To evaluate orchardgrass individuals, digestibility-estimating equations were introduced from the results of analysis of multiple regression between digestibility and some plant characters (Table 2). The effectiveness of these equations in the breeding program was studied. In 1977, 159 plants from 1488 orchardgrass plants in blocks I and III where plant characters were investigated were selected for high and low digestibilities of first cutting and aftermath, basing on the estimated digestibility calculated from the equations. In 1978, digestibilities of the selected plants were evaluated by the one-step cellulase method (OSDMD) (J. Japan. Grassl. Sci., 23, 177-182). Ranges of OSDMD's of both high and low groups of first cutting were similar to each other (52-76%). Means of OSDMD were 57.9% and 66.4% for groups selected for high and low digestibilities respectively, resulting in selection opposite to the expected (Fig.1). Results of selection based on OSDMD in block II was similar to those in selection by the estimated digestibility. There was observed a negative correlation for digestibility of varieties between in 1977 and in 1978 (Fig.3), which was presumed to be caused by meteorological factors, temperature and percipitation, affecting heading dates of late-maturing varieties, but not affecting that of early-maturing varieties (Figs.4 and 5). Digestibility of late-maturing varieties was higher than that of early-maturing varieties in 1977 when growth and heading of late-maturing varieties was accelerated, and vice versa in 1978. In aftermath, means of OSDMD of high and low groups selected by estimated digestibility were 60.2% and 57.0% in 1978 respectively (Fig.6). Digestibility of aftermath was not seriously affected by the meteorological factors, and estimated digestibility from some plant characters is applicable to individual selection of orchardgrass.

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For a step to decide the suitable grazing periods which enable to utilize in the succeeding years and to know the cutting time for effective destruction of Sasa nipponica community, an attempt was made on investigating the annual growth pattern of its community, viz., seasonal fluctuation of dry weight of each plant organ, number of culm, leaf area, productive structure, and number of winter-bud. This experiment was conducted in a closed plant community extenaing on southern slope of Mt. Asama, Nagano prefecture. 1. The biomass above ground increased rapidly from spring to summer, reached maximum in late August, and turned to decrease gradually towards spring in the next year. Contrastingly, the biomass under ground showed a trend of decrease from mid-spring to summer and of increase towards late autumn. Thus, total biomass has kept almost constant throughout the year (Table 1), suggesting that the amount of newly produced plant organs is almost equal to the withered organs in this closed community. 2. Leaf area index (LAI) in the community varied in similar way with the biomass above ground and closely related to the fluctuation of the number of leaves emerged on current culms (Tables 1 and 3). 3. Height and biomass of the wintered plant were exceeded by those of the currently sprouted in June and almost withered at the lower layer of the community untill December. Therefore, it was suggested that average life span of aboveground part in the closed community of Sasa nipponica was about 18-20 months after new shoot sprouted on the ground surface (Tables 1 and 2). Ratio of the aboveground parts to underground parts (T/R ratio) showed muximum value in summer and minimum one in winter (Table 1). 5. Productive structure of the community varied with the season (Fig.1), coinciding with the seasonal pattern of dry weight fluctuation of each organ as indicated in Table 1. Relative light intensities on the ground surface in the community ranged from 10 to 20 percent during the period of winter to spring and 1-5 percent during the growing season. The extinction coefficient of light in the community showed narrow range 0.742-0.778. 6. Number of winter-buds on rhizome also showed a seasonal variation: most of them sprouted during the end of April to the end of May ; they extremly decreased in summer and turned to increase rapidly during September to October and maintained the fixed value hereafter (Fig.2). Contrastingly, number of new rhizome increased rapidly during June to August. 7. With the results above, it was suggested that the suitable grazing periods for the utilization in the succeeding years was late autumn to spring and the cutting time for the effective destruction of Sasa nipponica community was summer.

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This paper dealt with dry matter production and ecological chracteristics as affected by the time and the frequency of the cutting in conjunction with the previous paper 1 which attempted to show the suitable grazing periods which enabled to utilize in the succeeding years and the cutting time for the effective destruction of Sasa nipponica community. This experiment was conducted during 1966-1968 in the almost identical community reported in the previous paper 1. The plant was cut at monthly intervals from May, 1966 to April, 1967 for the trial of cutting time and 0-4 times during June to September, 1967 for the trial of cutting frequency. The followings were the items measured for both experiments in August or in September in the following year, viz., the biomass above/under the ground, leaf area index, and number of culms. 1. When cut monthly, the biomass above ground became less than 60 percent of the nocutting treatment. Summer cuttings, in general, more decreased the biomass when compared with autumn-spring cuttings. Especially, cutting in August induced drastical decrease in the biomass (Table 1). 2. The biomass under ground, LAI, and number of culms were affected by the cutting treatments in similar way to the biomass above ground, thus, showing lower values by summer cuttings, especially, by the cuttings in August as compared with autumn to spring cuttings (Table 1). 3. The increased cutting frequencies tended to decrease the biomass above/under the ground (Table 3). 4. The cutting time and the cutting frequency affected number of culms with a close relation to their effects on the biomass fluctuation above ground (Tables 1 and 3). 5. Winter-bud formation occurred during September to October and sprouted in spring in natural condition. Cutting in August has drastically reduced winter-bud formation as compared with other cuttings (Fig.2). 6. From the results above, we can conclude that November to April is a suitable periods for grazing which enables utilization in the succeeding years and August is the month for cutting for effective destruction of Sasa nipponica community.

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This study was carried out to make clear the effects of day length on formation of winter-bud and new rhizome in Sasa nipponica. The plant materials used in this study were transplanted to pots from field in April, 1967 and grown under natural day length till the start of experiment. This study consisted of two experiments which were conducted in summer (July 1-July 31) and in autumn (August 13-October 31). Treatments imposed in both experiments were short day (8.5 hrs) and long day (15 hrs). Results obtained were as follows: 1. The short day length induced more winter-buds on rhizome than long day length. 2. The long day length, on the other hand, increased number of new rhizome than the short day length. 3. These results may suggest that the day length is a factor which is involved in the seasonal fluctuation patterns of numbers in winter-bud and new rhizome in the natural community of Sasa nipponica reported in the previous paper I.

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The experiment was carried out to clarify the effect of nitrogen fertilizer rate, leaf nitrogen concentration and chlorophyll content on photosynthetic activities of some subtropical grass species. Species used were rhodesgrass (Chloris gayana KUNTH.), dallisgrass (Paspalum dilatatum POIR.) and bahiagrass (Paspalum notatum FLUGGE). Results obtained were as follows: 1. Photosynthetic rate per plant (P) under low nitrogen fertilizer treatment showed the lowest in rhodesgrass at the weeks of advanced growth. This seemed to be caused by the remarkable drop in photosynthetic rate per unit leaf area (P_0) which resulted from the marked decrease of leaf nitrogen concentration due to the serious nitrogen deficiency in rhodesgrass plot. In contrast, rhodesgrass showed the highest P value followed by dallisgrass and bahiagrass under high nitrogen fertilizer treatment. This specific difference was considered to be based on the difference in their ability of leaf area expansion. 2. The three species equally increased their P_0 as leaf nitrogen concentration increased up to about 3% and their P_0 reached 60mg CO_2/dm^2, hr. But, beyond this nitrogen level their P_0 were independent of leaf nitrogen concentration. 3. The three species contained about 4.5mg chlorophyll per dm^2 leaf area at 3% leaf nitrogen concentrations. Positive correlation between their chlorophyll contents and P_0 were observed within the range of up to about 4.5mg/dm^2 chlorophyll, but beyond this value their P_0 were independent of chlorophyll contents.

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The producing characteristics of corn as silage materials were investigated of early, medium and late maturing varieties, at Memuro in the central part, Shintoku in the piedmont and Churui in the coastal part in north-eastern Hokkaido. The results obtained were as follows: 1. Increases of dry matter and TDN production were contributed mainly by increases of the ear production covering each ripening period. The range of dry matter content as materials for high quality silage which is 25-35% was attained at the period from early to late dent or glaze stage. In this point, the early varieties were adapted in these areas. 2. In addition, the right stage for cutting lasted for about a week in early varieties, but was short in medium and almost non-existent in late maturing varieties. 3. In the central part of the area, the cropping combination of early and medium maturing varieties is suited at present, but we must develop new varieties having medium maturity between above-mentioned variety groups in the near future. At present we have only one early maturing variety suited for the piedmont and coastal parts. For right cropping combinations, we must develop new varieties having earlier maturity than the present early cultivars.

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In 1973-1977, the response of yield and quality as silage materials on two planting density were investigated in early, medium, and late maturing varieties at Memuro in the central part, Shintoku in the piedmont, and Churui in the coastal part in north-eastern areas of Hokkaido. The results obtained were as follows: 1. In central parts dry matter or TDN yield of early varieties increased by about 30% in dense planting, and was as high as other maturing groups. 2. There were no differences between two planting densities for dry matter contents as an indicator of the quality of silage materials in early and medium maturing varieties, but TDN in dry matter of late variety groups decreased a little in dense planting. 3. The high rate of barren plants and nubbin ear plants by dense planting could observed in late maturing varieties than others, and those rates were augmented by the increase of lodging. 4. Improvement in adaptability to high planting density and in lodging resistance of early and medium maturing varieties are seemed effective in corn breeding for high yielding-good quality varieties.

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For the purpose of local assignment and combination of varieties different in maturing dates, the constancy and efficiency of some measures for heat-unit accumulation were investigated by data from 1963 to 1977 at various locations in Hokkaido, Japan. The results obtained were as follows: 1. The measure for heat-unit accumulation that had the least coefficient of variation through years within locations was the one accumulated temperature more than zero C. It was recognized that the heat-unit accumulated by this method had high utility than the others. It is called the simple heat-unit accumulation by the author. 2. From seeding to the best cutting stage for silage materials, that is 25-35% in dry matter percentage, the simple heat-unit accumulation in early, medium, late and latest varieties were estimated as 2,100-2,550, 2,250-2,700, 2,400-2,850 and 2,550-3,000℃, respectively. 3. The effective utilization of heat-unit accumulation on maize breeding for high yielding ability by augmenting seed germinability in low temperature conditions was discussed.

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Pure swards of orchardgrass Phyllox, Kitamidori and St. Hokkaido, were harvested at the stages of maturity during first growth in the spring, and in the subsequent regrowth. Each batch of harbage was fed to 5 wethers ad libitum and a digestion trial was conducted. Forage and feces density were determined by MONTGOMERY'S method to get relationships between digestibility and physical form. The results are summarized as follows: 1. Dry matter digestibility (DMD), TDN and digestible energy (DE) contents of aftermath in summer (summer grasses) were lower than those of first cutting grasses in spring (spring grasses) and of aftermath of last cutting of the year in autumn (autumn grasses). 2. First cutting grasses showed the fall in digestibility and voluntary intake with increasing maturity. Intake of DE/dry/kg. W^<0.75> and nutritive value indexes of spring grasses and autumn grasses were generally higher than those of summer grasses. 3. Digestibility of cell wall was depressed much more at high intake than digestibility of cell contents. 4. Significant negative correlation was observed between the contents of cell wall in aftermath and its density, and same correlation was observed in feces. DMD of grasses had significant effect on feces density.

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Pure swards of orchardgrass, Phyllox, Kitamidori, and St. Hokkaido were harvested at the stages of maturity during first growth in the spring, and in the subsequent regrowth. Each batch of harbage was fed to 5 wethers in a digestion trial under the condition of voluntary intake. These 32 fresh orchardgrass samples were used to evaluate the relationships between the voluntary intake (VI) and the chemical composition, digestibility, digestible nutrient. VI was significantly correlated with the contents of crude protein, ADF, ADL, digestibility of crude protein, cell wall (CW), dry matter, gross energy, and the amounts of DCP, TDN and DE. It was generally observed that VI was estimated as the ratio of fecal dry matter excretion to the percent of dry matter undigested. Fecal dry matter excretion (g/day/W^<0.75>) of wethers in their full intake was about 22g, was varying little between the first cutting in spring and aftermath. There was not significant correlation between VI and fecal dry matter excretion. Digestibility of dry matter: VI (r=0.70, p<0.05) and indigestibility of dry matter: indigestible CW content (r=0.93, p<0.01) all have significant correlations. These data are consistent with the theory that indigestible CW inhibit VI and voluntary digestible nutrient intake.

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