Assessing and Sharing Breadfruit Management Practices

Final report for SW17-050

Project Type: Research and Education
Funds awarded in 2017: $220,811.00
Projected End Date: 03/31/2020
Grant Recipient: University of Hawai'i at Manoa
Region: Western
State: Hawaii
Principal Investigator:
Dr. Noa Lincoln
University of Hawaii at Manoa
Expand All

Project Information


Despite breadfruit’s array of potential ecological, social and economic benefits, realization of those benefits relates in large part to how the crop is grown. Hawai‘i’s long history with breadfruit is founded on a body of unique local knowledge, where most cultivation has traditionally taken place in diversified agroforestry settings.

Overall, a spectrum of production practices currently exists in Hawai‘i, with some producers pursuing industrial agriculture models (with no companion plantings, high application of pesticides to control weeds, and high levels of fertilizer and irrigation), others taking a more holistic stewardship approach that is largely informed by traditional cultivation methods (diversified agroforestry integrating many other plants into the system with little to no outside inputs), and still others taking various middle ground approaches (for instance, plantation-style orchards incorporating organic methods or some degree of co-cropping – typically in the form of perennial cover crops). Because the modern breadfruit industry in Hawai‘i is just emerging, there is a large degree of uncertainty among growers about best production practices and, consequently, a window of opportunity to influence management approaches and outcomes. We have identified over 2,500 trees established in commercial farms in Hawai‘i within the last 5 years alone, potentially equating to upwards of 1 million pounds of fruit per year becoming available within the next few years. Despite the rapidly growing industry, there has been very little on-the-ground research exploring best practices, environmental and economic impacts, phenology, and yields associated with breadfruit grown in different microclimates in Hawai‘i. Even the most simple questions regarding breadfruit production, such as average annual nutrient requirements or ideal foliar nutrient profiles, are non-existent.

We propose a long-term project in collaboration with local breadfruit producers to fill these knowledge gaps and create a network of information sharing that will allow for best practices that are economically viable, environmentally sound and socially responsible to quickly become adopted throughout the fledgling industry. Particularly because breadfruit varieties have traditionally been selected by traditional farmers to operate within agroforestry and not monoculture systems, we expect the more diversified practices to show increased yields and better fruit quality, as well as lower production costs and higher environmental services. A key goal of the proposed project is to connect producers and producer groups, particularly those utilizing different methods, to foster knowledge sharing and facilitate the implementation of sustainable practices. By creating opportunities to disseminate research-based information and enhance communication among farmers, Hawai‘i’s breadfruit industry can avoid the pitfalls of conventional agriculture and embrace sustainable approaches to help increase Hawai‘i’s food security, enhance environmental quality and the natural resource base, maximize efficient use of resources, sustain the economic viability of breadfruit farmers, and enhance quality of life for Hawai‘i communities as a whole.

Project Objectives:
  • To document soil and tree health, and fruit quality.

Start date: August, 2017

Completion date: January, 2020

A baseline assessment of soil health and fertility, tree nutrition, and fruit quality will be conducted for 20 breadfruit producers on four islands (Kauai, O‘ahu, Maui, and Hawai‘i) in year 1, with ongoing monitoring of these parameters conducted in year 3. This will contribute to developing an ideal nutrient profile for breadfruit trees (Objective 4) and to understanding best practices in breadfruit management (Objective 5).

  • To document managerial practices currently used for breadfruit production in Hawai‘i.

Start date: August, 2017

Completion date: September, 2018

For each of the sites studied above, a baseline assessment of management practices will be conducted in year 1, with shorter follow up assessments conducted in year 3 to collect updated information as needed (i.e. only if on-farm practices change significantly). Basic practices such as fertilizer and irrigation regimes, cover or co-cropping, etc. will be covered. This will contribute to understanding how farmers assess tree health (Objective 4) and understanding best practices in breadfruit management (Objective 5).

  • To catalogue variation in phenology across the diverse climates of Hawai‘i through “citizen science” monitoring and reporting.

Start date: August, 2017

Completion date: March, 2020

Breadfruit phenology has been observed to be highly variable, with small changes in climate resulting in large shifts in the timing of fruiting and flowering. Extensive work has been conducted examining phenology of multiple varieties within a single environment (Jones et al., 2010), however no studies have examined how the phenology of individual varieties shifts across climates. We aim to use Hawai‘i’s diverse climate and soils as a natural experiment to document variations in breadfruit phenology for the two most prevalent breadfruit varieties in the state – the Hawaiian ‘ulu and ma‘afala.

  • To utilize data on yield, fruit quality, and foliar nutrients in conjunction with farmer observation methods for tree health, to develop a simple tree assessment toolkit.

Start date: January 2019

End date: June 2020

Most established crops have known nutrient profiles and simple, standardized assessments to assess the crop health. These do not exist for breadfruit. Using results from Objectives 1 and 2, we will develop simple assessment tools to create simple assessments for breadfruit tree health. One assessment will be developing an ideal nutrient profile of a new canopy leaf, so that farmers can cheaply assess nutrient deficiencies or imbalances by sending a lead sample to our local agricultural diagnostics center. A second, visual assessment, which will be correlated to the nutrient-based assessment, will be developed that farmers can use for free.

  • Identify best practices and disseminate production recommendations through education and outreach that simultaneously fosters and facilitates knowledge sharing among producers, producer groups and other industry stakeholders.

Start date: July, 2019

Completion date: June, 2020

Information gathered through previous objectives will be synthesized into comprehensive guide for breadfruit producers, consisting of suggested “best practices” regarding breadfruit production. Information will be disseminated through several outreach and educational efforts, extension publications, and through direct dissemination to key organizations.


Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Alyssa Cho (Researcher)
  • Dr. Rajesh Jha (Researcher)
  • Dr. Tomoaki Miura (Researcher)
  • Dr. Theodore Radovich (Educator)
  • Elihu Isele (Educator)


  • That preliminary understanding of breadfruit nutrient requirements and best-practices can be understood by analyzing current growers' practices, soils, trees, and fruit
  • That phenological differences are apparent in different environments in Hawai'i 
Materials and methods:
  • Baseline analysis was conducted in year one, with a follow up analyses in years 2-3 that examined nutrition trajectory. Sampling of the farms was conducted in the late summer/early fall, which is generally the peak fruiting season and also a generally low rainfall month for most locations in the state. Analysis of samples was conducted in subsequent months, with the final analyses completed no later than January following the collection. Soils were assessed using composite samples to 30cm depth. Soils were be described by texture, color, and NRCS classification; parameters to be quantified are pH, total carbon, total and inorganic nitrogen, exchangeable and total cations, and total and available phosphorus. Tree nutrition was assessed using composite samples of newly emerged canopy leaves; foliar measurement of coloration, chlorophyll, water content, and elemental concentrations of carbon, nitrogen, phosphorus, calcium, potassium, magnesium, and sodium. A visual analysis of tree health was also conducted through detailed color analysis, growth pattern, and leaf density. Fruit quality was assessed in mature fruits using composite samples, and will be assessed for moisture content, pH, sugar content (glucose, fructose, and sucrose), vitamin C, dietary fiber, total fat, total protein, amino acid profile, vitamin A, vitamin D, total starch, and elemental concentration of potassium, calcium, magnesium, and sodium. All analyses were conducted using standard practices as described by the NRCS Soil Survey Laboratory Methods Manual, and the Soil and Plant Analysis Council Handbook of Reference Methods for Plant Analysis. Soil and plant analyses were conducted by Dr. Noa Lincoln at UH Mānoa, and fruit quality was conducted by Dr. Rajesh Jha at UH Mānoa. Graduate students will contribute to the laboratory analyses of Dr. Lincoln and Dr. Jha.
  • A citizen science project was initiated in the fall of year one, and ran for two years.  In total we had over 200 citizen participants and 10 paid interns (for quality control) monitor over 450 trees across the state. A number of training and recruitment sessions were held to promote the effort and teach people how to appropriately engage. An online platform was built and hosted on that used an automated database generator to input and store the data. The data checks (by paid, trained interns) show that the citizen data was accurate and reliable. 
Research results and discussion:

A total of 43 farms were assessed in terms of practices, soil health, tree health, foliar nutrition, and fruit quality. Individual reports were produced for every participating farms, with in person visits to discuss their farm results and how they compared to other producers in the state. From initial visits farmers expressed their general feelings and concerns with their production, and subsequent reporting back to the farmers were able to, in many cases, directly address their concerns. The data generated from this study provided to core data for multiple extrapolations that laid an essential foundation for understanding breadfruit orchard management. Most importantly, this study helped to clarify (1) that visual assessment of the tree health was a poor indicator of actual productivity, (2) the best standardized method for assessing foliar nutrients was the petiole rather than any portion of the leaf (specifically the third petiole from the growing branch tip), (3) that nutrient management appears to be at the core of several problems expressed by farmers, including high rates of fruit abortion and high variability in yields, (4) initial recommendations for fertilizer requirements based on potential yields and quality fruit nutrient profiles, and (5) initial foliar nutrient concentration targets for high quality and quantity production. Overall, we feel that this Objective was hugely successful and contributed enormously to the necessary information needed for quality breadfruit management. 

One unexpected result was that farmer indicators of tree health, and indeed overall visual tree health, was a poor indicator of both fruit quality and quantity.  As such, the goal of making a visual guide for farmers was not accomplished.

While we have made good progress on foliar nutrient testing and recommendations, we found that most farmers, which primarily were diversified growers, were not exceptionally interested in performing ongoing foliar testing to fine tune fertilizer applications. However, we did develop fertilizer recommendations (both conventional and organic options) that were well received with positive success stories. These stories pertained to both fruit drop (a major production problem in which breadfruit can abort very large amounts of its yield before maturity) and variable yields. We developed both generic recommendations for breadfruit production, but also worked with several producers one on one to alter their fertilization practices. One farmer, D. Ward, we convinced to severely reduce nitrogen application (she was using high amount of chicken manure) and increase potassium (via seaweed) and her fruit drop rate was reduced from (in her estimates) over 90% from the past several years to less than 5% this year. Another farmer (R. Kodani) changed from his fertilizer regime to our generic recommendation and increased his yields from about 200 lbs/tree to nearly 500 lbs/tree.  Several other farmers altered their fertilizer regime with positive outcomes, and we expect that more farmers will continue to convert because the success stories are permeating the farming community and more and more people are reaching out to get information and advise on fertilization and orchard management. 

The second objective that relates to phenology was also, we would argue, a large success.  We greatly exceeded our expectations of 100 participants (to nearly 250) and the data generated appears to be of high quality. While the differences in seasonality as driven by environment was smaller than we expected, there were significant differences that could be exploited to play a role in spreading the seasonality out to aid in consistency of supply and reduce the peak season burden on processors. 

Research conclusions:

Primary conclusion:

  • The quality and quantity of breadfruit fruit is poorly assessed by visual tree health or farmer intuition. 
  • Foliar nutrient sampling is best represented by the petiole of the third fully-open leaf from the branch tip
  • Recommended foliar nutrient concentrations have been produced (Lincoln et al, 2019)
  • Recommended fertilizer regimes have been produced, with a general nutrient profile very similar to coffee cherry or banana fertilizers
  • Seasonality is influenced by variety, environment, and the interactions between the two

These results represent the very first derived recommendations for fertilization and foliar nutrient assessment to aid in nutrient management of breadfruit production. Such information is critical to appropriately managing trees for higher yields (and therefore incomes) for all farmers, and in particular for giving farmers the confidence of scaling up breadfruit production with assurances that high yields can be managed for. We have already seen direct impact on the quality and quantity of fruit production in those farmers that have adopted our recommendations and expect further adoption as the success stories continue to spread. 

Participation Summary
43 Producers participating in research

Research Outcomes

4 Grants received that built upon this project
8 New working collaborations

Education and Outreach

80 Consultations
4 Curricula, factsheets or educational tools
6 Journal articles
6 On-farm demonstrations
1 Published press articles, newsletters
2 Tours
14 Webinars / talks / presentations
8 Workshop field days
3 Other educational activities: Industry Report on Phenology
Extension Book Publication
Facebook Page

Participation Summary:

600 Farmers participated
200 Ag professionals participated
Education and outreach methods and analyses:

As part of our initial surveys in year one, we conducted on-farm consultations with all participating farmers (43). Actual discussions and limited sampling was conducted with 54 farmers, but we are counting only the farmers who completed all aspects of the study. In years two and three we conducted subsequent follow-up consultations with participants that wanted further input (we contacted all participants to ask), which consisted of an additional 40 consultations. As part of the initial outreach we also created individual reports for each farm (43 total reports). We have conducted six on-farm demonstrations open to participants, two in each of the three years; one each on pruning, variety identification, agroforestry approaches, propagation and two on nutrient management. We have conducted one tour through the USDA germplasm collection to share about variety differences and access that was attended by ~30 participants in year one, and a second tour through a series of different farms to examine different management practices attended by approximately 20 farmers. In years two and three we have created three fact-sheets in partnership with the Hawai'i 'Ulu Producers Cooperative--on pruning, propagation, and harvesting --and one fact sheets individually on nutrient management; these are freely available on the web. We have given 14 presentations, four at the Hawaii State Farmers Union United on breadfruit propagation, post-harvest, nutrient management, and incorporating breadfruit into diversified farming (each attended by ~50 participants), three at Hawaii Farmer Union United chapters (Waimanalo, Maui, and Kona) on general breadfruit growing practices (each attended by ~30 participants), one at the USDA focused on variety identification (attended by ~30 participants), two at the annual Lā ‘Ulu Breadfruit Festival on cultivation (each attended by ~150 people), two at the Hawai'i AG conference on cultivation, production, and consumption (each attended by ~ 75 people), and a four part series at Kahumana Farms on all aspects of breadfruit history, cultivation, post-harvest, and usages (each attended by ~50 people). We have conducted eight farm-day presentation - five for participation in our statewide phenology study each attended by 5-18 participants, and two for nutrient management at Big Island farms each attended by ~20 people, and one at our Waimanalo breadfruit variety trial attended by ~35 people. We have eight peer reviewed articles resulting at least in part from this work: two in Sustainability (Langston and Lincoln 2018; Needham and Lincoln 2019), HortTech (Lincoln et al 2019), Hort Review (Lincoln et al 2018), Journal of Food and Composition (Needham et al 2020; Needham et al in preparation), Agronomy (Lincoln et al 2019) and PLoS ONE (Mausio et al in press). The project has also culminated in the substantial rewrite and republication of a popular book "Hawaiian Breadfruit," which is in the editorial process of reprint with the PI as a new author to the book (Meilleur et al in press). We produced one industry report on phenology with targeted recommendations to aggregators and processors as to how they can leverage locational sourcing of fruit to extend the harvest season for their product production. We also had one non-peer reviewed article in Rural Connections (Langston and Lincoln 2019). Finally, we have created a popular and successful Facebook page "Breadfruit Growers" that has over 200 unique users where farmers and agricultural professionals can post questions, share knowledge, and create industry connections. 


Link to extension materials:

Sample Farmer Report Produced for all participating farms after year 1:

"Breadfruit Growers" Facebook Page curated by PI, Hawai'i Tropical Fruit Growers Association:

Peer Reviewed Paper Citations (in order of relevance of objectives):

Lincoln, N.K., Radovich, T., Acosta, K., Isele, E., Cho, A. (2019). Towards standardization of foliar tissue sampling of breadfruit. Hort. Tech. 29(4):443-449

Needham, A., Jha, R., and Lincoln, N. (in prep). Nutrient Diversity of Hawai'i Grown Breadfruit. Journal of Food Composition and Analysis

Mausio, K. and Lincoln, N.K. (in press) An Empirically-Validated Model for Breadfruit (Artocarpus altlis) and Global Projections Under Climate Change. PLoS ONE.

Lincoln, N.K., D. Ragone, N. Zerega, L.B. Roberts-Nkrumah, M. Merlin, and A.M Jones. (2018). Grow us our daily bread: A review of breadfruit cultivation in traditional and contemporary systems. Horticultural Reviews. Vol. 46: 299-384.

Needham, A., Jha, R., & Lincoln, N. K. (2020). The Response of Breadfruit Nutrition to Local Climate and Soil: A Review. Journal of Food Composition and Analysis, 103451.

Langston, B., and Lincoln, N. (2018). The role of breadfruit in biocultural restoration and sustainability in Hawai‘i. Sustainability, 10(11), 3965.

Lincoln, N. K., Cho, A., Dow, G., & Radovich, T. (2019). Early Growth of Breadfruit in a Variety× Environment Trial. Agronomy Journal111(6), 3020-3027.

Needham, A., & Lincoln, N. (2019). Interactions between People and Breadfruit in Hawai’i: Consumption, Preparation, and Sourcing Patterns. Sustainability11(18), 4983.

Non-Peer Reviewed Papers

Langston, B. and Lincoln, N.K. (2019). Benefits of Citizen Science in Agronomic Research: The Breadfruit Phenology Project. Rural Connections, Spring/Summer 2019.

Extension Book: Link to Previous Version that is being updated with results from PI's research:

Extension handout for Breadfruit Nutrition:

Extension publication for Breadfruit Pruning produced in partnership with Hawaii 'Ulu Cooperative:

Extension publication for Breadfruit Propagation produced in partnership with Hawaii 'Ulu Cooperative:

Extension publication on Breadfruit Post Harvest produced in partnership with Hawaii 'Ulu Cooperative:



12 Farmers changed or adopted a practice

Education and Outreach Outcomes

Recommendations for education and outreach:

There is so much more that needs to be done for breadfruit. Its potential is huge and unrealized, and the growers and pursuing the crop and the markets in the face of huge unknowns. This industry should certainly continue to be supported and researched through technical support. From this work we have identified numerous needs for the industry in Hawai'i, the Pacific, and globally. Key needs include propagation and access to varieties (particularly at scale), better pruning management, information on co-cropping and agroforestry management, post-havest practices, product development, and disease and pest management. 

12 Producers reported gaining knowledge, attitude, skills and/or awareness as a result of the project
Key areas taught:
  • Variety Identification
  • Pruning
  • Nutrient Management
  • Phenology
  • Orchard Design
Key changes:
  • Nutrient Management

  • Pruning Management

  • Post Harvest Practices

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.