Economics of milkfish (Chanos chanos) production in Hawaii*

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.     

Rice Germin-Like Proteins: Allelic Diversity and Relationships to Early Stress Responses

Germin-like protein (GLP) markers were associated with quantitative trait loci (QTL) for resistance to the rice blast pathogen, Magnaporthe oryzae in multiple rice (Oryza sativa) mapping populations. Twelve paralogous OsGLP gene family members are located within the physical QTL region on chromosome 8, and gene silencing studies suggest that they contribute collectively to the resistance phenotype. We compared sequence and expression profiles of OsGLP alleles in two resistant and two susceptible parental rice lines to find functional polymorphisms that correlated with the resistant phenotype. Based on coding and promoter sequences, the genes belong to two germin subfamily groups (GER3 and GER4). OsGLP members from both subfamilies were constitutively expressed and developmentally regulated in all cultivars. Transient induction above constitutive levels was observed for some OsGLPs, especially GER4 subfamily members, at early time points after M. oryzae infection and mechanical wounding. Varying 5′ regulatory regions and differential expression of some family members between resistant and susceptible cultivars corresponded with differential hydrogen peroxide (H₂O₂) accumulation after the same stimuli. OsGLP of both GER subfamilies localized to the plant cell wall. The protein location and early gene induction suggest that OsGLPs protect rice leaves at early stages of infection before fungal penetration and subsequent ingress. Our data suggest that regulation of OsGLP genes defines resistant versus susceptible phenotypes.     

The effect of simulated rat damage on irrigated rice yield and compensation

A field experiment was conducted to investigate the impact of simulated rat damage on grain yield in irrigated lowland rice in An Giang province, in the Mekong Delta of Vietnam. Rat damage was simulated by making a 45° cut at the base of the rice tillers about 3–5 cm above the soil surface. 0% (control), 5%, 10%, 25% and 50% of the tillers were removed at the tillering (25 days after sowing, DAS), panicle initiation (43 DAS), flowering (72 DAS) and ripening (87 DAS) stages. The total number of mature tillers, immature tillers and percent filled grains, the weight of 1000 grains and grain yields were recorded. The rice crop completely compensated by increased tillering and yield for tillers damaged up to 50% at the tillering stage. However, the damage and yield loss were highly variable. The ability of the rice crop to compensate at later stages progressively reduced. The implications for managing rat damage to rice crops are (1) rodent control activities should be applied before 10% of tillers are damaged at the tillering stage, and (2) a well balanced nitrogen supply during the tillering stage could potentially assist the rice plants to better compensate for rat damage.     

Schisandrin B co-treatment ameliorates the impairment on mitochondrial antioxidant status in various tissues of long-term ethanol treated rats

The effect of schisandrin B (Sch B) on long-term ethanol-induced oxidative stress in various rat tissues was investigated. Long-term ethanol treatment increased reactive oxygen metabolites (ROM) level in plasma. The ethanol-induced oxidative stress was assessed by mitochondrial glutathione and α-tocopherol levels, antioxidant enzyme activities, malondialdehyde (mtMDA) production and heat shock protein (Hsp) 25/70 levels. Liver was most susceptible to oxidative stress with a significant increase in mtMDA production. Long-term Sch B treatment enhanced mitochondrial antioxidant status in a tissue non-specific manner. Sch B co-treatment ameliorated the alterations in plasma ROM levels, mtMDA production and Hsp 25/70 expression in rat tissues.     

Isolation, structure characterization, and immunomodulating activity of a hyperbranched polysaccharide from the fruiting bodies of Ganoderma sinense

A polysaccharide (GSP-6B) with a molecular mass of 1.86 × 10? Da was isolated from the fruiting bodies of Ganoderma sinense . Chemical composition analysis, methylation analysis, infrared spectroscopy, and nuclear magnetic resonance spectroscopy were conducted to elucidate its structure. GSP-6B contains a backbone of (1→6)-linked-β-D-glucopyranosyl residues, bearing branches at the O-3 position of every two sugar residues along the backbone. The side chains contain (1→4)-linked-β-D-glucopyranosyl residues, (1→3)-linked-β-D-glucopyranosyl residues, and nonreducing end β-D-glucopyranosyl residues. An in vitro immunomodulating activity assay revealed that GSP-6B could significantly induce the release of IL-1β and TNF-α in human peripheral blood mononuclear cell (PBMC) and showed no toxicity to either PBMC or a human macrophage cell line THP-1. GSP-6B could also activate dendritic cells (DC) by stimulating the secretion of IL-12 and IL-10 from DC.     

Genetic characterization and evolutionary analysis of 4 Newcastle disease virus isolate full genomes from waterbirds in South China during 2003-2007

Complete genomes of four Newcastle disease virus (NDV) strains, isolated from ducks and wild birds in Guangdong province of China from 2003 to 2007, were sequenced and analyzed in this study. Pathogenicity tests in chicken embryos and chickens illustrate that D3 and R8 are lentogenic, and W4 and P4 are mesogenic strains. Phylogenetic analysis using all six genes provides a high resolution profile for genotype designation as genotype I for D3 and R8 strains and genotype VI for W4 and P4 strains. In addition, molecular dating based on different genes suggests that D3 and R8 diverged from their common ancestor at around 1998; W4 and P4 diverged from their common ancestor at around 1999. Subsequent selective pressure analysis displayed specific traits of genes evolution in all 4 strains since their divergence from the recent common ancestor. Furthermore, the geographic origins of 4 strains were deduced to be from Europe via two independent introduction events by phylogeographical analysis. This provides insights to the potential influence of waterfowl migration on NDV epidemiology.     

Does resource complementarity or prevention of lodging contribute to the increased productivity of rice varietal mixtures in Yunnan,China?

We conducted an experiment in Gejiu, Yunnan Province of China during the wet season of 2002 to examine the importance of resource complementarity and prevention of lodging in the fast-spreading practice of growing rice varietal mixtures in China to suppress rice blast disease and its associated damage. The hybrid rice variety Shanyou 63 and the glutinous or sticky rice variety Huangkenuo were used to study intra- and inter-varietal competition in the rice intercropping system. The experiment was laid out as a randomized complete block design in four replications with pure stands and mixtures of both varieties at different total planting densities and mixing ratios. In half of the pure stand treatments of glutinous rice a metal frame was installed to prevent lodging. The results showed that resource complementarity between the two rice varieties, resulting from niche differentiation, was marginal and did not greatly enhance the productivity of the rice varietal mixtures. In contrast, prevention of lodging of glutinous rice was identified as an important additional advantage of growing these rice varieties in mixture.     

Introgression of Xa4, Xa7 and Xa21 for resistance to bacterial blight in thermosensitive genetic male sterile rice (Oryza sativa L.) for the development of two-line hybrids

Bacterial blight (BB) of rice caused by X. oryzae pv. oryzae is a major production constraint in commercial hybrid rice production in the Philippines because most of the parental lines used in hybrid production do not carry resistance genes against the pathogen. In this study, three bacterial blight resistance genes, Xa4, Xa7 and Xa21, were introgressed to a temperature-sensitive genetic male sterile (TGMS1) line. A three-way cross of AR32-19-3-3/TGMS1//IRBB4/7 (PR36944) was made to produce 1,364 F₂ plants carrying various combinations of Xa4, Xa7 and Xa21. Individual plants were characterized for reaction to bacterial blight PXO61 (race 1), PXO86 (race 2), PXO99 (race 6) and pollen sterility. Of 144 F₂ plants demonstrating resistance against PXO61, PXO86 and PXO99, 22 exhibited highly resistant phenotypes with mean lesion lengths ranging from 0.37–2.97 cm. Analysis of disease reaction identified 20 potential TGMS F₂ plants containing Xa4, Xa7 and Xa21 while 78 plants with Xa4 + Xa7. Phenotypic and polymerase chain reaction (PCR) analyses confirmed PR36944-450, PR36944-473 and PR36944-700 as homozygous for Xa7 and Xa21 and highly resistant to all three Xoo races. Fertility of PR36944-450 and PR36944-700 was restored at permissive temperature in a growth chamber. BB-resistant TGMS lines should facilitate breeding two-line hybrids in the tropics.     

Pot2在稻瘟病菌群体结构分析中的应用

利用稻瘟病菌的一段倒位重复序列Ｐｏｔ２设计的一对引物直接对稻瘟病菌的ＤＮＡ进行ＰＣＲ扩增。根据带型相似性大于８０％为度可将国际水稻所一个稻瘟病圃上的３１０个菌株划分６个宗亲群（ｌｉｎｅａｇｅ）。这些依分子标记划分的宗亲群与品种的遗传背景有密切关系,而且各宗亲群在水稻不同生育期有不同的波动方式。     

Technical efficiency of carp production in India: a stochastic frontier production function analysis

This paper aims to examine the levels and determinants of technical efficiency in carp pond culture in India. The stochastic production frontier technique involving the model for technical inefficiency effects is applied separately to samples of semi‐intensive/intensive and extensive carp producers interviewed during 1994–95. The results showed significant technical inefficiencies in carp production in India, especially among extensive farms. The mean technical efficiencies for semi‐intensive/intensive and extensive sample farms were estimated to be 0.805 and 0.658 respectively. By operating at full technical efficiency levels, the semi‐intensive/intensive farms could, on average, increase their production from about 3.4 Mt ha^?1 to 4.1 Mt ha^?1. Likewise, the extensive farms could increase their production from 1.3 Mt ha^?1 to 1.9 Mt ha^?1. Much of these efficiency gains would come from improvement in the adoption of recommended fish, water and feed management and monitoring practices. Besides expanding production area, the results indicated several other possibilities for increasing carp production in India by increasing yields per hectare, such as: (1) increased intensification of carp culture (i.e. moving from extensive to semi‐intensive or intensive systems); (2) improvement in technical efficiency at the farm level; and (3) technological progress. However, the realization of these potentials will depend on continuous efforts by the government in ensuring an adequate supply of inputs, technology transfer and development and adequate provision of research, extension and credit services in aquaculture.