Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
56 巻 , 2 号
選択された号の論文の5件中1~5を表示しています
Original Article
  • Physicochemical Properties and Fertility Status
    Sunday Ewele OBALUM, John Chukwu NWITE, Yoshinori WATANABE, Charles Ar ...
    2012 年 56 巻 2 号 p. 39-48
    発行日: 2012年
    公開日: 2012/07/20
    ジャーナル フリー
    In spite of the leading position of the agrarian Bida suburbs in north-central Nigeria in the practice of the sawah system of rice production in Nigeria, there is no information in the literature regarding the chemical properties and fertility status of the paddy fields. In the present study, the topsoil properties of representative inland valleys for sawah rice culture were examined at four locations (Gadza, Nasarafu, Shaba-Maliki and Ejeti) in the area. Apart from Ejeti where the soil is a clay loam, the predominant texture is sandy loam. The parent materials are young, with a low weathering potential, as expected in soils with a high silt:clay ratio. The soil reaction was strongly to moderately acidic in water (pH range, 4.5-5.3). Values were generally low for the soil organic carbon concentration (range, 4.6-12.5 g kg -1) and total nitrogen content (0.42-0.98 g kg -1), while available phosphorus content indicated moderate values (11.5-26.0 mg kg -1). The ranges of values for the total exchangeable bases and acidity were, respectively, 2.04-4.62 and 1.1-2.7 cmol kg -1. The differences between effective and normalized cation exchange capacity (CEC) were somewhat wide and, consequently, the derived base saturation showed high (60.1%) and low (35.9%) mean values, respectively. Among the locations, Ejeti showed the most suitable values for almost all these parameters. The silt and clay fractions and the organic carbon concentration showed significant positive relationships with the effective CEC, implying that these parameters controlled the fertility of the inland-valley soils. Management strategies for coping with the low pH as well as the low organic carbon, total nitrogen and basic cations’ contents in the soils are suggested.
  • Kaihei KOSHIO, Yoshinori MURAI, Atsushi SANADA, Takaaki TAKETOMI, Masa ...
    2012 年 56 巻 2 号 p. 49-52
    発行日: 2012年
    公開日: 2012/07/20
    ジャーナル フリー
    Corosolic acid content and distribution in Lagerstroemia speciosa Pars. were investigated, indicating that the red leaves contained more corosolic acid than the green leaves and other plant parts such as petals, roots and seeds. The leaf redness was derived from cyanidin 3-O-glucoside which was first identified in this species. The contents of corosolic acid and cyanidin 3-O-glucoside were found to be well correlated, supporting the traditional perception of local people of the Philippines that red leaf banaba tea exerts more pronounced medicinal effects.
  • M. Umma KULSUM, Umakanta SARKER, M. Abdul KARIM, M. A. Khaleque MIAN
    2012 年 56 巻 2 号 p. 53-61
    発行日: 2012年
    公開日: 2012/07/20
    ジャーナル フリー
    Plant breeders evaluate their germplasm/ accessions in multi-environments to study their performance and adaptation to a specific or general environment. The problem of genotype-by-environment (GxE) interactions in the interpretation of multilocational trial analysis and the prediction of genotype performance can be eased with the adoption of the Additive Main Effects and Multiplicative Interaction (AMMI) model analysis. The AMMI model was used in the present study to evaluate 13 promising hybrid rice genotypes established at five different locations in Bangladesh to identify stable and adaptable genotypes, determine the magnitude of GxE interaction and identify factors contributing to the GxE interaction pattern. Analysis of variance showed that the effects of environments, genotypes and GxE were highly significant for plant height, days to maturity, panicle length and grain yield. BRRI1A/BRRI12R, II32A/BRRI10R and the standard check variety BRRI dhan29, which display a semi dwarf plant stature, were stable over all the environments. The promising hybrids BRRI1A/BRRI12R, BRRI10A/BRRI15R, BRRI9A/BRRI15R and BRRI hybrid dhan3 were stable across the environments with shorter growth duration. The hybrids II32A/BRRI15R, II32A/BRRI16R II32A/BRRI10R and BRRI hybrid dhan3 were also stable over all the environments with long panicle. Genotypes BRRI10A/BRRI12R, II32A/BRRI15R, II32A/BRRI10R, BRRI9A/BRRI15R, BRRI hybrid dhan2 and BRRI hybrid dhan3 were high-yielding and stable. While, the genotypes II32A/BRRI16R and II32A/BRRI12R were high-yielding but unstable. Wide variations in soil moisture availability were identified as a major causal factor of the interactions observed. Among the five locations, Barisal could be considered to be the optimum site for the selection of broad-based improved hybrid rice genotypes.
  • Hiroyuki SHIMONO, Hidetoshi MIYAZAKI, Hitoshi SHINJO, Hiromitsu KANNO, ...
    2012 年 56 巻 2 号 p. 62-70
    発行日: 2012年
    公開日: 2012/07/20
    ジャーナル フリー
    Optimal sowing date is essential to attain high maize (Zea mays L.) productivity despite environmental variation in low-input agriculture in Zambia. Local farmers generally plant maize as early as possible after the onset of the rainy season. However, there is no scientific evidence that this timing is optimal for attaining high productivity using local practices. To address this probem, we grew maize at three sowing dates in six fields of Zambia’s Southern Province in the 2008/09 and 2009/10 growing seasons. Grain yield was reduced by delayed sowing, by an average of 19% for all years and locations combined. The reduction resulted from decreased biomass production and harvest index. These results support the early sowing practice applied by local farmers.
  • P. K. BABIL, Daisuke YASUHARA, Keisuke SAKAGUCHI, Tsukasa IWASHINA, Ke ...
    2012 年 56 巻 2 号 p. 71-79
    発行日: 2012年
    公開日: 2012/07/20
    ジャーナル フリー
    Somaclonal variations in pigmentation occurred repeatedly during the clone propagation of the landrace ‘Okinawa A’ of water yam, Dioscorea alata L. An initial variation appeared when clone propagation of ‘Okinawa A’ started in 2000. Reverting variants, closely resembling the original type appeared several times during the cloning of the initial variants. In 2009, a second variant without pigmentation emerged from the initial one. Every observed trait of the original type and the three types of variants was ordinarily transmitted to later generations during clone propagation by tuber. Genealogical tracing of clone pedigrees and analyses of variance in leaf and stoma traits indicated that these variants might be caused by tissue chimeras resulting from changes in the number or structure of chromosomes. However, the possibility that transposable elements were involved could not be excluded. The recurring somaclonal variations are considered to affect the genetic diversity within the species and to provide useful genetic resources for improvement of water yam.
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