Tropical grasses have been widely utilized as warm-season grasses in the warm temperate zone since the early 20th century because of their high yields as well as for perennial forages in their native tropical areas. The high yield of tropical grasses is mainly due to C₄ photosynthesis. However, the soaring demands for animal production sparked by economic development in tropical countries mean genetic improvement of such grasses is urgently needed. Considerable breeding efforts have been made to create and develop new tropical grass cultivars, although direct selection from natural populations remains the main method used for breeding. Cross-breeding has not proliferated due to a lack of genetic information concerning the polyploidy, high sterility, outcrossing, and apomixis of these grasses, although several of these difficulties are starting to be resolved by advanced research using molecular biology tools. These tools are an effective means of achieving genetically improving of tropical grasses, and further development is anticipated. In this review, achievements in the improved guineagrass, brachiariagrass, sorghum, and zoysiagrass are introduced and discussed.

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The characteristics of Japanese soil were developed by wide paddy field farming, the influence of volcanic ash on soil, and a perudic moisture regime under temperate climatic conditions. Major soil classifications in Japan have developed in line with public work projects and soils in Japan have tended to be classified independently depending on the land use, such as cultivated area, forest, and so forth. Consequently, there is no available soil map drawn with a single framework of soil classification on a practical map scale, which hampers the progress of environmental studies such as watershed-level nutrient cycling, carbon sequestration and so on. In response, we published the Comprehensive Soil Classification System of Japan – First Approximation; a more practical system that enables the nationwide classification of soils. In it, we defined the following categories: soil great group, soil group, soil subgroup, and soil series group, determined by dichotomous keys. The proposed system contains 27 soil groups, 116 soil subgroups and 381 soil series groups. Setting these 4 category levels renders the system usable for both general outlines and detailed descriptions, and to create soil maps and soil information on various scales.

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We evaluated an air-assisted strip seeder, developed by the Hokuriku research center, in farmers’ fields for four years. Plantings using the seeder had more panicles and a higher yield than those using a shooting hill-seeder. The early growth of planting using the air-assisted strip seeder was promoted by increasing the rate of seedling establishment because the seeding depth of plantings using the air-assisted strip seeder was shallower than that of plantings using the shooting hill-seeder. Tillering in this planting was also promoted, which boosted the yield, while simultaneous seeding with fertilizer application using the air-assisted strip seeder was also compared with conventional practice over two years in a field at the Hokuriku research center. During simultaneous seeding with fertilizer application, the rate of seedling establishment was equivalent to that in conventional practice. After seedling establishment, growth and yields in the simultaneous seeding with fertilizer application were equivalent to or exceeded those in conventional practice.

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We summarize the basic techniques used to save energy in a greenhouse and discuss the development of a new energy-saving pipe-framed greenhouse, similar to the type used on most small-scale farms in Japan. To enhance the thermal insulation performance of a pipe-framed greenhouse, a multi-layered thermal curtain was installed. As a result of our experiments, both the heating load and the heating oil consumption in the greenhouse with a multi-layered thermal curtain (M-house) were approximately 40% lower than those in the control greenhouse with a conventional thermal cover (C-house). Furthermore, the heating oil consumption was also reduced by approximately 60% in the M-house equipped with water heat storage, which stored solar energy in daytime and released heat to the greenhouse at night. This multi-layered thermal curtain is expected to gain recognition as the most effective energy-saving material available and immediate widespread use nationwide is expected. Another experiment was performed concerning the structural reinforcement of pipe-framed greenhouses. Pipe-framed greenhouses are usually constructed with single-arch pipes in Japan and there has been a recent increase in greenhouses collapsing due to strong winds. Accordingly, techniques to reinforce the structure of pipe-framed greenhouses were also developed.

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To date, most studies on biological nitrification inhibition (BNI) in sorghum have been performed with plants grown in hydroponic systems. However, the current study was conducted to determine whether or not sorghum inhibits nitrification in fields of Alfisols, and clarify the mechanism that results in inhibition of soil nitrification in the field. Nitrification activity in the rhizosphere of sorghum (Sorghum bicolor (L.) Moench) i.e. soil attached to its roots within a few millimeters was measured and compared with those in adjacent bulk soil. Sweet sorghum (6 varieties) and grain sorghum (3 varieties) were cultivated in 4 Alfisol fields in a semi-arid tropical region of India during the 2010 or 2011 rainy seasons. Soil samples were collected three times during the growing season. Nitrification activity in the rhizospheric soil was significantly lower than that in the bulk soil during 8 out of 12 samplings while the pH (H₂O, 1:2) of the rhizospheric soil was significantly lower than that of the bulk soil in 10 out of 12 samplings. Acidification of the soil by sulfuric acid decreased the nitrification activity to a comparable extent, as emerged in the rhizospheric soils. Our results indicate that acidification of soil around roots would be one of the main causes of nitrification inhibition by sorghum in the field.

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The authors have considered introducing a molecular breeding technique called ‘genomewide selection (GwS)’ to effectively improve the yield of maize for whole-crop silage use. The GwS for this purpose requires training populations (TPs) where individual plants having been developed from three-way crosses are examined in their phenotypes as well as in molecular-marker genotypes. The purpose of this study was to evaluate the (broad-sense) heritability of maturity- and yield-related traits in such TPs, because a former simulation study by the authors showed that the heritability should exceed 25% for the success of the GwS. Five preliminary TPs were grown to estimate the heritability of silking date, ear dry weight and culm length from 2011 to 2013 on two planting density levels, the higher of which was for productivity testing and the lower for accurate individual phenotyping. The results indicated that heritability exceeded 25% in all cases, and that the higher planting density did not result in lower heritability. Accordingly, it was concluded that the maize GwS to improve yield is sufficiently feasible in terms of maintaining high heritability in the TPs, and that planting density for TPs should be that for productivity testing because it is known to have remarkable interaction on yield with genotypes.

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To establish sustainable agricultural practices, monitoring soil water and solute distributions in actual field conditions is important. Because the estimation of electrical conductivity (EC) using time domain reflectometry (TDR) is considered to be affected by Andisols because of their unique dielectric properties, in this study, we investigate the potential for the continuous monitoring of EC and nitrate concentrations using TDR in an Andisol field. The study was performed from December 2007 to August 2008. To estimate soil solution EC (EC_w), the relationship among EC_w, apparent EC (EC_a) and volumetric water content (θ) for an Andisol was investigated, and three models (Rhoades model, Extended Rhoades model and Hilhorst model) were applied to describe this relationship. The Rhoades model was found to be reasonably accurate in describing the EC_w-EC_a-θ relationship, while the Hilhorst model showed reasonable agreement with the experimental data. In the field experiment, EC_w values estimated using TDR with the Rhoades model correlated with those obtained from solution samples and a linear regression between EC_w and soil nitrate concentrations was obtained from the field experimental data. The use of this regression with EC_w estimated from TDR measurements, together with the Rhoades model, is considered a useful tool for the continuous monitoring of soil nitrate concentrations in Andisol fields under transient conditions.

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The aim of this study was to investigate the effects of lipooligosaccharide (LOS) core truncations on the ability of Campylobacter jejuni to attach to glass and form biofilms under aerobic conditions. We compared the wild-type and previously constructed glycosyltransferase mutants of two C. jejuni strains, NCTC 11168 and 81-176, in terms of the numbers of attached cells, biofilm formation, autoagglutination (AAG) activity, and extracellular DNA (eDNA) release. All LOS mutants of NCTC 11168, except cj1138 mutant, and 81-176 waaC mutant with most severe LOS truncation, exhibited increased attachment and biofilm formation. Conversely, waaC and lgtF mutant of both NCTC 11168 and 81-176 showed significantly reduced AAG activity. There was no significant difference between all LOS mutants and the wild-type with respect to eDNA production. The biofilm formation levels correlated significantly with the attachment numbers (p < 0.05, R² = 0.95) but not with the AAG activity and eDNA levels (p ≥ 0.48, R² ≤ 0.72). These results suggest that various LOS core truncations have different impacts on C. jejuni attachment, biofilm formation under aerobic conditions, and the AAG activity levels, whereas they may not affect eDNA production. Bacterial attachment, but not the AAG activity and eDNA release levels, may cause changes in C. jejuni biofilm formation because of LOS core truncations.

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We developed a multiplex polymerase chain reaction (PCR) method using primers specific to the capsular polysaccharide biosynthesis genes (cps) to type Actinobacillus pleuropneumoniae serovars 1, 2, 5, 7, and 15. This multiplex PCR method may be useful for the typing of serovar 15, which is recently becoming more prevalent, as well as the most prevalent serovars 1, 2, 5, and 7 in Japan.

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The Atlantic Forest, Humid Chaco, and Dry Chaco are major eco-regions in Paraguay, but information on forest carbon stocks in these forest types remains limited. To establish a system to measure, report and verify forest carbon change under the REDD+ mechanism, we developed new allometric equations to estimate tree biomass in each eco-region. Three models of total and aboveground biomass were developed from destructive sampling data. The models performed well, explaining ≥96% of the variation in aboveground and total biomass, although the best model differed among the eco-regions. The inclusion of height and wood density improved fit in the Atlantic Forest model, but including wood density did not enhance the Humid and Dry Chaco models. Our models will improve the estimation of biomass in Paraguay because they provide better estimates of total and aboveground biomass in each eco-region than pan-tropical generic models.

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We assessed cellulase activity in several crustaceans of different taxonomic groups inhabiting the mangrove areas of Malaysia to clarify whether these animals could digest cellulose derived from mangrove trees. We investigated four Copepod species, two Mysida species, and ten Decapoda species. Three copepod species demonstrated multiple cellulase active bands that differed among species in a zymographic assay, suggesting that these animals were equipped with distinct cellulases. Interestingly, the way the cellulase were expressed in the zymographic assay differed, even among members of the same species collected at different locations, suggesting that cellulase expression patterns of copepod species are regulated by environmental factors. Although no significant cellulase activity was detected in two of the Mysida species, widespread distribution of cellulases was also detected in decapod species. Multiple common active bands in the various organs of decapod species were detected by the zymographic assay, while remarkable activity was detected in the hepatopancreas in the reducing sugar assay. The above findings suggested that cellulases are synthesized in the hepatopancreas and then secreted into digestive tracts such as the stomach and intestine. The present study shows that various crustaceans comprising most of the biotic resources in mangrove areas may be there because of their ability to digest cellulose.

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