Research for Tropical Agriculture
Online ISSN : 2187-2414
Print ISSN : 1882-8434
ISSN-L : 1882-8434
Volume 13 , Issue 1
Showing 1-11 articles out of 11 articles from the selected issue
Original Article
  • Comparison of the ITPGR and the Convention on Fisheries Resources
    Kunihiko KOBAYASHI
    2020 Volume 13 Issue 1 Pages 1-7
    Published: 2020
    Released: April 23, 2021
    JOURNALS FREE ACCESS

    The purpose of this paper is to clarify the balance in how to define each public interest by conservation and utilization for plant genetic resources and fishery resources, using International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGR) and the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR).ITPGR has built its own system, Multilateral System (MLS), with the intention of promoting the use of plant genetic resources, and the public interest by the conservation and utilization of plant genetic resources should enhance the public interest of conservation through the utilization of plant genetic resources. In other words, the balance of the public interest is secured by “connecting” the benefits arising from utilization to conservation of plant genetic resource. On the other hand, the CCAMLR focuses on the finiteness of fishery resources, and uses various functions prescribed by the Convention in consideration of the effects on ecosystems including fishery resources and conserves them. Though it is the same category of resources, it was clarified that the adjustment of the public interest of conservation and utilization of each resource differs depending on the characteristics of the resources: the case where the public interest is ensured by considering the effect of utilization (fishery resources) and the case where the benefit generated from utilization is connected to conservation (plant genetic resources).

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  • Yoshinobu KAWAMITSU, Mai NAKABARU, Hiroo TAKARAGAWA, Hoang T. DINH, K ...
    2020 Volume 13 Issue 1 Pages 8-19
    Published: 2020
    Released: April 23, 2021
    JOURNALS FREE ACCESS

    In order to stabilize sugarcane production by utilizing the limited water resources of the island area, it is necessary to determine the amount of irrigation while measuring soil moisture, evapotranspiration and plant conditions. In this report, we tried to estimate the rate of transpiration per plant, which is the basis of the water saving irrigation. Meteorological factors measured by the newly developed weather station (Halser View) and transpiration rate using an electronic balance were measured at 10-min intervals, and the relationship between those parameters were analyzed. The transpiration rate of sugarcane was measured under the following three conditions; 1) normal irrigation, 2) acute water stress, and 3) gentle water stress. As a result, under sufficient irrigation conditions, the transpiration rate of sugarcane plants could be regressed by solar radiation, vapor pressure deficit, temperature, and relative humidity. However, using the measured values for the first three days, we made a multiple regression model with these four factors as explanatory variables, and we could estimate the diurnal change of transpiration rate over the next 8 days with high accuracy. On the other hand, the irrigation was stopped and under the water stress of pF 2.5 and above the transpiration rate fell rapidly, almost to zero at pF 4. However, even under such water stress conditions, the diurnal changes in transpiration rate could be estimated by adding a correction term based on the soil pF value.

    Thus, the possibility of smart agriculture that can estimate the transpiration rate of sugarcane individuals using meteorological factors and soil moisture data and determine the timing of irrigation in real time has been shown.

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  • Hiroo TAKARAGAWA, Yoshinobu KAWAMITSU
    2020 Volume 13 Issue 1 Pages 20-26
    Published: 2020
    Released: April 23, 2021
    JOURNALS FREE ACCESS

    Sugarcane is grown under adverse conditions. Planting several varieties with different geo-ecological types is suggested to enhance risk diversification against such condition, which could result in stable production. The importance of varietal diversity has been paid attention from the early era of breeding in Japan. However, its quantitative evaluation considering both number and area ratio of cultivated varieties has never been attempted, which prevents further discussion concerning optimum variety composition. The present study attempted to quantify varietal diversity using ecological means with the objective to discuss the current status and perspective of the diversity. Varietal diversities were different between two administrative divisions (Okinawa and Kagoshima prefectures) and between two milling regions in Okinawa (Centrifugal and non-centrifugal) with different policies and preferences. Variety evenness was suggested to contribute to the increased diversity in Kagoshima and non-centrifugal region in Okinawa, while variety richness did in centrifugal region in Okinawa. In addition, multiplicative beta diversity indicated that variety composition tended to be similar between regions despite of increased number of varieties in Okinawa. These results suggested that update of the extension strategies would accelerate an effective variety choice and utilization. Because there is a limitation to improve varietal diversity only by increasing number of varieties, an additional approach to manage evenness, namely variety composition is also required. A new administrative system such as control of propagation and public awareness for optimum variety use should be considered.

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