Innovative Research
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Impactful Solutions
The Department of Tropical Plant and Soil Sciences is dedicated to addressing the most critical agricultural challenges in Hawaiʻi, the Pacific, and other vulnerable regions worldwide. We prioritize two primary grand challenges: enhancing food self-sufficiency and sustainability in the face of a changing climate, and strengthening the resilience and economic vitality of the agriculture sector in Hawaiʻi. Through impactful research, innovative solutions, and unwavering support for the agricultural community, we strive to ensure long-term success. Our aim is to foster a sustainable and prosperous future, not only for our local food systems but also for the wider community we serve.
Research Programs
Soil Fertility, Soil Health and Nutrient Management
Dr. Jonathan Deenik
Our research focuses on soil fertility and nutrient management with increasing attention to soil health across the spectrum of tropical agroecosystems. We conduct basic and applied research addressing nutrient cycling and organic matter dynamics as affected by clay mineralogy, climate, and human activities. Our work addresses student needs by providing exciting opportunities to investigate key research areas in tropical soil management. We address farmers needs through collaborative applied research activities on fertilizer and organic matter management, water management, and strategies to enhance farm productivity and soil health. water management in farming systems with an eye on conservation.
Objective
Approach
Through collaborative partnerships involving farmers, students, and scientists across a range of disciplines and geographic regions seeks to understand the complex interaction of soil diversity, cropping system, and eco-sociological context to develop strategies to improve food security, ecosystem services, and community well-being.
Impact
Crop & Wild Crop Relative Evolution
Dr. Michael (Mikey) Kantar
The Lab is interested in the intersection between genomics, agriculture and ecology. The goal is to examine complex interactions so that everyone can work toward creating food systems that are more productive, healthy and sustainable. Currently the lab broadly focuses on the breeding and genetics of crops through the use of crop wild relatives.
Objectives
Understand plant breeding efficiency.
Understand what limits the use of different types of crops.
Understand the dynamic interplay between people and food.
Approach
We use techniques from genetics, genomics, plant breeding, ecology, geography, and agroecology to develop new crops and improve old ones for a changing environment.
Impact
It directly address what people grow where, how plants can be adapted and what plants people want. Where food comes from and why you like eating it.
Tropical Landscape & Human Interaction
Dr. Andy Kaufman
The Tropical Landscape and Human Interaction program is a multidisciplinary research laboratory dedicated to studying the connection between plants, the outdoor landscape and the associated human responses. The lab draws upon the disciplines of environmental psychology, horticulture, sociology, psychology, and landscape architecture in order to reveal, understand and improve people’s emotional, psychological, social and physiological responses to plants and outdoor/indoor designed spaces.
Objectives
Addressing how plants and landscaping addresses peoples’ social, psychological, and physiological responses. How green landscape technologies (green roofs, living walls, rain gardens) address climate change and the sense of place.
Approach
Landscape design, psychophysiology, quantitative and qualitative landscape research methodologies, green roof and living wall research.
Impact
1) Increase the awareness of people’s and society’s need for ornamental and native plants and landscapes, and green roofs, living wall, and rain gardens. 2) Educate about the use of and care for green landscaping to help individuals, families, and communities flourish.
3) Assist the landscape design, installation, and maintenance profession of the importance of proper plant selection, installation and care as a component of built and natural landscapes. This is to effectively create and promote healthy environments for people to live, work, and recreate in.
4) Inform and educate policy makers of the importance that plants and the designed landscape are for healthy communities and individuals; and the need for appropriate legislation to foster these environments.
Controlled Environment Agriculture for Tropical Crop Production Systems
Dr. Kent Kobayashi
The Controlled Environment Agriculture for Tropical Crop Production Systems program develop and use alternative ways to control growth and enhance crop growth and yield using light quality manipulation to help reduce chemical inputs and environmental impacts. Effects of light spectrum — comparing LED and high output fluorescent lighting; effects of different light spectrum; effects of photoselective shadecloths, plastic films, acrylic greenhouse coverings, and smart glass.
Objectives
We develop information on the use of photoselective shadecloths, plastic films, acrylic greenhouse coverings, and smart glass to control the growth and development of vegetable and ornamental crops. We also develop information on the use of LED lighting and high output fluorescent lighting on the growth and yield of hydroponic vegetable crops.
Approach
Compare photoselective shadecloths, plastic films, acrylic greenhouse coverings, and smart glass for their effects on the growth and flowering of ornamental plants and vegetables. Compare high output fluorescent lighting and LED lighting, and 2) compare different ratios of red:blue LED lighting for their effects on hydroponic vegetable growth and yield.
Impact
Scientific knowledge will be advanced through the development and use of alternative ways to control growth and enhance crop growth and yield using light quality manipulation to help reduce chemical inputs and environmental impacts. Knowledge in effects of light spectrum will be advanced—comparing LED and high output fluorescent lighting; effects of different light spectrum; effects of photoselective shadecloths, plastic films, acrylic greenhouse coverings, and smart glass.
Improvement of Ornamental Plant Varieties for Hawai’i’s Floral and Landscape Industries
Dr. Kenneth Leonhardt
Alien, invasive plant species have become a serious threat to the unique flora and fauna of the Hawaiian Islands and have taken over the habitats of many native Hawaiian plants, causing their extinction. Most invasive plant species were introduced nursery/landscape plants. The main reason that many ornamentals become invasive is that they are prolific seed producers. My project produces seedless versions of invasive or potentially invasive, economically important landscape species and hybrids. My seedless cultivars can be used in landscapes without any risk of putting additional seed into the environment.
Objective
To create and introduce improved ornamental plant varieties for the advancement of Hawaii’s floral and landscape industries.
Approach
Traditional breeding and polyploid induction.
Impact
Our program has created a number of impactful introductions to the landscape industry in Hawai’i. Of these are the production and introduction of sterile landscape trees, polyploid induction and release of a number of ornamental and landscape plants. Of these are the sterile hybrids of shower trees. Improved cultivars of Leucospermum, Stephanotis, and Dendrobium.
Indigenous Cropping Systems
Dr. Noa Lincoln
The Indigenous Cropping Systems laboratory focuses on indigenous agroecosystems, emphasizing the links between knowledge intensive practices and agricultural production. We employ interdisciplinary methods to generate a holistic understanding of agrarian systems as situated within environmental and social contexts. In particular, we focus on our Pacific Island ancestors and think about islands as model socioecosystems for our planet. Our analytical laboratory focuses on biogeochemical analyses, exploring nutrient cycles in plant and soil systems. We also utilize ethnographic, geographic and ecological methods to engage in holistic investigation of indigenous land management systems in the past and today. We work closely with farming and indigenous communities, extension faculty and staff, industry players, and high-quality researchers to improve the awareness, understanding, and adoption of traditional practices.
Objective
To support indigenous crops and cropping systems to improve local food security, sustainability, and cultural well-being.
Approach
Plant and Soil Science Ethnography Spatial Analysis Modeling Archaeology
Impact
We highlight and support the use of underutilized crops and indigenous values to support the transformation of agricultural practices from one of social and environmental extraction to one that supports well-being of couple human-environmental systems.
Nutrient Dynamics in Tropical Agroecosystems
Dr. Tai Maaz
Soil health is a concept that cannot be directly measured. And so, we explore novel ways of conceptualizing and evaluating soil health in agroecosystems. We seek to provide evidence-based recommendations to improve soil health, reduce nutrient losses, and enhance agroecosystem vitality.
Objective
Our primary objectives are to develop recommendations that enhance the sustainability of the agroecosystems of Hawaiʻi and the Pacific Basin and to propose innovative strategies for managing soil health and nutrients. We generate new knowledge and tools to help practitioners achieve a range of agroecosystem goals, while minimizing negative environmental impacts.
Approach
We utilize advanced statistical methods such multilevel modeling, multivariate analysis, and structural equation modeling to interpret the impacts of our management in light of the complex relationships between plants, soils, microbes, and environmental conditions. Our focus is to develop key methods for assessing soil health in Hawaiʻi, quantifying human disturbance, building predictive models to evaluate soil health, and applying machine learning algorithms to analyze large datasets related to soil health.
Impact
The Hawaiʻi Soil Health Index is a major contribution that will allow our community to measure soil health. This has laid the foundation to help us understand the drivers of soil health to help us recover soil health, better maintain our soil and nutrient resources, and meet our agroecosystem and state-wide goals.
Genome engineering to sustain crop improvement (GETSCI)
Dr. Michael Muszynski
The GETSCI program uses genomic approaches to understand plant developmental genetic network function and applies this knowledge to build enhanced crop breeding tools that will improve crop productivity and sustainability. We ask which genes control specific developmental processes and how do they function to affect important agronomic traits. Once these questions are answered, we then ask how can their function be modified to create an altered phenotype that has agronomic value. Answering these questions requires collaborative efforts and so my lab works with other labs that have expertise in plant transformation and tissue culture in order to modify gene function.
Objective
Currently, our main project centers on studying flowering time in tropical maize with the goal to down regulate the photoperiod sensitivity in this germplasm in order to create tropical inbreds that can flower in any day-length. This would permit maize breeders world-wide to access the rich genetic diversity in this germplasm for their breeding program. We also have started a new project investigating the genetic basis of plant architecture in tropical yam Dioscorea alata.
Approach
Landscape design, psychophysiology, quantitative and qualitative landscape research methodologies, green roof and living wall research.We primarily use genetic, molecular biology, and functional genomic approaches conducted in lab, greenhouse and field studies. We also are optimizing the reagents for improved gene editing in tropical maize and other tropical crops.
Impact
We have generated the first transformed tropical maize inbreds in Hawaii or anywhere. We are optimizing a new maize leaf transformation method for tropical maize that will simplify this complicated procedure. We hold a yearly “A-maize-ing” Science Fair on campus each December to communicate the value and safety of the research we do and why maize is so awesome.
Improving Soil Health through Organic Amendments
Dr. Hue V. Nguyen (N. V. Hue)
Organic inputs, such as green and animal manures, composts, and biochars, are applied to highly weathered soils of Hawaii to improve their biological, chemical, and physical properties. How organic amendments alleviate soil acidity. How organic phosphorus be made available for plant uptake, especially in organic farming.
Objectives
Correcting aluminum and manganese toxicity in acid soils with green manure and biochar. Biochar use in soil remediation. Arsenic chemistry, toxicity, and bioremediation. Efficient use of phosphorus sources in organic farming.
Approach
Heavy metals speciation, availability, and chemical and spectroscopic measurements. Organic carbon and enzyme analyses.
Impact
Our work would help to improve soil health, increase crop production, and maintain the environmental quality. Soil acidity correction using green manure and biochar. Arsenic remediation for contaminated soils in Hawaii. Correcting iron chlorosis in macadamia and manganese toxicity in watermelon.
Soil Microbial Ecology
Dr. Nhu Nguyen
We study the interactions across the plant-microbe-soil continuum to understand how these interactions shape the ecology of soil organisms and the functional outcomes of soil processes.
Objective
1) To describe and quantify the processes that shape soil microbial interactions and how these interactions in-turn shape soil processes.
2) To build modern microbial diagnostic, monitoring, and predictive tools to support sustainable agriculture.
Approach
We use modern high-throughput (‘omics) tools to navigate the complexity of the soil system. These include but not limited to amplicon metabarcoding, metagenomics, transcriptomics, metabolomics, electron and light microscopy, and high-throughput culturing techniques. We also use isotopic methods to trace carbon and nitrogen compounds as they move through the soil. We apply both descriptive and experimental approaches to systems
Impact
Our research builds an understanding of how microbiomes function across the complexity of soil agroecosystems in a changing climate. With this understanding, we can build tools based on the microbiome that supports current concepts in soil health, and ultimately the goals of sustainable agriculture.
Plant Physiology, Postharvest Handling and Storage of Tropical Fruit, Vegetables and Ornamentals
Dr. Robert Paull
My area of research interest is in plant physiology and its relevance to the post-harvest physiology, handling and storage of tropical fruits, vegetables and ornamentals. The research program projects range from basic science to the adaptation and application of technology to the improvement of post-harvest quality and handling in an integrated and systematic way.
Objective
An overall interest is in the evolution of fleshy fruit and fleshy fruit ripening that arose independently numerous times during angiosperm evolution. This is approached by studies on gene expression, biochemical studies of enzyme activity and their role in fruit ripening.
Approach
Landscape design, psychophysiology, quantitative and qualitative landscape research methodologies, green roof and living wall research. Gene expression during fruit growth and development, biochemical analysis of enzyme activity and its modification during post-harvest handling, microbial studies on biocontrol of post-harvest diseases and measurement of fruit and vegetable maturity and quality evaluation.
Impact
This research has lead to improvement in production practices, and the post-harvest handling and marketing of these commodities. All the research is done in conjunction and with the support of local industries and individual growers, shippers and marketers.