Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
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Original Article
  • Saki YOSHIDA, Chigusa TANI, Min San Thein, Ohm Mar Saw, Kenji WAKUI, ...
    2020 Volume 64 Issue 3 Pages 107-112
    Published: 2020
    Released: October 17, 2020
    JOURNALS FREE ACCESS

    Mustard (Brassica juncea L.) is an important vegetable worldwide. Its floral initiation has been reported to be related to the basic vegetative growth phase, a low-temperature, and a long-day requirements. Late flowering is required for year-round production when mustard is cultivated as a leaf vegetable, but many aspects of the flowering response are unclear. Herein, we investigated the responses of mustard genetic resources, collected from a tropical and/or sub tropical area of Myanmar under natural conditions, grown in an experimental field and under different temperature and day-length conditions, controlled by a phytotron. A total of 22 accessions from Myanmar were grown in a field in Tokyo, and the earliest accessions, M39 and M109, bolted at 38 days, M116 bolted at 71 days. The number of days from sowing to bolting varied widely among the accessions, up to 33 days. Regarding low-temperature requirements, we classified the accessions into three types: low requirement for low temperature (M44), high requirement for low temperature (M15), and neutral requirement for low temperatures (M36, M42, M96, P1). We observed that accessions J1, P2, M15, M36, M42, M44, and M96 could bolt without low temperature under certain long-day conditions. Conversely, we observed that J2 was a very late-maturing cultivar that did not bolt without low temperature even under long-day conditions.The critical day length of M15, M36, M42, M44, M96, J1 and P2 was estimated to be approx. 12 hr.

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  • Factors Shaping Permaculture Farm Systems in Humid Tropical Indonesia
    Radityo Haryo PUTRO, Rie MIYAURA
    2020 Volume 64 Issue 3 Pages 113-124
    Published: 2020
    Released: October 17, 2020
    JOURNALS FREE ACCESS

    Permaculture-based farming systems are relatively unexplored in the humid tropics. A few studies have shown that permaculture in such areas has diverse roles and contributions, but these are poorly understood. We hypothesized that the unique social needs of local people or the natural environment in the humid tropics influence how permaculture systems are shaped to operate and have roles that fit under local context. The present study sought to identify and validate these influences toward three different aspects of the permaculture farm: 1) operations, 2) management, and 3) crop diversity. Field surveys were conducted in Indonesia between 2016–2019. A total of six permaculture farms were found across the country, and four farms (one in Yogyakarta and three in Bali) were able to cooperate for the present study. Analysis of quantitative data, such as for determining crop diversity, involved using the Shannon and Simpson diversity indices. We identified that the surveyed permaculture farms’ operations, farm management, and crop diversity were shaped by fundamental permaculture principles, socioeconomic factors such as operational needs and profit-related managerial decisions, and socio-cultural factors such as the beliefs of owners and local societal needs. All permaculture farms shared structural similarities with the Indonesian home garden, ‘pekarangan’ and it is preliminarily assumed that they were based on such design. A combination of these factors shaped Indonesian permaculture systems to operate in multiple ways, with unique farm management practices, and produce diverse types of crops.

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  • Yoshinori YAMAMOTO, Tetsushi YOSHIDA, Isamu YANAGIDATE, Febby Jeanry P ...
    2020 Volume 64 Issue 3 Pages 125-134
    Published: 2020
    Released: October 17, 2020
    JOURNALS FREE ACCESS

    The growth characteristics and starch productivities of four major sago palm folk varieties (spiny types: Ihur, Tuni, Makanaru; non-spiny type: Molat) were compared on Seram and Ambon Islands, Maluku, Indonesia. These folk varieties were recognized there by spiny or non-spiny; length and density of the spine; the angle of leaf crown; the attaching features of leaflets to the rachis (horizontal or V-shaped); drooping of the leaflet tip; starch productivity; starch color, etc. There were no significant differences in growth characteristics, leaf and leaflet characteristics, starch content, and characteristics related to starch content among the four major folk varieties on Seram Island. The trunk growth characteristics and starch content of the Ihur and Tuni on Ambon Island were comparable to those of Seram Island. In addition, the starch productivities of the four major folk varieties, 500–600 kg plant-1, were superior to those of sago palms in Malaysia and in western areas of Indonesia. The starch contents were as high as those of the late-flowering folk varieties of the Indonesian territory on New Guinea.

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  • Yoshinori YAMAMOTO, Isamu YANAGIDATE, Tetsushi YOSHIDA, Akira MIYAZAKI ...
    2020 Volume 64 Issue 3 Pages 135-145
    Published: 2020
    Released: October 17, 2020
    JOURNALS FREE ACCESS

    The purpose of this study was to clarify the growth characteristics and starch productivity of wild sago palms (folk varieties Manno Kecil and Manno Besar) growing around Lake Sentani near Jayapura, Papua, Indonesia, as compared with the main cultivated folk varieties (Rondo and Para). Manno Kecil and Manno Besar were an early- and a late-flowering folk variety, respectively. Even when the number of years until flower bud formation, which is the optimum harvesting period, was almost equal, growth characteristics such as trunk length, diameter, and weight of the wild varieties were inferior to those of the cultivated ones. The starch productivities of the wild folk varieties were significantly lower than those of the cultivated ones due to the lower dry matter and starch percentages in the pith. On the other hand, the wild folk varieties had significantly higher total sugar, glucose, and fructose contents in the pith than did in the cultivated varieties. From these results, differences in the types of enzymes and their activities involved in starch synthesis in the pith between the wild and cultivated folk varieties might be suggested as the reason for the wild folk varieties’ starch contents being lower than those of the cultivated varieties. Regarding the inorganic component, the Ca contents in the pith of the wild folk varieties were significantly higher than those of the cultivated ones probably due to the differences in the degree of cell wall development in the pith cells.

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  • Faruque F. R. RAGU, Uwitonze THEOGENE, Hiromi TOMIZAWA, Hisashi URAYAM ...
    2020 Volume 64 Issue 3 Pages 146-152
    Published: 2020
    Released: October 17, 2020
    JOURNALS FREE ACCESS

    To provide a realistic regression equation appropriately expressing the relationship between rice yield and weather variables, multiple regression models were developed using a set of data measured during 2009-2017 at an experimental field at JICA Tsukuba Center, Japan. Correlation, stepwise method, and multiple regression analysis were applied to create regression equations predicting rice yield during a growing season. Yield of IR-28 and/or NERICA 4 was used as the dependent variable, and weather variables were used as the independent variable. A realistic criterion is that the adjusted R2 is comparatively high and the p value of significant value F is p < 0.05, and also p value for coefficient of independent variables is at the level p < 0.05. Applying the above criterion it was found that the regression equation which includes average daily temperature, total precipitation and evapotranspiration during the growing season is favorable for predicting crop yield with “IR-28”, while prediction for crop yield of “NERICA 4” is best estimated using the regression equation which includes maximum daily temperature and total precipitation during the growing season.

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