Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
52 巻 , 4 号
選択された号の論文の4件中1~4を表示しています
Original Article
  • Junichi KASHIWAGI, L. KRISHNAMURTHY, Pooran M. GAUR, Teruhisa UMEZAKI, ...
    2008 年 52 巻 4 号 p. 89-96
    発行日: 2008年
    公開日: 2009/11/10
    ジャーナル フリー
    Eight chickpea genotypes were evaluated for seed yield and maturity time at three temperate locations in Japan and one semi-arid tropical location in India over a two-year period to obtain baseline information on chickpea adaptation to Japan. The average seed productivity under Japanese environments, except in the northern area with growth under cool and semi-humid climatic conditions and a longer photoperiod, was lower than that in the semi-arid tropical environment in India. The kabuli chickpeas, especially, ICCV 92311 and ICCV 92337, showed a higher productivity in northern Japan. For chickpea cultivation in Japan, it is recommended to adopt modified agronomic practices to reduce humidity in the crop canopy, for example, wider plant spacing, cultivation under rain shelter, and selection of genotypes with a high assimilate remobilization rate as well as resistance to higher humidity-promoted diseases. Growing chickpea crop in the northern part of Japan by adopting such agronomic practices and the right genotypes could be suitable. However, a larger number of studies should be carried out to analyse the various mechanisms that contribute to a better adaptation of chickpea to environments with a high soil moisture and humidity.
  • — A Case Study in Southwestern Niger —
    Hitoshi SHINJO, Keiichi HAYASHI, Tahir ABDOULAYE, Takashi KOSAKI
    2008 年 52 巻 4 号 p. 97-103
    発行日: 2008年
    公開日: 2009/11/10
    ジャーナル フリー
    An investigation conducted in southwestern Niger, Africa, revealed livestock management practices based on the relationship between farmers and sedentary pastoralists to promote efficient use of livestock excreta through corralling in the Sahel region. Transhumance was found to be essential for households residing in an area with a high rate of cropping because they had to remove their herds from cropped fields to a drier region in the rainy season. Corralling, parking herds in harvested fields at night, by the sedentary pastoralists was carried out mainly in fields rented from farmers. Another type of corralling was performed on a contract basis in farmers’ fields, on the condition that the farmers provide food for the pastoralists staying for corralling. About half of the sedentary pastoralists were not engaged in the practice of contract corralling or contracted livestock, suggesting the existence of a loose relationship between the farmers and sedentary pastoralists in terms of corralling and livestock grazing. In half of the households with contract corralling, the practice changed in two consecutive seasons. This implies that contract corralling is a flexible practice to compensate for the shortage of millet production and forage resources. Considering the amount of livestock excreta applied and the percentage of the area corralled, two-thirds of the households had the potential to promote contract corralling for more efficient use of livestock excreta.
  • Tang Thi HANH, Takuya ARAKI, Pham Van CUONG, Toshihiro MOCHIZUKI, Atsu ...
    2008 年 52 巻 4 号 p. 104-110
    発行日: 2008年
    公開日: 2009/11/10
    ジャーナル フリー
    In the present study, the characteristics of the CO2 exchange rate (CER) of flag leaves during the grain filling stage were compared between a Vietnamese hybrid rice cultivar Vietlai 20 (VL20) and its parent cultivars, the female line 103S and the male line R20. The CER and the related parameters were measured in the morning (8:00-10:00) and in the afternoon (14:00-16:00) at 3 days before heading (DBH), and at 7 and 17 days after heading (DAH). The results showed that there was no significant difference in the CER of flag leaves among the three cultivars at 3 DBH, while at 17 DAH, VL20 exhibited a higher CER than the parents both in the morning and afternoon. Stomatal conductance (Gs) decreased considerably in the afternoon, compared to that in the morning at 7 and 17 DAH for all the cultivars. In fact, VL20 showed lower Gs than the parents at 17 DAH, indicating that the CER was negatively affected by the stomatal behavior. The changes in the mesophyll conductance (Gm), as an indicator of CO2 fixation ability, were similar to those in CER in all the cultivars at the three stages. In particular, VL20 always exhibited higher Gm than the male parent R20 both in the morning and afternoon, which is consistent with the higher nitrogen content in the flag leaves. These results suggested that the high mesophyll function could contribute to the high photosynthetic potential of flag leaves in VL20 during the grain filling stage despite of the stomatal limitation.
  • Tang Thi HANH, Takuya ARAKI, Pham Van CUONG, Toshihiro MOCHIZUKI, Atsu ...
    2008 年 52 巻 4 号 p. 111-118
    発行日: 2008年
    公開日: 2009/11/10
    ジャーナル フリー
    Photosynthetic activity of flag leaves and dry matter production during the grain filling stage of Vietlai 20 (VL20), a Vietnamese hybrid rice variety, were examined and compared to those of its maternal cultivar (103S) and paternal cultivar (R20) under standard nitrogen (SN) and low nitrogen (SN) conditions. The results showed that the above-ground dry matter weight (DW) was not significantly different between VL20 and 103S under the LN condition. Also, there was no difference in the DW between VL20 and R20; while, VL20 exhibited a higher rate of panicle dry weight increase (PDW) than R20 under both SN and LN conditions. Because 103S is a thermo-sensitive genic male sterile line, PDW was negligible in 103S during maturity in the present experiment. With a restriction in N supply, the maximum CO2 exchange rate (CERmax), flag leaf nitrogen content (FLNC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content decreased in VL20 and R20. However, VL20 exhibited a higher sustainability in both duration of grain filling and response to N deficiency in terms of CERmax value, FLNC and Rubisco content than R20. VL20 also showed significantly a higher value of quantum yield efficiency of PSII (ΦPSII) and lower value of non-photochemical quenching (NPQ) than R20 under the LN condition. Although the chlorophyll (Chl) content was not significantly different between VL20 and R20, the ratio of Chl/Rubisco was lower in VL20 than in R20 under the LN condition. These results indicated that the high FLNC and Rubisco content, and relatively low Chl/Rubisco ratio would result in a high photosynthetic rate and ΦPSII value in the F1 hybrid during the grain filling stage under the restriction of N supply.
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