NERICAs (New Rice for Africa), new genotypes produced from the interspecific hybridization of Oryza sativa and O. glaberrima, have been bred in an attempt to improve the yield potential of rice cultivars adapted to resource-limited conditions in Africa. Identification of physiological traits responsible for their high-yielding potential under such conditions should be useful for rice-breeding programs to be employed not only in Africa but in other regions where rice production is being undertaken under low input conditions. In a series of experiments, we evaluated the growth and yield performance of upland NERICAs under rain-fed upland conditions with two levels of nitrogen application in comparison with Japanese elite rice cultivars, and attempted to identify the physiological traits responsible for the superior yield, if any. The upland NERICAs (NERICA 1 and NERICA 5) exhibited greater biomass production and yield than Japanese cultivars. The NERICAs also showed a higher rate of transpiration and exudation during the ripening stage, compared with elite Japanese cultivars. These results suggested that the greater water uptake ability of NERICAs appeared to be associated with their high N uptake capability, leading to greater biomass production and yield under water- and N-limited ecosystems. Further studies are needed to identify the specific root morphology involved in the water uptake ability of NERICAs.

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In the field of farm management and in related multidisciplinary fields such as bio-economic farm modeling and hydro-economic regional modeling, much attention has recently been paid to positive mathematical programming (PMP), primarily because of its ability to exactly reproduce an observed set of endogenous input variables in the model (e.g., an observed land-use pattern for crop productions) as the result of optimization. In mathematical terms, PMP is an inverse problem of quadratic programming (QP), where the objective function is calibrated on the basis of the Kuhn-Tucker conditions for the optimization of the QP model and of a linear programming model that is prepared for the calibration of parameters in the QP model. The two types of optimum conditions derived from the models are combined to obtain linear equations for the calibration of the QP model. However, as is often the case with inverse problems, the equations for the calibration are indefinite because the number of parameters to be calibrated surpasses the number of equations. As a result, various methods have been proposed to solve this so-called “ill-posed” problem. The main objectives of the present paper are to examine how the calibration methods developed in previous PMP models are related to one another and to propose practical procedures for determining which calibration method is the most appropriate from the viewpoint of sensitivity analyses. A simple conceptual framework is proposed to relate the previously developed calibration methods, and it is then applied to exemplify criteria for selecting a calibration method from the viewpoint of simulation results. A new direction in PMP-based farm modeling in which more feasible simulation results can be derived is also discussed.

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Many kinds of sugarcane hybrids and relatives were planted in two sites, Tsukuba and Nasushiobara, in the northern Kanto region of Japan to evaluate their overwintering ability and biomass production. JW49 (Saccharum spontaneum L.), US56-15-2 (S. spontaneum L.) and Ponape Hurukimura (Saccharum barberi Jeswiet) were able to overwinter in the field experiment conducted in Tsukuba, but not in Nasushiobara. In the field experiment conducted in Nasushiobara, only two lines, JW599 (Saccharum spontaneum L.) and JW630 (Erianthus spp.), overwintered. JW630 also showed good ratooning ability in Tsukuba, even though the results were obtained from the experiment without replication. The newly planted JW599 and JW630 were small in the first year, but from the second year the biomass production of the ratoon plants became huge. The dry matter yields of JW599 and JW630 in the first year were 0.07 and 0.13 kg per hill, respectively, and the average dry matter yields of JW599 and JW630 during three years of ratoon cultivation were 1.46 and 2.63 kg per hill per year, respectively. Assuming that they are planted at 1.5-m inter-row intervals and 0.3 m inter-hill intervals, and each hill can accumulate the same dry matter yield, the dry matter production of the ratoon plant of JW599 and JW630 is estimated to be 32.5 and 58.4 t/ha, respectively.

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Citrus trees affected by greening (huanglongbing, HLB) often develop symptoms that resemble those of Zn or Fe deficiency in their leaves. However, there have been few studies of mineral concentrations in infected leaves. To examine the effects of infection by ‘Candidatus Liberibacter asiaticus’ (the causal organism of the Asiatic form of HLB) on mineral nutrition, Citrus jambhiri (Lush.), C. reticulata cv. Siem, and C. depressa Hayata were patch-grafted with infected bark squares and grown in pots in greenhouses in Japan and Indonesia. In addition, leaves were collected from field-grown C. tankan Hayata and C. unshiu Marc. in Japan and C. reticulata cv. Siem in Indonesia, and their disease status was determined by PCR. Leaf samples were homogenized in 2-(N-morpholino) ethanesulfonic acid buffer and the concentrations of water-soluble Cu, Fe, Mn, and Zn in the macerate were determined using inductively coupled plasma atomic emission spectrometry (Japan) or atomic absorption spectrometry (Indonesia). In general, infected leaf samples had lower Fe and Zn. On average, the concentrations of Fe and Zn in infected plants were approximately half those in healthy plants. Cu was not significantly reduced by infection and Mn was occasionally lower. In C. unshiu, the concentrations of Fe and Zn were reduced before chlorosis appeared. These results suggested that the concentrations of particular elements (Fe and Zn) rather than element concentrations in general are reduced by infection by ‘Candidatus Liberibacter asiaticus’.

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In this study, the influence of individual cuticular hydrocarbons on nestmate recognition in Japanese hornets was investigated. Cuticular hydrocarbons were extracted from the individuals of several colonies of Japanese hornets, Vespa analis Fablicius (Hymenoptera: Vespidae), and analyzed by combined gas chromatography and mass spectrometry (GC-MS). In the case of V. analis, the results of the GC-MS analyses showed 12 major components and 20 minor components. The results showed some intraspecific variation in the quantities of each component of the profiles even within the same colony and same cast. The number of cuticular hydrocarbon compounds of V. analis was relatively high compared with that of V. crabro. Discriminant analysis of the cuticular hydrocarbon profiles of the workers and queens showed that the wasps could be grouped by colony and by caste even if the colonies were located at a close distance. The cuticular hydrocarbon profiles of workers and males were different.

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One of the direct approaches for obtaining a high yield of strawberries is high-density cultivation. Such cultivation improves the efficiency of space utilization in a greenhouse; however, it requires the movement of planting benches. The aim of this study is to develop a circulating-type movable bench system for strawberry cultivation that realizes high-density cultivation and improves work efficiency. The developed system, which is 16.0 m long and 9.2 m wide, consists mainly of two longitudinal conveying units, two lateral conveying units, two nutrient supply units, a chemical sprayer, 62 planting benches, and a control unit. The design of the longitudinal conveying mechanism combining the rotating and sliding movements of rods for pulling the benches and a method of controlling the conveying units achieves effective circulation, resulting in a cycle time of 67.0 s during which the successive bench reaches the initial position. This cycle time could be shortened by increasing the speed of lateral conveying. The planting density obtained using this approach is 16.0 to 20.0 plants m^-2, which is roughly 2 to 2.5 times the plant density obtained in the conventional method of cultivation. Furthermore, the four cultivars used in this study showed vigorous growth, and the cultivars Akihime and Moikko showed a marketable yield twice as high as the conventional yield.

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In this study, the effects of dibutyryl cyclic AMP (dbcAMP) on the preservation of porcine oocytes were investigated. Oocytes were preserved for 24 h or 48 h in modified NCSU37 supplemented with or without 1 mM dbcAMP. After the preservation, 98.3% and 95.2% of oocytes incubated with dbcAMP for 24 h and 48 h, respectively, were at the germinal vesicle stage, whereas about a half of the oocytes incubated without dbcAMP underwent germinal vesicle break down. These preserved oocytes were cultured for 46 h. The in vitro maturation (IVM) rates of oocytes preserved with dbcAMP for 24 h (84.0%) and 48 h (55.3%) were significantly higher than those of oocytes preserved without dbcAMP (48.0% and 21.6%, respectively). IVM oocytes with a visible first polar body were selected, fertilized in vitro (IVF), and cultured for five days. The rate of oocytes preserved for 24 h with dbcAMP and developed to the blastocyst stage after IVF was 21.4% and did not differ from that of oocytes without preservation (23.8%); however, the blastocyst development rate significantly decreased for oocytes preserved with dbcAMP for 48 h (5.2%). These results indicate that dbcAMP is effective for the preservation of porcine oocytes for 24 h without decreasing their developmental ability after IVF.

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This study examined the rate of fertilization in the Argentine shortfin squid Illex argentinus after artificial insemination using sperm from different sources, as well as the effect of cold-storage on the fertilization capacity of gametes from mature squids, and the impact of mechanical agitation on embryonic development. In addition, the process of chorionic expansion during the course of embryonic development was also examined. High fertilization rates were obtained from spermatophores (76-95%) and spermatozoa from the vas deferens (73-87%), but no fertilization was observed using spermatozoa from testes. Female and male gametes stored at 0°C had a high fertilization capacity (>72%) within 24 h. Embryos (stages 4 to 17; 3 to 61 h at 20°C) subjected to mechanical agitation at a critical period (stages 5 to 12; 5 to 20 h at 20°C) exhibited high mortality and abnormal development. In the course of embryonic development, the chorion expanded four times: once at fertilization and then at developmental stages 15-16, 17-21, and finally at stages 25-27. The growth rate of the third expansion corresponded with an increase in embryonic body length. To improve the fertilization rate and increase the production of healthy paralarvae in on-board experiments, factors such as the origin of spermatozoa, gamete storage methods, and the handling of fertilized eggs during the critical period should be carefully controlled.

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We studied the relationships among the soil C stock in tropical monsoon forests, the type of forest, and the environmental factors in the lower Mekong basin in Cambodia. We analyzed nine soil profiles in evergreen and deciduous forests growing over sedimentary rock and basalt. Evergreen forest soils tended to have a larger C stock than deciduous forest soils within geological formations. In evergreen and deciduous forest soils, carbon stocks were 56.9 ± 30.0 (mean ± SD) and 34.9 ± 23.5 Mg C ha^-1, respectively, in the 0- to 30-cm depth range, and 108.7 ± 53.0 and 53.2 ± 30.4 Mg C ha^-1, respectively, in the 0- to 100-cm depth range. Soil C stock was highly positively correlated with soil water content in the dry season, which is likely affected by the openness of the forest canopy and by soil clay content.

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With the aim of establishing silvicultural techniques for tree species indigenous to monsoon tropical areas, we examined the survivorship and growth performance of three tree species under different light conditions. A 23-year-old Acacia mangium plantation was thinned in different ways: group selection thinning (gap creation, 50 m by 60 m in size), 2/3 random selection thinning based on basal area, 1/3 random selection thinning, and no thinning (control). The seedlings of Hopea odorata, H. ferrea, and Xylia xylocarpa var. kerrii were planted in each treatment area with three replications. At 30 months after planting, all species achieved a high survival rate (>90%) in all treatments, perhaps owing to intensive tending in the experimental plots. Both stem thickening and height growth were promoted as light conditions improved: most in the gap plot and least in the control plot for all species. H. ferrea grew to a large height even in dark conditions, suggesting that this species is considerably shade-tolerant. In contrast, X. xylocarpa var. kerrii was light-demanding owing to vigorous growth in the gap plot. The growth of the seedlings seemed to be associated with regeneration patterns in their natural habitats. The group selection thinning seemed to be most suitable for the growth of indigenous tree species.

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There is an increasing interest in the sustainable supply of wood from New Zealand's plantation forests. This is due to the importance of New Zealand in global trade and uncertainty about the sustainability of supply from other countries, such as Russia. The aim of this paper is to identify important factors that influence log supply and demand for New Zealand and its key Asian markets (South Korea, Japan and China). To this end we used annual time series data from 1990 to 2008 to estimate export supply and import demand functions by two stage least squares with stepwise regression estimation. We found that New Zealand's log exports to Japan and South Korea are not sensitive to price, but exports to China are sensitive to price, while New Zealand's total harvest has a stronger influence on log export supply to China and South Korea. New Zealand's domestic log consumption competes with exports to Japan, but does not compete with supply to South Korea or China. Import demand in South Korea, Japan, and China for New Zealand logs is negatively affected by import price, with Japan's import demand the most price-sensitive. The three markets differ in the impact of gross domestic product on import demand. Gross domestic product has a strong positive impact on log demand in Japan and China, but a modest impact in South Korea.

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Paddy rice cultivation in rainfed areas in northeast Thailand has been practiced mainly by transplanting. However, the introduction of direct seeding is increasing in rainfed paddy fields for a variety of reasons, including saving on labor. To elucidate the relationship between the introduction of direct seeding, the selection of paddy lots, and precipitation in rainfed paddy field, we surveyed two small watersheds in Nong Saeng village, Khon Kaen prefecture, central-northeast Thailand. The surveys were carried out on a lot-by-lot basis between 2002 and 2004. In 2002, despite the lagging expansion of transplanting due to low precipitation in the early rainy season, direct seeding was not introduced. On the other hand, in 2003, direct seeding began before the transplanting area was expanded after rainfall in late August. In 2004, direct seeding began in the early rainy season of June and July. As to its relationship with topography, direct seeding was not conducted in the lower paddy fields in one watershed. However, the ratios of direct seeding increased in the middle and upper paddy fields in both watersheds in 2004. There were few households that did not continue direct seeding cultivation after introduction.

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