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.

Effects of green manure and coral lime on corn growth and chemical properties of an acid Oxisol in Western Samoa.

Abstract: Effects of local green manure (GM) and lime on soil productivity in a low-input agricultural system were evaluated by growing three successive crops of sweet corn (Zea mays) on an acid Oxisol (Typic acrorthox, Togitogiga series) in Western Samoa. The soil was amended with coral lime at 0, 5, and 10Mgha–1 and with cowpea GM at 0, 7.5, and 15Mgha–1. Commercial NPK fertilizers at 50kgha–1 each of N, P, and K were included for comparison. The amendments were applied only once prior to planting of the first crop. Response parameters measured included nutrient composition of leaves at tasseling and grain yield of each crop, and selected soil chemical properties at each planting. Yields of the first crop were nearly tripled with GM additions and doubled with lime additions. Such yield increases were caused mainly by better K nutrition and to a lesser extent by enhanced P nutrition. Yields of subsequent crops were much lower than those of the first, and the declines were much steeper for the GM treatments than for the lime treatments. Thus, the enhancement effect on K nutrition did not last beyond one crop. Poor growth of the second and third crops was caused by K deficiency; probably coupled with Mn toxicity. Significant yield reductions were found when Mn-to-K ratios in leaves exceeded 0.010. As for effects on soil, soil pH was increased significantly by lime but only slightly by GM. Given the variable charge property of this Oxisol, each unit pH increase corresponds to a cation exchange capacity (CEC) increase of 5cmolckg–1. Having greater CEC, the amended soil retained K more effectively, thereby causing yield increases, especially of the first corn crop, which required at least 0.75cmolckg–1 of exchangeable soil K or 7% of CEC for adequate growth.

‘KX4-Hawaii’, Seedless Interspecific Hybrid Leucaena

Abstract: ‘KX4-Hawaii’ is a tropical, seedless, multipurpose legume tree developed at the College of Tropical Agriculture and Human Resources of the University of Hawaii. It represents a sterile triploid hybrid between Leucaena leucocephala (Lam.) de Wit ssp. glabrata (Rose) S. Zarate (2n = 104) and L. esculenta (Mocino et Sesse ex DC) Benth. (2n = 52). ‘KX4Hawaii’ is a rapidly growing tree to 15 m in five years. Its evergreen canopy is open and it has proved to be attractive as an ornamental, windbreak, and shade tree. It has potential also for use as a coppiceable, high-value hardwood grown on eightto 12-year rotations. It is normally single-stemmed with major branches arising at 3 m or higher. It can be coppiced to create a multistemmed tree for biofuel and is readily cloned. It has been grown at many locations throughout Hawaii, showing high drought tolerance and wide environmental adaptability. It has no known pests or diseases. Several of the 22 recognized species in the New World genus Leucaena (Hughes, 1997) are grown as shade or ornamental trees. Two species are widely cultivated internationally, L. leucocephala (Lam) de Wit and L. diversifolia (Schlecht) Benth. Both are recognized as shade or support trees for crops like coffee, cacao, pepper, and quinine, and both are selfseeding polyploids (2n = 104). Leucaena leucocephala ssp. glabrata (formerly known as L. glabrata Rose) is the widely grown multipurpose subspecies that is highly valued for timber, fuelwood, fodder, food, and green manure (Anon., 1977; Shelton and Brewbaker, 1994). Significant cultivars bred in Hawaii include K8 (Brewbaker, 1975) and K636, marketed as ‘‘Tarramba’’ (Dalzell et al., 2006). New hybrids such as ‘KX2-Hawaii’ have been bred to be largely self-sterile, similar to most species of the genus (Brewbaker, 2008). Self-seediness is associated with invasiveness and can greatly reduce wood and fodder yields of tropical legumes. These facts encouraged our extensive evaluations of the 12 major seedless hybrids in the genus we have created in Hawaii (Gonzalez et al., 1967; Pan and Brewbaker, 1988; Sorensson and Brewbaker, 1994).

Assessing intervention fidelity in a multi-level, multi-component, multi-site program: the Children’s Healthy Living (CHL) program

Abstract: Addressing complex chronic disease prevention, like childhood obesity, requires a multi-level, multi-component culturally relevant approach with broad reach. Models are lacking to guide fidelity monitoring across multiple levels, components, and sites engaged in such interventions. The aim of this study is to describe the fidelity-monitoring approach of The Children’s Healthy Living (CHL) Program, a multi-level multi-component intervention in five Pacific jurisdictions. A fidelity-monitoring rubric was developed. About halfway during the intervention, community partners were randomly selected and interviewed independently by local CHL staff and by Coordinating Center representatives to assess treatment fidelity. Ratings were compared and discussed by local and Coordinating Center staff. There was good agreement between the teams (Kappa = 0.50, p < 0.001), and intervention improvement opportunities were identified through data review and group discussion. Fidelity for the multi-level, multi-component, multi-site CHL intervention was successfully assessed, identifying adaptations as well as ways to improve intervention delivery prior to the end of the intervention.

Genomic analysis of the Phalaenopsis pathogen Dickeya sp. PA1, representing the emerging species Dickeya fangzhongdai

Abstract: Dickeya sp. strain PA1 is the causal agent of bacterial soft rot in Phalaenopsis, an important indoor orchid in China. PA1 and a few other strains were grouped into a novel species, Dickeya fangzhongdai, and only the orchid-associated strains have been shown to cause soft rot symptoms. We constructed the complete PA1 genome sequence and used comparative genomics to explore the differences in genomic features between D. fangzhongdai and other Dickeya species. PA1 has a 4,979,223-bp circular genome with 4269 predicted protein-coding genes. D. fangzhongdai was phylogenetically similar to Dickeya solani and Dickeya dadantii. The type I to type VI secretion systems (T1SS–T6SS), except for the stt-type T2SS, were identified in D. fangzhongdai. The three phylogenetically similar species varied significantly in terms of their T5SSs and T6SSs, as did the different D. fangzhongdai strains. Genomic island (GI) prediction and synteny analysis (compared to D. fangzhongdai strains) of PA1 also indicated the presence of T5SSs and T6SSs in strain-specific regions. Two typical CRISPR arrays were identified in D. fangzhongdai and in most other Dickeya species, except for D. solani. CRISPR-1 was present in all of these Dickeya species, while the presence of CRISPR-2 varied due to species differentiation. A large polyketide/nonribosomal peptide (PK/NRP) cluster, similar to the zeamine biosynthetic gene cluster in Dickeya zeae rice strains, was discovered in D. fangzhongdai and D. solani. The D. fangzhongdai and D. solani strains might recently have acquired this gene cluster by horizontal gene transfer (HGT). Orchid-associated strains are the typical members of D. fangzhongdai. Genomic analysis of PA1 suggested that this strain presents the genomic characteristics of this novel species. Considering the absence of the stt-type T2SS, the presence of CRISPR loci and the zeamine biosynthetic gene cluster, D. fangzhongdai is likely a transitional form between D. dadantii and D. solani. This is supported by the later acquisition of the zeamine cluster and the loss of CRISPR arrays by D. solani. Comparisons of phylogenetic positions and virulence determinants could be helpful for the effective quarantine and control of this emerging species.