In developing countries of the Asian monsoon region, participatory irrigation management (PIM) was introduced in the 1990s so that farmers rather than government staff could be partly or wholly responsible for operating, maintaining and managing irrigation projects. Whether or not farmers continuously participate in maintenance activities depends on the degree of their willingness to perform such activities. This study reviews the objectives, achievements and significance of a series of our six research papers that use a range of methods to increase the willingness of farmers to engage in maintenance activities, and also summarizes future perspectives of PIM sustainability. The results of the research papers showed a practical method and a new perspective for an efficient increase in the willingness of farmers; firstly by choosing factors with a new indicator, “maximum effective number of target persons”, and then improving details of how the chosen factors were encouraged by adding an incentive perspective with “no decrease in vested benefits”. Conversely, to simplify the questions regarding the selection of encouraging factors, the papers disregarded conditions such as the time and cost required for encouragement. The first priority is therefore to clarify the content of incentives based on factors that should be encouraged. Second, the findings of the papers cover only the most fundamental factors associated with PIM sustainability. Therefore, to effectively and efficiently improve PIM sustainability, there is a need to analyze “factors other than willingness” that influence the inclination to engage in maintenance activities.

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Various carotenoids with diverse structures are present in foods and have been reported to have beneficial effects on human health. Owing to their hydrophobicity, however, poor solubilization in the aqueous milieu of the digestive tract restricts their intestinal absorption. Fats and oils were found to increase the solubilization of carotenoids into mixed-micelles, which would therefore enhance their bioavailability. The uptake of carotenoids solubilized in the micelles by intestinal cells are thought to be mediated by simple diffusion and/or facilitated diffusion through scavenger receptors. Lipids that constituted the mixed-micelles affected the uptake of carotenoids. In particular, lysophosphatidylcholine significantly enhanced uptake. Highly polar carotenoids, meanwhile accumulated in mice but not in humans, suggesting discriminate absorption and metabolism in the latter. The metabolism of provitamin A carotenoids is well known to be mediated by the central cleavage enzyme. Recently, another cleavage enzyme was found to cleave various carotenoids asymmetrically into apocarotenoids. Xanthophylls were found to be oxidized to unstable keto-carotenoids in mice. These metabolic conversions are thought to affect the levels of bioavailable carotenoids in tissues. In this article, the solubilization into mixed-micelles, intestinal absorption and oxidative metabolism of carotenoids are reviewed to understand the factors that determine the bioavailability of carotenoids ingested from fruit and vegetables.

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To illustrate the differences in toxicities between deoxynivalenol (DON) and nivalenol (NIV), cell proliferation, cytokine secretion, and the involvement of heat shock protein 90 (Hsp90) were investigated. Both toxins retarded the proliferation of all four cell lines tested. NIV was more potent than DON in human promyelocytic leukemia cell line HL60, human lymphoblastic leukemia cell line MOLT-4, and rat aortic myoblast cell line A-10. In contrast, both toxins exhibited almost equivalent potencies in human hepatoblastoma cell line HepG2. If both toxins exert their toxicities through the same mechanism, one should be more potent than the other, regardless of cell types. While exposure to DON significantly induced the secretion of anti-hematopoietic cytokines macrophage inflammatory protein-1α (MIP-1α/CCL3) and MIP-1β/CCL4, treatment with NIV decreased the secretion of these cytokines in HL60 cells, indicating that the toxicity mechanisms of these toxins differ. An Hsp90-specific inhibitor radicicol canceled the effect of DON on these cytokine secretions, indicating that Hsp90 plays a crucial role in these DON-induced cytokine secretions in HL60 cells. Conversely, the results of treatment with NIV and radicicol indicate that radicicol does not mitigate the effect of NIV. When viewing the above results collectively, although these toxins share highly similar chemical structures, there are evident differences in their toxicities.

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The infection process of the anthracnose fungus Disculatheae-sinensis in tea was investigated in detail by fluorescence microscopy. Leaves of the susceptible tea variety ‘Yabukita’ spray inoculated with the conidial suspension were collected sequentially and examined after fluorescence staining with fluorescein-conjugated wheat germ agglutinin. Conidia adhering to the trichomes germinated and formed very short germ tubes. Penetration hyphae grew from the germ tube tips into the cell walls of the trichomes, and formed infection hyphae by 12 h after inoculation. Hyphae that had invaded the mesophyll were confined to the small round spots that formed surrounding the infected trichomes. However, hyphae that had reached the veins extended through the phloem, causing necrosis of the neighboring mesophylls and eventually the formation of large necrotic lesions.

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To clarify the diversity of blast (Pyricularia oryzae Cavara) races in West Africa, we investigated the pathogenicity of 96 blast isolates collected from different ecosystems in six countries, Bénin, Burkina Faso, Côte-d’Ivoire, Ghana, Mali, and Nigeria, and characterized using rice (Oryza sativa L.) differential varieties for 23 resistance genes and a susceptible control variety Lijangxintuanheigu (LTH). Virulent blast isolates occurred with high frequencies against LTH or differential varieties carrying Pia, Pik-s, Pi19(t), Pi12(t), Pit, Pii, Pi3 and Pi5(t). Conversely, they occurred at low frequencies against differential varieties carrying Pish, Pi9(t), Piz, Piz-5, Piz-t and Pita-2 and at intermediate frequencies against those carrying Pib, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pita and Pi20(t). The isolates were recharacterized as reaction types of five groups, U, i, k, z and ta; accordingly, LTH and the differential varieties were categorized based on the chromosome locations of the resistance genes harbored in each genetic background. Twelve, seven, thirteen, eight and seventeen reaction types were found in groups U, i, k, z and ta, respectively. Thirteen of these, namely U43, U63, i7, k100, k106, k177, z00, z03, z04, ta003, ta031, ta403 and ta431, showed high frequencies of blast isolates and were considered dominant reaction types. We used the infection types of the differential varieties against these blast isolates to conduct a cluster analysis, and the isolates were classified into two clusters, I and II. Substantial differences in frequencies between both clusters were found in the reactions of differential varieties carrying these genes in the Pii, Pik and Pita chromosome regions. Both clusters I and II were distributed in an upland ecosystem with high and similar frequencies, whereas group II was mainly distributed in the irrigated lowland. These results suggested that many types of blast races were distributed in the upland ecosystem, while the limited ones were in lowland in West Africa. Finally, these blast isolates were categorized into 79 races in accordance with a new designation system based on the five differential variety groups used for reaction typing.

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DNA sequence analysis of the mitochondrial cytochrome oxidase I (COI)-leucine tRNA (tRNA^Leu)-cytochrome oxidase II (COII) regions was performed to elucidate the phylogenetic relationships among 465 summer and winter-form psyllids from Saga and Yamaguchi prefectures in Japan. Multiple alignments of these sequences revealed 2 single-nucleotide polymorphisms (SNPs) at nucleotide positions 78 and 258 in the COI and tRNA^Leu regions, respectively. Based on the nucleotide changes at these loci, these 465 insects were grouped into 3 genotypes: 78A/258A, 78G/258G, and 78G/258A. All but 2 of the 225 insects in Saga belonged to the genotype 78A/258A, and the 2 exceptions belonged to the genotype 78G/258G. Conversely, all the insects (105) collected from Shimonoseki city in western Yamaguchi prefecture belonged to the genotype 78G/258G, while eighty percent of the 135 samples from eastern Yamaguchi prefecture belonged to the genotype 78G/258G. Among the other 27 insect samples, 24 were 78G/258A and 3 were 78A/258A. Using POPTREE2, the psyllids were divided into 5 populations associated with the geographical distribution. The results suggest that the genetic population structure of these psyllids varied widely between Saga and Yamaguchi prefectures.

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In Japan, the production of Satsuma mandarin (Citrus unshiu Marc.) is seriously affected by Satsuma dwarf virus (SDV). This study provides evidence of the natural SDV infection of two woody plants, Daphniphyllum teijsmannii and Viburnum odoratissimum var. awabuki, which are common in the warm temperate forests of Japan. Forty-four species of wild woody plants that grew near several SDV-infested fields were surveyed for the presence of SDV using immunochromatography assay (ICA). Five D. teijsmannii trees and four trees of V. odoratissimum var. awabuki tested positive for SDV. Trees of D. teijsmannii and V. odoratissimum var. awabuki that grew far from the citrus fields tested negative for SDV, suggesting that these species are hosts but not the main natural reservoirs of SDV. Comparisons of the partial nucleotide sequences of the larger coat protein gene showed that SDV isolates from closely-grown trees of citrus, D. teijsmannii, and V. odoratissimum var. awabuki were genetically very homogeneous. The results suggested that the natural transmission of SDV occurred among trees of citrus, D. teijsmannii, and V. odoratissimum var. awabuki.

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Rice blast, caused by Pyricularia oryzae Cavara (Magnaporthe grisea (Hebert) Barr), is one of the most severe global rice diseases. The Philippine rice landrace ‘Ingngoppor-tinawon’ (IT) displays not only high field resistance to rice blast but also high tolerance to lodging, despite its very long culms. These characteristics make IT suitable for use in breeding animal feed varieties as whole-crop silage (WCS). To characterize the blast resistance of IT, quantitative trait locus (QTL) analysis of the resistance using simple sequence repeat (SSR) markers was conducted in F₃ progenies derived from crossing IT with a susceptible lowland variety, ‘Koshihikari’. A QTL for blast field resistance (qBFR4) was identified on chromosome 4, and the resistance allele was derived from IT. The QTL explained 73.5% of the phenotypic variation for blast resistance. qBFR4 mapped to almost the same position as that of the blast field-resistance gene Pi39. Inoculation assays revealed that IT (containing qBFR4) showed resistance characteristics that differed from those of Mineharuka (containing Pi39), making it very likely that resistance derived from IT is distinct from Pi39. IT showed broad resistance to Japanese isolates and race-specific resistance to some Philippine isolates.

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Although Shaanxi province is the largest in China, both in terms of apple production and cultivated areas, with local farmers’ income mainly sourced from apples, the per-capita net income of farmers in Shaanxi province remains behind the national average. Since the market channel choice of farmers could be perceived as one of the available income strategies, this paper provides empirical evidence to measure the impacts of market channel choice on farmers’ income using a Heckman sample selection model and an OLS model based on a farm household survey of 243 apple farmers in Baishui and Luochuan counties of Shaanxi province, China. Moreover, this paper discusses the different impacts of market channel choice on household income among farmers who are cooperative members and those who are not.

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During arching cultivation of roses in autumn and winter, long-day treatment using fluorescent lamps placed above the base of the plants slightly increased the number of cut flowers and also tended to increase the cut flower length in the first year. To further investigate these effects, the light condition of assimilation shoots was modified by supplemental lighting using white light-emitting diodes (LEDs) placed above the assimilation shoots. Supplemental lighting at two different levels of photosynthetic photon flux density (PPFD), 100 and 250 μmol m⁻² s⁻¹, increased the number of cut flowers from the middle portion of the assimilation shoots, and the total number and weight of cut flowers according to the light intensity. Irradiation at 250 μmol m⁻² s⁻¹ PPFD also increased the number of cut flowers over 80 cm long and the length, weight and stem diameter of cut flowers over 60 cm long. Long-day treatment using fluorescent lamps did not affect the number of cut flowers in the second year. These results indicate that long-day treatment using fluorescent lamps can effectively increase the yield of cut rose flowers in some years, while supplemental lighting using white LEDs for assimilation shoots is a method of increasing it more strongly.

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Kyushu island, in southern Japan, is one of the main producers of green asparagus (Asparagus officinalis L.) in Japan, accommodating protected mother-fern culture in plastic greenhouses (PMC) as a conventional crop. In PMC, since few spears are produced from November to January, we attempted to produce spears during this period by prolonging the harvest of PMC to November and introducing “Fusekomi” forcing culture (FFC), in which rootstocks grown outdoors are transplanted into heated and/or thermal-retained culture beds in a plastic greenhouse in late autumn or early winter and spears are generally harvested for the following two or three months. In PMC, a combination of a foliage spray of Benzyladenine solution with thermal retention treatment in autumn prolonged the harvest period to the end of November without any significant decrease in yield the following spring. In FFC, rootstocks grown in the lowlands showed inferior spear productivity when transplanted into a greenhouse in late November, probably due to insufficient exposure to low temperature for breaking dormancy. In contrast, rootstocks grown in the highlands showed superior in productivity because they would be sufficiently exposed to low temperature for breaking dormancy by the time of transplanting. In lowlands, heating of greenhouses was unnecessary for FFC throughout the harvest period due to the mild winter climate. These results suggested that profitable year-round production of green asparagus without heating could be realized in Kyushu by combining PMC and FFC cropping types.

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The growth of the juvenile sea cucumber, Holothuria scabra, was studied under captivity to elucidate the growth variation pattern and determine the best-fit growth model to estimate age- and size-specific growth rates. Individual growth was extremely variable, with some individuals below the mean initial weight and some expanding their original body length (L) and weight (W) by up to 6.4 and 156 times, respectively; during 84 days of culture starting at 127 days of age. Some of the smallest individuals showed a higher condition factor than larger individuals in the presence of ample food, indicating that lack of food may not be the only impediment to growth. Among the three growth models compared (von Bertalanffy, Gompertz and logistic), the Gompertz model was considered optimal to express H. scabra growth; both in L and W. The age- and size-specific daily growth rate for L and W up to 365 days of age, as estimated by the Gompertz model, had a range of two and nine orders of magnitude in L (0.035 – 0.96 mm/day) and W (3.4 × 10^-7 – 3.5 g/day), respectively. Use of the Gompertz model over the linear model, which tends to overestimate growth rates, is encouraged to estimate the growth of H. scabra more accurately.

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Winter wheat is an important crop for many countries, and monitoring of its planted area is considered important. Optical sensors have been used to monitor agricultural land, and have shown good classification and monitoring capabilities. However, observations using optical sensors sometimes suffer from interference due to cloud cover or rain. In contrast, synthetic aperture radars (SAR) can be used for Earth observation even under rainy, cloudy or dark conditions, hence SAR is expected to be effective in monitoring agricultural fields and identifying winter wheat fields. The objective of this study is to analyze the potential of TerraSAR-X dual images, in the StripMap mode, for mapping winter wheat planted areas. Using the separability statistic (D), it emerged that the sigma naught acquired in mid-July possesses great potential. The method applied in this study has an overall accuracy exceeding 96% for HH and VV polarization data for identifying winter wheat fields.

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This paper describes a method for monitoring winter wheat growth using multi-temporal TerraSAR-X dual-polarimetric data. Six TerraSAR-X HH/VV images were collected in Hokkaido, and the temporal responses to the winter wheat fields were analyzed. The height, moisture content and dry matter of the crops were measured at nearly the same time as TerraSAR-X data was acquired, and the relationships between these parameters and SAR data, including sigma naught and coherence, were studied. Quadratic relationships between the crop height and sigma naught were observed for HH polarization. The determination coefficient was 0.73 and the model had an RMS error of 0.17 dB for the validation data. Coherence is expressed as a regression equation with two explanatory variables: crop height and elongation. Next, the determination coefficient of 0.69 was observed for HH, while the RMS error of coherence was 0.01 for the validation data. The possibility of using the co-polarization ratio of TerraSAR-X to estimate the vegetation’s water content was also analyzed and a determination coefficient of 0.70 was obtained. The results confirm that X-band SAR data possess great potential for the development of an operational system for monitoring wheat growth.

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