Current Projects:

Reducing heavy metal contamination in Peruvian vegetables The presence of high concentrations of heavy metals in soils is a significant health concern for vegetable growers and consumers in southern Peru. To help overcome this challenge, we aim to identify key environmental and management practices regulating microbial transformations and partitioning of heavy metals in soil and within vegetable crops. This project is funded by the Arequipa NEXUS Institute and is being conducted in collaboration with Dr. Sara McMillan, Purdue Agriculture and Biological Engineering. Two postdoctoral research associate positions are currently available in the McMillan and Hoagland Labs to support this project. Click here NEXUS post-doc ad to learn more about these positions and apply.

Practical approaches for mitigating cadmium contamination in cacao Production of cacao seeds for chocolate is a rapidly growing component of Colombia’s agricultural economy. The presence of high concentrations of cadmium in soil  threatens this industry because this heavy metal can accumulate in cacao seeds and negatively impact the health of chocolate consumers. The goal of this project is to help address this challenge by identifying spectral images that can be used to detect the presence of heavy metals in plants, and evaluate the potential for endophytic microbes to sequester cadmium in plant roots, thereby preventing uptake into cacao seeds. This project is jointly funded by the USDA-AID project Cacao for Peace, and a Colfutura Scholarship provided by the Colombian Government. Graduate student, Ms. Maria Paula Zea, is working on this project.

Identifying locally available soil amendments that can reduce heavy metal uptake in leafy greens With over half of the world’s population now living in urban areas, production of vegetables in soils contaminated with heavy metals is becoming increasingly problematic, because heavy metals can accumulate in edible crop tissues and negatively affect human health. To overcome this challenge, we aim to identify locally available soil amendments that can improve soil health and reduce heavy metal uptake in vegetable crops. Amendments we are currently evaluating include composts made from different feedstocks, biochars made from different feedstocks and processing temperatures, and various microbe combinations obtained from commercial inoculants or isolated from our other trials. Ms. Hannah Komanapelli, a Purdue Undergraduate Honors Student is currently working on this project, and former visiting students Mr. Gustavo Mendizabel and Ms. Liliana Gomez previously worked on this project. This research is currently being funded by Purdue Agriculture Research Programs, and has previously recieved support from the Purdue-Colombia Partnership and the Purdue-Zamorano Partnership.

Changes in soil microbial community structure in response to heavy metal contamination and consequences for uptake and partitioning in sorghum plants The long-term goal of this project is identify and isolate soil microbes that can help plants tolerate heavy metal stress and prevent accumulation of heavy metals in aboveground plant tissues. To accomplish this goal, we collected soil from plots that were contaminated with heavy metals in the 1970’s by urban sewage sludge that was used as a fertility amendment. We quantified changes in soil microbial community structure after 40+ years of heavy metal contaminating using next-gernation sequencing and are determining how the presence of these altered soil microbial communities can affect cadmium partitioning in sorghum plants. This research is funded by Purdue Agricultural Research Programs and is being conducted by visiting scientist, Ms. Lina Gonzalez.

Biological control strategies for Verticillium Wilt in Mint Spearmint and peppermint are important specialty crops in the Midwest region, however, once soils become infected with the soilborne pathogen Verticillium dahliae, production is dramatically reduced. The goal of this project is to determine whether Anaerobic Soil Disinfestation (ASD) can be used to eradicate this devestating pathogen. We also aim to identify locally available substrates that can be effectively used for ASD, and elucidate the microbial mechanisms mediating this new form of biological disease control. This project is funded by the NC-SARE program and is being conducted in collaboration with Dr. Petrus Langenhoven, Purdue Horticulture and Landscape Architecture. Postdoctoral research associate, Dr. Sahar Abdelrazek, is the lead researcher on this project.

Tomato Organic Management and Improvement Project (TOMI) In a recent survey, organic tomato growers identified foliar pathogens as their greatest production challenge. The goal of this multi-state, interdisciplinary research project is to overcome this challenge by: 1) identifying practical approaches to improve the efficacy of biological fungicides for the control of  foliar pathogens, 2) develop new improved tomato varieties that are more resistant to foliar pathogens yet still have the great flavor consumers expect in traditional heirloom tomato varieties, and 3) further elucidate the mechanisms regulating induced systemic resistance to foliar pathogens by beneficial soil microbes so this form of disease control can be integrated into future breeding projects and applied on farms. This project is funded by the NIFA-OREI program and is being conducted in collaboration with other scientists at Purdue University (Dan Egel, Tesfaye Mengiste), Oregon State University (James Myers), University of Wisconsin-Madison (Julie Dawson), North Carolina State University (Jeanine Davis), North Carolina A&T University (Sanjun Gu), and the Organic Seed Alliance (Micaela Colley, Jared Zystro). The Hoagland Lab is participating in all components of this project and postdoctoral research associate, Dr. Amit Jaiswal, is the lead researcher on the induced systemic resistance component of this project. More information about this project can be found at the following website:

Carrot Improvement for Organic Agriculture (CIOA) The broad goal of this project is to develop new novel colored and nutritious carrot varieties that are best adapted to organic farming conditions across the U.S. This large multi-state, multidisciplinary project is funded by the NIFA-OREI program and is being conducted in collaboration with Dr. Phil Simon USDA-ARS and other scientists at the University of Wisconsin-Madison, Washington State University, University of California-Riverside and the Organic Seed Alliance. In the Hoagland lab, we are investigating how carrot plants interact with beneficial soil microbes to mediate pathogen severity, scavange nutrients and prevent heavy metal uptake. Former graduate student, Sahar Abdelrazek, determined that endophytes, which are microbes that spend at least part of their life cycle inside plants, are abundant in the seeds and roots of carrot plants. These endophytic microbes possess numerous plant growth promoting abilities, and they can help carrots withstand assault by Alternaria dauci, a key carrot pest. The composition of carrot endophyte communities are influenced by carrot genotype indicating that it might someday be possible to select for these microbes in breeding prorgrams. Graduate student Narda Silva, is now following up on Dr. Abdelrazek’s research, investigating how the presence of endophytes as well as microbes in the rhizosphere can help carrot plants scavenge nitrogen, and visiting student Ms. Gabriela Santos is determining how these microbes interact with carrot genotypes to affect cadmium accumulation. More information about this project can be found at the following website:

Healthy transplants for healthy crops: developing a protocol for organic transplant production Healthy seedling establishment is one of the most important factors in vegetable production systems. The Hoagland Lab is participating in this project by conducting soil physical, chemical biological assays on the various substrates being tested for transplant production to determine their quality, and quantifying how a few of the substrates affect colonization and survival of arbuscular mycorrhizal fungi and other microbes in the rhizosphere of vegetable transplants following establishment in the field. Ms. Xiaojun Zhao worked on this project and an undergraduate research position is available to continue the project in 2019. This project is funded by an Indiana Specialty Crop Block Grant (IN-SCBG) and is being conducted in collaboration with Dr. Elizabeth Maynard, Purdue Horticulture and Landscape Architecture.

Role of arbuscular mycorrizal fungal community dynamics in mitigating water stress Arbuscular mycorrhizal fungi (AMF) are well known for their potential to help plants acquire nutrients, especially phosphorous. These microbes also have potential to help plants withstand biotic and abiotic stress, though the benefits conferred by these microbes can depend on the species of AMF. Over 200 species have been positively identified to date, though it is suspected that more than 1600 species could exist. The goal of this project is to determine how the composition of AMF communities change in response to crop management practices and affect the potential for crops to withstand water stress. This project is funded by Purdue Agriculture Research Programs and the Purdue-Colombia Exchange Program. Graduate student Ms. Lisseth Zubieta is working on this project.


Past Projects:

Optimizing the potential for microfiltration coupled with enzymatic digestion to isolate and quantify foodborne pathogens and endophytes Collaboration with Drs. Eduardo Ximenez, Michael Ladisch and Seockmo Ku, Purdue Agricultural and Biological Engineering

Biostimulants: do altered plant microbiomes play a role in mediating plant abiotic and abiotic stress by these products? (Funded by Itallpolina and conduced in collaboration with Drs. Giuseppe Colla and MariaTeresa Cardarelli)

Biological control strategies for mitigating Phytophthora blight (Funded by an IN-SCBG, a Purdue AgSeed Grant, and the Indiana Vegetable Growers Association)

Role of organic fertilizer amendment composition and location on nitrogen cycling and pest dynamics (Funded by The Ceres Trust)

Managing soil health and pathogen dynamics in high tunnel production systems (Funded by Purdue Agriculture Research Programs)

Midwest hop production: best trellis systems and varieties (Funded by the IN-SCBG program and a Purdue Rice Grant)

Biodegradable mulch in sweet potato (Funded by Purdue Agriculture Research Programs)

Organic hop production (Funded by NIFA-OREI)

Wheat-diazotroph dynamics (Funded by NIFA-Integrated Organic Program)

Organic orchard floor management (Funded by the Organic Farming Research Foundation (OFRF) and the WSU Center for Sustainable Agriculture and Natural Resources)

Transition strategies for organic dryland wheat (Funded by the NIFA-Organic Transitions Program)

Diversifying corn-soybean systems with specialty crops (Funded by the UNL Agricultural Research Programs)