Orchardgrass plants of a single clone were transplanted 10cm apart on Nov. 23rd 1969, and were cutted 5cm above ground level when plants got about 30cm, 40cm or 50cm in height (named 30cm cut, 40cm cut or 50cm cut sward, respectively) between 1970 and 1972. Seasonal fluctuation of tiller numbers of each plant was investigated during the years, and the dates of emergence of tillers and death of them were observed between Apr. 14 and Oct. 9 in 1972. 1) With the start of rapid plant growth at the beginning of Apr. in 1970, vigorous tillering occurred, and it continued until the first of May (Fig.1). As many of tillers were cutted at culm at the first cutting of each treatment, the number of shoots being capable of regrowth decreased, but tiller numbers per plant were immediately recovered by active tillering, which continued until the time of summer depression. In contrast, poor tillering was observed from spring to early summer in 1971 and 1972, when tiller populations were greater than at the same season of 1970. The increase of tiller numbers was most abundant in automn, especially in 30cm cut sward, during 3 years. 2) From heading to late Aug. of 1972 the rate of tiller emergence was largest in 50cm sward, and little in 30cm cut sward, but most of these tillers died at the early stage after emergence, thus the greater part of tillers which emerged after Apr. 14 disappeared during the summer (Fig.5). 3) Though the sward was constituted with the plants genetically identical in this experiment, the fluctuation in size arose among plants of same cuting treatment. The basal area of plants in 50cm cut sward was most uneven after 3-year-treatment (Fig.8). One of the probable reasons that caused this phenomenon may be related with the repetition of frequent emergence and death of tillers during growing seasons.

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From 1967 to 1971, the dynamics of vegetation by grazing, the grass productivity and the grazing capacity of the pasture were observed in the bush type steep mountainous land with gradients from 17 to 39 degrees. The pasture observed was established by the top-dressing and surface sowing method, without plowing and disking, immediately after felling and burning bushes on the steep mountainous land in the fall of 1966. Young cattle of Japanese Black breed were grazed from April to October between 1967 and 1971, the dynamics of vegetation by grazing, the grass productivity and the grazing capacity of the glassland were studied. The results were also compared with those from an adjoining flat pasture established by the plowing method in the fall of 1965. Orchardgrass, tall fescue, perennial ryegrass, Kentucky blue grass, red top, Italian ryegrass and New Zealand white clover were mixed-seeded at the rates of 3, 1.5, 1.5, 0.5, 0.5, 1.0 and 0.5kg per 10a, respectively, in the fall of 1966. In the fall of 1971, the SDR_3 of each pasture species were 100, 66, 30, 45, 16, 0 and 53, respectively, and that of wild grasses was 15. By each successive year a remarkable increase in the tall fescue and fair increase in the white clover were observed, but the red top showed a tendency to decrease. It was considered that the red top would be depressed by the other vigorous species under the fertile pasture conditions. The ratio of harvested pasture plants to all plants harvested was 88.4% in the first year after establishing the pasture, in the third year it was about 95%, and thereafter it remained above the 90% level. The results were considered at almost same level to that for the adjoining flat pasture. The estimated grazeable herbage yield per 10a was 3,000kg in the first year and 3,200kg in the fifth year. Between the steep unploughable pasture and the flat ploughable pasture, there was little difference in the chemical composition of herbages clipped, the grazing capacity and the daily liveweight gain of young steers and heifers of Japanese Black breed. If better grazing management is practiced, the higher grass productivities and grazing capacities will be attained even at unploughable pastures in steep mountainous lands.

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1. In order to obtain the fundamental informations to select the warm season grasses suitable for the mineral soil which has poor physical conditions and to control the soil moisture conditions in seed bed layer by watering or other methods, the relations between osmotic suction (+atm.) and the seed germination of warm season grasses as shown in table 1 were examined in the definite temperature room kept in 29-30℃. Osmotic solutions were prepared and adjusted by polyethylene glycol. 2. The germination percentage in all species lowered with the increase of osmotic suction, but the degree of decline varied considerably by species (Fig.1). Germination characteristics among the species differed by the levels of osmotic suction were shown as in table 2. 3. In general, the germination percentage in those species which seed were relatively small such as Panicum spp. and Rhodes grass was much more severely affected and lowered by lower osmotic suction in comparison with the species of large seed such as Sorghum spp. and Millet spp. Among the species of small seed, Love grass and Makarikari grass were less severely affected. 4. The germination rate of almost all species declined linearly with the increase of osmotic suction, but the extent of interspecific differences were not recognized so evidently as those observed in the decline of germination percentage (Fig.2).

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1. In this study, the interrelation between soil water suction and germination and the emergence above the soil surface after germination was investigated at 30℃ constant temperature using representative warm season grasses with the alike object as has already been reported on the previous paper. Water suction-water content curve of the mineral soil tested was as show in fig.1. 2. The percentage of germination and emergence of all species did not vary at the lower levels of soil water suction and decreased rapidly at the some levels above the limit of water suction (fig.2). But the degree of such decline varied by the species and Sorghum spp. and Millet spp. well-emerged evidentlly in the higher levels of soil water suction. Among the small seed species, Panicum spp. and Rhodes grass were much more severly affected at increased soil water suction and decreased rapidly at some levels over the limit of water suction. 3. Soil water suction permitting the relative germination and emergence percentages of 0% and 50% (percentage at 0.03atm.=100) and also that over which emergence percentage began to lower rapidly were shown as in table 1. 4. The rate of emergence of almost species declined slowly with the increase of soil water suction at the lower levels in which the percentage of emergence did not declined, and decreased rapidly at the some levels above the limit of water suction. But there were no differences among the species in the degree of such reduction (fig.3).

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In order to look into the adaptive role of surviving rate and mortality in grasses, mortalities under different environments were observed in perennial ryegrass (Lolium perenne) and orchardgrass (Dactylis glomerata). Three varieties of each species were tested. Four hundred viable seeds per plot (1 m^2) were sown in 1970 September in pure stand (6 varieties) and in species mixture (1: 1, 9 varietal combinations). The fifteen populations were grown on road side (2 replications) and in an experimental field (four different managements; clipping, herbicide treatment, and two controls with and without white clover). Number of surviving plants were counted four times until 1973 April. Measurements of several characters were also taken. Since the experimental plants on road side died in the next year on account of vigorous gorwth of summer weeds, data obtained from field plots were mainly analyzed. Seedling mortality was obviously higher than adult mortality. Orchardgrass had higher seedling mortality but the remaining plants survived longer than those perennial ryegrass. A negative exponential model, Y_t=Y_o・e^<-bt>, was used for representing the survival curve of each variety. Variance analysis of mortality data showed that the two species significantly differed in mortality as well as in its response to enviromental stresses. Varietal differences within the same species were partly significant. Generally, plant density and mortality were positively correlated, while seedling mortality were negatively correlated. This suggests that death was at least partly density-de-pendent. "Self-thinning " might have worked to regulate the number of plants per unit area. Perennial ryegrass had a higher ability of sexual reproduction and produced more offspring by seed than orchardgrass. The degree of phenotypic plasticity in response to clipping was higher in perennial ryegrass than in orchardgrass. Mortality was generally lowered by clipping or by herbicide treatment, the tendency being more pronounced in perennial ryegrass than in orchardgrass. Perhaps perennial ryegrass copes with environmental stresses by its high survival rate at the cost of plant size. The effects of species competition was represented by the differences in chara values and mortality between pure and mixed plots. Orchardgrass was advant in competition to perennial ryegrass and the relative frequency of orchardgrass plots rapidly increased. It may be concluded that perennial ryegrass has a relatively short life resistance to enviromental stress. In contrast, orchardgrass seems to span, higher vegetative reproduction rate and stronger competitive two species seem to differ in adaptive strategy. (J. Japan. Grassl.

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In the present paper, the seed germination and the seedling growth under various environmental conditions were investigated to get the fundamental data on the cultivation and the utilization of Japanese barnyard millet as soiling crop. 1) The optimum temperature for the seed germination of Japanese barnyard millet was 35℃, the maximum temperature was between 40℃ and 45℃, and the minimum temperature was below 10℃. As the seeds can germinate after 4 days of seeding at 15℃, it is possible to seed safely when the average daily temperature reached to 15℃. 2) As mesocotyl showed a remarkable elongation, 70 per cent of seedlings emerged under deep sowing of 10cm and 30 per cent under 15cm. Therefore, under dry soil surface, the high percentage of seedling emergence may be expected by deep sowing such as 5〜6cm than shallow sowing such as 1〜2cm. 3) No emergence of seedling was found in dry soil of pF 4.2 (about 15% moisture ratio), but the emergence of seedling was found in the soil of pF 4.1 (about 16% moisture ratio). In the soil which pF ranged 3.4 to 3.8 (about 22〜30% moisture ratio), the percentage of seedling emergence was not decreased, although some delay of seedling emergence was observed. 4) The percentage of seed germination in the deep water such as 10〜15cm was not reduced at all, but the seedling growth was inhibited. This inhibition of seedling growth in the water was removed by adding hydrogen peroxide (100ppm). 5) In over-moist soil such as 5cm ground water level, the seed germination was about 90 per cent and the stand establishment was nearly 100 per cent. The plant height and dry matter weight on 30 days after seeding were the highest in the soil of 15cm ground water level.

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The process of disappearance of cellulose, lignin and silica in the rice straw packed in a silk bag and placed in the rumen was investigated quantitatively. The correlation coefficient between the disappearance rate of these components and that of dry matter was estimated. Quantitative analysis of cellulose, lignin and silica in the rumen of fistulated cow was carried out by five days period experiment. The disappearance rates of these components and of dry matter were compared. 1. The lowest disappearance rate was obtained in the rice straw of the highest cellulose and lignin-content. The rice straw containing silica at average level gave the highest disappearance rate of silica in the rumen. Both higher and lower level of silica than the average gave lower value of the disappearance rate. 2. Correlations between the disappearance rate of dry matter and that of cellulose, lignin and silica were estimated. Cellulose followed by lignin, influenced most effectively on the disappearance rate of dry matter. Correlation coefficients at the first day after placing the rice straw in the rumen were 0.842 (P<0.05) and 0.794 for cellulose and lignin, respectively. 3. Negative correlation was observed between the contents of cellulose, lignin and silica in the rice straw, and the disappearance rate of dry matter. After third day of the experiment period, the correlation was statistically significant. Higher contents of cellulose and lignin gave low value of the disappearance rate. 4. The same experimental results as described above were obtained in the cases of wheat straw, orchardgrass and ladino clover.

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In this experiment, the changes of the number of tillers in unit area, the relation among number of tillers, weight of a tiller and yields were investigated in some grass species, that is, perennial ryegrass, timothy, tall fescue, red top and Kentucky bluegrass. Each grass was sown respectively in May 1971, the examination started from 1972 for two years applying with the treatment of three levels of fertilizer application and two different cutting frequency. The results were summarized as follows; 1) The number of tillers in unit area were greater in perennial ryegrass and Ky bluegrass than in timothy and tall fescue, and was greater in 5 times cutting than in 3 time cutting. The application of fertilizer made the number of tiller increased to a certain extent, but heavy application made it decreased. 2) The relation between number of tillers and weight of a tiller which estimated from the dry matter yields in each cutting was described as next empirical equation, W=kN^<-a> (W: weight of a tiller N: number of tillers in unit area) but, the value of (a) were varied by the difference of cutting frequency and growing period, the value of (a) was larger in 3 times cutting than in 5 times cutting, and was larger in reproductive stage than in vegetative stage. 3) The influence of the number of tillers and weight of a tiller to the yields were varied by the difference of cutting frequency, fertilizer application level and growing peried, as the relation between the number of tillers and weight of a tiller were changed by these influences as above mentioned. In the swards of 3 times cutting the grass species which has heavier tiller weight but few number of tillers were more productive than the grasses which has greater number of tillers, and in 5 times cutting the grass species which has greater number of tillers were more productive.

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Orchardgrass seedlings were grown for about seventy days in the glass houses kept at four constant temperature levels of 15, 20, 25 and 30℃ in order to clarify the effects of temperature on the appearance and decay of a single leaf and their influences upon the total number and weight of the leaves borne on a main stem and a whole plant. These measurements were taken at the beginning of the treatments and after 18, 36, and 72 days. The results obtained were as follows: 1) The life span of a single leaf was longer under the lower temperature treatment. A leaf on the upper node of a main stem had the longer life span than the lower one (Table 2). The period from the early to the full decay of a leaf blade was longer under the condition of the higher temperature (Fig.1). 2) Leaf emerging rate on a main stem was promoted at 25℃ throughout the experiment and number of decayed leaves was advanced at 30℃ from beginning to the 22nd day of the treatment, but thereafter 25℃ surpassed it (Fig.3). 3) Mean weight of a single leaf was the heaviest at 25℃ among the treatments. The number of living leaves increased from beginning until 18th day on a main stem and until 36th day of a whole plant, and decreased thereafter. The total weight of leaves was maintained the highest at 25℃ and the lowest at 30℃ (Fig.3). 4) Total weight of whole leaves per stem consists naturally of the weight of a single leaf and the number of live leaves. The number of live leaves on a stem was affected by the life span or duration of a single leaf together with the rate of leaf appearance (Fig.2). Both the number of live leaves and the weight of a single leaf showed a similar trend to that of the total weight of leaves during the early stage, but the number of live leaves at the later stage showed difference from the total weight (Fig.3). 5) Figure 4 shows the relationships between the total weight of leaves and the number of live leaves or the weight of a single leaf. In this figure, all the measurements of each age are experessed as deviation percentages from the mean of values of the 4 temperature treatments. Correlation coefficient between the total weight of leaves and the number of live leaves was γ=-0.241 but between the former and the single leaf weight, it showed γ=0.939 in the case of the main stem. And in a whole plant, these were calculated as γ=0.157 and 0.734** respectively. (**means significance at 1% level of the probability.) 6) By these facts, it is concluded that the mean single weight of a leaf contributes more efficiently towards the total weight of leaves, and accordingly, towards the whole weight of a stem or a plant than the number of attached live leaves at the late vegetative stage of orchardgrass.

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