Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
60 巻 , 3 号
選択された号の論文の10件中1~10を表示しています
Original Article
  • Moe Swe YEE, Eiji NAWATA
    2016 年 60 巻 3 号 p. 137-145
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    In the Dry Zone of Myanmar, the traditional upland farming systems were able to secure people’s home consumption with adaptability to the environment, in addition to providing income. In the recent decades, local people there considered the introduction of new cash crops to increase the yield and income compared to those in the conventional cropping systems. Kyauk Pyote village, one of the typical upland crop-producing villages in Yinmarbin Township, Sagaing Region was studied for the introduction of thanakha (Limonia acidissima), a highly promising cash crop with adaptability to the agro-environment in the Dry Zone, based on farm household interviews and field observations. In this area, sesame, pigeon pea and tomato were traditionally cultivated for daily foods and basic household needs. The local people introduced thanakha and diversified their farming systems for food and income security, and crop diversification might generate a higher income and contribute to rural development. Although commercial cultivation has widely expanded in the surveyed area with villagers’ expectation, the introduction of thanakha is at a trial stage and has not produced profits yet.

  • Mitsutoshi FUKE, Yosei OIKAWA, Vũ Linh NGUYỄN, Masaaki YAMADA, Sakae S ...
    2016 年 60 巻 3 号 p. 146-154
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    In the highlands of central Vietnam, producers attempt to cultivate profitable temperate crops that could not grow in the lowlands. We, therefore, examined the possibility of strawberry (Fragaria × ananassa Duchesne) cultivation under a rain shelter in the highlands (1,320 m AMSL) of Bạch Mã Mountain. Strawberries grew vigorously in the dry season from March to September. We observed flowering, fruiting and runner growth. Many fruits were malformed or unfertilised, but normal fruits were produced by artificial pollination. In the rainy season from October to February, the plant growth was stagnant. Lower leaves turned brown and wilted, and many plants died. The analysis of climate data and comparison of cultivation methods suggested that the stagnant growth and death of the strawberry plants were related to the light intensity and relative humidity rather than to the air temperature. We investigated plant responses such as stomatal conductance under variable light intensity and humidity conditions at different leaf positions using a portable photosynthesis system in a phytotron. The stomata of the mature leaves tended to close in response to a low light intensity and high humidity. When the light intensity was increased, the transpiration rate of the mature leaves remained markedly low. The difficulty to grow strawberries in areas with frequent rain is attributed to prolonged low light intensity and high humidity, which lead to stagnant water flow in plants. We discussed the possibility of strawberry cultivation in tropical highlands with high rainfall.

  • Hiroshi MATSUDA, Hirokazu HIGUCHI, Tatsushi OGATA
    2016 年 60 巻 3 号 p. 155-161
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    Pre-anthesis night temperatures (1800–0900 h) surrounding cherimoya flowers were sectionally regulated at 4–35ºC, and pollen germination was examined immediately after their anthesis. Developmental changes in pollen starch were also anatomically observed, and the night temperature effects on pollen starch and germinability were discussed. Pollen germination percentage was largely affected by pre-anthesis night temperatures, being highest (≈70%) at 20–22ºC. Germination decreased at temperatures below 14ºC, and decreased remarkably below 6ºC. Tube elongation was also restricted below 6ºC. At 4ºC, the pollen often shriveled. Germination also decreased over 27ºC. Germination and elongation were low at 35ºC. Night temperatures also affected anthesis time. The time was earliest at 18–22ºC (1500–1600 h) and was delayed at higher and lower temperatures. Pollen starch only accumulated in the generative cell until 1 week before anthesis. From 3 days before anthesis to the morning of the anthesis day, starch accumulation was sometimes observed in the whole portions in pollen. The accumulation was not affected by temperatures. At 10–20 minutes before anthesis, the pollen was filled with starch. Immediately after anthesis, starch was observed in only half of the pollen. The disappearance of starch was not affected by temperatures. No apparent relationship between germination and starch accumulation was found. Cherimoya pollen germination declined remarkably when flowers were exposed to temperatures lower than 14ºC or higher than 27ºC even for one night previous to anthesis.

  • A Case of Slash-and-burn Rice Farming in South Konawe Regency, Southeast Sulawesi Province, Indonesia
    Mayumi KIKUTA, Yoshinori YAMAMOTO, Yulius Barra PASOLON, Fransiscus Su ...
    2016 年 60 巻 3 号 p. 162-171
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    Farmer interviews and a yield survey were conducted to elucidate the actual conditions of upland rice cultivation by the Tolakinese, the native people of Southeast Sulawesi Province, Indonesia. The interview results indicated that native farmers had been cultivated upland rice by slash-and-burn farming during the rainy season for personal consumption because of its good flavor, especially aroma, despite the low productivity. We categorized the topographical conditions in our survey field as either: flat, sloping, or depression. The growth and yield of upland rice varied according to these different topographic conditions. Our results of the yield survey suggest that uneven upland rice fields generate different cultivation environments and crop management strategies, which contribute to the variability in grain yields. Moreover, grain yield was highest under depression condition where more water was available, followed by flat and sloping condition. These findings suggest that soil water conditions are important in rainfed upland rice cultivation.

  • Kazuhiro NEMOTO, Mineo MINAMI, Tsukasa NAGAMINE
    2016 年 60 巻 3 号 p. 172-178
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    Excluding cereals, grain amaranths are known as the only crop with non-waxy and waxy starch types in seeds. We examined the amylose content stored in the perisperm and starch types; non-waxy, waxy and low-amylose types in 266 accessions of three grain amaranth species i.e. Amaranthus hypochondriacus L., A. cruentus L. and A. caudatus L. from around the world. In the accessions from the New World where these species were domesticated, a wide range of amylose contents and all the starch types were detected. Conversely, very limited variation of this trait was observed in the accessions from Asia and Africa. We concluded that the waxy type originated in the New World before being disseminated into Asia and Africa. However, the selection pressure for the waxy type in the perisperm of grain amaranths in the New World was considered to differ from that acting on cereal crops because of differences in the use and people’s preference for sticky food.

  • Akira MIYAZAKI, Daisuke WATANABE, Yoshinori YAMAMOTO, Tetsushi YOSHIDA ...
    2016 年 60 巻 3 号 p. 179-184
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    Root development and distribution in sago palm grown on mineral soil in Malaysia and Indonesia were investigated from 2007 to 2010 and compared among different ages, regions and folk varieties. Soil blocks (30 × 30 × 30 cm) were sampled by a trench method horizontally at 0, 1 and 2 m from the trunk base and vertically at 0–30, 30–60 and 60–90 cm from the ground surface. Root dry weight per palm (expressed per soil volume) was significantly higher in the harvest stage (bolting stage) than in the trunk elongation stage (2 years after trunk formation), and was also significantly higher in Kendari, Indonesia than in Mukah, Malaysia. The folk variety Molat had a higher root weight than Rotan in the harvest stage. The root dry weight did not differ significantly in the horizontal direction in the trunk elongation stage, while in the harvest stage it was higher at 0 m than at 1 and 2 m. The ratio of the root dry weight at 0 m to total weight increased from 42% in the trunk elongation stage to 69% in the harvest stage, suggesting that the root dry weight increased with age near the trunk base. On the other hand, the root dry weight in the deeper layers (30–60 and 60–90 cm) was significantly lower than in the surface layer (0–30 cm). However, the root dry weight ratio at 60–90 cm increased from 11% in the trunk elongation stage to 18% in the harvest stage, suggesting that downward development increased with age. These study results suggested that variety had more effect than region.

  • Abdul Qayom REZAEI, Hidehiko KIKUNO, Kaoru SUGIYAMA, Pachakkil BABIL, ...
    2016 年 60 巻 3 号 p. 185-190
    発行日: 2016年
    公開日: 2017/03/20
    ジャーナル フリー

    The effect of fertilization on lesser yam (Dioscorea esculenta L.) growth is not clearly understood. Increased lesser yam production in Okinawa prefecture, Japan, is desired due to increasing demand for use in commercial health supplements. However, fertilization guidelines for production are not yet available in Japan. This study aimed to reveal the effects of nitrogen application on growth of lesser yam in Okinawa from April 2014 to January 2015. Growth with urea application (N treatment) and without urea (control) were compared. N treatment had a positive effect on growth and tuber yield in soil with poor organic matter. Yellowish leaves were observed in control plants from 120 days after planting (DAP), but plants grew until 240 DAP. It was possible to grow lesser yams under poor fertile soil conditions. The δ15N values of the N treated plants suggested that nitrogen was absorbed from the urea; however, the source of nitrogen in the control plants was not identified. The quantity of nitrogen required for a stable yield of lesser yam is thought to be less than that required for water yam (D. alata).

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