This experiment was carried out to elucidate the extent to which wintering of grasses and legumes was influenced by their freezing resistance in Nemuro-Kushiro district. Freezing resistance of different organs of 9 grass and 3 legume species were tested in December 1974-1976, and temperatures of different organs of each species were determined during winter. The results obtained are summarized as follows: 1) Crowns of grass species with the above-ground crown such as orchardgrass, meadow fescue or perennial ryegrass were injured slightly by freezing at -7〜-10℃ for 16 hours, and led to death with -15℃ freezing. They were in danger of heavy injury under the condition without snow cover in December or January. Especially, primordia of heading stem suffered injury with -7〜-10℃ freezing. 2) Of the grasses with subterranean organ, the hardest was timothy and critical temperature for the death of its crown was -25℃. In other species, rhizome and shoot were damaged heavily with -13〜-20℃ freezing, but the organs could survive because they were located at around 1〜5cm below ground surface and were not cooled till their critical temperature. 3) Freezing resistance of legume species was less hardy, and they suffered heavy injury with -7〜-10℃ freezing. Therefore, in order to assure their good survival, they should be mixed with grass species, or, their fall growth should be promoted to have better winter cover.

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The crown-freezing technique, developed by Marshall for the determination of the cold hardiness of winter oats, was adopted for use in orchardgrass and the suitable application was devised. Five experiments were conducted for this purpose and the best conditions for the determination were as follows. (1) In case that materials are hardened under the field conditions in autumn, they are sown on September 1 and dug from the field from mid-November to early December. On the other hand, in case that materials are hardened under the controlled conditions in a growth cabinet, they are grown in pots in a greenhouse 70 days after sowing and thereafter hardened in the cabinet at 3℃, 8 hours photoperiod for 3 weeks. (2) The root and tops of each plant are cut off apporoximately 0.5cm below the base of the crown and 4 to 5cm above the base of the crown, respectively. (3) The crowns are washed with cold water and divided into some groups of equal numbers, which are wrapped up with aluminium foil. Two replications of approximate 10 crowns may provide precision enough to distinguish about 18% of survival difference between cultivars. (4) The packages of crowns are laid out randomly in a freezer (±0.5℃). The temperature in the freezer is initially maintained at ℃ during 2 to 4 hours, and thereafter lowered at the rate of 2℃ per hour to the desired final temperature. The packages of crowns are frozen at the final temperature for 16 hours and thawed at 2℃. If necessary, the packages of crowns can be stocked in the freezer at -3.0℃ during 2 to 3 weeks before the freezing treatment. (5) The crowns are plugged in vermiculite benches in a greenhouse and grown for 3 weeks. Percent plant survival is determined on the basis on the number of crowns which show rooting from the crowns.

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Winterkilling of orchardgrass, caused by cold damage and snow mold diseases resulting from the infection of Sclerotinia borealis and Typhula spp., is very common in eastern Hokkaido, Japan. Especially, in winter of 1974-75, severe damage was caused by S. borealis and many acreage of the damaged pastures were obligated to renovation. For the purpose of breeding a cultivar resistant to winterkilling, the author collected 934 plants of surviving orchardgrass from these pastures and developed 100 maternal lines from this stock. In the present study, winter hardiness components and other important growth characters of 10 strains, which were selected randomly from the maternal lines, were compared with those of 12 commercial cultivars. Field and controlled environment trials showed that the strains was less susceptible to S. borealis, higher in cold hardiness, more vigorous in spring growth and earlier in retardation of vegitative growth in late autumn than the cultivars. It was also found that vigour of vegetative growth in summer and annual forage yield of the strains were similar to those of the cultivars. When correlation coefficients were calculated between above mentioned characters, high significant correlation was obtained between susceptibility to S.borealis and cold hardiness (r=-0.824) , susceptibility to S. borealis and earlier retardation of autumn growth (r=0.603), and cold hardiness and earlier retardation of autumn growth (r=0.721) .These correlations were examined further by principal component analysis. The results indicated that the first and second principal components represented winter hardiness and winter dormancy, respectively and that these two components accounted for 77% of the total variation. The scatter diagram of strains and cultivars obtained from scores of these two components indicated that strains and cultivars could be classified clearly into two groups having reverse characteristics. The strains were located on the plane of, the diagram which showed higher winter hardiness and deeper winter dormancy, while the cultivars situated on the opposite plane with an exception of the most winter hardy commercial cultivar "KAY". On the basis of these results, it was concluded that the plants collected from the almost completely winterkilled pastures were valuable for breeding material of winter hardiness.

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Electrophoretic variation of peroxidase isozyme in Italian ryegrass cultivars was detected by means of thin layer gel isoelectric focusing method. Peroxidase isozyme was extracted from leaf blade in a total of 224 stocks belonging to 23 Italian ryegrass cultivars. The results obtained were as follows ; 1. Fifteen bands were detected on the zymograms of peroxidase, and 7 banding types were identified in this test. 2. Banding types of most cultivars were observed to vary within each cultivar, while a few cultivars' banding types were clarified not to vary. Therefore, affinity between cultivars was estimated by the similarity of banding type and the frequency of the same banding type. 3. It was recognized that there were three banding groups in Italian ryegrass cultivars. Most of the cultivars had two typical banding groups (one was I-1 type's group and the other was II-1 type's group), but some others had another banding-group (the group had I-1, …II-3). 4. No Significant correlation was observed between banding type and respective characters such as poliploidy or earliness.

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In orchardgrass, low temperature has been regarded as one of the major factors which cause floral-induction. Under natural conditions, however, plants are often exposed to temporary high temperatures at several phases of floral-induction. The present studies were conducted to define the inhibitory effect of high temperature on floral-induction. In Experiment I, ten clones were used. Six of them were derived from "Aberystwyth S143", and the other four from "Aonami", "Latar", "EV-700" and "Dactylis glomerata ssp. judaica", respectively (Table 1). Aged tillers were obtained by dividing each clone which had been grown under continuous light in a warm (25℃ day/15℃ night) glasshouse for longer than six months. Then the tillers were subjected to floral-induction treatments of natural spring temperatures with 8-, 12- and 16-hour day-lengths for 3 and 5 weeks (Figs.1 and 2). After the treatments, their heading behaviour was observed under continuous light in a warm glasshouse. From the results, it was indicated in clones from "Aberystwyth S143" that floral-induction stimulus brought about by low temperatures during the initial 3 weeks of treatments was reversed by high temperatures at 4 to 5 weeks of treatments when the treatments were made under 8- and 12-hour day-lengths. But the reversal of floral-induction hardly occurred under 16-hour day-length. On the other hand, in four clones from different origins, the reversal effect of high temperature was not recognized irrespectively of day-length (Table 2 and Fig.5). The above findings suggested the genetic differences in the critical temperature for reversal of floral-induction. In Experiment II, aged tillers of clones from "Aberystwyth S143" were subjected to floralinduction treatments consisted of two sub-treatments, that is, (1) pre-treatment of natural low temperatures and short day-lengths in autumn, and (2) post-treatment of high temperature (20℃) and short day-length (10-hour) (Figs.3 and 4). From the heading behaviour after the treatments, it was clarified that high temperature under short day-length somewhat promoted the initial phases of floral-induction but conspicuously reversed the later phases of it (Table 3 and Fig.6).

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A two-year field experiment of double cropping system (long or short summer-cropping system) with different cropping period combining green panic or rhodesgrass as a summer forage grass and Italian ryegrass as a winter forage grass was carried out to determine the annual total yields of dry matter and some nutrients, and to discuss the difference in dry matter yield between both cropping systems in relation to the air temperature. In the long summer-cropping regime winter forage grass was alternated with summer forage grass seeded early in time at the mean daily temperature of ca. 17℃ in spring, and in the short summer cropping regime the summer forage was seeded at ca. 21℃ in late spring. In both years the annual total yield of dry matter under the short summer-cropping regime averaged 300kg/a and significantly exceeded that under the short summer-cropping regime by ca. 41kg/a under the condition in this experiment. The summer-cropping regime outyielded by 60〜80% that under the short summer-cropping regime. On the contrary, the winter forage under the short summer-cropping regime showed only 20〜30% higher in dry matter yield than that under the long summer-cropping regime. A significant difference in the annual total yield of digestible dry matter was found between the cropping regimes as well as in the dry matter yield except for the rotation including green panic in the 2nd year. The similar tendency was shown in the annual total yield of crude protein. From a regression analysis of the daily dry matter production of summer forage in each harvest on the average daily mean temperature in each growth period, similar regression lines were obtained at the rising temperature period (from spring to summer) under both cropping regimes, though different linear regressions were found at the falling temperature period (from summer to autumn), showing a steeper slope under the short summer-cropping regime than under the long summer cropping regime. It was considered that the grasses, when passed initially lower temperature period of spring, could construct the production system for the regrowth after cutting, namely increases in plant height, stem number and/or root system, which might result in the response to the daily production at the falling temperature period.

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Heating at temperature of 30℃ is thought to be one of dormancy breaking methods for green panic seed. This experiment was done to find the most effective way of the heating treatment at temperature of 30℃. Germination tests were made 4 times, 5, 9, 14 and 20 months after seed harvest, and in the tests at 9 and 20 months after seed harvest, seeds with soaking in gibberellic solution were also incubated. Experimental results were as follows ; 1) The heating treatment for a month, started one month after seed harvest, had some adverse effect to germination. 2) Of the heating treatments during 2〜9 months after seed harvest, the longer one was the more effective to germination. The treatments for a month had similar effects to germination irrespective of time of the treatment. Later application of the treatment for 2 months showed a better effect to germination than earlier one, except in the case that the gibberellin treatment was made. 3) By additional gibberellin treatment, germination increased by 20〜30% 9 months after seed harvest, and very high germination percentage (80〜90%) was shown in all treatments 20 months after seed harvest. 4) It was thought that the seed tested consisted of five groups varied in depth of dormancy. Each group reacted differently to the treatments. About 30% of the seed was easy in breaking dormancy, and not affected adversely to germination by the heating treatment during 1〜2 months after seed harvest.

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A field experiment was conducted in Fukuoka, Japan, to evaluate the dry matter yield and nutritive value of sorgo/legume mixed culture comparing with those of the pure culture. Four forage crops used were sorgo (Sorghum bicolor Moench), Soybean (Glycine max Merr.), cowpea (Vigna sinensis Endl.) and Dolichos lablab (Lablab purpureus Sweet). All seven treatment plots were replicated three times and all of the forages were cut at booting, heading and dough-ripe stages of sorgo. 1) Dry matter yields in the mixed cultures were lower than in the pure culture of sorgo at booting stage, but higher at heading and dough-ripe stages. Especially the dry matter yield in the mixed culture of sorgo/soybean was significantly higher (P<0.05) than in the pure culture of sorgo at dough-ripe stages. 2) Nitrogen yields in the mixed cultures were significantly higher (P<0.05) than in the sorgo pure culture at heading and dough-ripe stages. 3) Digestible dry matter yields in the mixed cultures of sorgo/soybean and sorgo/lablab at heading stage and sorgo/soybean at dough-ripe stage, were significantly (P<0.05) higher than in the sorgo pure culture. 4) The relative yield total (RYT) in all the mixed cultures was under 1.0 at booting stage. But at heading and dough-ripe stages, it was over 1.0 and the relative yield (RY) of each component species was over 0.5. 5) The decrease of light intensity in the upper layer of canopy was found to be greater in the mixed culture of sorgo/climbing type legume species (cowpea, lablab), comparing with the mixed culture of sorgo/soybean. Therefore, it was presumed that sorgo in the mixed culture with soybean received more light than in those with climbing type legumes. 6) It was suggested that an effective canopy structure with regard to light utilization might have been established in the mixed culture of sorgo/non-climbing type soybean, bringing about higher dry matter yield, comparing with the mixed cultures of sorgo/climbing type legumes.

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Vegetatively propagated clones of Lolium perenne (PRG) and Festuca arundinacea (TF) were planted separatly (S) and in an equiproportionate mixture (M) in containers of 41×61×31.5cm size, so that genetic variation might be extinguish within a species population, at three levels of density, viz. 400, 100, and 44 ramets per m^2 (HD, MD and LD) in order to know whether competitive advantage of one species over another continues in subsequent canopies recovered after defoliation. The treatments were duplicated in a randamized block design. The plants were cut to 3cm on June 17, July 20, September 8, October 16 and November 25. On each cutting date, productive structures were figured by the measurements of dry matter weights of assimilatory and nonassimilatory organs, leaf area index (LAI) and relative light intensity (RLI) at each 5cm layer of canopy. Although competition affected little on plant height (Fig.1), it brought significantly on quantitative bias of tiller number per plant since the period of the second revived canopy where LAI reached 0.6〜1.0 in a mixture (Fig.5) in such a way that tiller number increased much more in mixed plots than in monoculture plots for PRG and vice versa for TF (Fig.2). The results were almost the same with those of the previous work (Yamada et al, 1981) in which primary canopy was established by seeding, showing the successive competitive superiority of PRG which was an initial aggressor to TF which was an initial subordinate. Such constant competitive relation between the two species seemed to be caused mainly by root competition because of the following two facts. Firstly, PRG was no advantage of plant height on which top-competitive ability was usually dependent, as detected in the previous report (Yamada et al, 1981) and also in the present experiments (Fig.1). Secondly, competitive effects were already observed soon after defoliation when mutual shading did not occur yet, as indicated in the experiments of the privious and present reports (Yamada et al, 1981 ; Fig.2). As far as tiller number was concerned, competitive effect in a revived canopy should be overall or cumulative as given by summing each effect in each of past successive canopies. This might result in outward lowering or increasing of competitive effect on tillering limitted for a regrowth period, particularly in an aged sward. Thus, tiller numbers newly formed in each regrowth period were presented with the overall numbers counted at each time of defoliation minus those counted at the time of the preceding defoliation (Table 4). Tillering was clearly affected by competition from the period of the second revived canopy onwards for TF, except in LD of the third revived canopy, and only at the third revived canopy for PRG. The results were little different from those obtained by the overall number (Fig.2 and Table 3), though there existed the above exception. The degree of competitive effect, however, was much more enlarged for new tillers than for cumulative tillers, as detected in the comparision of competitive-values obtained by the two series of tiller number. In other word, the estimation of competitive effect by the overall number of tillers tends to lower the potential effect in a regrowth period of canopy.

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The presence of unaccounted nitrogen in silages has been reported by many workers and this study was undertaken to make clear a part of the unaccounted nitrogen by measuring nucleic acid bases. Ladino clover was ensiled with and without glucose, formic acid or formaldehyde in order to prepare different types of silages. Silages of moderate quality were obtained from the untreated herbage. Glucose treatment improved silage quality by enhancing lactic fermentation. Formic acid was effective in restricting silage fermentation but formaldehyde treatment rather enhanced clostridial fermentation. More than 7% of the total nitrogen of the herbage was present as nucleic acids and parts of which were decomposed during ensilage. The decomposition rate was lowest (68%) in the formic acid treated silages and the highest (85%) in the untreated silages with statistical significances among the three silages including the glucose treated ones. The ratios of DNA to RNA in the remaining nucleic acids in every silage prepared were similar (r=0.87, P<0.01). Except for the formaldehyde treated silages, the increase of free guanine during ensilage was correlated (r=0.95, P<0.01) with the decrease of nucleic acids. Free adenine was observed to be unstable compared with guanine. The recovery of the nitrogen of decomposed nucleic acids in free purines was 15% in average. Although quantitative determination of pyrimidines could not be made, it was confirmed that the free pyrimidine content of the silages was greater than the free purine content of them. The absorbances of cytosine and uracil extracted from the silages with some interfering substances had significant correlations with guanine content (r=0.90, P<0.01 and r=0.74, P<0.05, respectively) and decomposition rate of nucleic acids (r=0.93, P<0.01 and r=0.80, P<0.01, respectively) except for those of the formaldehyde treated silages. Nucleosides were not present in both the herbage and the silages. Nucleotides determination was not made. Besides peptide-, amino-, amide-, amine-, nitrate-, purine- and ammonia-nitrogens, there were still some unaccounted nitrogens in the non-protein nitrogen fractions of the herbage and silages. Parts of the unaccounted nitrogens were pyrimidine bases.

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Ensilage experiments with bag silos were conducted in order to know the effect of nitrate addition with and without glucose addition on the silage quality. The materials were orchardgrass and alfalfa of 10.9% and 5.4% (of dry matter) WSC, and five levels of nitrate addition as potassium nitrate (0, 0.1, 0.2, 0.3 and 1.0%) were combined with and without 2% glucose addition. The results obtained were as follow. 1. The control silages with no added nitrate and glucose were of very poor quality in the both forages. 2. When the addition of nitrate exceeded 0.1% and 0.2% of fresh alfalfa and orchardgrass, respectively, silages of good quality with no or very little butyric acid were always obtained without glucose addition. 3. In orchardgrass, the effect of improving silage quality by nitrate addition was superior to that of glucose addition, and the synergestics effect of nitrate addition and glucose addition was recognized. In alfalfa, synergestics effect was not recognized, because the quality of the silages were markedly improved by only glucose addition. 4. These findings suggest that the silage quality are improved by nitrate addition in spite of the low WSC of material.

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Ensilage experiment was conducted in order to know the effect of nitrate addition, glucose addition, temperature during ensilage, and their interaction on the silage quality. Orchardgrass was ensiled in laboratory silos of one-litre with the four levels of nitrate addition (0, 0.2, 0.4 and 1.0%) and the two levels of glucose addition (0 and 2%) at two ensilage temperature (20 and 30℃). The results obtained were as follow. 1. Although the silage with no added nitrate and glucose were of poor quality, the silages of higher temperature was poorer than that of lower temperature. 2. The silage quality were markedly improved by only nitrate addition, the synergestics effect of nitrate addition, glucose addition and lower temperature was also recognized. 3. These findings suggest that the silages of good quality were always obtained by the addition of higher nitrate.

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In order to demonstrate the changes in the cell wall digestibility of herbage tissues during growth, five samples of orchardgrass, collected at various growth stages and cutting times, were divided by pectinase treatment into two tissue fractions: the parenchyma fraction and the mechanical tissue fraction. Most of the cell wall of the original plant material recovered in both tissue fractions. The amount of cell wall recovered in the parenchyma fractions remained almost constant but that in the mechanical tissue fractions varied with sample. This suggests that the percentage of mesophyll cell wall in orchardgrass remains constant regardless of the cutting time, and the changes in the percentage of cell wall during growth are attributed to the sclerenchyma, vascular bundle, and epidermis. The cell walls of all the parenchyma fractions were almost completely digested in vitro. In contrast, the cell wall digestibility of mechanical tissue fractions was much lower and varied correspondingly with the changes of the original plant material. The results of this experiment indicate that the changes in digestibility of orchardgrass during growth depend on the indigestible material derived from the sclerenchyma, vascular bundle, and epidermis.

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In order to establish a guideline for the management of grazing cattle in hot climate, the changes in grazing behavior of cows under high temperature conditions and their relationship to the respiratory rate were investigated. Holstein cows of Sumiyoshi Farm of Miyazaki University were used. They were grazed during six hours, from 10:30 to 16:30, every day on the pastures dominated by Bahia grass. 1. Air temperatures on the pasture in June (late), July and August were very high and they were 27.0-30.5, 31.5-35.0 and 29.5-31.0℃, respectively. In this season cows repeated frequent changes from ingesting behavior on a pasture to resting behavior in a shelter (forest) and vice versa, and their total ingesting period was very short during the grazing hour. On the other hand, air temperatures of June (early), September and October were 24.5-27.0, 24.5-27.0 and 21.0-26.0℃, respectively, and cows, in contrast to the hot season, scarcely showed any alternation of ingesting and resting behavior, spending most of the grazing hour for ingestion. 2. The respiratory rate during rest was higher in June (late), July and August than that in June (early) and September, and that in October was lower. In hot months the respiratory rate during rest decreased greatly as the resting period prolonged. When cows stopped ingestion and took a rest their respiratory rate increased, and when cows stopped a rest and restarted ingestion it decreased, although such behavioral changes were not always accompanied by the fixed rates of respiration. These phenomena appeared to give the evidence that respiration in itself did not disturb the ingesting behavior. The respiratory rate during ingestion differed between the seasons or the individuals, although that of an individual was almost static in a season.

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This paper described the utilization of the pasture by grazing cattle and the palatability of forage plants in the forest which was established by 3 stand-densities of Japanese red pine of 20〜25 years old. A palatability was evaluted with the preference ranking by cattle in grazing trials and that of sheep in cut-feeding trials, and several chemical components in these forage plants were compared with each other. The highest acceptability of the pasture was shown by grazing cattle in the control plot (open area), followed by 50% more heavily thinned plot (779 trees/ha) and 25% more heavily thinned plot (1, 147 trees/ha) successively. The ordinarily thinned plot (1, 578 trees/ha) was the lowest acceptable in the grazing trials. This tendency was also obtained in the cutfeeding trial. In comparison between the orchardgrass cultivated under shading condition to 50% of solar radiation by cheese clothes and under non-shading condition, the non-shaded one was more palatable. The percentages of both 85% ethanol+water soluble and total soluble carbohydrate were higher in the forage from the control plot (non-shaded) than from all of the forest plots (shaded). On the other hand, the nitrate nitrogen percentage of the forage in the forest plots was particularly high. From the results of these experiments, it seems that the decrease of the utilization of the pasture in middle-aged Japanese red pine forest by grazing cattle depend primarily on the reduction of their palatability and this can be ascribed to the change of several chemical components rather than that of availability of forage such as grass species, density, height and standing crop, caused by the shortage of solar radiation. It is thought that the nitrate nitrogen should be investigated as a very important factor which influences on the palatability of forage plants in middle-aged Japanese red pine forest in view of the relationship between the injurious component and the palatability of forage.

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In this experiment, Freezing resistance was tested on 4 grass Species encased in ice. All species encased in ice suffered heavier injury than those not encased in ice by freezing treatment at -15℃ or -20℃. It was assumed that winterkilling of grasses were caused mainly by freezing injury, when they were encased in ice entirely in winter without snow cover in Nemuro〜Kushiro district.

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