Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
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Original Article
  • Sota YAMAMOTO, Wardis GIRSANG
    2021 Volume 65 Issue 1 Pages 1-9
    Published: 2021
    Released: July 16, 2021
    JOURNALS FREE ACCESS

    We conducted an ethnobotanical survey on Capsicum peppers on the islands in Maluku Province, Indonesia to investigate the local nomenclature for, and distribution and usage of, Capsicum peppers. Two species, C. annuum and C. frutescens, are distributed in Maluku Province. A general name for Capsicum peppers on Ambon Island is “cili”, which is probably derived from “chile” in Spanish. However, other general names, which have unknown origins, are used on the other islands. On Buru Island, the C. frutescens cultivar with small fruit that are green when immature (GR type) has a specific local name “arbasina”. Furthermore, many people think that the GR type is native to their region. It is possible that the GR type was the first to be widely distributed across islands in the Pacific region. The GR type is commonly thought to be the spiciest and have a pleasing aroma. Fresh, dried, and salted fruit, as well as fruit soaked in palm vinegar or lime juice are widely used as spices and condiments. Fresh fruit are also added to palm wine or liquor to make it spicier and stronger-tasting. Few people use Capsicum leaves as a vegetable. In terms of medicinal usage, leaves are used to treat boils and swellings, and fruit are applied to wounds. These two remedies are commonly applied throughout Maluku Province. Regarding popular beliefs, fruit are used to stop rain events and for getting rid of snakes from houses or fields.

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  • Yuya ASAMI, Asako KARASUDANI, Horng-Liang LAY
    2021 Volume 65 Issue 1 Pages 10-16
    Published: 2021
    Released: July 16, 2021
    JOURNALS FREE ACCESS

    Waterlogging changes the soil environment. The excessive amount of water in soil inhibits oxygen supply to the roots, by developing anoxic conditions at the depth of a few centimetres from the soil surface. Lack of oxygen slows the growth of plants, occasionally leading to the death of the whole plant. This study investigated the individual and combined effects of waterlogging on Chrysanthemum indicum (C. indicum) growth and its flower components, using a pot experiment in a greenhouse with four different waterlogging stress treatments (ws): 1, 3, 5 and 10 days waterlogging stress (ws 1, 3, 5 and 10d) and normal watering: control (ck). For ws 5d and 10d, both the above-ground dry weight and that of the roots decreased at DO values below 5.0 mg L-1. At the beginning of the waterlogging treatment, the growth of ws 5d and 10d slowed down and finally, after two weeks, the latter completely died. Moreover, the flowering of the ws 5d was delayed due to waterlogging, making it impossible to harvest the flowers. As the period of waterlogging became longer, the dry weight of the flowers decreased. Also, that of the flowers of ws 3d significantly decreased by 80% compared with ck. Similarly, the components of the flowers became remarkably less for ws 3d. Finally, this study showed that the dry weight and flower components significantly decreased under waterlogging stress for 3 days or more.

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  • Yoshinori YAMAMOTO, Naoya TAKEMORI, Fransiscus Suramas RENBON, Tetsush ...
    2021 Volume 65 Issue 1 Pages 17-28
    Published: 2021
    Released: July 16, 2021
    JOURNALS FREE ACCESS

    The biomass of sago palms, growing in the natural forest of South Sorong, West Papua, Indonesia, was measured by fresh and dry weights, and the change in the biomass production in each organ/part with age was examined, using the number of leaf scars and leaves as an index of palm age (a total of 16 plants with 19–145 number of leaf scars and leaves). The biomass increased exponentially after trunk formation, especially after attaining 80 leaf scars and leaves and the fresh and dry weights of the above-ground part (shoot) at the optimal harvest stage (from bolting to the emergence of the inflorescence stage) were 3200–3700 kg and 1030–1230 kg, respectively. The trunk mainly contributed to the increase in the shoot biomass, and the leaf contribution was small. With increasing palm age, the ratio of leaves—mainly the petiole and leaf sheath—in the shoot biomass decreased, while that of trunk, mainly pith, increased. The fresh and dry weight ratios of the pith at the harvest stage to the shoot weight were 66% and 57%, respectively, and 80% and 71% to the lower trunk weight, respectively. Sago palms in the natural forest tended to have a lower dry matter percentage in the pith, a higher ratio of bark and a lower ratio of pith in the dry weight at the harvest stage than did the sago palms under cultivation conditions.

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  • Lu Trong LE, Hoang Thai DINH, Kenta WATANABE, Kenji URESHINO, Masashi ...
    2021 Volume 65 Issue 1 Pages 29-40
    Published: 2021
    Released: July 16, 2021
    JOURNALS FREE ACCESS

    Sugar content is an important consideration when evaluating the quality of strawberry fruit and is governed by the interaction between the plant and its environment during growth. In this study, we examined the reproductive growth rate of strawberry and its relationship with sugar accumulation in the fruit under different phosphorus concentrations (2, 6, and 12 mM) and light spectra (purple light-emitting diode [LED] light [PL], white LED light [WL], and white fluorescence light [WF]) under plant factory conditions. In the early growth stage, the plants grew best with the P6WL treatment, which led to a low relative growth rate (RGR) in the reproductive stage. During the reproductive period, the net assimilation rate had a major effect on the difference in RGR among treatments and was mainly controlled by the phosphorus concentration. Relative allocations of RGR to vegetative and reproductive growth rate were impacted by both of phosphorus concentration and light spectrum; 6 or 12 mM phosphorus and white spectra enhanced the reproductive growth rate, while 2 mM phosphorus and PL significantly improved the vegetative growth rate of the plants. A high reproductive growth rate together with high sucrose phosphate synthase activity resulted in higher levels of fruit sugar accumulation, with the reproductive growth rate and sugar accumulation being highest in the P6WL treatment and lowest in the 12WF treatment. Therefore, we demonstrated that controlling the phosphorus concentration and light spectrum could direct plant growth and fruit sugar accumulation in strawberry.

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  • Sumetee LISWADIRATANAKUL, Michel OUYABE, Hideki HINOMIZU, Kanako TAKAD ...
    2021 Volume 65 Issue 1 Pages 41-48
    Published: 2021
    Released: July 16, 2021
    JOURNALS FREE ACCESS

    Soil fertility is one of the most important limitations in yam (Dioscorea spp.) growth and yield. This study evaluated the effect of bacterial inoculation on the growth and source of nitrogen in water yam (D. alata L.) cv. A-19 under growth chamber conditions. The plants were inoculated with two different inoculant concentrations (10+4 and 10+6 CFU.ml-1) of Agrobacterium sp. strain 343, which was previously isolated from the root of water yam cv. A-19, along with a non-inoculated as the control treatment. Sterilized vermiculite was used as a growing substrate and data were collected at 30, 60 and 90 days after inoculation. The inoculation significantly improved most of all growth parameters (i.e., the number of leaves, leaf area, plant dry weight and chlorophyll content) and nitrogen content in leaves of inoculated plants compared with the control. The δ15N results suggest that 33 to 51% N in inoculated plants could be derived from the atmosphere. To the best of our knowledge, this is the first work reporting the effects of its root endophytic bacterial inoculation on yam.

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