaluated in a controlled environment study and various morphological characteristics were correlated to brown patch severity. A 45% reduction in brown patch was observed with a resistant cultivar, and cultivars with faster growth rates, wider sheath widths and shorter sheath length correlated with reduced brown patch resistance. A field study evaluated five cultivars fertilized with urea-N from April to July, totaling 73.5 or 245.0 kg N ha^-1. A resistant cultivar had the greatest influence on reducing disease, and N-rate generally did not influence disease severity. Differences in seasonal brown patch was compared in a three-year field study for various natural organic fertilizers. Feather-bone meal and soybean meal-based products decreased disease compared to non-fertilized turf. Chemical suppression of leaf-wetness was studied using different surfactant chemistries applied on a 14 to 21-d application frequency and some chemistries reduced disease. When evaluating the various interactions of cultivar, N rate, and surfactant compared to a granular fungicide, the greatest impact was achieved when planting a resistant cultivar, reducing disease severity by 68%. Additionally, the combination of a resistant cultivar and application of a surfactant had the same seasonal brown patch compared to a susceptible cultivar with fungicide applications during year two of evaluation. In summary, these studies demonstrate significant reductions in brown patch can be achieved when utilizing the aforesaid best management practices which can substantially reduce the need for frequent lawn fungicides.  </p>