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Volume 38 (1993)
- Issue 4 Pages 253-
- Issue 3 Pages 159-
- Issue 2 Pages 69-
- Issue 1 Pages 1-
- Issue SupplI Pages 2-
Volume 38, Issue 2
Displaying 1-11 of 11 articles from this issue
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Koichiro Komai1993 Volume 38 Issue 2 Pages 69-75
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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Yasuo Hanioka1993 Volume 38 Issue 2 Pages 76-81
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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Tohru Tominaga1993 Volume 38 Issue 2 Pages 82-89
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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Kazuyuki Matsuo, Tetsuo Kubota1993 Volume 38 Issue 2 Pages 90-96
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSIn order to examine the role of the temperature in the regulation of dormancy of weed seeds, tests for germination of 9 winter and 6 summer annual upland weeds were conducted under 6 thermal regimes with alternating temperatures (15/5, 20/5, 25/5, 20/10, 25/10 and 25/15°C) following the exposure of seeds to three treatments (storage under air-dried conditions, stratification at 5°C for 60 days or at 20°C for 30 days). The effects of burying seeds in soil for varying periods of time on germination of summer annuals were also analyzed.
Winter weeds, in general, showed a low level of dormancy but the temperatures required for maximum germination varied with the species. Stratification at 20°C for 30 days was more effective than at 5°C in breaking the dormancy and in reducing the minimum temperature required for germination. The results obtained suggest that some winter annuals may germinate immediately after maturation in early summer, while most of the others lose their dormancy under the warm and humid conditions of the summer season and emerge in the following autumn.
Seeds of the summer weeds stored under airdried conditions showed a high level of dormancy while stratification at 5°C for 60 days was effective in breaking their dormancy. Four species (Echinochloa crus-galli, Digitaria ciliaris, Amaranthus hybridus and Portulaca oleracea) germinated only at high temperatures but the effects of stratification at 5 and 20°C were largely similar. On the other hand, seeds of Persicaria vulgaris and Setaria viridis could germinate even at low temperatures but stratification at 20°C for 30 days was ineffective in breaking their dormancy. In contrast, the other summer annuals are unable to germinate even if their seed dormancy is lost in the autumn, due to the very low temperatures prevailing at that time in the Tohoku region. The increase of the duration of the burial period of seeds in the soil, in general, had no influence on the germination of P. vulgaris and S. viridis. However the greater ability to germinate even at low temperatures appears to be the cause of rapid emergence of P. vulgaris and S. viridis in early spring.View full abstractDownload PDF (952K) -
Koichiro Komai, Satoshi Omori, Mituru Shimizu, Masayuki Hamada1993 Volume 38 Issue 2 Pages 97-102
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSThree glucosides, paederoside (Pa), paederosidic acid (Paa) and scandoside (Sca) were isolated as iridoid glucosides from Paederia scandens Merrill. For the examination of their biological activities, iridoid glucosides including asperuloside (As), deacetyl asperulosidic acid (Daa) and deacetyl asperuloside (Da) were also used as a reference (Fig. 1).
The inhibitory activities of Paa and Sca, which were produced by the cleavage of a lactone ring and desorption of S-methyl thiocarbonate were reduced compared with those of Pa, which has a lactone ring. Sca also displayed a promoting activity fowards the growth of lettuce seedlings. Pa showed a similar inhibitory activity to that of Asp and Da in the plant growth inhibition test and antimicroorganism activity test (Tables 1, 2 and 3).
These results suggest that the lactone ring is the essential part of the structure for the activity.View full abstractDownload PDF (726K) -
Allelopathic Potential of Eupatorium odortum in Abandoned Shifting Cultivation Fields in the TropicsNaoki Nakamura, Masayuki Nemoto1993 Volume 38 Issue 2 Pages 103-108
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSEupatorium odoratum (Asteraceae), a perennial weed, rapidly invades abandoned shifting cultivation fields in tropical Asia and tends to become the predominant weed there. The effects of leaf and stem exudates of E. odoratum on the seed germination and seedling growth of four commonly occurring weeds in an abandoned shifting cultivation field were studied. Crassocephalum crepidioides, Ageratum conyzoides, Cynodon dactylon and E. odoratum were employed as acceptor plants.
The effects of aqueous leaf extracts on seed germination of the four weed species were investigated using petri dishes. The germination of all the species was delayed by two to four days (Fig. 1).
The seedlings of the acceptor plants were grown in pots containing quartz sand in which powder from fresh leaves, dead leaves and stems of E. odoratum was added. The growth of the seedlings of C. crepidioides was most strongly inhibited by the exudates from each powder preparation, followed by the E. odoratum seedlings. On the other hand the growth of A. conyzoides and C. dactylon was less affected than that of the above two species. The exudates of dead leaves induced a remarkable growth inhibition among all (Fig. 2-4).View full abstractDownload PDF (744K) -
Koji Hasegawa, Midori Amano, Chikako Asakawa, Hideo Kakuta, Junya Mizu ...1993 Volume 38 Issue 2 Pages 109-111
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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Do-Jin Lee, Kenji Usui, Kozo Ishizuka1993 Volume 38 Issue 2 Pages 112-114
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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1993 Volume 38 Issue 2 Pages 115-128
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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1993 Volume 38 Issue 2 Pages 129-138
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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Hiroshi Matsumoto, Tohru Tominaga, Tadashi Sumiyoshi, Masaaki Tachiban ...1993 Volume 38 Issue 2 Pages 139-144
Published: July 31, 1993
Released on J-STAGE: December 17, 2009
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