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Volume 49 (2004)
- Issue 4 Pages 277-
- Issue 3 Pages 169-
- Issue 2 Pages 95-
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Volume 49, Issue 1
Displaying 1-11 of 11 articles from this issue
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Hiroyuki Kobayashi, Shigenori Miura, Atsushi Oyanagi2004 Volume 49 Issue 1 Pages 1-7
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSThis study seeks to clarify how a cover crop over the preceding winter suppresses the emergence of Digitaria ciliaris (Letz.) Koeler, the most important weed in no-tillage soybean in Japan. Winter barley was grown as a cover crop with row spacings of 20cm, 40cm, and 60cm, and no-tillage soybeans were subsequently grown. Fresh D. ciliaris seeds were sown in cylinders set on the soil surface of all plots the previous autumn. The phenology and the number of D. ciliaris emerging, as well as their spatial distribution in the plots, were compared with those in a plot of no-tillage, continuous soybean without winter crop. In addition, light quality, light intensity, and soil-surface temperature were measured.
Most D. ciliaris seedlings from sown seeds emerged before soybean planting in all plots. Its emergence was strongly suppressed in the barley plots. Emergence was more strongly suppressed near the barley rows; it coincided with decreased light intensity, R/FR ratio, and the magnitude of diurnal fluctuations of the soil-surface temperature caused by barley sod. Fewer seedlings of D. ciliaris emerged naturally in the barley plots, particularly near the barley rows, before soybean planting.
These results suggest that the preceding winter barley suppressed the emergence of D. ciliaris due to changes in light intensity, light quality, and soil-surface temperature caused by the barley sod.View full abstractDownload PDF (913K) -
Yuko Suto, Masaru Ogasawara, Takayoshi Nishio, Nobumasa Ichizen2004 Volume 49 Issue 1 Pages 8-14
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSThe present study was conducted to clarify the ecological characteristics of the weed vegetation of small cavities formed in gaps at junctions of curbstones and sidewalks. Weed vegetation of the cavities was investigated at 78 points from March 18 to April 25 (spring) and at 71 points from October 17 to October 29 (autumn) in 2002 in Utsunomiya City, Tochigi Pref. The average (SE) width (depth) of cavities was 11.8 (±1.1)mm (77.2(±7.4)mm), and the pH of the soil contained in the cavity was 7.58 (±0.06). The weed vegetation was analyzed in terms of the frequency of occurrence, summed dominance ratio, life form, and ratio (%) of naturalized weed. The vegetation of the cavity consisted of 74 weed species belonging to 25 families in total for spring and autumn. Eight weed species, Cerastium glomeratum, Arenaria serpyllifolia, Setaria viridis, Euphorbia supina, Eragrostis multicaulis, Eleusine indica, Poa annua and Artemisia princeps dominated, and Arenaria serpyllifolia was nominated as a characteristics species of the vegetation of the cavity. From the point of floristic composition, weed vegetation of the cavities differs from the floristic compositions of paddy fields, upland fields and turf. However, in terms of life form, vegetation of the cavities included a large number of Th-R5-D4 type weeds (therophyte, without connection to underground and the ground, and seed spraying by gravity or the wind), as in arable land. The ratio (%) of naturalized weeds in spring (autumn) was 38.8% (37.5%).View full abstractDownload PDF (2578K) -
Ryuichi Sago, Kaori Uchiyama2004 Volume 49 Issue 1 Pages 15-20
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSIn 2000, three strains of Echinochloa phyllopogon were collected from farmers' fields in Biggs, California, USA. Greenhouse experiments for whole-plant bioassays were then conducted at the Ibaraki University Experimental Farm to determine levels of resistance to herbicides currently available in Japan. Although two strains of E. phyllopogon (R1, R2) exhibited resistance to treatment with the recommended field rates of molinate and thiobencarb, they were killed by pretilachlor, oxaziclomefone, pyriftalid and cafenstrol at less than the recommended field rates.
The seed germination rate of the resistant strains (R1, R2) was higher than that of the susceptible strain (S) at all periods examined, and the seeds of the resistant strains (R1, R2) were less dormant than those of the susceptible strain (S). However, the temperature index of germination, mean germination rate, and leaf emergence rate of the resistant strains (R1, R2) were very similar to those of the susceptible strain (S).View full abstractDownload PDF (714K) -
Hiroo Otsuka, Suzue Kobayashi, Shinya Masuda, Masayuki Nemoto2004 Volume 49 Issue 1 Pages 21-35
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSThis report describes the results of vegetation surveys of herbaceous communities distributed over unconsolidated paddy fields and their surroundings on valley floors in hilly terrain in Chiba Prefecture, Japan. The surveys were performed in areas where rice is cultivated and also in areas containing rice paddies that not been cultivated had for 20 years. There were 112 herbaceous and tree (seedling) species present in the valley where rice was actively cultivated, and stands were classified into five types of landscape based on their topography and type of utilization. In contrast, there were 79 species present in the valley where rice cultivation had ceased, and the stands were classified into three types of landscape. The quadrates surveyed were divided into seven categories at a 50% level of similarity by cluster analysis based upon the relative importance of each species. The categories do not necessarily correspond to landscape elements. The cluster b-1 contains dominant species that were found around footpaths, irrigation ditches, the forest margin, and the forest floor. This result indicates that the floristic composition of cluster b-1 consists of precursor species at the valley site. The dominant species was subsequently divided based on their utilization type. The species richness-diversity relationship in abandoned rice paddies was positively correlated. The landscape elements in areas where rice is actively cultivated were divided into three groups based on the extent to which they were disturbed: scarcely, moderately, and intensively. Both the species richness and the diversity index were highest in the moderately disturbed group and lowest in the intensively disturbed group. These results indicate that the cessation of rice cultivation led to an overall simplification of the landscape elements and floristic composition of the valley ecosystem.View full abstractDownload PDF (4101K) -
Ryuichi Sago, Takafumi Takeshita2004 Volume 49 Issue 1 Pages 36-41
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSEchinochloa crus-galli (L.) Beauv. var. crus-galli, Echinochloa crus-galli (L.) Beauv. var. formosensis Ohwi and Echinochloa oryzicola Vasing. are found in paddy rice fields. The difference between these three Echinochloa spp. strains, in terms of susceptibility to herbicide, is unclear. These three strains, collected from 13 paddy rice fields in Japan, were tested for susceptibility to six herbicides in a whole-plant assay. The three strains were nearly equally susceptible to the 90% growth-inhibition dosage of herbicide, excepting oxaziclomefone and pyriftalid. This dosage was near the recommended dosage of these herbicides.
Though Echinochloa crus-galli (L.) Beauv. var. crus-galli and Echinochloa crus-galli (L.) Beauv. var. formosensis Ohwi were selected by pretirachlor, molinate and mefenacet at a 90% growth-inhibition dosage for three years, their susceptibility level to herbicides did not change.View full abstractDownload PDF (831K) -
Mitsuyoshi Suzuki2004 Volume 49 Issue 1 Pages 42-44
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSDownload PDF (345K) -
Seturo Satou, Syunji Kurokawa, Hidehiro Inagaki2004 Volume 49 Issue 1 Pages 45-62
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
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Motoaki Asai2004 Volume 49 Issue 1 Pages 63-67
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
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Masatoshi Gohbara, Masayuki Hattori, Shizuko Ishikawa, Matsuo Itoh, Ak ...2004 Volume 49 Issue 1 Pages 72-81
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSDownload PDF (1433K) -
[in Japanese]2004 Volume 49 Issue 1 Pages 82
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSDownload PDF (153K) -
[in Japanese]2004 Volume 49 Issue 1 Pages 83
Published: March 31, 2004
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSDownload PDF (144K)
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