College of Tropical Agriculture and Human Resources

About: College of Tropical Agriculture and Human Resources is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 513 authors who have published 604 publications receiving 15798 citations.

Short-rotation forestry as an alternative land use in Hawaii

Abstract: The traditional mainstays of Hawaii's economy: sugarcane and pineapple crops, have declined such that as much as 80,000 hectares of agricultural land are now available for alternative land uses. Concurrently, imports of fossil fuels continue to accelerate and now provide over 90% of the total energy supply at a cost exceeding $1 billion annually exported from the local economy. The feasibility of short-rotation forestry on these former sugarcane and pineapple plantation lands to produce a variety of wood products, including biofuels, is being evaluated using a species-and site-specific empirical model to predict yields of Eucalyptus saligna , a system model to estimate delivered costs of wood chips to a bioconversion facility, and a geographic information system to extend the analysis to areas where no field trials exist and to present results in map form. The island of Hawaii is showcased as an application of the methodology. Modeling results are presented for using tropical hardwoods as dedicated feedstocks from biomass energy plantations to produce methanol, ethanol and electricity. A hypothetical, integrated, high-value hardwood, veneer, utility lumber and wood-chip operation is featured in contrast to the biomass energy plantation scenario. Short-rotation forestry may hold some promise for the greening of Hawaii's energy system and even greater promise for the industrial production of value-added wood products for the benefit of the state's citizens and visitors. The methodology is readily transferable to other regions of the United States and the rest of the world.

Taro Germplasm Evaluated for Resistance to Taro Leaf Blight

Abstract: SUMMARY. Taro leaf blight (TLB), caused by the oomycete pathogen Phytophthora colocasiae, is a worldwide disease that threatens the sustainable cultivation of the tropical root crop taro (Colocasia esculenta). To evaluate taro germplasm from Asia, Hawai‘i, and several South Pacific Islands for resistance to TLB, 119 cultivars were planted along the Hamakua Coast of Hawai‘i (mean annual rainfall of 130 inches) in plots containing five or 10 plants that were replicated over time from 1993 through 2005. Fresh and dry weights of corms were measured after about nine months, with rotten portions removed and weighed. When epidemics of TLB occurred (in nine out of 12 years), visual estimates of disease severity on leaves were assessed using a modified Horsfall–Barratt scale. The correlations between mean dry weight yields for each cultivar and mean severity of TLB, and, respectively, between mean yields and mean severity of corm rots were calculated. As severity of TLB or severity of corm rots increased (suggesting increased susceptibility of particular cultivars to TLB or corm rots), mean dry weight yields decreased significantly (r 2 = 0.37 and 0.22, respectively). ‘‘Multiple comparisons with the best’’ (MCB) were conducted on fresh and dry weight yields, severity of TLB, severity of corm rots, percentage dry matter of corm, and consumer acceptance. Five cultivars were found to be ‘‘among the best’’ with: 1) fresh or dry weight yields that did not differ from the highest level; 2) severity ratings for TLB that were significantly lower than the highest level, suggesting TLB resistance; and 3) percentage of corm rots that were lower than the highest level, suggesting disease resistance. These cultivars, four of which originated from Palau, were Dirratengadik, Merii, Ngesuas, Ochelochel, and Sawa Bastora. Two commercial cultivars from Hawai‘i, Bun Long and Maui Lehua, had fresh and dry weight yields that were significantly lower than the maximum and severity of TLB injury that did not differ from the highest level, indicating that conventional breeding of taro to improve TLB resistance could improve yields of commercial taro cultivars, particularly in areas where epidemics of TLB occur.

Using Academic Journals to Help Students Learn Subject Matter Content, Develop and Practice Critical Reasoning Skills, and Reflect on Personal Values in Food Science and Human Nutrition Classes

Abstract: It has been reported that students learn best when they use a wide variety of techniques to understand the information of the discipline, be it visual, auditory, discussion with others, metacognition, hands-on activities, or writing about the subject. We report in this article the use of academic journals not only as an aid for students to learn about content knowledge needed in an Experimental Foods course, but also as a way to have students think about and reflect on their own personal values. The topics of these journal entries cover several of the core competencies in the Institute of Food Technologists (IFT) Undergraduate Education Standards for Degrees in Food Science. These are basic principles of food science, as well as address several “Success Skills” (written communication, critical thinking, professionalism, life-long learning, interaction skills, and organizational skills). While there are no quantitative “measurements” of gains in learning, comments from the students indicate that learning took place, critical reasoning occurred, and personal values were analyzed. A guideline for writing and grading academic journals and a simple rubric for scoring the quality of the writing are included.

Strategies for Utilizing Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Microorganisms for Enhanced Phosphate Uptake and Growth of Plants in the Soils of the Tropics

Abstract: One of the major constraints for plant productivity in tropical regions is low soil phosphate (Pi) availability. Phosphate ions are rendered unavailable for plant uptake due to adsorption onto the surface of soil minerals and precipitation by free aluminum and iron ions. In highly weathered soils, this is so intense that plant crops commonly exhibit Pi-deficiency. High rates of soluble Pi-fertilizers are employed to meet plant P demands. However, the large quantity of Pi required in order to offset the high Pi-retention capacity of the soils and the high cost associated with it makes it inaccessible to the vast majority of growers in the region. An alternative means of improving plant Pi-uptake from insoluble native and applied rock phosphate is the use of arbuscular mycorrhizal (AM) fungi. These fungi form a symbiotic association with most plants and improve the efficiency of associated plants to take up Pi from the soil solution. Other soil microorganisms commonly known as phosphate-solubilizing microorganisms (PSM) can replenish soil solution Pi by solubilizing complex phosphorus compounds found in soil or added to it, mostly through the release of organic acids. In this chapter, an attempt is made to highlight the interactions of these two distinct groups of soil microorganisms and the mechanisms by which they facilitate plant available Pi and enhance plant growth in the soils of the tropics.

Nutrients, amino acid, fatty acid and non‐starch polysaccharide profile and in vitro digestibility of macadamia nut cake in swine

Abstract: The highly variable cost and limited availability of conventional feedstuffs make it imperative to explore alternative feedstuffs to be used in swine. Macadamia nut cake (MNC), a coproduct of the macadamia nut oil industry, has not been well studied. MNC was analyzed for its nutrient profile, gross energy (GE), fibers, amino acids and fatty acids content. Dry matter (DM) and GE digestibility of MNC in swine was determined using an in vitro model. On a DM basis, ash, crude protein, ether extract, NDF, ADF, lignin and GE were found to be 3.7, 25.5, 11.9, 35.8, 28.0, 16.0% and 5581 kcal/kg, respectively. Total and soluble non-starch polysaccharide content were 32.2 and 11.8%, respectively. The concentration of lysine was found to be 0.7%. The DM and GE digestibility were found to be 75.7 and 71.4%, respectively. Gross energy content of MNC is comparable with that of corn and higher than soybean meal, while protein content is twice as high as corn but lower than soybean meal. In conclusion, MNC is not merely a good source of protein and energy but also has fairly high digestibility in swine. Hence, it can be used as a viable alternative source of energy and protein in swine diets.