This paper provides new information on the distribution of Japanese native Vigna species in the subgenus Ceratotropis. The azuki bean complex (Vigna angularis) in Japan consists of cultigen, wild, weed and complex population types. Population genetic studies of this complex based on AFLP and RAPD analyses have revealed clinal variation in Japan. Population analyses have also provided support for hypotheses related to the origin of weedy azuki bean. The complex population type displays greater genetic variation than other population types in the azuki bean complex. Thus complex populations are the logical focus for both in situ and ex situ conservation. The wild and weedy Vigna species of Japan are a potential source of useful traits for agriculture and agriculturally related industries. Currently V. riukiuensis (V. minima subsp. minor var. minor) is being used as a bridging species to enable gene transfer among sexually incompatible Vigna cultigens. The potential of the genus Vigna to become a genetic model to enhance the understanding and genetic improvement of the tropical grain legume cultigen group is discussed.

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We determined the gross rates of nitrification and nitrate immobilization in soil using a ¹⁵N-nitrate isotope dilution technique. We also measured the amounts of nitrate immobilization and denitrification simultaneously by combining the acetylene inhibition technique and mass balance of nitrate. The immobilization rate of nitrate was enhanced by about 2 orders of magnitude by the addition of straw, while it did not increase significantly by the addition of manure. The denitrification rate in soil under anaerobic conditions was remarkably enhanced in the presence of straw, and enhancement of denitrification was also observed to some extent by the addition of manure or bark manure. In the soils treated with straw, the immobilization rate of nitrate under aerobic conditions was 24% of the denitrification rate under anaerobic conditions. Effect of water addition on nitrate immobilization and denitrification in soil was investigated in the presence or absence of straw. The amount of nitrate immobilization in the soils with straw did not change drastically with the moisture content, while that of denitrification changed by 2 or 3 orders of magnitude with the moisture content between 54-84% of the maximum water-holding capacity of soil irrespective of straw addition.

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Recently, Etiella behrii has been identified as a pod borer of soybean in Indonesia. This species had been presumably confused with E. zinckenella due to their similarity in external characters. We, therefore, compared the characteristics and sex pheromone between the two Etiella species. They could be accurately discriminated based on some external characters at both larval and adult stages, without examination of their genitalia. Duration of developmental stage of the insects reared on an artificial diet was 8 days longer in E. behrii than in E. zinckenella at 25°C. Premating period was 3 days longer in E. behrii than in E. zinckenella. Other biological data concerning mating and oviposition were similar between the two species. The sex pheromone of E. behrii was found to be a mixture of (E)-9-dodecenyl acetate (E9-12:Ac), (Z)-11-tetradecenyl acetate (Z11-14: Ac), dodecyl acetate (12:Ac), and (E)-11-tetradecenyl acetate (E11-14:Ac). Z11-14:Ac and E11-14:Ac are the common components in the two species. E9-12Ac and 12Ac in E. behrii, and 14:Ac and Z9-14:Ac in E. zinckenella could be key components in reproductive isolation between the two species. Moreover, the optimum dose of the mixture for capturing E. behrii males was much smaller than that for E. zinckenella males.

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The objective of this study was to develop an automated rice transplanting system in paddy fields. It is necessary to determine the precise position and direction to control the vehicle automatically in paddy fields. In this paper, the position of the rice transplanter was determined by real-time kinematic GPS (RTKGPS). The inclination of the rice transplanter influenced the RTKGPS position data, including time delay because the GPS antenna was set at a 2 m height from the ground. The correction can be performed by measuring the roll, the pitch and the yaw angles of the rice transplanter. The yaw angle was measured using a fiber optic gyro (FOG) sensor and the roll and pitch angles were measured using an inclination-measuring apparatus consisting of 3 FOG sensors and 3 accelerometers. When the rice transplanter was driven automatically along the desired straight path, the deviation from the desired straight path was less than 10 cm.

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The gene expression of proteins involved in adipose tissue metabolism was compared among rats fed a low-fat diet (2% safflower oil), and high-fat diets containing 20% saturated fat (palm oil) or unsaturated fat rich in linoleic acid (safflower oil) for 3 weeks. High-fat diets decreased the lipoprotein lipase mRNA level in the epididymal but not in the perirenal white adipose tissue. Leptin gene expression in the perirenal but not in the epididymal white adipose tissue was significantly higher in rats fed high-fat diets than in those fed a low-fat diet. mRNA levels of glucose transporter 4, both in the epididymal and perirenal white adipose tissues, were lower in rats fed high-fat diets than in those fed a low-fat diet. High-fat diets increased the gene expression of uncoupling protein 1 and lipoprotein lipase in the interscapular brown adipose tissue, but did not affect that of leptin. Adipose tissue mRNA levels of various proteins were comparable between rats fed diets high in safflower and palm oil. We concluded that the high-fat diet influenced the gene expression in adipose tissue in a site-specific manner. The difference in the degree of unsaturation of dietary fats was rather irrelevant in modifying the level of mRNAs for proteins related to energy metabolism and expenditure in adipose tissue.

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As vegetables are often grown under continuous cropping in Japan, injury associated with continuous cropping is frequently observed. Although the methods of control are based on the use of chemicals, the importance of promoting sustainable cultivation and environment-friendly technologies is being increasingly recognized. Plant diseases caused by fungi or bacteria, such as clubroot, yellows are major problems. To address these problems, crop rotation with sweet corn, introduction of resistant radish varieties as trap crops or inoculation with endophytes have been applied. Injury caused by nematodes is also a serious problem. Practical methods using antagonistic plants such as marigold have been developed, because only one season is required to introduce these plants with only minor changes in the cropping systems. Selection of crop combinations is essential. Taro (Colocasia esculenta Schott.) is severely damaged by a root lesion nematode (Pratylenchus coffeae). By examining the degree of suppression of this nematode by many kinds of crops, determination of crop sequence efficiency became possible for the control of nematodes and offers a wider range of selection of crop combinations. Taro is injured by P. coffeae and by the root knot nematode (Meloidogyne incognita), while radish (Raphanus sativus L.) is attacked by the root lesion nematode (Pratylenchus penetrans). The combination of these 2 vegetable crops with a third one, such as vegetable soybean (Glycine max), can minimize the injury caused by these 3 nematodes.

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A technique of forcing bloom of carnation for special market demand was developed. It enables ornamental growers to produce a large amount of cut carnation flowers during the intended period at a low cost. The outline of the technique is as follows. 1) Pinching shoots at the higher node and level them. By this treatment, many axillary buds start to grow simultaneously. 2) Carrying out shoot thinning and temperature control based on the degree of shoot growth. The date of budding, the bud size and the distance from the top of the pre-budding stem to the tip of the leaves can be used as indices for the estimation of growth and for the prediction of the flowering time. During the intended period of 12 days, the cut flower yield by this technique was as high as 20 stems per stock and 134 stems in each 1 m² bed area using standard type carnation cv. ‘Francesco’. The appropriate time of the last pinching extended from the end of October to the middle of November in the warmer regions of Japan. In addition to the advantage of cost reduction by decreasing the number of carnation seedlings and fuel expenditure, this technique is suitable for continuous culture for 3 years.

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Experiments were conducted using Satsuma mandarin trees grown in small containers to investigate the effects of mild salt (5 and 10 mM NaCl in irrigation water) and water stress on growth, photosynthesis, transpiration, fruit quality as well as macro- and micro-element contents in leaves of Silverhill Satsuma mandarin (Citrus unshiu Marc.) grafted on trifoliate orange (Poncirus trifoliata (L) Raf.) rootstocks. Salt and, to a greater extent, water stress treatments resulted in reduced photosynthetic rates, although there were no significant effects on tree growth estimated by recording the increase in stem diameter. Water stress decreased the leaf water potential and increased the stomatal resistance compared to control and salt-stressed trees which showed similar values, while the concentrations of sodium and chloride of the spring-flush leaves were not affected by the salt or water stress treatments. Potassium concentration of these leaves, however, was reduced significantly by 10 mM NaCl and water stress. Fruit maturity was advanced by water stress although the fruit size (diameter) and fresh weight were reduced. Internal fruit quality in terms of Brix value and Brix:citric acid ratio was improved for the trees irrigated with 10 mM NaCl solutions or subjected to water stress.

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In order to screen mulberry genotypes suitable for fruit production, fruit traits of 260 genotypes were examined. Forty-three genotypes were classified into staminate, 137 were pistillate and 78 were hermaphrodite. Fruit quantity and size showed wide variations among the genotypes. Itouwase, Shizensei-roso and Tenmokuyotsume bore more fruits than the other genotypes. Okaraguwa bore the largest fruits, which were 4.9 cm long and weighed 7.15 g. The sugar content of the fruit ranged from 6.6 to 20.8%, and the highest content was observed in Myurienoaaru. Most of the taste panelists rated Okaraguwa and Kataneo higher than the other genotypes. Thus, these 2 genotypes were selected as the most suitable for fruit production. In the next step, we attempted to develop polyploids from these genotypes by colchicine treatment to achieve a high productivity. After the treatment, we propagated the shoots with putative tetraploids to obtain the strains. The 2 strains thus developed were mixoploids of diploids and tetraploids, but it is considered that they were both peripheral chimeras and that their structure remained stable. One of the strains, FRM-01 developed from Kataneo, bore many fruits in the second year after planting in the field. Almost all the fruit traits of this strain were the same as those of the original strain, except that the size became larger and the fruit yield was increased by about 60%.

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In order to clarify the ecological habit of the skipjack tuna, Katsuwonus pelamis, at the juvenile stage, we implemented a research program from 1992 to 1996. For the main activity of the program, we conducted survey cruises to determine the distribution of juvenile skipjack tuna in the offshore areas of Palau and Micronesia, in the tropical western Pacific, during October to December. We developed a new sampling gear, a high-speed midwater trawl net with a large mouth that enables to collect large numbers of juvenile tunas. We analyzed the relationship between the horizontal and vertical distribution of the juveniles and oceanographic conditions, feeding habit of the juveniles based on stomach content analysis, and growth process of juveniles by otolith increment analysis. The results of our analyses indicated that juvenile skipjack tuna was widely distributed in the offshore area from the North Equatorial Current to the North Equatorial Counter Current, around the Palau and Micronesian Islands. We concluded that these areas were important for juvenile skipjack tuna as a nursery ground.

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