Journal of Hawaiian and Pacific Agriculture, 2007, Volume 14
UHH Home > Academics > College of Agriculture, Forestry and Natural Resource Management > Research
- N. V. Hue, G. Uehara,
R. S. Yost, and M. Ortiz- Escobar. 2006. Distribution of Soil Orders
in Hawaii. In Press.
- Abstract: Different soils exist around the world and in Hawaii (Buol et al., 2003). For example, a soil is said to behave like a sponge if it can hold a large amount of water against the force of gravity. Such a soil would not need to be irrigated as frequently as a soil that behaves like a sieve. A wetland taro-farmer wants a soil that can be wetted and made to behave like a viscous liquid. In contrast, an engineer prefers a soil that can be compacted to behave like an elastic solid. Our goal is to predict soil properties and performances. We would like to know if a soil could perform well as a taro patch, vegetable farm, coffee orchard, reservoir, road or foundation for a building.
- A.M. Kawabata, M.A. Nagao,
T. Tsumura, D.F. Aoki, K.Y. Hara and L.K. Pena. 2006. Phenology and
Fruit Development of Rambutan (Nephelium lappaceum L.) Grown
in Hawai'i. In Press.
- Abstract: Flowering, flushing, and fruit development of 8 rambutan ( Nephelium lappaceum L.) cultivars grown along the eastern coast of Hawai'i Island were studied over 4 consecutive years (2002 Jan. to 2005 Dec.) at 2 orchards near Hilo, HI. Phenology data were collected at monthly intervals on 5 trees of each cultivar by estimating the percentage of the total canopy that was flowering, flushing, or had developing fruits. Development of individual 'Binjai' fruits was also monitored from anthesis until maturity at 2 locations. The data showed that cultivars generally flowered 2 to 3 times a year, and an individual tree could flower up to 3 times over a twelve month period. Major flowering periods occurred from July to August and additional flowering peaks occurred in April and October. Trees could exhibit vegetative flushing up to 3 times a year. Developing fruits exhibited a simple sigmoid growth pattern and matured approximately 18 to 20 weeks after anthesis. Weather in East Hawai'i was very different from weather patterns found in the native growing region of Southeast Asia where monsoon seasons create distinct wet and dry seasons and individual trees flower only once a year. Hilo's climate was stable throughout the year with mean monthly temperatures of 23.8 o C and rainfall varying between 10 and 50 cm/month. The multiple flowering peaks coincided with periodic drier weather encountered in winter and summer and were influenced by non-synchronous vegetative flushing within the canopy.
- Keywords: flowering; fruit development; phenology; rambutan.
- Marcel
M.C. Tsang and S.C. Furutani. 2006. A Low Cost Hydro-cooling Unit for
Horticultural Commodities. In Press.
- Abstract: An ice chilled hydro-cooling unit for small scale farms was developed. Sixteen rows of spray nozzles, pressurized with a 2-stage booster pump, were enclosed in an insulated chamber. Cucumber, lychee and 2 lettuce varieties were successfully hydro-cooled without injury. Cucumbers required 40 min and lychee required 12 min to obtain a core temperature of 15C and 5C, respectively. Green Mignonette, semi-heading lettuce, and Green Towers MTO, a cos lettuce, required 22 and 8 min, respectively, to acquire a core temperature of 5C. The tightness of the lettuce head is associated with the hydro-cooling period required to lower the core temperature of lettuce.
- Keywords: Lettuce, Lactuca sativa L., Cucumber, Cucumis sativus L., lychee, Litchi chinensis Sonn., precooling.
- A.M. Kawabata, Joanne
S. Lichty, Kent D. Kobayashi a and William S. Sakai. 2006. Effects of
Photoselective Shade Cloths on Potted Dracaena deremensis Janet
Craig and Dracaena marginata Colorama. In Press.
- Abstract: Tip cuttings of Dracaena deremensis Engl. 'Janet Craig' and Dracaena marginata Lam. 'Colorama' were grown for 4 months under 70% black, red, blue, and gray photoselective shade cloths. The 70% designation referred to the weave of the cloth with 70% covered by the fabric and 30% open. Because the fabric of the blue, gray and red shade cloth did not fully block radiation this weave produced 80%, 79%, 76%, and 68% shade of photosynthetically active radiation (PAR) and 72%, 66%, 74%, and 48% shade of total solar irradiance (TSI) for the black, blue, gray, and red shade cloths, respectively. These differences in PAR and TSI are closely related to the differences in growth reported in this study. D. deremensis 'Janet Craig' plants, under the red shade cloth, produced the most new leaves, 10.4, and this appeared to be related to the higher level of PAR. The red shade cloth grown plants had the smallest first fully expanded leaf of all treated plants, 341 cm 2 . This appeared to be related to the very high level of TSI. Grower evaluation ratings were lowest for the red shade cloth treatment. Blue shade cloth grown plants had decreased SPAD chlorophyll measurements, 48.2 versus 52.9 for the standard black. Although blue light is essential for synthesis of chlorophyll in angiosperms, the relationship between lower levels of red light and photosynthesis is discussed. Simulated shipping treatment had no effect on SPAD readings. D. marginata 'Colorama' plants under the red shadecloth produced more new cane growth, 20.2 cm, and the highest number of new leaves, 26.2. This is related to the increased level of PAR. No difference in the number of new leaves produced per centimeter of new growth and internode length indicated that the red shade cloth produced a taller plant while maintaining a full appearance.
- Keywords: photosynthetically active radiation, PAR, total solar irradiance, light quality, vegetative growth.
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Abstract: Few studies have been conducted to determine the efficacy of composted sugarcane (interspecific hybrids of Saccharum spp.) processing by-products (SPB) as soil amendments and horticultural growing media. A mature SPB compost derived from chopped sugarcane tops, bagasse, and cane wash (soil washed from cane harvested by the push rake-crane grab method) was obtained from a recently closed commercial sugar mill. Three experiments were conducted under greenhouse conditions to evaluate the nutrient supplying capacity of SPB compost using ‘Tex-Cuban’ silage corn (Zea mays L.) as the test crop. The SPB compost had an intermediate N supplying capacity between a good quality yard compost and a Hilo silt loam (medial over hydrous, ferrihydritic, isohyperthermic Acrudoxic Hydrudands) field soil. However, SPB compost had a lower natural P supplying capacity than Hilo soil at a similar concentration of modified Truog (0.01 M H2SO4 + 0.02 M [NH4]2SO4) soil test P. While a lack of available P was found to be the primary limitation to SPB compost use as a growing media it supported vigorous plant growth once the P deficiency was eliminated via P fertilization. The SPB compost is adequate in exchangeable K and tends to be sufficient to nearly sufficient in most other mineral nutrients. Arsenic contamination of SPB compost from its cane wash soil component was not considered to be a major concern because the As was primarily in forms of limited bioavailability.
Abstract: Decision support systems can help improving nutrient management in agricultural and forest ecosystems. We suggest that the practical components of nutrient management are 1) Diagnosis, 2) Prediction, 3) Economic analysis, and 4) Recommendations. Nutrient management and agronomic information for perennial crops such as peach palm (Bactris gasipaes Kunth) revealed important differences from annual crops because of differences in growth phases and in dominant nutrient processes in each of the phases. We recognize four phases in perennial crops 1) Nursery, 2) Establishment, 3) Fast-growth, and 4) Mature. In the Establishment phase, plant growth is highly dependent on soil properties, and there is more concern for soil nutrient intensity rather than quantity. Instead, large soil nutrient stores are needed in the Fast-growth phase not just high nutrient intensity. The nutrient status in the Mature phase is characterized by extensive recycling of nutrients already in the biomass and less dependence on soil nutrients. A decision support system for koa (Acacia koa A. Gray) would aid new koa stand establishment, and would be important to identify stands that are in need of management or in decline.KEYWORDS: decision steps, growth phases, soil nutrients, peach palm, koa.