Research for Tropical Agriculture
Online ISSN : 2187-2414
Print ISSN : 1882-8434
ISSN-L : 1882-8434
Volume 2 , Issue 1
Showing 1-15 articles out of 15 articles from the selected issue
Original Article
  • Masato ODA
    2009 Volume 2 Issue 1 Pages 1-7
    Published: 2009
    Released: August 21, 2013
    The applicability of water-saving tomato cultivation technology using plant acclimation was examined in the dry season from December 2003 to April 2004 in Northeast Thailand. Seeda tomatoes were planted in 2 experimental plots measuring 1 × 30 m each, with and without plastic mulch. The seedlings were spaced at 1-m intervals to avoid the effects of their neighbors. The soil of the field was loamy sand. At 0, 16 and 35 days after the transplantation, 250 mL of water was applied to each plant. At the latter 2 time points, the water contained liquid fertilizer (NPK: 120-90-60 ppm). Control plants were irrigated with 250 mL of water 3 times a week. The soil condition was extremely dry at the time of transplanting. A rainfall event of 29 mm occurred at 11 days after the transplantation, and the soil reached field capacity. There were almost no rainfall enevts for 61 days after this rainfall. The root systems of the unmulched plants deeply extended into the soil, while those of the other plants exhibited a large root mass near the soil surface. The root zone area of the mulched plants was especially large. The Brix values of the fruits were 4% for the controls and 7-8% for the others. The yield range per plant was 0-388 g for the mulch treatment, 0-65 g for the absence of mulch treatment, and 0-210 g for the control. Some plants were died provably not because of water shortage but due to other effects such as nutrition shortage. The maximum yield with plastic mulch was 1035 g·m-2, based on the standard planting density. The yield was almost equal to 1133 g·m-2, which is the yearly local average. Thus, it appears that with the use of plastic mulch, it may become possible to plant Seeda tomatoes with minimal watering during the dry season in Northeast Thailand.
    Download PDF (1003K)
  • Yoshimi YONEMOTO, Tatsushi OGATA, Naoko KOZAI, Tomohiro KONDO, Hirokaz ...
    2009 Volume 2 Issue 1 Pages 8-14
    Published: 2009
    Released: August 21, 2013
    Pitanga cultivars ‘Lover’ and ‘Vermilion’ were introduced from California to Okinawa as a new tropical fruit crop. Characteristics of fruit growth and fruit quality of the new cultivars were observed. As a result of our study, we could harvest the fruits twice in a year, in spring and fall, in Ishigaki Island. The taste of the fruits harvested in fall (fall fruits) was better, with a higher Brix value of 17.0 compared to that of the fruits harvested in spring (spring fruits) which showed a Brix value of 12.0. It took about 50 days for the skin color of the spring fruit and 40 days for that of the fall fruits to become yellow (a* value 11.2 and b* value 32.1). Then, the fruit skin color changed to orange, red and dark red at an interval of two days and the fruits dropped after the development of a dark red color. For both spring and fall fruits, cumulative daily average temperature necessary for fruit maturation was 1200°C. Major organic acid of pitanga fruit was malic acid, and its concentration reached a peak when the fruit became yellow, and it decreased constantly until dark red fruits dropped. In contrast, the soluble solids content increased rapidly after orange color development and reached a peak when the fruits dropped. Sugar and acid ratio was 4:1 for orange color and 19:1 at the dark red color stage when the fruits dropped. These results indicate that harvesting fruits just before fruit drop is the optimum time to enjoy the best taste. Pitanga juice contained only a small amount of sucrose, while an equal amount of fructose and glucose. It was demonstrated that pitanga fruits contained a larger amount of polyphenol than guava, which is known to be a Myrtaceae fruit with a high content of polyphenol. The ratio of seed weight to fruit weight was high, i.e., approximately 10-20%. The new cultivars, ‘Lover’ and Vermilion’, exhibit a less resinous odor and lower tartness than Okinawan native seedlings, and they have an excellent taste and flavor, based on sensory test evaluation. As a result, these new cultivars are a promising new fruit crop in Okinawa.
    Download PDF (1132K)
Short Report
Research Meeting
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
Commemorative Lecture by the Winner of Iso Award-out line
Commemoratice Lecture by the Winner of Award for Academic Excellence in Tropical Agriculture-out line