A mathematical model which incorporates the leaf (lamina) growth, leaf consumption, animal growth, dung excretion, dung distribution and dung decomposition in pastures was constructed to evaluate the effects of dung from grazing animals on pasture production and utilization and animal production. Comparison of simulation results under dung-free and dung-deposited conditions in a bahiagrass pasture with varying numbers of Holstein heifers revealed the following points. 1. Dung deposition increased before-grazing leaf mass and leaf allowance at all stocking rates. 2. Dung deposition decreased leaf intake and daily liveweight gain per animal at high stocking rates, but no effects on them at low stocking rates. 3. Dung deposition reduced both maximum liveweight gain per hectare and optimum stocking rate for the maximum gain. 4. Dung deposition resulted in uneven distribution of leaf mass in pasture. It was suggested that the patchy grazing by animals is more resposible for the heterogeneity than the patchy return of nutrients and the patchy killing of leaf by dung pat cover.

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As a part of studies on the mass multiplication of elite plants in timothy, the possibility of utilizing proliferating spikelets was examined. In this experiment, proliferating spikelets were collected from one plant of timothy 「Kitami No.15」 naturally grown in the field. Parental plant (P_0), plants regenerated from proliferating spikelets of P_0 (P_<0-1>) and progeny plants of P_<0-1> (P_1) were exposured to higher temperature of 18℃ or above under greenhouse condition at their spikelet defferentiation stages and transplanted to a field in late June at Kunneppu, Hokkaido. Proliferating spikelets were induced in all plants of P_0 in 1987 and 1989, and P_<0-1> in 1987, and in 94% of heading plants of P_1 in 1989. Good seeds were harvested from these plants grown at spikelet defferentiation stage under cool condition in early spring of Kenneppu. No proliferating spikelet was induced in P_0, P_<0-1>, and P_1 plants and mean seed weight per plant 2.04g in P_0, 2.76g in P_<0-1> for 1988, and 24.01g in P_1 for 1990, respectively. It is assumed that the proliferation of spikelets in timothy plants may be a general genetic feature, because proliferating spikelets were induced to all P_0, P_<0-1> and P_1 plants. High temperature treatment during the spikelet differentiation stage is a relatively simplified method to induce proliferating spikelets of timothy plant than hormone treatment and it is assumed that using proliferating spikelets provides a high possibility for mass multiplication of plants of timothy.

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Horses walk around without sleeping in night grazing, so bring an immediate adopted method on rearing strong race horses. But this method is adopted in only few large scaled ranches, because horses are timid especially at nihgt, so may stampede at the slightest sound or light. 1. Night grazing is good for limb training by roaming in a group for more than 20 km. Also night grazing is expected that wild nature is taken. 2. The danger of stampede can be prevented to a certain extent by improving environments and taming. There is instance that night grazing without accidents is possible in small paddocks of about 1 ha. The other horses do not roam at by the side of a great forest zone.

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In the past, cows and horses were treated as if they were livestocks in the same category and it was often thought that in the grazing lands, they could be managed similary. But great difference are found out in grazing sward height or grazing system. 1. Rotatinal grazing at the sward canopy height or 20-30 cm is used for cows, but set grazing of sward with a height of only about 5-10 cm is used for horses. 2. When the pasture plants grow to a height of more than 10 cm over and the top of leaves low as if they put on the lid of grassland, horses do not graze down the grass. Horse should dislike the vile smell of mold.

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The effect of herbage allowance on daily weight gains (DG) in young cattle grazing a mixed species pasture under a rotational system was investigated. Annual average of daily leaf allowance (ADLFA), annnual average of daily living part allowance (ADLVA) and total herbage (including dead part) allowance (ADHBA), during a single grazing season for approximately 190 days, were calculated as dry weight in g/cattle body weight kg/day. A rectangular hyperbola curve was applied to describe each annual average of herbage allowance-annual average of DG was discussed in relation to initial total body weight of a herd, leaf mass production, and ADLFA.

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As a sequel to the previous report, variability in germination was investigated using ferile seeds produced under uniform field conditions from about 290 clones of 39 local populations. Based on the results of the preliminary experiment, an incomplete pretreatment (NaOH alone) and sub-optimal temperature (30℃) were purposely adopted as tes conditons for acutualizing potential variability in germination response. The results obtained were presented in terms of CZABATOR's germination value (GV). The two experiments conducted in successive years using the seeds produced in each previous year revealed significant differences in GV both between and within the local populations tested. Accoding to variance analysis, these populations were classified into three groups, A, B, and C. These groups were characterized by easy germinability with GV of 71.3, intermediate germinability with GV of 17.8, and by difficult germinability with GV of 2.2, respectively. In this case, the distributional area of constitutive populations of these groups roughly corresponded to southern, central and northern Japan. respectively, suggesting and eco-clinal variation pattern as a whole. The exact relationship between the provenance of population and the germinability of seeds produced from them was not clear, however. A high correlation of r=0.83 was recognized between the results obtained from the experiments for two years. This was considered to suggest that germinability of seeds in this plant species are under genetic control to a considerable degree. On the other hand, a significant negative correlation of r=-0.50 was established between the number of fertile seeds produced per unit are and percentage germination of the seeds. The significance of this negative correlation was briefly discussed from ecologicaland agronomical points of veiw.

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Deproteinized juice of alfalfa (Medicago sative L.), a liquid waste of leaf protein production process is known to be effective on the growth of alfalfa and rice seedlings. However, the active fraction was not weparated and the responsible compound was not identified. In this investigation, plant fraction containing the responsible compound was investigated on the basis of growth promotion of rice seedlings. It was clear from ion exchange chtomatographical experiment that the active compounds were acidic and non-ionic. However it was not possible to extract them from acidified alfalfa juice with organic solvent such as ethyl ether. Besides, it was found thet the active compounds were not absorbed by charcoal and that their molecular weights were lower than 500. Paper chromatographical experiment showed the presence of two active and one inhibitory peaks in the (acidic+non-ionic) fraction fractionated by ion exchange chromatography as described above. Moreover, the addition of phenolic adsorbent (polyvinylpolypyrrolidone) to alfalfa juice was observed to be promotive for plant growth, and the difference of growth response between deproteinized alfalfa juice and known plant hormones was compared.

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