|Current Research and Extension||
Date Last Edited: 08/24/2001
BIOPHYSICAL CONSTRAINTS TO TARO PRODUCTION
Miyasaka, S. C.
of these experiments were reported to taro farmers. Farmers growing taro under
upland conditions were concerned about the sensitivity of taro to drought
stress; however, they also worried about the difficulty and added costs of
applying mulches. Future experiments need to determine the most cost-effective
treatments to reduce drought stress of taro grown under upland conditions.
Farmers that produce taro under wetland culture were concerned about potential
copper toxicity, and all had ceased to use copper sulfate for apple snail
control. These farmers were interested to be shown symptoms of copper toxicity
in taro, and they worried about the possible involvement of copper toxicity in
observed long-term taro yield losses.
AVOIDANCE OF ALUMINUM INJURY IN LEGUMES:
ROLE OF ROOT BORDER CELLS
Most researchers have ignored the
potential role of border cells in detection and avoidance of aluminum toxicity.
An increased understanding of aluminum toxicity and aluminum tolerance
mechanisms in plants is necessary to develop crop plants that are better able
to grow productively in acid soils.
USE OF VESICULAR-ARBUSCULAR MYCORRHIZAL
FUNGI TO IMPROVE EARLY FOREST TREE ESTABLISHMENT
Volcanic ash soils found along the Hamakua
Coast of Hawaii are known to "fix" phosphorus in forms unavailable to
most plant species. Arbuscular mycorrhizal fungi are known to form symbiotic
associations with many plant species, increasing the ability of roots to
explore a soil volume for immobile nutrients such as phosphorus. Inoculation of
tree seedlings with an effective AMF could help to reduce the necessity for
high levels of phosphorus fertilization during early tree establishment.
PLANT GENETIC RESOURCES CONSERVATION AND
'Egami' is a new longan (Dimocarpus
longan) cultivar was made available to growers of tropical fruits in
Hawaii. The selection is an
open-pollinated seedling of unknown origin and formerly has been referred to as
'Kona No. 1', 'Mauka' and 'Kainaliu'. 'Egami' consistently bears large clusters
of fruits and produces crops more regularly than 'Kohala' longan. Egami' is a very productive cultivar that
consistently bears large clusters of high quality fruits and produces crops
more regularly than 'Kohala' longan. When compared with nine other cultivars in
the collection at the Kona Research Station, 'Egami' was preferred based on
taste and ranked second for flavor and third for pulp crispness.
EFFECT OF TREE THINNING ON SUSTAINED
Several potential macadamia selections
have been identified and may provide growers with cultivars for orchards with
higher tree densities and greater resistance to insect pests. Among the
distinguishing characteristics of selections 879 and 932 are their very upright
stature, which allows for closer tree spacing and higher planting densities and
may reduce or delay the need for tree thinning. Selection 900 had lower percent
kernel and a thicker shell, which may provide protection against stinkbug and
tropical nut borer damage.
EFFECT OF MACADAMIA PREMATURE FRUIT
ABSCISSION AND MINERAL NUTRITION ON SHRIVEL KERNEL DEVELOPMENT
A comparison of kernel quality between 4
macadamia cultivars planted in the Keaau District of the Island of Hawaii
showed that the 294 variety tended to have consistently higher kernel quality
compared to 344, 508 and 660. Both 660 and 508 had the lowest kernel quality
(kernels with specific gravity less than 1.00) over the harvest season. Insect
damage (Koa seedworm) was highest in 660 but was not the major cause for the
reduction in kernel quality.
POSTHARVEST PHYSIOLOGY OF FRESH HAWAIIAN
The following recommendation have been
made for Red Ginger postharvest commercial practices: 1. Inflorescences should
be harvest at mature stage (at least 2/3 open stage). 2. After harvest,
inflorescences should be washed in tap water containing detergent to remove
insect contamination and field heat. 3. Despite seasonal variation in the
effecting of hot water treatment (preconditioning at 40 C for 15 min, and then
hot water treatment at 50 C for 10 min (winter) to 12 min (summer)) to extend
vase life, the treatment should be applied as it suppressed geotropic response
during transportation. 4. Inflorescences should be sprayed with 200 ppm of BA
before shipping. 5. Inflorescences can be packed wet (moistened newspaper) or
dry (dry newspaper), but the plastic liner (20 um thickness) in the cardboard
box should not be omitted. 6. After packing, horizontally storage and shipping
should not lead to any geotropic curvature for at least 7 days following the
heat treatment. 7. The application of chemicals to control ethylene synthesis
and action is not effective.
SOURCE - SINK RELATIONSHIP DURING PAPAYA
FRUIT GROWTH AND DEVELOPMENT
A trans-membrane sucrose gradient between
the phloem and apoplast of adjacent cells can be maintained or increased by
apoplastic invertase by cleaving unloaded sucrose into glucose and fructose. A
high apoplastic invertase activity in sinks may increase sucrose transport to
these organs and thus increase sink strength. The increase in invertase
activity, protein level, and mRNA level during the late stage of fruit
development suggested that cell wall invertase was a major contributor to sugar
partitioning during papaya fruit maturation and ripening. Western analysis and
invertase activity assays confirmed that cell wall invertase was the major form
during these late stages of papaya fruit development. This conclusion agrees
with the model proposed by others for phloem unloading. Our observations were
supported by previous experiments in which modification of cell wall or
vacuolar invertases using antisense in potato, tomato, and carrot dramatically
affected plant development and sugar partitioning in sink tissue. Furthermore,
the different expression patterns of invertase and SS in the sink tissues
suggested that, with regard to sugar partitioning, SS was a predominant enzyme
in young fruit and petioles, while invertase was more important in the young
leaves, flowers and mature fruit. The result implied that the sugar unloading
pathway in papaya fruit changed from symplastic in young fruit to apoplastic in
MANIPULATION OF HORTICULTURAL CROPS
THROUGH ORGAN, TISSUE, AND CELL CULTURE
The first non-proprietary protocol for
propagation of ‘awa’ through tissue culture will be available for dissemination
to growers in Hawaii, as well as, other interested parties especially in the
IDENTIFICATION AND CONTROL OF DISEASES AND
WEEDS SPECIFIC TO THE PROPAGATION OF TROPICAL SPECIES
Field studies of chemical and biological
control of tropical species are managed and conducted by ARS researchers. Field
trials to correlate plant traits with total leaf, stem and root wet and dry
weights are being conducted by ARS researchers. Results of field studies will
be reported by ARS researchers, Plant Science Institute, Weed Science
Laboratory, Beltsville, MD. Weed control methods developed in Hawaii are being
used in Central and South America.
IMPROVED BIOLOGICAL NITROGEN FIXATION
The project is developing liquid
inoculants for commercial use. Given
the 6% yield response recorded in our field trials and assuming up to half the
world's producers may be interested in adopting liquid inoculant formulations
this technology could result in aggregate yield increases of 1.2 million
mt/year worth $360 million U.S..
PLANT PROTECTION AND ADAPTATION OF TOMATO,
EGGPLANT, AND PEPPER
A new facet of eggplant breeding is
underway which involves hybrids of the Nitta backcross selections with a
bacterial wilt selection,97E60. Selection 97E60 is highly resistant to bw but
does not have desirable traits as it has a multiple fruiting habit. As a result
it produces many small fruit with extremely tough skin. An initial planting of
the cross showed the hybrid to an improvement over the bw parent. It is very
productive but fruit quality is much more desiable over 97E60. F2 seed and the
F1 are being planted in bw infested soils to evaluate resistance. Developing
eggplant and tomato varieties with disease resistance that are high yielding
and high quality would be a benefit for the producer and the consumer.
SOIL MANAGEMENT CRSP
Improved access to information on soil
management practices will provide options to intermediate agents such as
extension agents and researchers to assist the ultimate end-user of technology,
the resource-poor farmer in developing countries, to better address issues on
MOLOKAI APPLIED RESEARCH & DEMONSTRATION FARM
Increase farm productivity and profitability;
develop and maintain an integrated approach for the management of insects,
diseases, nutrients, and other related disciplines affecting crop production
and/or increase multi-disciplinary efforts in resolving problems affecting the
agricultural industries on Molokai and Lanai; increase efficiency in the
delivery and dissemination of research-generated information furthering the
mission of extension and the College of Tropical Agriculture and Human
1. Conducted observational trial to determine the adaptability of pepeiao, Auricularia cornea, to produce under the native tree canopy and primarily on the fallen branches Kukui
2. In April 2000 63 Hawaiian taro varieties were planted for evaluation of their nutritional characteristics by Dr. Alvin. Huang. In April 2000, Molokai Taro Workshop and Field Day was held, at which more than 80 participants attended. New Hawaiian taro varieties are being produced for the export and value added market. Varieties such as Piko Uaua and Eleele Naioea, not commonly produced today, are being marketed. More than 2100 taro huli were distributed to growers during the Field Day in April.
3. Installed Palauan taro variety trial in November 1999 to evaluate and demonstrate their tolerance to taro disease, Phytophthora Leaf Blight.
4. Installed a dessert guava trial in January 2000, evaluating 2 varieties (total of 25 plants), obtained from Dr. Francis Zee of USDA ARS for their productivity and adaptability to arid growing conditions of Moloka'i.
STATEWIDE TARO INITIATIVE: LEADERSHIP DEVELOPMENT
(1) Organize statewide and regional taro grower's organizations.
(2) Address critical issues faced by the taro industry.
(3) Conduct statewide activity.
(4) Conduct educational workshop on each island.
Taro is one of the crops CTAHR identified as an impact crop. As a result the Statewide Taro Initiative program was developed. The original taro initiative program defined 2 projects that address the issues taro growers were most concerned about. The 2 projects were Leadership Development of Taro Producer and Taro Production Issues. Accomplishing these two projects concurrently is critical to achieve the initiative performance goal of to annually increase the total dollar value of new and value-added taro products introduced into domestic and foreign. However due to CTAHR constraints, the Statewide Taro Initiative focused only on implementing Leadership Development of Taro Producer. Some of the Taro Production Issues are being addressed in other CTAHR programs such as IPM, Water Quality and in individual faculty projects.
1. Participated and contributed to statewide growers meeting. CTAHR representative participated and contributed to 6 statewide growers meeting and 3 sub committee meetings. Taro growers benefitted from the dynamics generated from an organization. Growers were able to develop statewide network for communicating needs and gaining support. The organization provided a vehicle for growers to express their need to community leaders.
2. Participated and contributed to educational workshops and industry promotions. Growers organized, conducted and participated in 6 taro workshops and industry promotion activities. Taro workshops and festivals were held on Hawaii, Maui, Molokai, Oahu (2) and Kauai.
3. Supported legislation for taro industry needs. Taro growers organized a campaign that supported legislation for taro research.
4. Conducted survey of growers on taro production and their needs. The survey interviews are completed. CTAHR, ADSC, provided support by developing data management template and inputted the survey information.
5. Conducted discussions with regulatory government agencies on water issues for growers. A growers committee has been organized.
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