To clarify the variation in intra- and inter-populations of I. cylindrica var. koenigii on Kii-Ohshima Island, the plant size, morphology, pollen fertility, and seed set were investigated in 11 populations. Five clones well separated each other within each population were collected. Five ramets of each clone, a total of 275 ramets were planted in about 6000cm³ pots filled with clay loam on June 10, 1983. The seed set in the natural population was investigated for three years, from 1982 to 1984.
The seed set percentage in the natural populations greatly varied among populations and among the three years. The value of the foredune population was very low, 0.10 to 0.46%, because of male sterility. That of the other ten populations ranged from 1.05 to 59.07%, though the pollen fertility of each population reached 94.08 to 99.15%.
Under a cultivated condition, the seed set percentage of bagged panicles varied 0.00 to 0.35% and 100 kernel weight was 11.07 to 13.15mg. The five clones did not differ within a population in plant length, total dry matter weight, the number of shoots, the total rhizome length, the weight of 1cm length rhizome, anther size and dry matter partitioning ratio to rhizome, though significant differences were obtained among populations. The variability was smaller within the foredune population than in the other ten populations.

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1. Echinochloa crus-galli var. praticola seeds were imbibed for 0, 6, 12, 24, 36, 48, 60 and 72 hours and then measured for their ATP content. ATP level increased very rapidly after seed imbibition for 6 hours, becoming almost constant after 36 hours. The highest ATP content was observed at 72 hours of imbibition.
2. ATP content during the storage period of E. crus-galli var. praticola which had been harvested between 1972 and 1986 was examined and the relationship with viability sought. It was found that: 1) ATP content progressively decreased with increasing storage period over 3 years after harvest and reached an undetectable in seeds eleven years after harvest. 2) Only those seeds harvested in 1980 to 1986 germinated, with 1984 seeds showing the highest percentage. 3) A very close relationship was found between ATP content and germination rate, suggesting that the mechanisms responsible for ATP production and consumption function with 48 hours of imbibition.

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Experiments were carried out using cucumber (Cucumis sativus L. cultivar. Suyo) as a test plant which was grown in a pot or a seedling case containing a medium consisting of a mixture of quartz sand and leaf powder of several weeds or crops. Stem length and dry weight of the test plants were measured to analyse the allelopathic effects of leaves incorporated into the medium. Results obtained are summarized as follows.
1. Stem length and dry weight of the organs of cucumber plants increased when leaf powder of Pueraria lobata OHWI was added into the medium. The values were almost the same as in the control when Fagopyrum esculentum MOENCH or Oryza sativa L. was added. The values decreased when leaf powder of Chenopodium album L., Datura stramonium L., Artemisia princeps PAMP. or Digitaria adscendens HENS. was added (Figs. 1-2).
2. Stem length and dry weight of the organs of cucumber plants decreased in proportion to the amount of leaf powder of Chenopodium album or Datura stramonium added to the medium (Figs. 3-4).
3. Growth of cucumber plants was depressed when leaf powder of Chenopodium album, its ethyl alcoholic extract or its residue was added. In particular, the dry weight of the plants was reduced when leaf powder or the residue was added (Fig. 5).
4. Depression of growth of cucumber plants in the medium containing Chenopodium album was assumed to be caused by the increase of the osmotic pressure and pH of the solution in pots and by the growth-inhibiting substances from the leaves.

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In order to obtain basic information for the control of broadleaf dock (Rumex obtusifolius L.), an aggressive weed in grasslands, experiments were conducted using 1/2000 a wagner pots at different shading intensities, control (no shading), 80, 90, 95 and 100% to determine the effects of shading starting at different growth stages (seed, cotyledon, 1st leaf, 3rd leaf and 5th leaf stages) on early growth and regrowth of this weed under spring sowing. Tops of all the plants were clipped on the day when non-shaded plants were at the full-bloom stage. These continued to grow without shading thereafter.
In the early phase of growth, emergence percentages at each shading intensity were high for the control and 100% shading treatments, and low for the 80-95% shading treatments (Table 1). Plant length, leaf number, leaf area and top dry weight (seed, leaf and stem weight) decreased with the increase of the shading intensity and when the shading treatments were initiated at early stages. Especially, the leaf area and top dry weight decreased remarkably under shading treatments as compared with the non shading treatments. Seed production was not observed except for the control and 80% and 90% shading treatments which were initiated from the 5th leaf stage (Fig. 1, 2, 3, 4).
For the regrowth, the sprouting percentage decreased with the increase of the shading intensity in all the plants regardless of the growth stages when the treatment was initiated (Table 2). The viability of the plants at harvest was almost 0 percent under 95% and 100% shding treatments irrespective of the growth stages when the shading treatment was initiated. The top and root (tap and lateral roots) dry weight decreased linearly with the increase of the shading intensities and when the shading treatments were initiated at earlier stages (Fig. 5).
These results suggest that the shading treatment exerts a highly inhibitory effect on the seedling growth of broadleaf dock. It was suggested that 90% shading treatments should be applied until the 1st leaf stage at the latest e. g. using quick growing grass species, for restricting the emergence and early growth of the seedlings of this weed at the time of spring renovation.

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Seasonal variations in the emergence of propagules from tubers in an arrowhead (Sagittaria trifolia L.) under natural conditions in a paddy field and in concrete pots were analyzed in relation to the changes in soil moisture. To analyze the emergence from the tuber, combinations of changes in the period of initial flooding, depth of burial of tubers, tuber size as well as degree of reduction of submerged soil and soil temperature were tested in the laboratory or in the fields.
The results obtained are as follows
1) Slow emergence from late-June (after puddling time) to early-August (mid-summer drainage time) was observed in rice fields under normal season culture. Continuous emergence with a small peak after puddling time and larger peak after mid-summer drainage time was observed in concrete pots under appropriate drainage conditions.
2) Also continuous emergence from early-May to late-August was observed in concrete pots under ill-drained conditions under early season and normal season rice culture.
3) The changes in the period of emergence from the tubers were associated with the time when flooding started, depth of burial of tubers and tuber size. Especially, the emergence was remarkably slow when flooding started in May under early season rice culture as tuber dormancy was not broken at the start of flooding.
4) The elongation of the terminal buds of the tubers in which dormancy was broken in water in the dark, was faster of a constant temperature of 25°C than of 20 or 30°C. At 10 or 40°C few tubers elongated.
5) The larger the quantify of starch added to soil, the later the emergence and the lesser the soil reduction, the faster the elongation of the tuber buds in puddled soil.
6) The relationships between the methods of weed control and emergence of the weed in paddy fields were analyzed.

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Studies were carried out to analyse the effect of seed size and biological space of broadleaf-dock on germination, growth and survival immediately after emergence in a mixture with orchardgrass. Results obtained are as follows.
1. The size of most of the seeds of broadleaf-dock produced in a grazing pasture exceeded 1.0mm (Table 1).
2. Germination percentage was higher for the large seed size class than for the small size class. The percentage and speed of germination of broadleaf-dock seeds were superior to those of orchardgrass (Fig. 2).
3. In the broadleaf-dock plants with larger seed size profuse growth of top and roots (Table 2) was observed in the early stages.
4. When the biological space of broadleaf-dock was large at emergence and/or located far from orchardgrass, growth was profuse in the early stages (Fig. 3). Even when the size of the biological space at emergence was small, broadleaf-dock was able to continue to grow under such conditions.
5. Due to these ecological characteristics, it is considerd that broadleaf-dock is able to grow at high population density of herbage at the time of pasture establishment.

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[in Japanese]

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1. Three ATP extraction methods for Echinochloa crus-galli var. praticola imbibed seeds were tested: 1) boiling intact seeds 2) boiling cracked seeds and 3) grinding seeds with or without 5% TCA. With the two boiling methods a very small amount of ATP was detected. The grinding method accomplished in a very short time using Triton X-100 as an extract solution for ATP gave the best results.
2. Three methods of cleaning for various durations were compared in E. crus-galli var. praticola seeds: 1) dipping in 70% ethyl alcohol (EtOH), 2) dipping in 1% NaClO solution and 3) exposure to formaldehyde gas. The results showed that dipping in 70% EtOH or exposing to formaldehyde gas for 3 minutes is an appropriate means of cleaning E. crus-galli var. praticola seed for ATP assay.

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Tolerance of fourteen Thai RD-rice cultivars (Oryza sativa L.) to the herbicides simetryn (2, 4-bis (ethylamino)-6-methylthi-o-s-triazine) and dimethametryn (2-(1, 2-dimethylpropylamino)-4-ethylamino-6-methylthio-s-triazine) was surveyed. When the herbicides were applied to roots through a nutrient solution, dimethametryn was more phytotoxic to the plants than simetryn. Differences in tolerance to the herbicides were observed in the nutrition solution treatment. RD-1, 21, 23, 25 and 27 were relatively tolerant and RD-11, 13, 15 and 17 were susceptible to both herbicides. When the herbicides were applied to the soil, no clear difference in tolerance was noted among the cultivars; in this treatment, dimethametryn was less phytotoxic. The data demonstrated that relative phytotoxic activity of the herbicides changed depending on the method of treatment.
Adsorption and movement of the herbicide in the soil may contribute to its phytotoxicity.

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