Tropical Agriculture and Development
Online ISSN : 1882-8469
Print ISSN : 1882-8450
ISSN-L : 1882-8450
Volume 55, Issue 4
Displaying 1-7 of 7 articles from this issue
Original Article
  • Tomohiro KONDO, Hirokazu HIGUCHI
    2011 Volume 55 Issue 4 Pages 129-134
    Published: 2011
    Released on J-STAGE: January 07, 2012
    Less acid passion fruit has being increasingly demanded for fresh fruit consumption recently. To examine the effect of matter distribution into fruit on fruit acidity, three different fruit loads, heavy, medium, and light, were established, and fruit acidity was measured. The heavy-fruit-load treatment represented the utmost level of fructified load, and plants were not able to bear further fruit. The numbers of fruits in the medium- and light-load treatments were 2/3 and 1/3 of those in the heavy-load treatment. Acid content increased remarkably as fruit load increased. The acid content of ripened fruit in the light-load treatment was 1.77 %, which was markedly lower than that in the heavy- (2.50 %) and medium- (2.16 %) load treatments. In the heavy-load treatment, Brix sugar content was lower than in the other two treatments, although the difference was small. The sugar/acid ratio, which reflects savor, improved markedly as fruit load decreased. Fruit weight and dimensions increased as fruit load decreased, and the effect of fruit load on fruit weight was more significant than the effect on fruit dimensions. The acid content of passion fruit was found to decrease as matter distribution into fruit increased. These results indicate that a reduction in fruit load by more than 1/3 from the bearing capacity might be effective to produce substantially less-acid passion fruit.
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  • Chu Ngoc KIEN, Sota TANAKA, Nguyen Van NOI, Le Thanh SON, Nguyen Minh ...
    2011 Volume 55 Issue 4 Pages 135-141
    Published: 2011
    Released on J-STAGE: January 07, 2012
    Mining activities in the Co Dinh chromite mine, Vietnam, have exerted adverse environmental impacts due to the dispersal of heavy metals from the mine to downstream agricultural soils. In the present study, the extent and degree of heavy metal accumulation in rice plants were investigated and the potential health hazard caused by polluted agricultural products in this area was evaluated. Rice plants (Oryza sativa L. var. Lua Nep) were sampled from four paddy fields at different distances (2.5-6.0 km) from the mining site. The rice plants grown in fields near the mine contained significantly higher amounts of Ni, Cr and Co than those grown far from the mine, due to severe contamination of the soils with these elements as a result of mining activities. Among the examined elements, Ni appeared particularly problematic owing to its considerably high concentration in brown rice (2.66-4.29 mg kg-1). The estimated daily intake (EDI) of Ni through the consumption of brown rice (0.019-0.030 mg kg-1 day-1) exceeded the tolerable daily intake (TDI) recommended by WHO (0.011 mg kg-1 day-1), indicating a potentially serious health risk to the local inhabitants. Moreover, high concentrations of Ni were also detected in leaf blades and sheaths (3.66-28.2 and 9.79-93.1 mg kg-1, respectively) which are fed to livestock. These findings raise the possibility of an increased health hazard as Ni could further accumulate in the food chain from crops to humans.
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  • P.K. BABIL, Chikano FUNAYAMA, Ken IIJIMA, Kenji IRIE, Hironobu SHIWACH ...
    2011 Volume 55 Issue 4 Pages 142-147
    Published: 2011
    Released on J-STAGE: August 01, 2013
    Water yam (Dioscorea alata L.) is one of the most popular cultivated species of yams. It is dioecious and scarcely flowers. Moreover, the lack of synchronization in flowering of male and female plants hampers hybridization and sexual reproduction. Although somaclonal variation such as polyploidy has been considered to be useful for improving water yam; no efficient technique for inducing polyploid variants has yet been developed. In the present study, somaclonal polyploid variation was successfully induced at a high frequency by in vitro treatment of water yam with colchicine. The highest rates of polyploid induction, 26.7% and 16.7%, were obtained after 0.1% colchicine treatment in accessions No. 132 and No. 127, respectively. Tetraploid variants tended to display the somewhat rounder leaves than their diploid parents. The size and shape of water yam stoma have also been found to be affected by levels of ploidy. Tetraploid variants exhibit larger stomata at a lower density compared to the diploid parents. The technique of somatic polyploidization presently proposed is considered to be useful for the improvement of water yam.
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    2011 Volume 55 Issue 4 Pages 148-156
    Published: 2011
    Released on J-STAGE: January 07, 2012
    GGE-biplot analyses were applied to multi-environment trials of sugarcane, at 22 locations in 11 provinces in central and western Thailand, using 12 genotypes in 3 crop cycles (newly planted, first-ratoon and second-ratoon crops). The objectives of the present study were to evaluate the use of the GGE-biplot method to analyze the effects of genotype (G) and genotype-environment interaction (GE) in sugarcane breeding, to identify the representative locations for reducing the number of test environments and to classify the sugarcane genotypes based on their adaptation to several environment groups. The largest variations were found for the crop-cycle in all the traits, and the location also showed large variations. The variations from crop-cycle, location and location x crop-cycle interaction were more important than that of genotype, although the effects of the genotype and related interactions were significant. In the GGL (Genotype x Genotype-Location) biplots, the coordinates and vectors of locations and genotypes clearly explained the associations among them, suggesting that the biplot technique was highly effective to reveal the relationships among tested locations and genotypes. Regarding sugar yield, 4 groups of locations were classified in these regions. In the future experiments, the sugarcane breeders may be able to reduce the number of test locations to these 4 representative environments without substantial loss of information about the genotypes. K90-77 was classified into a generally adapted genotype, whereas the genotypes K88-92 and UT5 were specifically adapted to the central and western regions of Thailand.
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