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Volume 20, Issue 3
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Tomosaburo YABUNO1975 Volume 20 Issue 3 Pages 97-104
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
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1. Relation between Temperature and EmergenceMitsuyoshi SUZUKI, Takahisa SUTO1975 Volume 20 Issue 3 Pages 105-109
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSNineteen species of weeds in rice were sown on paddy fields at various times from Apr. 20 to Aug. 2 in order to know the relation between temperature and weed emergence.
1) Weed seeds stored in four differnt conditions during winter were tested for emergence. Of these storage conditions, the seeds stored in soil at upland soil moisture gave the best emergence.
2) The beginning time of emergence varied evidently with weed species. Weeds such as Callitriche verna and Alisma canaliculatum emerged first, and the average temperatures of air and water at emerging time were 8°C and 13°C respectively. Emergence of Monochoria vaginalis and Vandellia angustifolia occurred last of the weed species tested and began at 15°C to 16°C and 19°C of the respective average temperatures. Weeds such as Echinochloa crus-galli and Eleocharis acicularis were mediate of these two groups.
3) The accumulative air- or water-temperatures for the period from sowing to emergence were almost same among the different sowing times in each species except the sowing at low temperatures. The value of accumulative temperatures required for emergence varied with weed species, and was negatively correlated with the period from sowing to emergence.
4) The relationship between the period from sowing to emergence (y) and the average air- or water-temperature (x) gave a satisfactory fit to the formula y=axb. The values of parameters a and b were different among species.
5) In each of seven monocotyledonous species, leaves emerged with a regular time interval at early growth stages.View full abstractDownload PDF (599K) -
2. Duration and Rate of EmergenceMitsuyoshi SUZUKI, Takahisa SUTO1975 Volume 20 Issue 3 Pages 109-113
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSWeeds in rice were sown on paddy fields, as described in the previous paper, in order to make clear the differences in duration and rate of emergence among weed species. Weed seeds tested were stored under four different conditions during winter.
1) The period from sowing to completion of emergence, which was influenced by storage conditions of seeds as well as weed species and sowing times, generally was less than 45 days. The seeds stored at air-dry condition required longer period for complete emergence than the seeds stored at the other conditions.
2) Weeds were classed in seven groups according to the patterns and rates of emergence, which were also influenced by seed storage conditions and sowing times.
3) Irrespective of the sowing dates, Alisma canaliculatum and Sagittaria trifolia showed the highest rate of emergence among weed species examined, and next was Echinochloa crus-galli. Seeds of Alisma canaliculatum, Echinochloa crus-galli, Monochoria vaginalis, etc., when they were stored in water submerged soil, emerged with considerably high rates even by the sowing at early August.View full abstractDownload PDF (495K) -
3. Weed Emergence and Weed Damage in Paddy Rice FieldsMitsuyoshi SUZUKI, Takahisa SUTO1975 Volume 20 Issue 3 Pages 114-117
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSChanges in weed emergence with time and the relation of weeding to weed damage were examined in the transplanted rice fields, in which young rice seedlings were transplanted at different three dates with transplanter. Results obtained were as follows:
1. Seventeen species of eleven families were found in the experimental fields.
2. Emergence of Echinochloa crus-galli, Aneilema japonica and Eleocharis congesta decreased with the deley of transplanting. On the other hand, amounts of emergence of Cyperus difformis and Elatine triandra were scarcely changed among transplanting times.
3. Twenty-five to fifty-four percent and ca. ninety percent of the final amounts of emergence were emerged within 12 days and 43 days after puddling, respectively. Period of complete emergence, however, varied with transplanting time, and it was 70, 60 or 50 days in early, ordinary or late season culture, respectively. Elatine triandra, Monochoria vaginalis and Eriocaulon robustinus, among weed species found in fields, continued to emerge until later growing season.
4. Complete weeding for 40 days after transplanting eliminated the yield loss by weeds in early or ordinary season culture.
5. When weeds were permitted to grow without any control, weeds rapidly increased their weight around 40 to 60 days after transplanting and strongly inhibited the tillering of rice, which was the major cause for yield loss.View full abstractDownload PDF (462K) -
3. A Correlation between an Average Responsiveness Index of Weed Populations and Soil Acidity in the Volcanic Ash-kuroboku Soil ZoneSeiko SUGAWARA1975 Volume 20 Issue 3 Pages 117-123
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESS1. It was examined in the present study whether the ordinal number, an index of the responsiveness of weed types to varying degrees of soil acidity, determined for weeds in the volcanic ash-kuroboku soil zone in Muramatsu, Niigata Prefecture are applicable or not to weed types growing in soils of similar nature in other four localities in the same prefecture.
2. Data were collected from four districts such as Kanai, Myoko, Nagamine and Tokamachi. In all of these districts, many weeds sampled from uncultivated as well as immature and mature upland fields were found to be expressed by ordinal numbers. There was a highly significant difference among average responsiveness indice of different weed populations. These findings show that the classification system of weeds adopted in Muramatsu district can also be applicable to weeds in the other districts.
3. It appears that, if sampling points are large enough, an average responsiveness index can be obtained without referring to the individual number of weeds with or without an ordinal number and to the type of weeds.
4. Determination of ordinal numbers for may other weeds and the alucidation of a correlation between the average responsiveness index of weed populations and the soil acidity in many other districts of different soils might eventually enable to establish a standard index for soils or climate which would be applicable to every district of this country.
5. In uncultivated and cultivated upland fields in the volcanic ash-Kuroboku zone examined in this study, it was possible to know the maturity of a ffeld by knowing the average responsiveness index of weed population in the given field, and conversely it was possible to predict weed types or the structure of weed populations vegetating in a certain field by knowing its soil acidity. These features seem to be extremely advantageous for an effective operation of weeding.View full abstractDownload PDF (910K) -
II. The Heading BehaviorHiroshi SUGE, Tokuichi KUSANAGI, Kinjiro HATTORI1975 Volume 20 Issue 3 Pages 123-126
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSFourteen strains of a perennial weed, Cyperus serotinus, in paddy fields collected from different places ranging from Akita to Miyazaki in Japan were grown under 3 different photoperiod conditions, and their heading behaviors were examined.
These strains were found to show different responses to photoperiods, indicating the existence of ecotypes within the species. Differentiation of heading behavior was found even in the strains collected from the same places. All strains were found to fail heading under 20hr photoperiod, however, critical duration of light per 24hr cycle at which floral induction occurred was not determined at this experiment.
Geographical cline was not evident among strains within the limit of this experiment.View full abstractDownload PDF (4239K) -
Goro HASHIMOTO1975 Volume 20 Issue 3 Pages 127-134
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
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Shigeru TAKAYANAGI, Minoru TAKABAYASHI, Katsuyoshi NOGUCHI1975 Volume 20 Issue 3 Pages 135-139
Published: November 25, 1975
Released on J-STAGE: December 17, 2009
JOURNAL FREE ACCESSDownload PDF (766K)
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