Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
58 巻 , 2 号
選択された号の論文の7件中1~7を表示しています
Original Article
  • Yoshinori YAMAMOTO, Kazuki OMORI, Youji NITTA, Kenichi KAKUDA, Yulius ...
    2014 年 58 巻 2 号 p. 43-50
    発行日: 2014年
    公開日: 2014/09/11
    ジャーナル フリー
    We analyzed the leaf characters of the two folk varieties of sago palm, Molat (Roe) and Rotan (Rui), from the time of trunk formation until harvesting (from the flower bud formation to the flowering stage) in Kendari, Southeast Sulawesi Province, Indonesia. Leaf length, petiole + leaf sheath length, and specific leaf area (SLA) tended to decrease with increasing years after trunk formation (YATF) in both varieties. The length of the leaf, rachis, and petiole + leaf sheath sharply decreased acropetally at the flowering stage in Rotan. In Molat, the number of leaves, number of leaflets per leaf, longest leaflet length, leaflet width and area, and area per leaf and per palm increased with increasing YATF. In Rotan, the leaf and leaflet characters showed very few changes, only the number of leaflets increased with increasing YATF, except at the flowering stage. In both varieties, the average leaf area per leaf was more closely related to the leaflet area than to the number of leaflets, and the leaf area per palm was more closely related to the number of leaves than to the leaf area per leaf. Except for SLA, all the leaf and leaflet characters showed higher values in Molat than in Rotan. For almost all the characters, the magnitude of the difference between varieties increased with increasing YATF. These results suggest that the difference in starch yields between the two varieties might be related to differences in the leaf area per palm.
  • Identifying High-Yielding Rice Varieties Adapted to Rainfed Upland Conditions in Benin and Their Plant Characteristics
    Kazuki SAITO, Yoshimichi FUKUTA, Seiji YANAGIHARA, Kokou AHOUANTON, Yo ...
    2014 年 58 巻 2 号 p. 51-57
    発行日: 2014年
    公開日: 2014/09/11
    ジャーナル フリー
    Four rainfed upland experiments were conducted in Benin to assess yield differences in 65 rice varieties, including the interspecific hybrids: the upland New Rice for Africa (NERICA) varieties developed from crossing Oryza sativa L. and O. glaberrima Steud.. The mean grain yields ranged from 32 to 350 g/m2 across experiments. The genotype × environment (G×E) interaction accounted for 15% of the total sum of squares, with environment and genotype responsible for 74 and 12%, respectively. Upland indica B6144F-MR-6-0-0 performed well in three out of four environments, showing consistently higher yields than other upland NERICA varieties and their parents. Upland indica Aus257 was stable across environments with good adaption to poor soil fertility. None of the upland NERICA varieties showed consistently higher yields than their parents across the four environments. The group of long-duration varieties (e.g. IR 8, IR 24, Taichung Native1) performed well only in most-favorable environments. The high-yielding varieties B6144F-MR-6-0-0 and Aus257 were intermediate in panicle number (160–180 panicles/m2 on average). This was the only common characteristic among the highest yielding varieties. These results suggest that further increases in rice yields in the rainfed uplands of West Africa are most likely to occur through using upland indica varieties as donors.
  • Naoko KOZAI, Orwintinee CHUSRI, Theerawut CHUTINANTHAKUN, Sombat TONGT ...
    2014 年 58 巻 2 号 p. 58-65
    発行日: 2014年
    公開日: 2014/09/11
    ジャーナル フリー
    Erratic fruit set occurs occasionally during durian cultivation, even when flowers are artificially pollinated. In this study, early reproductive organ development in durian and its relationship with self-incompatibility were observed over a single season in Thailand. Cross-, self-, and non-pollination treatments were applied to the ‘Chanee’, ‘Monthong’, and ‘Kradumthong’ durian cultivars. Developmental stages of individual ovules, size of the primary ovule, and pollen-tube penetration into the primary ovule were observed at 1, 3, and 7 days after anthesis (DAA). Ovule development was classified into five stages: eight-nucleate, mature, endosperm nuclei division, deformed, and degenerated. Fruit set was determined at 7 and 14 DAA. Fruit set percentage in flowers of the self-pollinated cultivar ‘Chanee’ after 14 days was much lower (28%) than that of both ‘Monthong’ (80%) and ‘Kradumthong’ (81%). Most ovules in the non-pollinated flowers had degenerated by 7 DAA in all cultivars. In cross- and self-pollination, most ovules developed to the stage of endosperm nuclei division at 7 DAA in all cultivars including ‘Chanee’. These results indicate that ‘Chanee’ is a post-zygotic self-incompatible cultivar, and in this cultivar particularly manual cross-pollination is important to ensure fruit set. The percentages of ovules that had reached the endosperm stage were the lowest in cross- and self-pollinated ‘Monthong’ flowers at 7 DAA. Lower sink activity resulting from fewer fertilized ovules could cause flowers to abscise. Intensive management to prevent physiological fruit drop would be required in ‘Monthong’ especially. Successful fertilization and fruit set was observed in both cross- and self-pollinated ‘Kradumthong’ flowers.
  • Samuel M. CONTRERAS, Gavino Isagani P. URRIZA, Fujio NAGUMO, Silvino Q ...
    2014 年 58 巻 2 号 p. 66-74
    発行日: 2014年
    公開日: 2014/09/11
    ジャーナル フリー
    Experiments were conducted to assess and evaluate the effects of pigeon pea (Cajanus cajan) cover cropping and no-till practice on corn (Zea Mays) yield, surface runoff and soil erosion. The experimental site was a grassland with a uniform slope of 10% and low fertile clay loam surface soils located at the Soil and Water Conservation Station, Brgy. Baligatan, Ilagan, Isabela, Philippines. There were 3 treatments, namely; fallow + till (F+T), fallow + no-till (F+NT), and pigeon pea (Cajanus cajan) + no-till (PP+NT). Pigeon pea was grown during the period of February to May, 2008, then cut and mulched on the soil surface before corn planting. After corn harvest in September, the second corn cropping was conducted during the period of November, 2008 and February, 2009. Organic matter content in the PP+NT treatment increased significantly during the experimental period unlike that for the other treatments. PP+NT also led to a lower maximum soil temperature at a depth of 5 cm compared with the other two treatments. PP+NT also led to a soil water depletion behavior in deeper soil horizons during the lull period probably due to deep root penetration and active photosynthesis during the maturation period. The 20 hill-based corn yield for PP+NT was improved by almost 1 t ha-1 compared with that for F+T, although the values were not statistically significant, probably due to the nutrient contribution from pigeon pea biomass. PP+NT also contributed to reducing soil runoff and soil erosion, particularly during peak rainfall events. Hence, pigeon pea cover cropping in combination with no-till, with proper management, was found to be effective in ensuring sustainable corn production in sloping lands by improving crop yield, minimizing soil erosion and nutrient loss.
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