Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
64 巻 , 1 号
選択された号の論文の7件中1~7を表示しています
Original Article
  • Hironobu SHIWACHI, Natsumi MIWA, Kanako TAKADA, Michel OUYABE, Babil P ...
    2020 年 64 巻 1 号 p. 1-6
    発行日: 2020年
    公開日: 2020/07/02
    ジャーナル フリー

    In our previous experiment, water yam (Dioscorea alata L.) was able to grow under low-fertility soil conditions and nitrogen in the plant was found to be derived from the air. Moreover, some genera of nitrogen-fixing bacteria (NFB) were subsequently isolated. The objective of this study, therefore, was to confirm and identify the infection route of NFB in water yam plants. Plants were grown in pots with sterilized river sand (control) or river sand plus non-sterilized soil (treatment) in an artificial climate chamber. The soil used was the same as that used in our previous experiment in which NFB were isolated. Control and soil-treated plants were grown till harvest at 120 days after planting under no-fertilizer conditions. Endophytic NFB were isolated from the roots, vines, and leaves of control and treatment plants. Fourteen genera of NFB endophyte were identified after culture on SMM-N and MR media. The results suggested that NFB infect water yam plants via the soil, seed tubers, or airborne transmission. The seed tuber surface was subsequently sterilized with fungicide, and the results suggested that the NFB were transmitted via the air or from inside the seed tuber. This is the first report to identify the bacterial infection route in water yam plants.

  • Gulbuddin GULAB, Saidajan Attiq ABDIANI, Naoki TERADA, Atsushi SANADA, ...
    2020 年 64 巻 1 号 p. 7-12
    発行日: 2020年
    公開日: 2020/07/02
    ジャーナル フリー

    In Afghanistan, urbanization, population increase, climate change, the application of chemical inputs, hybrid seeds, greenhouse and processing technologies, trade activities and other facilities have brought about great changes in production and the consumption rate of vegetables, especially in the case of tomato. A field survey on the production, trade and post-harvest handling of tomatoes was conducted in Eastern region of Afghanistan, using questionnaires. The interviewees were agricultural organizations, producers, traders, consumers and university professors. The objective of the survey was to evaluate the tomato production, trade, and the post-harvest handling process in the area, and it was found that the availability of quality inputs such as hybrid seeds and fertilizers had a great impact on the yield and quality of the fruit as well as the post-harvest technology on the prevention of fruit loss. According to the results, the SWOT (Strengths, Weaknesses, Opportunities, and Threats) matrix was summarized. Based on the findings, we hope to improve the pre-and post-harvesting activities in order to increase the income of stakeholders through better agriculture practices and a reduction of loss.

  • Case Studies in Two Karen Villages of the Bago Mountains, Myanmar
    Khin Nilar SWE, Eiji NAWATA
    2020 年 64 巻 1 号 p. 13-22
    発行日: 2020年
    公開日: 2020/07/02
    ジャーナル フリー

    The dynamic and complex nature of swidden agriculture makes it difficult to detect the area from satellite images and Landsat-related methodologies in many studies. Thus, mapping methods for current agricultural land use and swidden land use detection methods from freely available time series satellite images were developed, integrated with detailed information of ground truths and interview surveys in order to contribute to sustainable land use management for legally unrecognized swiddens in Myanmar. Satellite images were classified by using the NDVI break value method and maximum likelihood method, which were then specified with the multiple criteria of ground truths such as the elevation and size of swidden fields. The accuracy of these methods was examined with actual ground truth data collected in 2016. As the maximum likelihood method showed better accuracy to detect the swidden fields, it was, therefore, selected. The accuracy test revealed that over 70 % of the actual swidden plots were detected and the failures of such detection were mainly caused by incomplete burned fields and small-sized swidden plots as well as the topography. However, the developed method is applicable for swidden land use detection at the plot level with preferable accuracy in undulating hilly regions.

  • Yoshinori YAMAMOTO, Isamu YANAGIDATE, Akira MIYAZAKI, Tetsushi YOSHIDA ...
    2020 年 64 巻 1 号 p. 23-33
    発行日: 2020年
    公開日: 2020/07/02
    ジャーナル フリー

    The names of 21 folk varieties of sago palm (hereafter varieties) were mentioned by the sago palm growers around Lake Sentani near Jayapura, Papua State, Indonesia, which is included in the sago palm’s area of origin, based on the earliness of flowering, morphological differences, starch yield and quality, ecological characteristics, etc. Among these varieties, 8 major varieties focusing on starch productivity were selected, and 5 to 7 palms of each variety were sampled at the optimum harvest stage (flower bud formation to fruit-setting stage) to obtain and compare their growth characteristics and starch productivity. The early-flowering variety (one variety) had a short growth period of about 13 years, but both the trunk length and diameter were inferior to those of the late-flowering varieties (years to harvest: 19 to 21 years), and the starch productivity was also lower. In late-flowering varieties (7 varieties), differences in the trunk weight and volume were found due to differences in the trunk length and diameter. The varietal difference in starch percentage in the pith was small, so the starch content (yield) was determined by the pith dry weight, closely related to trunk weight and volume. The starch content was highest for the variety Para, which showed an average content of 674 kg, with a maximum content of 975 kg. The content of macronutrients in the pith tended to be higher in the order of K> N> Ca> Mg> P, and the content per plant was mainly determined by the pith dry weight.

  • Kazutsuka SANMIYA, Yoshito KOJA, Akira IGUCHI
    2020 年 64 巻 1 号 p. 34-40
    発行日: 2020年
    公開日: 2020/07/02
    ジャーナル フリー

    In view of the progression of global warming, the molecular breeding of crops, tolerant to high temperatures is an urgent concern for agricultural practices in the future, particularly in the tropical and sub-tropical areas. This makes it necessary to elucidate the molecular mechanism of heat-shock response (HSR) in plants. It has been demonstlated that heat-shock factors (HSFs) play central roles in regulating most of the genes involved in HSR, including those for heat-shock proteins (HSPs). Among the HSFs, HSFA1 is an essential factor involved in HSR, while HSFA2 and HSFA3 directly induce the expression of genes essential for overcoming high-temperature stress (HS). In this study, we cloned the HsfA1, HsfA2 and HsfA3 cDNAs from tobacco, which were designated as NtHsfA1, NtHsfA2 and NtHsfA3, respectively. Sequence analyses of the cDNAs revealed that they were partial cDNAs. Phylogenetic analysis confirmed that they could be classified into three groups, namely, HsfA1, HsfA2 and HsfA3. A comparison of tobacco HsfA1 with its homologous genes suggested that this gene group is more diverse than the groups of HsfA2 and HsfA3.

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