Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
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Displaying 1-5 of 5 articles from this issue
Original Article
  • Suguru TSUCHIMOTO, Hiroe SAKAI, Kiichi FUKUI
    2022 Volume 66 Issue 3 Pages 83-88
    Published: 2022
    Released on J-STAGE: November 08, 2022
    JOURNAL FREE ACCESS

    Jojoba (Simmondsia chinensis [Link] Schneider) is a shrub mainly cultivated in subtropical arid countries. Its seeds produce a unique oil, called jojoba oil, that consists of liquid wax monoesters similar in structure to the wax component of human sebum. Jojoba oil is well known as a skin moisturizer. To examine the potentials of jojoba as a crop in a subtropical arid country, we established a 4.2 ha experimental jojoba farm in Egypt in 2017. After two years’ cultivation, the first seeds were harvested in 2019. To elucidate the properties of crude jojoba oil extracted from them, oxidative stability and antioxidant activity, both of which are significant properties for natural oils, were compared with other oils. We observed that crude jojoba oil had higher oxidative stability and antioxidant activity than over two-thirds of the other oils. Although refined jojoba oil exhibited the highest oxidative stability among all oils, its antioxidant activity was poor, unlike the crude type, suggesting that the latter oil is suitable for cosmetic use because it has both good oxidative stability and antioxidant activity. These properties are also useful for other applications such as industrial lubrication, suggesting that jojoba is a promising fruit crop in subtropical arid countries, which will also contribute to economically-sustainable desert greening.

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  • Tomohiro KONDO, Kenta IKAZAKI, Jonas KOALA, Koichi TAKENAKA
    2022 Volume 66 Issue 3 Pages 89-94
    Published: 2022
    Released on J-STAGE: November 08, 2022
    JOURNAL FREE ACCESS

    Mango is one of tree crops in Burkina Faso. Young plant, which is propagated at nursery, is generally used for planting. The root system of young plants was poor in the nursery. This would be due to the excessive water stress caused by improper irrigation and poor drainage. Therefore, we examined the effects of a porous material as well as reduced irrigation frequency on the vegetative growth of the mango plants at the Saria station of Institut de l’Environnement et de Recherches Agricoles. The porous material was created from indigenous materials. The pot experiment was conducted with a two-factor factorial design; the porous material was placed at the bottom of pot (BTTM), mixed with the pot soil (MIX), or not used (CNTRL_P). The plants were irrigated once in the morning (AM) or afternoon (PM), or twice a day (CNTRL_I). Two-month-old mango plants were transplanted to the pots on July 20 and growth parameters were measured monthly. Survival rate and vegetative growth for MIX was enhanced; trunk diameter, plant weight and height, leaf number and length, and SPAD value for MIX were higher than for CNTRL_P. Vegetative growth for BTTM were also improved but the survival rate was not. Vegetative growth and survival rate for AM did not decrease compared with those for CNTRL_I, though those for PM decreased. Mixing porous material with pot soil would be effective cultivation method for young mango plant and reducing irrigation frequency would be possible at the nursery in Burkina Faso.

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  • Yoshinori YAMAMOTO, Ayumi OCHI, Isamu YANAGIDATE, Hiroto ISHIMA, Tetsu ...
    2022 Volume 66 Issue 3 Pages 95-103
    Published: 2022
    Released on J-STAGE: November 08, 2022
    JOURNAL FREE ACCESS

    We investigated the changes in the leaf characteristics and shoot biomass with plant age of ‘sagu baruk’ on Sangihe Island, North Sulawesi, Indonesia. ‘Sagu baruk’ has a long trunk length but its diameter is small and a poor crown development. Therefore, due to the small leaf area per plant (maximum about 90 m2), the biomass production system was inferior. Shoot fresh and dry weights at harvest stage (about 550 kg; 250–300 kg, respectively) were inferior even when compared to the sugar and sago palms, which are the same or a little earlier in the number of years until the optimal harvest stage. Furthermore, in ‘sagu baruk’, the relative proportion of the fibrous tissue at the peripheral part of the pith, which developed with plant age, increased because the trunk diameter was small, and the pith weight ratio in the trunk weight-fresh weight: 72.3%; dry weight: 69.5%-was lower than those of other starch-accumulating palms. Thus, its low biomass production and low pith weight ratio in the trunk weight were considered to be the cause of the low starch productivity per plant (about 90 kg). Although ‘sagu baruk’ has a low starch productivity per plant, it is easy to propagate due to its being a clump palm which can possibly grow under relatively dense condition because of its small trunk diameter. Therefore, it is necessary to study its growth characteristics, biomass production, and starch productivity per area under different planting densities.

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  • Yutaro OSAKO, Hisayo YAMANE, Shu-Yen LIN, Po-An CHEN, Ryutaro TAO
    2022 Volume 66 Issue 3 Pages 104-109
    Published: 2022
    Released on J-STAGE: November 08, 2022
    JOURNAL FREE ACCESS

    The seed size of litchi (Litchi chinensis) influences the flesh rate and is therefore an important fruit quality parameter. In China, the cultivar ‘No Mai Tsz’ (NMT) produces a high frequency (approximately 85%) of fruits with aborted seeds (“chicken-tongue-seeded” fruits), and this may be true in Taiwan as well. However, few detailed investigations have been conducted on Taiwan NMT fruits with focusing on seed characteristics and their diversity. To gain information on NMT in Taiwan, we conducted a study of more than 1,000 commercially available NMT fruits obtained from Taiwanese markets. We previously developed a cultivar discrimination model using litchi fruit images, and this model indicated that the majority of collected fruits were indeed NMT fruits. We found that approximately 40% of NMT fruits collected in Taiwan were chicken-tongue-seeded fruits, which is a lower frequency than reported in China. Seed size and flesh rate varied greatly among 15 different sampling dates and locations. The fruit recognition model was able to distinguish fruit images of three of these groups, which had smaller seeds and a higher flesh rate, from the remaining groups with high accuracy (approximately 80%). Taken together, our results suggest that some strains genetically close to NMT but producing a lower frequency of chicken-tongue-seeded fruits have been mistakenly propagated in Taiwan as NMT. Our results and previous studies collectively suggest the necessity of the re-evaluation of genetic identification and diversity of NMT in Taiwan.

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