Research for Tropical Agriculture
Online ISSN : 2187-2414
Print ISSN : 1882-8434
ISSN-L : 1882-8434
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Showing 1-14 articles out of 14 articles from the selected issue
Original Article
  • Tomohiro KONDO, Kakeru KOGA
    2021 Volume 14 Issue 1 Pages 1-7
    Published: 2021
    Released: September 09, 2021
    JOURNAL FREE ACCESS

    Rice bean and local adzuki bean variety (swidden adzuki) used to be cultivated in low fertile soil under swidden conditions in Shiiba village, Miyazaki, Japan. These beans might have some ability to absorb minerals from the low fertile soil. To clarify N and P absorption ability of these two beans, these beans were cultivated in pots applying N, P, or no fertilizer, using soil at 22-month after burning. Modern adzuki bean variety, ‘Dainagon’, was also cultivated for comparison. Numbers of leaf increased with N and P fertilizer and P fertilizer postponed leaf aging. Number of flower was not affected by fertilizer and yield increased with P fertilizer. Numbers of flower and yield of the rice bean were more than those of the two adzuki varieties. Leaf N content increased with N fertilizer and leaf P content increased with P fertilizer. Leaf P contents in the rice bean and swidden adzuki were higher than that in Dainagon. Moreover, leaf P contents in the rice bean and swidden adzuki without fertilizer were higher than that in Dainagon with P fertilizer. With Truog method, available phosphate in the soil after cultivation did not differ by varieties, but with Bray 2 method, that in the rice bean was lower than those in the two adzuki varieties. Thus, the rice bean and swidden adzuki are suggested to have high P absorption ability. Especially, the rice bean was found to absorb P from Al- and Fe-P.

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  • Koji UCHINO, Hitoshi KUKITA, Osamu KUMAMOTO
    2021 Volume 14 Issue 1 Pages 8-13
    Published: 2021
    Released: September 09, 2021
    JOURNAL FREE ACCESS

    In this study, the fruit quality of ‘Natsutayori’ loquat was compared with ‘Nagasakiwase’ and ‘Mogi’ in Tarumizu City, Kagoshima Prefecture. In ‘Natsutayori’, the fruit weight was heavier and the flesh firmness was lower than ‘Nagasakiwase’ and ‘Mogi’. In addition, the fruit was sampled in three times (12 May, 19 May and 26 May) during harvest period, and the relationship between the skin color a* value and the fruit quality in ‘Natsutayori’ was investigated. On all harvest dates, as the skin color a* value increased, the fruit weight tended to increase. At the beginning (12 May) and at the middle (19 May) of harvest, the flesh firmness tended to decrease as the skin color a* value increased. At the end (26 May) of harvest, no significant difference was observed in the flesh firmness of fruit with skin color a* value of 8-14. And then, as the skin color a* value increased, the sugar content increased and the titratable acidity decreased. Based on the relationship between the skin color a* value and the fruit quality, it was determined that the skin color a* value for the appropriate harvest time in ‘Natsutayori’ was 8.

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  • Yuya ASAMI, Asako KARASUDANI, Horng-Liang LAY, Shoji INOUE
    2021 Volume 14 Issue 1 Pages 14-18
    Published: 2021
    Released: September 09, 2021
    JOURNAL FREE ACCESS

    The objective of this study is to analyze the effects on the growth and on the proportion of components of Bupleurum kaoi Liu. (B. kaoi) under the fertilizations of six different concentration rates of nitrogen. B. kaoi is a perennial herb native to Taiwan, and its roots are used for herbal medicines. The fertilizer of Hoagland solution was applied to B. kaoi plants only one time per week. Six different Hoagland solutions contained different amounts of NH4NO3: 0, 2, 4, 10, 16 and 22 mM. Also, the dry mass production and the proportion of components in the roots were recorded. The analysis of components of B. kaoi was conducted by using five types of Saikosaponins (SS): a, b1, b2, c and d. Turning to the growth and the property of dry mass production, the result demonstrated that the growth and the property tended to increase at the value above 10 mM in terms of the length of the plant, the numbers of leaf, and SPAD. Similarly, the dry mass of the plant both above and underground increased at the value over 10 mM. During the late growth stage, the growth underground continued at the value above 10 mM. By contrast, in the area in which the overall value was above 10 mM, there was no significant differences between growth and dry mass production. Also, the growth and the property of dry mass production were substantially high at the value above 16 mM in the analysis using the main types of Saikosaponins: SSa, and SSd, whereas the rate of components and the total amount of Saikosaponins elevated at the value above 10 mM with Sb1, SSb2, and SSc. From these results, the concentration rate over 10 mM of nitrogen in fertilizer, the proportion of components in the roots of B. kaoi attained its saturation point; therefore, the value of 10 mM could be the optimal nitrogen concentration for fertilizer.

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  • Kosuke SHIMIZU, Kentaro TATSUMI, Naoki UTSUNOMIYA, Shinya KANZAKI, Kim ...
    2021 Volume 14 Issue 1 Pages 19-25
    Published: 2021
    Released: September 09, 2021
    JOURNAL FREE ACCESS

    Recently, mangoes are cultivated in various regions in Japan, but domestic cultivation still depends on one cultivar, ‘Irwin’. ‘Aiko’, a new cultivar bred in Kindai University, is characterized by larger fruits, less pulp fiber, later harvesting time than ‘Irwin’, and expected as an alternative cultivar to ‘Irwin’. As ‘Aiko’ has strong biennial-bearing tendency, it’s necessary to clarify flowering characteristics to establish a cultivation management suitable for ‘Aiko’. In this study, we investigated the effects of the previous year’s fruiting and the number of flushes on the proportion of reproductive shoot. Furthermore, the expression profile of MiFT gene was analyzed. The results showed that ‘Aiko’ has lower floral inducibility than ‘Irwin’, and that the previous year’s fruiting strongly influenced the proportion of reproductive shoot in ‘Aiko’. In both cultivars, the number of flushes was higher in unfruited branches than in fruited branches. The proportion of reproductive shoot in ‘Irwin’ was high regardless of the number of flushes, while that in ‘Aiko’ was higher for branches with more frequent shoot expansions. MiFT expression was hardly affected by the intensity of crop load and was higher in ‘Irwin’ than in ‘Aiko’. In ‘Aiko’, it was shown that it is important to secure a shoot that has flushed more than three times after pruning. Thus, the cultivation method like intentional biennial bearing method, in which productive and non-productive years are clearly distinguished, should be considered for ‘Aiko’.

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Short Report
Symposium
Commemorative Lecture by the Winner of Award for Academic Excellence in Tropical Agriculture-out line
Commemorative Lecture by the Winner of Promotional Award for Achievement in Tropical Agriculture-out line
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