To clarify mechanism of freezing damage and factors concerning freezing resistance of several grasses, some fundamental experiments were carried out for timothy, the most winter hardy species and for orchardgrass, less winter hardy one in Nemuro-Kushiro district. The results obtained were summarized as follows: 1. The effect of speed of cooling or rewarming on the freezing injury was examined. It was observed that the degree of injury was accelerated by rapid freezing and not affected by speed of rewarming so much. The injury was accelerated by rapid cooling at the temperature range below freezing point of the tissue. But when the speed of cooling was 5℃ per hour, the freezing damage was less severe. 2. The injury was caused when sample was frozen at lower temperature than critical freezing temperture. Freezing injury increased with the duration of frozen hours, but its increase was remarkable at earlier period and became smaller after 16 hours of treatment. 3. In late autumn or early winter, the most effective method for enhancing the freezing resistance was to keep samples at -3℃ for 2 weeks, but when natural hardening progressed further, it was better to expose orchardgrass 0〜-3〜-5℃ for 1 week at each temperature, and timothy -3(7 days)〜-5(10 days)〜-7(3 days)℃ successively. 4. Timothy was hardier than orchardgrass in all cases of these experiments, and it coincided with the wintering habit by field observation.

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The light recieving structure of Italian ryegrass population in each season was investigated by measuring the light diminution coefficient (K').This light diminution coefficient was determined with the negative regression coefficient between increase in LAI and decrease in relative light intensity at the ground level, and indicated the mean light recieving structure throughout the growth of the population. 1) The light diminution coefficient showed different values in each season, and when these values were indicated with average values of six years, they were 0.52 in autumn, 0.38 in spring and 0.33 in winter respectively. 2) In autumn (γ=-0.727) and spring (γ=-0.849), close negative correlations were obtained between light diminution coefficient and LAI at the optimum cutting stage, despite of different experimental years. 3) In autumn (γ=0.988) and spring (γ=0.968), close positive correlations were recognized between yearly changes of LAI at the optimum cutting stage and degree of light penetration-mean daily solar radiation (I_0) /K'-, as shown in the equation (1) and (2), despite of different experimental years. LAI at the optimum cutting stage in autumn=0.0212(I_0/K')-0.7 (1) LAI at the optimum cutting stage in spring=0.0068(I_0/K')+6.9 (2) 4) No significant correlation was recognized in autumn (γ=-0.611^<NS>) and spring (γ=-0.623^<NS>) between light diminution coefficient and NAR at the optimum cutting stage. 5) A close positive correlation was recognized in autumn (γ=0.949) and spring (γ=0.965) between NAR at the optimum cutting stage and degree of light penetration, as shown in the equation (3) and (4), despite of different experimental years. NAR at the optimum cutting stage in autumn=0.0006364(I_0/K')+0.3405 (3) NAR at the optimum cutting stage in spring=0.0000755(I_0/K')+0.2696 (4) 6) The maximum of average productivity, both in spring and in autumn, was mainly determined by light diminution coefficient (K') and mean daily solar radiation (I_0), as shown in the equation (5) and (6) respectively. max. of average productivity in autumn=0.00001349(I_0/K')^2+0.00677(I_0/K')-0.2384 (5) max. of average productivity in spring=0.00000513(I_0/K')^2+0.00704(I_0/K')+1.86 (6)

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In order to clarify the dry matter and leaf area productivity of the current year's stem of kudzu vines, stem length, dry weight and leaf area of the current year's stem, and percentage of dry weight of each organ in the stem were examined at monthly intervals from early May to early November. This investigation was conducted on a natural population of kudzu vines in Kitabata, located on the southern slope of the Rokko mountains, Motoyama-cho, Higashinada-ku, Kobe-shi. Stem length and dry weight of the current year's stem increased with time from eary May, and attained to a maximum of 390cm and 28g in early November, respectively (Fig.2, 3). Leaf area also increased from early May, reached a maximum level of about 2, 400cm^2 in early October, and tended to decrease thereafter (Fig.4). Out of total dry weight of current year's stem, percentages of stem-, petiole-, and leaflet-dry weights were 58, 10 and 32%, respectively, in early May, and then fluctuated in the ranges of 39-43, 14-18 and 40-44% respectively, until early September. The stem dry weight increased after September, whereas the petiole- and the leaflet-dry weight decreased. Flower clusters emerged from July onward. Dry weight of the flower cluster, being less than 2% at all times, increased only slightly thereafter (Fig.5). Thus, the seasonal changes were clearly recognized in the percentage of the total dry weight of each organ in the current year's stem.

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A comparison of the dry matter and leaf area productivity between the main stem and the branches of the current year's stem was made in this investigation. Dry matter and leaf area production in the current year's stem were brought about by only the main stem until early May, and by both the main stem and the 1st order branches in early June. The 2nd and 3rd order branches took part in dry matter and leaf area production after early July and the 4th order branches from early October onward. As to stem dry weight partitioning between the main stem and the branches of the current year's stem (Table 1), the main stem had a maximum dry weight and higher order branches had smaller dry weights at all times. From the results obtained about stem dry weight/stem length ratio (Table 6), it was supposed that stem dry weight partitioning above mentioned was related to more pronounced thickening and lignification of the main stem as compared with the branches, and of lower order branches as compared with higher order ones. Concerning leaf (leaflet+petiole) dry weight partitioning between the main stem and the branches (Table 2), the main stem had a maximum weight and higher order branches had smaller weight until early August. However, leaf dry weight of the main stem was less than that of the 1st order branches in early September and that of the 2nd order branches in early October. Leaf dry weight of the main stem decreased to less than 17% in early November. From the results obtained about the numeric proportion of nodes with leaves to the total nodes (Table 5) and leaf dry weight or leaf area/stem length ratio (Table 7, 8), it was supposed that the seasonal variation in leaf dry weight partitioning between the main stem and the branches as mentioned above could be attributed to the differences in the time of leaf appearance and leaf fall and the ability to produce leaves. Flower clusters emerged from July onward. There was no formation of flower clusters on the 4th order branches. Concerning dry weight partitioning of flower clusters between the main stem and the branches (Table 3), the flower cluster dry weight which emerged from the 1st and 2nd order branches reached more than 90% at all times. The seasonal change in leaf area partitioning between the main stem and the branches was recognized to be similar to that in leaf dry weight (Table 4).

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A sand culture pot experiment was conducted to trace time course of vegetative regrowth, nodule formation, dinitrogen fixation (C_2H_2→C_2H_4), and concentration of total non-stractural carbohydrate (TNC) in Leucaena leucocephala (Lam.) de Wit, which imposed with several harvesting treatments. Harvesting treatments imposed in this experiment were as below: [Table] (Plants were sampled ten times, viz., 0, 1, 2, 4, 8, 14, 21 29, 36, and 52 days after harvest). The vegetive regrowth and dinitrogen fixation after harvest were more inflenced with the differences in residual leaf area than with the amounts of reserved nutrients in stubble, showing a rapid regrowth in the plants having greater leaf area. The regrowth of the plants after harvest initiated at first in leaf area followed by stubble, root, and nodule. When lesser amounts of leaf area remained after harvest, TNC concentrations in the root mass played more important roles in accelerating the plant regrowth. The results of this experiment concluded that a clipping management for maximizing productivity of leucaena is to increase as much residual leaf area as possible after havest.

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Diurnal fluctuation of dinitrogen fixation (C_2H_2 →C_2H_4) was surveyed in conjunction with the nonstructural carbohydrate (TNC) concentration in the plant and with the photosynthetically active radiation (PAR) reached on the field using a plant community of Desmodium intortum cv. Greenleaf. Diurnal fluctuations either in PAR or in TNC concentration in the plant top and the root had shown close relations each other: The top TNC increased/decreased with increasing/decreasing PAR and the root TNC reacted contrast to the top TNC. Specific nodule activity (SNA) changed simultaneously with the root TNC, being increased/decreased with higher/lower TNC concentrations in the root. Photosynthetically active radiation, especially in a day previous to the sampling day seemed to much affect SNA level, showing lower values with lower PAR's in the previous day. The estimated amounts of the fixed nitrogen in this community ranged 11-159g/10a/day depending on the PAR's of a day previous to the sampling days. According to the results obtained in this experiment, the harvest after one or tow days of abundant PAR was recommended for increasing the rates of regrowth of this tropical legume.

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A field study was carried out to elucidate the effects of harvest time and fertilization level on content and yield of N, P, K, Ca, and Mg in the 2nd and 3rd crops of orchardgrass grown on volcanic ash soil. Experimental plots were prepared from the sward which had been managed by low fertilization level for 2 years after establishment. These plots were treated with 3 levels of fertilizer application which included low (20kg N+10kg P_2O_5+17.5kg K_2O/ha), medium (2 times of low plot) and high (4 times of low plot). The applications were made immediately after the 1st cut (23 May) and 2nd cut (4 July), and herbage samples were taken at one week interval onwards, up to 8 weeks for each crop. Changes of measured values in content and yield of minerals with time well fitted in cubic regression curves, except content of P for medium fertilization level in the 3rd crop. Nitrogen content was slightly increased, and other mineral contents were slightly or inconsistently changed by applying more fertilizer. The extent of change in content with time decreased by following order ; N>K>P≒Ca>Mg. Contents of N, K and Mg in the 2nd and 3rd crops and P in the 2nd crop were always highest in 1 or 2 weeks after cutting, and then declined to the lowest about 6 weeks after cutting. Calcium content gradually increased until the first 3 or 4 weeks of regrowth and then declined. Changes of P content in the 3rd crop with time showed different trends among fertilization levels. Compared with green matter, dead matter of the herbage sampled from 5 to 8 weeks after cutting showed lower contents of N, P, K, and higher contents of Ca and Mg. Maximum yield was obtained about 4 to 5 weeks after cutting (about maximum stage of average productivity) for N, and about 6 weeks after cutting for other minerals. Nitrogen efficiency (dry matter yield/N yield) in green matter of the herbage was highest about 6 weeks after cutting, and dead matter of the herbage was little up to that time except for high fertilization level. It is considered that about 6 weeks after cutting may be suitable cutting time for the low and medium fertilization levels in the 2nd and 3rd crops of orchardgrass, as N efficiency is more important than average productivity (dry matter yield/regrowth duration) at these fertilization levels.

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To examine changes in the flavor of pasture grass with growing, the volatile compounds from the fresh Italian ryegrass hand-harvested at the vegetative, bloom, milk and mature stages were trapped on Tenax-GC and identified using a GC and a GC-MS. Major volatile compounds were quantitatively determined by a GC. The amount (μg) of each compound in 100l of headspace gas over 150g of fresh Italian ryegrass varied with growth stage within the ranges shown in the parentheses. 1-Penten-3-ol (4.1-1.4), cis-3-hexenyl acetate (200-0.3) and cis-3-hexenyl-ol (50-1.3) decreased with growing whereas iso-amyl alcohol (0-2.7), 3-octanone (0.1-6.6) and 1-octen-3-ol (1.9-3.2) increased as growth advanced. Substantial contribution of cis-3-hexenyl acetate to the flavor of fresh Italian ryegrass was assumed because it was a main component in the headspace volatiles up to the milk stage and had a grassy odor like cis-3-hexen-1-ol. The components that increased up to the milk stage and decreased at the mature stage were ethyl acetate (5.6-10.2-0.4) and ethanol (0.3-1.9-1.0). trans-2-Hexen-1-ol (0.9-1.2) and trans-2-hexenal (0.6-0.9) were found at the vegetative and bloom stages but could not be detected at the milk and mature stages and 3-octanol (1.5) appeared only at the mature stage.

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A novel apparatus has been developed for the isolation of carbohydrates from forage plants. It has three functions ; that of a boiling beaker, an incubating bottle and a crucible. Cell wall constituents (CWC) and cellulase-hydrolyzed CWC were analyzed using this apparatus. A dried ground sample (0.5gm) was placed directly into this apparatus. Forty ml of neutral detergent solution was added and this mixture was boiled in a steam bath. After this heating the moisture was vacuumed to wash and remove dissolved substrates from the CWC. It was possible, without removing the specimen from this apparatus, to weigh CWC after drying and also to hydrolyze the specimen using cellulase within the same apparatus. Because of no necessity of transferring the sample from one apparatus to another, preparation for CWC determination and subesquent CWC hydrolysis was accomlished rapidly. Furthermore, the variation coefficients of this method in the determination of CWC and hydrolyzed CWC were lower and the reappearances of them were higher than those of the conventional method. It was therfore concluded that this apparatus is useful in the determination of fibers and carbohydrates in grasses and legumes.

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The relations between the nitrate content of the ensiled grass and the quality of resultant silages were investgated with orchardgrass fertilized with different levels of nitrogen. In the course of 2 years, 31 samples of orchardgrass ranging from 0.03-0.49% NO_3-N content on dry matter, were ensiled in experimental bag silos of 50kg capacity and left to ferment for 50 days. In the ensiled grass, the nitrate content was significantly correlated to crude protein content (r=0.671) and WSC content (r=-0.634). In the resultant silage, the lactic acid content was correlated to butyric acid content (r=-0.670), total acid content (r=0.433) and ammoniacal nitrogen (r=-0.476). The butyric acid content was correlated to acetic acid content (r=-0.486) and ammoniacal nitrogen (r=0.551). There was significant negative correlation between the Flieg's mark and ammoniacal nitrogen (r=-0.875). On the other hand, there were no significant correlations between the pH and other factors. The nitrate content of the ensiled grass was correlated to acetic acid content (r=0.838), butyric acid content (r=-0.586), total acid content (r=0.480) and Flieg's mark (r=0.485) of the silages. Furthermore, when the grass of high nitrate content (more than 0.2% NO_3-N in dry matter) was ensiled, silages of good quality with no butyric acid were always obtained regardless of the WSC and crude protein content. When the all silage samples were considered, the WSC content was not significantly correlated to lactic acid content. However, when only 12 high nitrate grass samples were considered, there was significant positive correlation (r=0.611). It was shown that, therefore, high nitrate content in grass may contribute to improve silage quality.

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The experiments were carried out to investigate the influence of variety and harvesting stage of corn on the excretion rate of indigestible grain when it was fed to cows as whole crop silage. The varieties of corn used in the study were HEIGENWASE, HOKUYU and PIONEER No.3715. The silages were prepared at two or four stages of maturity from milk to over-ripening. The nutritive value and the excretion rate of the indigestible grain were tested by the dairy cows. The results were summarized as follows. (1) The percent of perfect grains in silages increased gradually with the advance of maturity. (2) The indigestible grain was not excreted at below 30% of the grain ratio to dry weight in silages, but 7 to 13% of the grains were excreted in the case of above 40% of the grain ratio to dry weight. (3) The starch was excreted above 10% in the case of below 30% of the grain ratio to dry weight in silages, and the ratio of excretion reached to 15-20% in the case of above 40% of the grain ratio to dry weight. (4) The contents of the total digestible nutrients (TDN) in milk, early dent, late dent and over-ripening stages were recorded ; for HEIGENWASE ; 70.9, 73.6, 70.8 and 66.3%, and for HOKUYU ; 67.4 (late dent), 63.6% (over-ripening), and for PIONEER No.3715 ; 63.0 (milk), 56.0% (dough) respectively, and it was higher in the early varieties than in late varieties.

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In order to make clear the diurnal pattern of the grazing behaviour of dairy heifers under rotational grazing condition, their weights were measured at intervals of three hours from the day they were transferred to a new paddock to the following day. In experiment 1, the first group was moved to a new paddock at 1000 hours and the second group was moved at 1300 hours to the same paddock. In experiment 2, the first group and the second group were moved at 1000 and 1600 hours, respectively. The research was conducted for 6 periods in experiment 1 and for 3 periods in experiment 2 on the orchardgrass-dominant sward. In experiment 1, the behaviour of heifers was observed and the numbers of heifers grazing, ruminating (standing and lying), resting (standing and lying) and loafing were recorded every 10 minutes. The mean liveweights of heifers were 200-240kg. 1. Heifers grazed most intensively during the first three hours after the moving time and increased 10-16kg in their during these hours. They gained 2-3kg in weight during the second or third three hours after the moving time, but they lost 8-10kg in weight in the night time between 1900 and 0400 hours. However, heifers moved at 1600 hours extended their grazing time after sunset and their weights increased between 1900 and 2200 hours. 2. There were two peaks of grazing which occurred just after the moving time and in the late afternoon till just after sunset. But, there was a remarkable difference between two peaks from the view point of weight increase. It was supposed that heifers grazed less amount of herbage at the peak of grazing in the late afternoon than at the peak immediately after the moving time. 3. On the following day, there was no hasty increase in weight as was seen after moving time and weights of heifers did not reach to the maximum weight on the first day, although they kept still the higher weights than those of heifers before the moving time. It was concluded that from the pattern of weight change grazing behaviour of heifers on the following day was less active compared with that on the first day. 4. Ruminating behaviour was scarecely observed till the night on the first day, but on the following day there was a considerable time for ruminating behaviour during daytime. As above results, behaviour of heifers under rotational grazing was so strongly influenced by the transfer to a new paddock that they did not show such a normal pattern of behaviour as regular repetition of grazing, resting and ruminating on the first day. The diurnal pattern of grazing behaviour of heifers on the first day differed makedly from those on the second day.

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