Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822
Performing Department
Tropical Plant & Soil Science
Non Technical Summary
Over the last decade, banana has occupied a niche among the top 10 to 15 commodities produced in Hawaii. From 2002 to 2006, banana sales in Hawaii increased by 25%, but nearly all of that represented foreign imports. Local production has not kept up with demand. Foreign competition and crop diseases, particularly banana bunchy top virus (BBTV) and black leaf streak caused by the fungal pathogen Mycosphaerella fijiensis, have been important factors influencing this trend. Commercial banana production in Hawaii is based on two excellent dessert clones: the Cavendish clone Williams and the Dwarf Brazilian, an "apple" type banana. Of these, Williams has suffered more in the current market situation because world competitors produce the same Cavendish bananas, and consequently competition from imports is direct. Dwarf Brazilian is not typically a clone that enters world banana commodity trade, so local producers have unchallenged access to local markets. Williams is favored because of its higher yields, but it is more susceptible to both BBTV and black leaf streak. In spite of the good qualities of these two clones, everyone recognizes their vulnerabilities and the problems of depending on a limited number of production options. Luckily, the banana family (Musaceae) is tremendously diverse. Huge genetic variation is expressed in size, texture, and flavor nuances within dessert fruits, but goes beyond this familiar usage to include banana clones that are traditionally used for cooking, roasting, and even beer-making. Consequently, one option for the banana industry in Hawaii is to explore possibilities for developing local niche markets for new banana clones. Clones with better disease resistance or with interesting flavors, textures, or colors could be introduced by progressive growers at farmers' markets or by direct sales to restaurants and/or hotels for more exotic food applications oriented toward tourism. CTAHR has assembled a banana germplasm collection and has established it in the field on Oahu's North Shore. The CTAHR collection contains 57 clones that were imported in 2006 from the International Network for the Improvement of Banana and Plantain (INIBAP) in Belgium and from Kenyan sources cooperating with the national Kenya Agricultural Research Institute (KARI). Most of the clones are dessert types of the AAB "apple" genomic group similar to Dwarf Brazilian, but there are also clones of AA, AB AAA, ABB, and AAAB genome types that may represent potential new markets. CTAHR has an opportunity to screen these materials for local commercial potential. Objectives of the current proposal are to 1) evaluate horticultural characteristics of clones, including bearing height, bunch weight, finger size, and fruit quality, 2) tissue culture the collection for propagation and long term preservation, 3) evaluate BBTV resistance in greenhouse inoculation trials at UH Manoa, and 4) evaluate black leaf streak resistance in a replicated field trial at Waiakea, Hawaii. The anticipated outcome from the project is a banana industry invigorated by more production options allowing growers to overcome current limits imposed by foreign competition and disease.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Banana production in Hawaii is based on two clones: Williams Hybrid and Dwarf Brazilian ("apple"). In recent years, diseases and pests, particularly banana bunchy top virus (BBTV) and black leaf streak (Mycosphaerella), have threatened local banana production. Given the large array of banana clones in world germplasm collections, one option for the banana industry in Hawaii is to explore possibilities for developing local niche markets for new banana clones. Clones producing fruits with interesting flavors, textures, or colors could be introduced on a small scale by progressive growers and trial-marketed at urban farmers' markets or through direct sales to restaurants and/or hotels for more exotic food applications oriented toward tourism. In 2006, 57 banana clones from world collections were assembled at CTAHR as part of a now completed doctoral research program to define basic molecular-level relationships within this important crop. Objectives of the current proposal are to 1) evaluate horticultural characteristics of clones, including bearing height, bunch weight, finger size, and fruit quality, 2) tissue culture the collection for propagation and long term preservation, 3) evaluate BBTV resistance in greenhouse inoculation trials at UH Manoa, and 4) evaluate black leaf streak resistance in a replicated field trial at Waiakea, Hawaii. Outputs from the project will consist of recommendations regarding the suitability of the ~40 parthenocarpic banana clones for commercial production in Hawaii, as well as the banana clonal germplasm itself, which can be made available to interested growers after appropriate release of the plant materials by UH. Commercial suitability will be determined by analysis of data resulting from evaluation of horticultural characteristics and disease resistance of the clones, with specific information for growing conditions on Oahu's North Shore and near Hilo, Hawaii. These data will be tabulated and summarized in an extension publication and presented at a Hawaii Banana Industry Association conference.
Project Methods
Objective 1: Horticultural aspects to be evaluated include productivity, fruit appearance, and eating quality. We will harvest every second week for a year. Clones are replicated, so we can make statistically meaningful comparisons among clones for annual yield, frequency of harvest, bunch height, bunch weight, finger length and girth, and quality assessment on a hedonic scale. Height of bunches will be measured, and bunches will be harvested, weighed, and de-handed in the field. General vigor, suckering potential, and disease incidence will be noted on a relative scale, but not quantitatively measured during the bi-weekly visits. Fruit length and girth measurements, fruit appearance, and eating quality assessments will be done in the lab. Objective 2: During the first year, suckers of approximately 40 parthenocarpic (seedless) clones in the Kawailoa Ridge collection will be indexed for absence of BBTV by ELISA assay and established in tissue culture for micropropagation and long term storage. Basal portions of young suckers will be washed, stripped of leaf sheathes, and the apex trimmed to a 2.5-inch cube containing the meristem. After surface disinfestation in 100% Chlorox for 30 minutes followed by three washes in sterile water, the corm is reduced to a 4-mm cube containing the meristem. Longitudinal slices of the meristem will be cultured aseptically in solid banana medium at 28 C under 16/8 hr (light/dark) photoperiod. Banana propagules can be maintained in this medium for 3 to 4 months before requiring subculture. Objective 3: The Kawailoa Ridge collection will be screened for BBTV resistance at the UH Manoa campus. Five tissue-cultured plants of each clone will be placed in a screened enclosure when 10cm tall and inoculated with five viruliferous aphids (Pentalonia nigronervosa) per plant, using a fine paintbrush to make the transfers. Inoculated plants that remain symptomless after three months will be re-inoculated at three-month intervals. Inoculated plants will be maintained in the enclosure for up to one year. The time from the first inoculation to the appearance of the classic "Morse-code" leaf vein symptoms will be recorded as the measure of virus resistance. ELISA assays will be employed to confirm the presence of BBTV in tissues of symptomatic plants or its absence in symptomless plants. Objective 4: Screening for black leaf streak resistance will be conducted in a field at Waiakea Experiment Station on Hawaii Island, using a completely randomized design with three replicates of two tissue-cultured plants for each of 40 parthenocarpic clones from Kawailoa. Waiakea (120" annual rainfall) is a dependable location for black leaf streak. BBTV-indexed tissue-cultured plants will be sent in vitro from UH Manoa to Waiakea for establishment in the greenhouse and later transfer to the field. The 0.5-acre field will be planted on a 10' x 10' grid. Disease resistance data will be recorded beginning in the second year and repeated quarterly. The relative vulnerability of the clones to black leaf streak will be determined by comparing the mean number of healthy symptomless leaves occurring below the flag- or "cigar"-leaf.