Source: UNIV OF HAWAII submitted to
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
May 15, 2006
Project End Date
Sep 30, 2010
Grant Year
Project Director
Brewbaker, J. L.
Recipient Organization
Performing Department
Non Technical Summary
Most of Hawaii's beef animals are fed out on the Mainland due to lack of local feeds, and its dairy and poultry industries are moribund for the same reason. Corn is the answer. To provide high-yielding, tropically-adapted hybrids of feed and food corns that can be grown without pesticide in Hawaii.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Goals / Objectives
Collect, evaluate, and breed superior hybrid corn for silage or feed grain (e.g., energy source) and as food for the tropics. Evaluate silage and/or food qualities. Pyramid genes for tolerance to major diseases, stresses and pests. Identify quantitative trait loci undergirding essential tolerances. Produce and distribute hybrid and varietal seeds to Hawaii's growers.
Project Methods
Germplasm collections will be sought from public breeders worldwide and from the International Center for Maize and Wheat Research (CIMMYT). Evaluations will initially be made at Waimanalo Research Station, and subsequent inbreeding and testcrossing will be made at this location. Highland-adapted germplasm will be evaluated for performance at the Mealani Research Station (900m). Genetic populations appropriate to QTL identification will include RILs and NILs created in Hawaii. Seed production will be conducted by the Hawaii Foundation Seeds, under direction of authors.

Progress 05/15/06 to 09/30/10

OUTPUTS: TROPICAL CORNS: (1) Supersweet Hybrids; Six among ~40 tested CTAHR hybrids were selected for seed increase and commercial marketing by CTAHR to Hawaii's growers; (2) Supersweet Inbreds: Six among ~200 tested CTAHR inbreds were released by publication; (3) Field Hybrids; Two were chosen for Hawaii's silage growers; (4) Field Inbreds; 40 were registered by publication; (5) Field corn populations: Seven synthetics and composites, representing an average of 10 cycles of recurrent selection for yield and for disease and pest tolerance were released by publication. All published entries are in permanent storage by USDA and CIMMYT and by CTAHR's Hawaii Foundation Seeds. DATA: More than 40 yield trials and 60 breeding nurseries were conducted and summaries made available to scientists and growers. These included collaborative trials with six universities and four international institutions. WEBSITE: A website was created listing all 2000+ available seedstocks and germplasms of Hawaii Foundation Seeds. PARTICIPANTS: Graduate students working in this research but independently funded were A.D.Josue, Yoon Sup So and Huang Yu. Co-project leader Ooka provided no inputs to this study, but several CTAHR faculty served as consultants. The research would have been a disaster without impressive, dedicated support of farm managers R. Corrales in Waimanalo and M. Yamasaki in Mealani Research Stations. On-farm trials involved many growers in Hawaii. In USA collaborative projects included U. Wis., ARS/Tifton Ga., U. Fla., Purdue U., U. Ill. and Sugarcane Res. Sta., La. Primary international collaboration was with Kasetsart U. and Sweet Seeds Inc. of Thailand and with Dept. Primary Industries, Queensland, Australia. "Corn Field Days" held periodically since 1965 under this and related projects provided continuous and vibrant input from growers and consumers, and regular use of these research trials as demonstrations for student classes from UH Manoa and WCC Community College. TARGET AUDIENCES: Our plant breeding research focuses primarily on improved yields and qualities of tropically-adapted corns and their products. Because it does not reek of biotechnology it attracts little current political support. Because it cannot employ patented transgenes it cannot fully address some grower aspirations. Because it focuses on products like tropical sweet corn or silage for Hawaii it attracts no intrinsic enthusiasm, much less financial support, from the big temperate corn industries that dominate Hawaii's current agriculture. However, because (1) the earth's population has trebled since the author got his PhD in '52, and since (2) over a billion people starve daily in the tropics, and since (3) the price of corn to tropical consumers is doubling at present and (4) yields of corn in the tropics are less than 20% of USA's, the impact of tropically oriented corn research in Hawaii on the world's people and their health could be fantastic. Working in a superb climate we've been able to breed tropical corns of maximum yields and quality using no pesticide...unbelievable in most of the tropics. However, with almost no interest from USAID, almost none from CIMMYT (to whom all of Hawaii's germplasm has been provided, but who fails to work on corn as a vegetable), and with very limited funding from USDA, NSF, DOE, etc., it is unlikely that my successors will be able in the future to help out corn farmers and consumers in the tropics. PROJECT MODIFICATIONS: Not relevant to this project.

CTAHR sweet corn hybrids now dominate production in the State of Hawaii at about 80% of total, and CTAHR field corn hybrids dominate the small silage production, about 60% of total. Hawaii's sweet corn populations are grown in many tropical countries, and inbreds basic to these and other experimental hybrids have be used by breeders in many countries. Notable are uses of CTAHR inbreds in Thailand and Australia. Favorable reports also occur from countries such as Uganda, Malawi, India, Philippines, Mexico, Argentina and Peru. Evaluations of this research have led to seven awards to the project leader, including "Father of tropical sweet corn" from International Sweet Corn Development Ass'n (2007), "Years of Service to Maize Research", Guandong Academy of Agricultural Sciences, China (2007), "Seed Science Award" from Crop Science Society of America (2009), "Vegetable Breeding Award of Excellence" from Amer. Soc. Horticultural Science (2010), and "Life-time Achievement Award" from National Ass'n of Plant Breeders (2010). In great part these reflect the work of my 52 able grad students over the years and the occasional, but increasingly limited, support from USDA.


  • Seventeen publications since 2006, 8 previously recorded. Not listed:
  • Ji, H.C. and J.L. Brewbaker. 2007. Inheritance of long husk leaves in maize. Maydica 51:101-108
  • Brewbaker, J.L., I.F. Martin and T. Pulam. 2007. Genetics and breeding of sweet corn adapted to the tropics. Conf. on Genetics, Breeding, Planting and Industrialization of Sweet and Waxy Corn, Guangzhou, Guangdong, China. Nov. 26, 2007. pp.1-19.
  • Brewbaker, J.L. 2009. Maximizing yields of corn for silage and bioethanol in Hawaii by increasing plant density. CTAHR Publ. Soil and Crop Mge. 29. pp. 1-7.
  • Brewbaker, J.L. 2009. Breeding crops for sustainable pesticide-free production in Hawaii. The Food Provider, CTAHR. Dec. 2009.
  • So, Y.S., H.C. Ji and J.L. Brewbaker. 2010. Resistance to corn leaf aphid (Rhopalosiphum maidis Fitch) in tropical corn. Euphytica 172:373-381.
  • Brewbaker, J.L. 2011. Six tropical supersweet inbreds of maize. HortScience 45(9):1-4.
  • Brewbaker, J.L., S.K. Kim, Y.S. So, M. Logrono, Y.G. Moon, R. Ming, X.W. Lu and A.D. Josue. 2011. General resistance in maize to southern rust (Puccinia polysora). CropScience 51(2):000-000.

Progress 10/01/08 to 09/30/09

OUTPUTS: Breeding nurseries were again planted monthly to maximize disease and pest pressure in absence of pesticides that are never used in our corn breeding. Major genetic advance was made in selection of resistance to southern rust. The >2000 nursery rows included advanced generations of improvement of most Hawaii inbreds of silage and sweet corn, now summarized on (our Hawaii Foundation Seeds website). I published a summary of plant density trials of CTAHR hybrids designed to optimize yields of silage or lignocellulosic ethanol. Total silage biomass yields of 30 tons were achieved with negligible loss to lodging at densities of 45,000 plants per acre, a 20% increase above that in common use. We released bicolor supersweet hybrid "Sweet Jenny", and a publication was submitted on the achievement of sustainability in tropical corn yields through pyramiding genes for disease and pest tolerance. A publication was completed on our findings and genetic interpretation of aphid resistance. PARTICIPANTS: No inputs were made into this project by investigator Ooka. Collaborators include Ian Martin (DPI, Queensland), Taweesak Pulam (Sweet Seeds, Bangkok) and Torbert Rocheford (Purdue U.) Field research assistance notably by Waimanalo and Mealani Research Station staffs and by growers Danny Loeffler and Kyle Christensen. TARGET AUDIENCES: Island Dairy, Ookala, Big Island; Increasing their dairy herd to 1000 milking animals due to improved silage from CTAHR hybrids. PROJECT MODIFICATIONS: Early results in Vit. A. analyses of Hawaii's sweet corns in Australia (Dept. Primary Industry, Queensland) have led to expanded study of our germplasm for pro-Vit A components b-carotene, b-cryptoxanthin and zeaxanthin, and a major grant request has been made for support.

CTAHR-bred supersweet hybrids continued to dominate production by Hawaii's growers, with a few growers still attempting to grow ill-adapted Mainland hybrids (largely because of the ridiculous restriction on public use of the incredibly important transgenes BT and herbicide-resistance). Our dedication since 1962 to foster a vibrant seed industry has been rewarded by Hawaii's seed industry now ranking first among agricultural industries at $150 million, exceeding that of sugar and pine plus many other crops. Hawaii's major dairy continued to produce our hybrids and our work on high Vitamin A corn was recognized by invited consultancies in Australia and by collaborative projects with several US institutions.


  • Brewbaker, J.L. 2008. Sweet Corn. CTAHR FactSheet.
  • Brewbaker, J. L. 2009. Double-cob (dbcb) on Chromosome 1. Maize Genetics Newsletter (MNL) 84 (in press)
  • Brewbaker, J. L. and Huang Yu. 2009. Branched tassel (Brta) on Chromosome 2. Floppy tassel (flta) on Chromosome 9. MNL 84 (in press)
  • Brewbaker, J. L. 2009. Registration of nine maize populations resistant to tropical diseases. J. Plant Registration 3:10-13.
  • So, Yoon Sup, C. H. Chung and J. L. Brewbaker. 2009. Resistance to corn leaf aphid in tropical corn. Euphytica (in press)
  • Brewbaker, J. L. 2009. Maximizing yields of corn for silage and biethanol in Hawaii by increasing plant density. CTAHR Misc. Publ. (in press)

Progress 10/01/07 to 09/30/08

OUTPUTS: Corn research trials were conducted at four stations, focused on Waimanalo (Oahu) with >2000 plots and 9 seed production fields. Silage corn research focused on yield and included on-farm studies with Island Dairy, Hawaii, and verified the high performance in absence of pesticides of hybrid H1035 and planting densities ~40,000 per acre. Advanced selection led to completion of 92 cycles of breeding of six inbred-based synthetics (e.g., HIS1) and three composites (e.g., HIC1). Their formal release by publication was prepared and submitted. We continued to verify the extraordinary turcicum blight resistance of HIS1 and southern rust resistance of HIS3, and are preparing a publication on breeding and genetics of resistance to both diseases. Over 200 largely tropical inbreds have been repeatedly evaluated for each of these major diseases. Studies continue of linkage drag in our series of near-isogenic lines and of pro-vitamin A levels in tropical sweet and field corns. Three new genes were identified and mapped to chromosome. They are "branched tassel", "double cob" and "floppy tassel". PARTICIPANTS: Sweet corn collaboration continued with Dr. T. Pulam, Sweet Seeds, Bangkok, Thailand and Ian Martin, DPI, Queensland, Australia. Silage corn collaboration continued with U. Wisconsin (Dr. N. deLeon), with Island Dairy in Ookala, Hawaii, and with farmer D. Loeffler of Hilo, HI. Vitamin A research expanded with T. O'Hare and I. Martin in Australia and T. Rocheford, Purdue U., and near-isogenic studies of new corn genes was collaborative with M. Sachs and colleagues of U. Illinois. TARGET AUDIENCES: Hawaii has one silage grower and a dozen sweet corn growers, and all are familiar with our hybrids and varieties. Generally there is limited or no interest in corn feeding to beef or poultry in Hawaii, but we continue to speak with these people as they might achieve much greater economic benefits by using locally grown corn. The massive corn seed industry of Hawaii has only marginal interest in tropical materials, but Dow and Syngenta are evaluating our lines internationally. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Silage hybrids we've released performed very well for the largest of Hawaii's remaining two dairies, with improved milk production and economics (vs. imported feeds). Outstanding open-pollinated synthetics and F1 hybrids from our program continue in evaluations by the dairy. Increasing acceptance has also been observed among growers for modified single crosses of the "Sweet Sarah" type, with improved market quality and appearance. UH hybrids essentially dominate Hawaii's sweet corn market at present, with major use of breeding lines elsewhere in the tropics. One major study in Argentina is ongoing of Hawaii's silage hybrids by a private company. Our collaboration continues on identification of high pro-Vitamin A sweet and field corns with colleagues at Purdue and U. Queensland. Several UH lines have proved outstanding in beta-carotene and betacryptoxanthin levels, and additional support obtained to expand UH studies. Progress continues on preparation of a website for Hawaii Foundation Seeds, which I head.


  • Maize Genetics Newsletter, 2009 (in press): "Branched tassel (Brta) on Chromosome 2" by Brewbaker and H. Yu "Double-cob (dbcb) on Chromosome 1" by Brewbaker "Floppy tssel (flta) on Chromosome 9" by Brewbaker and H. Yu
  • J. Plant Registration, 2009 (in press) by Brewbaker Release of nine maize synthetics and composites resistant to tropical diseases

Progress 10/01/06 to 09/30/07

OUTPUTS: Corn research trials were planted every month this year at Waimanalo Research Station, normally with 400-500 plots for breeding and evaluation. An additional 10 seed increases were planted of major populations under development by recurrent mass selection. Additional trials were conducted at Mealani Res. Sta. (900m) and on Hamakua coast (200m) with grower Loeffler. One major series of trials evaluated the biomass potential of CTAHR tropical hybrids under high plant densities, where yields in two trials maximized at 110,000 plants/ha around 35 t/ha dry matter. We expect to extend trials to Illinois in '08. Extensive breeding continued with bm3 (low-lignin) and bm3gt (grassy tiller) populations collaborative with U. Wis., and a set of near-isogenic hybrids were created for the four bm (brown-midrib, i.e., low-lignin) loci. Studies continues of genes identified through our linkage-drag data on near-isogenic lines--factors affecting pollen shed and tassel configuration, leaf-erectness and size, and resistance to southern rust. Over 20,000 plants were scored for southern rust during 06-07 winter epibiotic, and outstanding resistance sources identified. PARTICIPANTS: Some collaboration has been held in these studies with: Dr. T. Pulam, Syngenta, Bangkok, Thailand Ian Martin, Dept. Primary Industry, Queensland, Kairi, Qld., Australia Dr. James Coors, U. Wis. Dept. Agronomy Dr. Aleksander D. Josue, recent PhD., CTAHR, Univ. Hawaii (PhD thesis on corn kernel genetic development has been submitted and will be recorded in AD421 next year) Dr. Hee Chung Ji, Korea U., Seoul, Korea Daniel Loeffler, Corn Grower, Hilo, Hawaii TARGET AUDIENCES: Corn growers and seedsmen in Hawaii; Our Annual Corn Field Day was expanded to a "Centennial Plant Science Field Day" on Sept. 21 in celebration of the centennial of our University of Hawaii. Demonstrated were ongoing research in corn bioenergy, improved corn silage quality, genes for disease and insect resistance, and improved food corn quality.

Increasing feed costs have led to major downsizing of Hawaii's dairy, poultry, and beef feeding operations. At the completion of our first year of research and evaluation, we are encouraging expanded corn-silage production in Hawaii based on CTAHR-bred hybrids that can be grown without pesticide. We summarized 10 years' hybrid yield-trial data for growers, indicating that corn silage could be harvested weekly from our H1035 or H1092 on any of Hawaii's major islands, with yields exceeding 15 tons/A in 100 days. Failure of adoption is largely due to the limited experience with crop production by our animal industry, and to lack of competent extension efforts by both industry and public sector. Although Hawaii's largest agricultural industry is now its seed industry, the industry itself focuses on temperate germplasm that is ill-adapted in the tropics. In the meantime, we continue at Hawaii Foundation Seeds to upgrade yields and tolerance of CTAHR's corn hybrids to pests and diseases, notably southern rust, earworms, and maize viruses.


  • Brewbaker, JL, IF Martin and T. Pulam. 2006. Development of supersweet maize adapted to the tropics. In "Breeding for Success; Diversity in Action", CF Mercer (ed). Proc., 13th Australasian Plant Breeding Conference, Christchurch, NZ. pp. 44-49
  • Ji, HC and JL Brewbaker. 2006. Inheritance of long husk leaves in maize. Maydica 50: (in press)
  • Brewbaker, JL and AD Josue. 2007. Registration of 27 maize parental inbred lines resistant to maize mosaic virus. Crop Sci. 47:459-461.
  • Brewbaker, JL and AD Josue. 2007. Near-isogenic lines of inbred Hi27; Grassy tiller and sweet corn; Heterosis among near-isogenic lines of Hi27. Maize Genetics Newsletter 81:15-17.

Progress 10/01/05 to 09/30/06

Since the recent inception of the project, 5/15/06, we have conducted eight yield and seed production trials (always pesticide-free) at the Waimanalo Research Station, and two trials at the Mealani Research Station (900m elevation). A Corn Field Day was held Sept. 23 with 200 visitors, and display of 40 superior CTAHR hybrids and attendant breeding and genetic studies. A publication has been submitted to Crop Science, due soon, on the breeding and release of 27 outstanding tropical field corn inbreds resistant to maize mosaic virus. A major study is nearing completion of grain-filling rates and durations among selected hybrids, in order to identify genes improving grain yields.

The studies seek to convince farmers and ranchers in Hawaii that locally bred corn hybrids of superior yield can be grown without pesticide as economic feed for Hawaii's animal industries.


  • No publications reported this period