Nitrogen Numbers 20 July 2021

Nitrogen Numbers

TPSS joins an international effort to standardize the datasets

Nitrogen is the unsung hero of food production. The common element is an essential nutrient for plant growth and health. It is found in the chlorophyll needed for photosynthesis, in the amino acids that form proteins, in the adenosine triphosphate (ATP) compounds that release energy, and in the DNA that codes all plant life. Yet, because nitrogen leaks from agricultural systems, nitrogen deficiency is a common nutritional problem for plants. There’s also the question of the excessive use of nitrogen fertilizers and their effect on sustainable croplands, as well as the environment. In a new international study meant to improve nitrogen management and better understand the global nitrogen cycle, researchers compared 13 nitrogen budget datasets covering 115 countries and regions over the past half-century. The team included an investigator from the Dept. of Tropical Plant & Soil Sciences and found that, while most datasets collected show similar patterns, some estimates vary quite widely. The authors propose a common benchmark for nitrogen budgets, based on median values and the range of estimates.

“Nitrogen budgets tell us how much nitrogen is present and moving through our systems, but they’re notoriously difficult to construct on regional, national, and global scales,” says Tai Maaz. “This study provides an opportunity to create a benchmark so that people who are interested in comparing models can use a common dataset.”

In other words, it will facilitate apple-to-apple comparisons between model structures, rather than apple-to-orange differences in data inputs. Once this happens, scientists will have a much better tool to help in ecological modeling. In addition, policymakers commonly use nitrogen budgets to evaluate the risk of environmental impacts and set effective policies. 

“I am honored to be part of this international team of researchers led by Dr. Xin Zhang,” Tai says. “I am hopeful this study will help us find ways for more sustainable management. Proper and robust nitrogen budgeting is important for Hawaiʻi to protect our water and sensitive ecosystems from nitrogen pollution.”

The study, Quantification of global and national nitrogen budgets for crop production, appears in a recent Nature Food.

Hormones vs. Environment 20 July 2021

Hormones vs. Environment

HNFAS is studying how fish tolerate environmental changes

Many types of fish live in variable environments, meaning they must constantly adapt to changes in water salinity, temperature, and chemical content (i.e., pollutants). Therefore, exactly how a fish responds – in order to keep surviving, growing, and reproducing – is a subject of deep interest for scientists and commercial aquaculture producers who rely on controlled environments. Ongoing work in the Laboratory of Fish Endocrinology and Environmental Physiology, part of the Dept. of Human Nutrition, Food and Animal Sciences, may provide some clues. In three lines of work, the HNFAS investigators are helping to better understand 1) how fish hormones mediate the impact of a rise in temperature, 2) how the actions of these hormones are affected by age, and 3) how chemicals and pollutants released in the environment can interfere with fish growth and reproduction. “Our NSF-, NIH-, and NOAA-funded projects are targeted to better understand how specialized cells can sense the environment, respond to environmental change, and regulate functions essential for survival, such as salt-and-water balance, as well as functions essential for animal production, such as growth and reproduction,” says Andre Seale, principal investigator who is overseeing the research groups.


The mechanisms responsible for how fish detect changes in salt concentration may be also at play when fish respond to a rise in temperature, notes HNFAS grad student Daniel Woo. He recently presented the evidence at the 45th annual Albert L. Tester Memorial Symposium and the 6th Biennial Conference of the North American Society of Comparative Endocrinology.

“This is because the cells that play an important role in detecting changes in salinity, through changes in volume and release of the hormone prolactin, also increase in volume and prolactin release when the temperature rises,” explains Andre.


Are cells that make those adjustments, in response to environmental changes, affected by age? In a new study, “Age-Dependent Decline in Salinity Tolerance in a Euryhaline Fish,” Andre and collaborators make the case that age does affect those cells, at least in regard to changes in salinity. Their study appears in a recent Frontiers in Aging.

“Older fish have a lower capacity to survive a transfer from fresh water to seawater,” he says. “The ability to acclimate between widely changing salinities is a key characteristic of the Mozambique tilapia, a fish commonly used in aquaculture due to its environmental resilience. At least partly underlying this decline in salinity tolerance is a reduction in the responsiveness of older fish to the hormone, prolactin.”

Introduced Chemicals

In a review of ‘endocrine-disrupting chemicals’ – chemicals and pollutants that cause adverse effects in organisms by disrupting the actions of hormones – Fritzie Celino-Brady presents a comprehensive analysis of the experimental approaches used for investigating their effects on fish growth and reproduction. Her article, “Experimental Approaches for Characterizing the Endocrine-Disrupting effects of Environmental Chemicals in Fish,” appears in

Ahaolelo and Aliʻi 20 July 2021

Ahaolelo and Aliʻi

Hawaiʻi 4-H adapts to continue its traditions

‘Ahaolelo’ means “to come together for a meeting” in Hawaiian, and the Hawaiʻi 4-H Ahaolelo Leadership Conference is rich in that tradition, playing an important role in the development of our 4-H members.

Held at the University of Hawaiʻi at Mānoa campus, the Ahaolelo provides local youths who’ve completed 8th to 12th grade with an excellent opportunity to meet other 4-H members, make new friends, exchange ideas, develop communication and leadership skills – and learn more about UH and college life.

Last year, the Ahaolelo switched to a virtual Aliʻi Ceremony due to COVID-19, and merged with a 3-day online conference with Idaho and Washington 4-H’s STAC (State Teen Association Conference) to allow more teen participants.

This year, Hawaiʻi 4-H formed an Ahaolelo Planning Team, with the theme “Overcoming Challenges, Shaping the Future.” The events included a community service project with the ceremony in the evening. 

“Although this was a very difficult year, we used our 4-H skills to overcome challenges and shape the future,” said Kaitlin Kitagawa of Maui, who was an emcee at the Aliʻi Ceremony. In all, 40 teen delegates, adult volunteers, and 4-H Agents and Staff were able to attend. The delegates joined virtual workshops and were inspired by the special presenters:

  • Dr. Lauren Tamamoto, 4-H alumni from the Teddy Bears 4-H Club and Kapiʻolani Community College Food Scientist and Research Chef who collaborates with CTAHR.
  • Myself, presenting on “Head” life skills such as solving problems, making decisions, and practicing creativity.
  • Rebecca Kanenaka, past 4-H Club Leader of the Golden Ripples 4-H Club, retired microbiologist, and currently a 4-H Volunteer Resource Leader.
  • Hallie Cristobal, Kauaʻi 4-H and Intergenerational Junior Extension Agent, presenting on foods and nutrition.
  • Carli Yamamoto, 4-H alumni from the Aloha Kids 4-H Club and athletic trainer at Konawaena High School, presenting on empathy, determination, and resiliency.

The speakers shared engaging and hands-on learning, referencing their 4-H experiences, the challenges they faced, and how they overcame and moved forward. They also shared about their careers and how they got to where they are today.

“It kept the attention of the audience well and the workshops were fun!” wrote one 4-H participant.


Aliʻi Ceremony

To gracefully end the 4-H Ahaolelo, we also held an Aliʻi Ceremony in the evening at the UHM campus, with virtual links for participants on the Neighbor Islands. The ceremony is another 4-H tradition, called “Gifts to the Aliʻi.” in which we recognize and honor guests who exemplify the 4-H values of leadership and community service. 

This year, Hawaiʻi 4-H was fortunate to have as our guest State Senator Lynn DeCoite, who we thanked and honored for her support and dedication to 4-H programs, not just in her Maui County district but throughout the whole state. 

“It’s a badge of honor from each and one of you,” shared Sen. DeCoite. “I love this conference, and I love the fact that you folks have 4-H Ahaolelo …(which) means ‘to come together’ … As I learned all my life in farming and ranching, we all need to come together to make a difference.”

Past Aliʻi date back to the&

Laulima in Action 20 July 2021

Laulima in Action

Kauaʻi Extension builds a new greenhouse for its Ag Station

The greenhouses at the Kauaʻi Agricultural Research and Extension Station (KARES) were in need of complete replacement, so in early 2021, thanks to the support of CTAHR leadership, we were able to have our two failing greenhouses removed, and approval to purchase two replacement greenhouse kits. Sandra Cabral (Kauaʻi County secretary) worked diligently to process this large purchase and get the new greenhouse kits on the boat and headed our way. Once the old greenhouses were demolished, and the pads were clear, the challenge of installing the new houses (each 35’ wide by 84’ long) began. The Kauaʻi team rose to the challenge! The talented farm team of Frank Matsuno (farm manager), Michael Carle (agricultural technician), Lou Nishida (mechanic), Michael Zins (seasonal volunteer), and myself worked through the many steps of putting the structure together.

We started with carefully setting the concrete footings, then installing the frame and hardware, fastening screening on the sides, rebuilding greenhouse benches, and, redoing the water lines.  The tricky last step was placing a single large sheet of plastic to cover the roof of the house.

Extension agents Emilie Kirk, Roshan Manandhar, James Keach, Amjad Ahmad, and others were on hand to make fine work of this. Please enjoy these photos, which show the demo and construction process over time. Now, it’s on to Greenhouse Number Two!

National Clean Plant Network 20 July 2021

National Clean Plant Network

Extension will use a new APHIS grant to study sweet potato

When a virus or virus-like agent infects a vegetatively propagated crop, the negative consequences can go far beyond a disappointing yield, appearance, taste, and plant longevity. If the difficult-to-find disease goes undetected inside the propagation material, the problem could be passed on to a new farm, establish itself, and spread even further. Since 2008, the National Clean Plant Network has brought together growers, scientists, and government agencies with the shared goal of safeguarding clean plants and ensuring a sustainable source of disease-free, vegetative propagation materials (such as cuttings, slips, scionwood, etc.). No less than the long-term viability of farmers and feeding a hungry planet are at stake. With a new grant from the USDA’s Animal and Plant Health Inspection Service, a group of CTAHR Extension agents and researchers on Oʻahu, Kauaʻi, Maui, and the Big Island have joined the network’s sweet potato group. For their first project, Amjad Ahmad, Rosemary Gutierrez, Roshan Manandhar, Susan Miyasaka, Sharon Motomura-Wages, and Jensen Uyeda, along with Dr. Jon Suzuki from the USDA ARS, DKI US Pacific Basin Agricultural Research Center (PBARC) in Hilo, will focus on ‘Okinawan,’ the purple-fleshed sweet potato variety that is a primary commercial cultivar in Hawaiʻi.

“During the first year, we hope to produce a total of 100 virus-tested ‘Okinawan’ plantlets in the tissue-culture laboratory of the Komohana Research and Extension Center, then distribute to Extension agents across the state,” Susan says.

The plan calls for these Extension agents to multiply the clean material to produce 500 cuttings, and distribute them to growers. The agents will use either pot or hydroponic cultures under conditions that will minimize any re-introduction of disease, while Dr. Suzuki will test for major sweet potato viruses in order to ensure that the propagating materials are clean. If all goes well, by the second year of funding, the agents will be able to ramp up production to distribute 2,500 clean cuttings to growers.

Read more about the National Clean Plant Network.