Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
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Original Article
  • Yoshifumi TERAJIMA, Amarawan TIPPAYAWAT, Werapon PONRAGDEE, Takshina S ...
    2019 Volume 63 Issue 1 Pages 1-11
    Published: 2019
    Released: August 20, 2019
    JOURNALS FREE ACCESS

    Northeast Thailand is a major sugarcane-producing area, accounting for 35% of the country’s total production, but low productivity during its long dry seasons has been a long-standing problem. Tetraploid Erianthus arundinaceus accessions collected in Thailand could potentially improve the drought tolerance and productivity of sugarcane here, but their early heading prevents intergeneric crossing with sugarcane. We previously developed and successfully applied a photoperiodic treatment (PT) in combination with different ratooning times to delay the heading of hexaploid E. arundinaceus in Japan. Thus, we evaluated the effectiveness of applying this method to tetraploid E. arundinaceus in the effort to enable intergeneric crossing with sugarcane. The effects of combining delayed heading by PT with two ratooning times (March and June) on five selected hexaploid E. arundinaceus accessions were evaluated in two years. The PT delayed the first heading dates by 31-35 days in combination with the March ratooning, and more (38-43 days) in combination with the June ratooning, relative to the heading dates of controls, exposed solely to natural light. Flowers obtained following the delays provided fertile pollen during the heading periods of the sugarcane breeding materials. Therefore, combining PT with different ratooning times can enable intergeneric crossing between these tetraploid E. arundinaceus accessions and sugarcane breeding materials heading from late November to early January. This delayed heading technique will expand the possibility of utilizing diverse tetraploid E. arundinaceus accessions for improving sugarcane in Thailand.

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  • Hiroaki SAMEJIMA, Byoung-Jae PARK
    2019 Volume 63 Issue 1 Pages 12-17
    Published: 2019
    Released: August 20, 2019
    JOURNALS FREE ACCESS

    Guava leaf extract has significant application in natural remedies and cosmetics. In this study, we have focused on the total polyphenol content and inhibition activity against skin dermis enzymes (collagenase, elastase, and hyaluronidase) and carbohydrate digestion enzymes (α-amylase and α-glucosidase). Dried powdered guava leaves were extracted in 70% methanol and lyophilized to produce a crude extract. Aliquots were further divided into Hexane fr., EtOAc fr., BuOH fr., and Water fr. Total polyphenol content was the highest in the BuOH fr. among the crude extract and the four fractions. The Hexane fr. did not reach the 50% inhibitory concentration (IC50) against all the enzymes studied. The crude extract, BuOH fr., and Water fr. showed low IC50 (high inhibition activity) against collagenase, elastase, and hyaluronidase, with the BuOH fr. having the highest inhibition activity. In addition, this had high inhibition activity against α-amylase and α-glucosidase. The ability to inhibit multiple enzymes, relating to skin aging or carbohydrate digestion, suggests significant potential for using guava leaf extract in natural remedies and cosmetics.

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  • Futoshi KATO
    2019 Volume 63 Issue 1 Pages 18-26
    Published: 2019
    Released: August 20, 2019
    JOURNALS FREE ACCESS

    In Tanzania, indigenous rice-cultivation productivity is generally lower than that of rice cultivation using modern irrigation systems, even though it is a nationwide practice. Practical improvements in indigenous rice cultivation are required to increase the productivity, stability, and sustainability of rice cultivation. Tanzania is a major rice-producing country in Africa and the demand for rice is continuously increasing; therefore, indigenous rice cultivation has also increased for more than 20 years. This study was focused on indigenous rice cultivation and aimed at elucidating the geographic distribution of indigenous rice cultivation and characterizing the techniques used. Fieldwork was conducted in Mwanza, Shinyanga, Tabora, Mbeya, Dodoma, Rukwa, Morogoro, and Dar es Salaam, which are the major rice-producing areas in Tanzania. Two basic rice-cultivation techniques are used in that country; one utilizes runoff from rainfall and the other uses floodwater from streams, rivers, and swamps. The former is practiced in northern and western Tanzania and is characterized by transplanting, building levees, and plowing with bullocks, while the latter is practiced in south-central Tanzania and is characterized by broadcasting seed, irrigating with floodwater, and using tractors. Furthermore, rice cultivation that utilizes runoff expanded from northern to southern regions of Tanzania in parallel with the migration of the Sukuma people; this has increased the diversification of Tanzanian rice cultivation. These indigenous rice-cultivation techniques were found to be affected by geographical, meteorological, and social conditions.

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Short Report
Information
  • Yu MON, Yoshinori YAMAMOTO, Mie Mie AUNG
    2019 Volume 63 Issue 1 Pages 38-46
    Published: 2019
    Released: August 20, 2019
    JOURNALS FREE ACCESS

    Of the 7,000,000ha of cultivated rice in Myanmar, submerged and deep- water areas account for 13.5% of the total area. Therefore, for cultivating submersion resistant varieties, the use of deep water- adapted cultural practices and/or the construction of drainage and flood protection infrastructures need to be undertaken to provide greater resilience from flooding especially in the delta region (Ayeyarwaddy, Bago and Yangon). The use of the cut-stem transplant method of rice production is practiced in Zee Pin and Ywa Houng villages (deep-water areas) situated in the Thanatpin Township, Bago Region. The method originated in Zee Pin village and was discovered accidentally when farmers observed root outgrowth from stem cuttings. At present, it is also practiced in Ywa Houng village in the Thanatpin Township. The seeds of the deep-water rice variety, Pawsan, are directly seeded in May after the start of the monsoon, and the elongated stems are cut at about 30cm above the soil surface in September when the seasonal water starts to recede. The stem-cut seedlings are about 100cm long and then, are brought by boat to the field where they are to be transplanted. Transplanting is done by women using wooden forks (Kauk Side Doke), placed between the first and second elongated internodes, to place the cuttings. Harvesting occurs around mid-December. Although the farmers believe that the yield from such a method is superior to the direct seeding method, further investigations are required to gain a clearer understanding of the benefits of the former method.

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