Varietal differences in cold tolerance of five important temperate grasses comprising timothy, meadow fescue, cocksfoot, tall fescue and perennial ryegrass were assessed by means of the modified laboratory techinique of LORENZETTI et al. (1971). Seedlings artificially hardened were exposed to -12℃ during 16 hours for four grasses excluding cocksfoot which was subjected to -10℃ during 16 hours. Cold tolerance of seedlings was ranked in the following order of decreasing tolerance, based on percentage plant survival: timothy (98-89%)≧meadow fescue (94-68%)>tall fescue (50-25%)≧perennial ryegrass (34-11%)>cocksfoot (73-16% at -10℃). These freezing treatments were suitable for meadow fescue and cocksfoot, while the treatment with -12℃ for 16 hours was too mild to detect differences among timothy varieties and was too severe for tall fescue and for perennial ryegrass, showing that it is necessary to improve the freezing methods. Cold tolerance in adult plant of temperate grasses gives the same rank as in seedlings above mentioned with an exception of cocksfoot, whose cold tolerance is supposed to be at least greater than that of perennial ryegrass, this suggests that cocksfoot should increase tolerance with time in greater rate than perennial ryegrass and/or the others. We also agree with earlier workers that the most imporatant factor common to these grasses responsible for cold tolerance is winter cold in the original habitat of breeding materials. In general, the Scandinavian and the Canadian varieties were hardy, the Japanese ones moderate, and the south European and the British ones tender. The varieties classified as the tenderest in this experiment may be vulnerable to winter cold, so that we should pay attentions when introducing them to the eastern Hokkaido, where the winters are severest in Japan.

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On the evaluation of breeding materials, productivity of 64 orchardgrass clones from different geographical origins was compared for 3 years under both grazing and clipping condditions, in order to investigate if clonal response to grazing differs with that to clipping and to clarify clonal difference of seasonal productivity. During July to September every year, arable weeds, mostly Digitaria adscendens HENR., invaded the plots, especialy the grazed plots. For the density of tillers after 3 years' treatments, treatment effect as well as clonal effect was statistically significant at 1% level, show-ing the scores of grazed plots more sparsely with greater variance than those of clipped plots. Analysis of variance on fresh yield showed that each of main effects ; treatment, clone, year and growing season, was statistically significant at 1% level. All of the two-factor interaction and most of the three-factor interaction were also significant at 1% level. Spearman's rank correlation coefficient on clonal order between grazing and clipping treatments was rather high as pooled data of whole clones, but response of each clone was a not always same under both treatments. Values obtained were not high, especially when clones were divided into such groups as ranking of yield or growth patterns. Such parameters as fresh yield averaged for 3 years, Finlay's regression coefficient, skewness, kurtosis, yearly tendency and grazing vs clipping ratio were adopted, on the evaluation of growth patterns of the clones. It was found that the characteristics of the clones were most typically expressed as seasonal growth patterns by which the clones were classified into 4 groups deeply correlated with their geographical origins.

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In the present research, LGR and average leaf area productivity (leaf area growth/regrowth period) was studied to analize leaf area growth of Italian ryegrass population, which was conducted on the bases of the logistic equations of leaf area growth regressive curve in each seasons of autumn, winter and spring. (cf. the previous report.) Obtained results are as follows. 1. LGR_<max>. and average leaf area growth max. (Maximum value of leaf area/regrowth period) showed different values in seasons, and when these values were indicated with average values of five years respectively, they were 5328 and 4062, cm^2m^<-2>day^<-1> in spring, 3570 and 2198 in autumn, and 1474 and 1058 in winter. 2. A close positive correlation (r=0.956) was recognized between LGR_<max>. and average leaf area productivity max., as shown in the equation (1), throughout the different experimental years and seasons. average leaf area prductivity max=0.769LGR_<max>.-159.6 (1) 3. Days to LGR_<max>. and days to average leaf area productivity max. showed different values in seasons, and when these values were indicated with average values of five years respectively, they were 20.0 and 27.6 days in spring, 31.8 and 44.0 days in autumn, and 71.3 and 98.3 days in winter. 4. A close positive correlation (r=0.998) was recognized between days to LGR_<max>. and those to average leaf area productivity max. as shown in the equation (2), throughout the different experimental years and seasons. days to average leaf area roductivity max.=1.314 days to LGR_<max>+1.804 (2) 5. Between days to average leaf area productivity max. (t) and mean temperature (T), the following approximate equations were recognized for each seasons. in spring t=280/T+5.2 in autumn t=280/T+27.0 in winter t=273+48.0

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Seasonal difference in the changing patterns of the top dry matter increasing rate with the growth of Italian ryegrass population was investigated with respect to the factors determining this rate, that is, the leaf area index and the net assimilation rate, and the factors controlling the seasonal productivity as well as how the optimum cutting stage at each season should be determined were discussed. The LAI-CGR curve differs with the seasons. In autumn, it is a nearly symmetric curve of the second order, and in winter a curve with a plateau. In spring, a linear relation is obtained between the LAI and the CGR until the LAI reaches 9〜12, and thereafter the CGR drops rapidly. The optimum LAI and the LAI at average productivity max. showed different values in seasons, and when these values were indicated respectively with average values of five years, they were 7.08 and 10.37 in autumn, 5.45 and 8.88 in winter, and 10.70 and 13.73 in spring. The LAI-NAR curve also differs with the seasons. During the population growth after germination in autumn, the NAR decreases linearly with the increase in LAI. During the population growth as the regrowth in winter and spring, the relation between the LAI and the NAR shows a special pattern. In the early period of the regrowth, the NAR has a negative value, and with the growth and expansion of the regrowing leaves, that is, with the increase in the LAI, the NAR increases, and when the LAI increases further, the NAR decreases. The NAR at average productivity max. showed different values in seasons, and when these values were indicated with average values of five years, they were 0.68 in autumn, 0.63 in winter and 1.04 in spring. The rapid increase in dry matter during spring flush is a result of the concurrent increase in LAI and NAR, and the maintenance of the high NAR level which is considered to be caused by the suppression of the increase in LAI after floral bud formation and by the high radiation level. For the production in autumn and spring, the values of the LAI and the NAR giving average productivity max. are obtainable by the equations a (1)〜(2) when the average productivity max. is given. in autumn LAI=0.0209NAR+0.4616 (r=0.917) (1) in spring LAI = 0.0996NAR+0.3245 (r=0.996) (2)

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Each 4 species of tropical and temperate grasses were grown under two photoperiod (LD: 14h, SD: 9h) combined with five temperature regimes (day-temperatures 15°-35°, night temperatures being 5°lower) and sampled at the same growth stage of respective species to compare the growth responses to these environmental conditions by growth analysis method and by nitrogen and carbohydrate accumulation. 1. Leaf appearance rate was great at lower temperatures in temperate grasses, but in tropical grasses it increased with increase of temperature. Plant height was greatest at 25/20°in tropical grasses, while in temperate grasses it increased with decrease of temperature, being greater under long day than under short day. Tiller number increased with decrease of temperature in both type grasses, but tillering rate (tiller number/days to sampling) increased with increase or decrease of temperature in tropical or temperate grasses, respectively. There was a tendency that tiller number was more under short day than long day at lower temperatures. 2. Relative growth rate (RGR) of tropical grasses almost doubled that of temperate grasses. RGR of tropical grasses except Japanese millet or of temperate grasses except tall fescue increased with increase or decrease of temperature, respectively. Japanese millet or tall fescue showed the greatest value at 25°〜20°or 20°〜25°day-temperature, respectively. RGR under long day was greater under short day. RGR had strong significant correlations with both relative Deaf area growth rate (RLGR) and net assimilation rate (NAR). The greater RGR of tropical grasses was due mainly to a greater NAR, and greater RGR under long day was due to both greater RLGR and NAR, especially the latter. 3. Nitrogen accumulation per day decreased with decrease of temperature in pearl millet and sudangrass, while in Japanese millet and Rhodesgrass it was greatestat intermediate temperatures. In temperate grasses it increased with decrease of temperature. Dry matter production, TAC (total available carbohydrate) accumulation per unit nitrogen accumulation were greater in tropical grasses and under long day than in temperate grasses and under short day, respectively. 4. Japanese millet and tall fescue showed a little different behavior from their respective groups, the former showing the greatest growth at relatively low and the latter at relatively high temperatures, respectively.

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The present studies were undertaken to reveal optimum conditions for seed formation from cut ear in orchardgrass under solution culture. Addition of sucrose, fructose or glucose in concentration of 3% to culture solution showed an enhancing effect on seed formation in culture of flag-leaf-attached cut ear. The seed formation was dependent upon concentration of sucrose in culture solution, and satisfactory 100-seed weight was obtained with sucrose solution of above 3% Increasing of sucrose concentration from 3% to 10% brought only a slight increase of seed weight. Sulfurous acid in concentration of 0.015% added to culture solution containing 3% of sucrose enhanced the seed formation through increased absorption of culture solution, while sulfurous acid alone showed no effect on absorption and it had an inhibitory effect on seed formation. Growth regulators, guch as gibberellic acid, indole acetic acid and kinetin, were ineffective or inhibitory on seed formation. Presence of flag leaf on cut ear for culture largely affected absorption of culture solution and seed formation under any culture conditions. The results obtained indicate that the culture solution containing 3% of sucrose and 0.015% of sulfurous acid is almost satisfactory for seed formation by culture of flag-leaf-attached cut ear in orchardgrass. Seed produced under this culture condition was responsible to prechilling treatment in germination, showing no significant change in germination in comparison with seed produced under field condition.

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The purpose of this investigation was to clear the acidity tolerance and the effect of soil acidity on symbiotic nitrogen fixation of 10 leguminous forages. Alfalfa (Medicago sativa L.), alsike clover (Trifolium hybridum L.), birdsfoot trefoil (Lotus corniculatus L.), common vetch (Vicia sativa L.), chinese milk vetch (Astragalus sinicus L.), hairy vetch (Vicia villosa ROTH.), common lespedeza (Lespedeza striata THUNB.), ladino clover (Trifolium repens L. var. giganteum), white clover (Trifolium repens L.), and red clover (Trifolium pratense L.) were grown in each pot containing 4kg of an acidic mineral soil (pH 5.0: unlimed soil) and the same soil adjusted to pH 7.0 with CaCO_3 (limed soil). Plant growth, nodulation, plant total nitrogen and nitrogen fixing capacity with acetylene reduction method were measured. The results obtained were as follows. 1. Plant yield and plant total nitrogen of the legumes were lower in unlimed plot than in limed plot except in common lespedeza. Though the degree depressed was different depending on the species, it showed a similar tendency with plant yield and the amount of plant total nitrogen. 2. Acidity tolerance of the legumes assessed by relative plant yield and the amount of plant total nitrogen in unlimed plots to those of limed plots were ranked: common lespedeza>alsike clover>ladino clover>white clovers red clover>alfalfa. Species excluded from above ranking had much difficulty to decide order. 3. Nodule formation on roots and symbiotic nitrogen fixation capacity were considerably depressed under acidic soil conditions especially in alfalfa and chinese milk vetch. In common lespedeza, the improvement of nodule formation induced by liming did not consistent with that of symbiotic nitrogen fixation capacity. 4. Symbiotic nitrogen fixation capacity per unit fresh nodule weight was not directly related with liming. 5. The decrease of plant yield under acidic soil conditions occurred by the restraint of nitrogen symbiosis. Therefore, heavy application of nitrogen fertilizer to grow leguminous forages under acidic conditions is recommendable. 6. Aluminum toxicity as an inhibitory factor for symbiotic nitrogen fixation system was also discussed.

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The cause of grasstetany incidence of grazing cattle was investigated on Sotoyama pasture in Iwate-pref. where the first outbreak of the disease was reported in Japan, in relation to organic acid components in grass. Samples of orchardgrass were taken from two types of swards used for grazing and cut in May, August and October, 1974, respectively. Analyses of organic acids were made for the samples by programmed temperature gas chromatography. The results obtained were as follows ; 1) The contents of malic and quinic acids in orchardgrass were considerably higher than those of other acids in most cases of sampling. 2) Orchardgrass did not show any significant trend concerning with contents of citric and t-aconitic acid which have been considered to be closely related to outbreak of the disease. The content of citric acid was rather low and showed little change between seasons, although incidence of the disease has appeared mostly in spring at Sotoyama pasture. Moreover, t-aconitic acid was not detected in any samples. 3) Seasonal changes of total organic acid and malic acid coincided with occurrence of grasstetany. Further investigation, however, should be done on this point.

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The change of organic acid components of several grasses was investigated in spring of 1975 on the swards of pure stand which had been kept for 6 years with 2 levels of fertilizer supply (N-P_2O_5-K_2O ; 1-1-1 and 4-4-4kg/a) and 11-13 cuts in each year, respectively. Species used, included Kentucky bluegrass, orchardgrass, perennial ryegrass, red top, and tall fescue which were widely distributed on pasture in Japan. The swards were treated with 2 levels of fertilizer supply (N-P_2O_5-K_2O ; 1/4-1/4=1/4 and 1-1-1kg/a) on April 25 after trimming and sampling had been taken onwards. The same procedure as previous report was adopted for treatment and analyses of the sample. The results obtained were as follows: 1) The marked differences between species were recognized in contents of malic, quinic, and t-aconitic acids at the first cut (May, 10th) after fertilizer application. Particularly, t-aconitic acid was remarkably high in only red top, but there was little difference in content of citric acid between species. 2) Higher rate of fertilizer supply caused higher content of malic acid in both orchardgrass and perennial ryegrass, and higher content of t-aconitic acid in red top. The effect, however, decreased to great extent at the second cut (May, 23rd) after fertilizer supply. 3) During advance of growth stage in spring, t-aconitic acid was not detected significantly in any species other than red top while the contents of citric acid were kept low in those species. 4) Different organic acid components were shown in each plant part of grasses in which it must be noted that t-aconitic acid in red top showed markedly higher content in its leaves. From above findings, it was concluded that further research should be made for the relation between red top and outbreak of grasstetany.

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To establish the countermeasures of soil amendment on pasture located at the mountainous sloping area, the distribution of K, Ca and Mg contents in soils was investigated in consideration of the topography. The surveys were conducted on the two volcanic ash soil pastures, Sotoyama and Kuzakai, situated at Kitakami mountainous area in Tohoku district. Before initial top-dressing at early spring, the surface soils to 10cm depth were collected at three sites with different sloping angle on the above two pastures and the exchangeable K, Ca and Mg were analysed. 1. The K contents in soils were markedly different from each sampling site ; the K content in soil was much higher at the gentle than at the steep sloping site. This indicated that animal excreatal return was mainly concentrated on the gentle sloping site, and this site was considered to be apparently excess in K content. 2. The variation coefficients of K distribution were 30-40% however, they were lower than those of Ca distribution. Therefore, the excreatal dispersion seemed to be relatively uniform on a certain area, if a pasture has been used in grazing for long term. 3. Even at the steep sloping site, the K contents of pasture soils were much higher than in neighbouring forest soils. Under the common practice of potassium fertilizer application, i.e., 60-120kg K_2O/ha/year, K accumulation in pasture soils seemed to occur after some duration. 4. There was a tendancy that soil Ca and Mg were higher at the gentle sloping site than at steep one. This might be occurred by the difference of excreatal return frequency. In pasture soils the Ca contents at any slope condition and the Mg contents at the steep sloping site were lower than those in the neighbouring forest soils. Therefore, the leaching loss of Ca and Mg was considered to be larger in pasture than in forest.

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The relations between K, Ca and Mg contents of orchardgrass and the amount of these exchangeable elements in soil were investigated in spring on the mountainous sloping pastures where the surveys of previous report were carried out. The present report dealt with the countermeasures of fertilizer application on Mg content and K/(Ca+Mg) ratio of Orchardgrass for the prevention of grass tetany occurrence in relation to the soil cationic levels. 1. Since the highly significant positive correlation of K contents was obtained between soils and orchardgrass, it was estimated that the critical level of exchangeable soil K was about 13mg/100g dry soil assuming the critical K content of the herbage to be about 2%, and if the optimum K content of the herbage were 2-3%, the soil K might be 14-19mg. However, because of the ununiform distribution of soil K on the pasture, it was considered that the soil K should be 21-24mg to avoid partial K deficiency for the plant, where the K content of the herbage might be 3.2-3.6%. 2. The negative correlations were found between Mg content of orchardgrass and K and Ca levels in soils, however, the positive correlation of Mg contents was not found between the herbage and soils, possibly due to the high amount of soil Mg across the field. The significant correlations were not observed between Ca content of the herbage and any one of K, Ca and Mg levels in soils. 3. The Mg content of spring orchardgrass could be maintained at 0 2% or more which is considered as the safe level by KEMP, if the sufficient amount of magnesium and the proper amount of potassium fertilizer were applied to the pasture. 4. Although the increased Mg content in the herbage decreased the ratio of K/(Ca+Mg) considerably, it was also necessary to lower the K content of the herbage to ensure the ratio below 2.2 of the critical level indicated by KEMP and 'THart ; the soil K should be less than 20mg to maintain the ratio below 2.2. Under this condition, however, the K deficient orchardgrass will appear at more than 10% ratio in the pasture, because of the ununiform distribution of soil K. Consequently, only by orchardgrass, it is not possible to maintain the ratio lower than 2.2. Therefore, the establishment of mixed herbage with legume is necessary to maintain the good pasture in both the view-points of plant and animal nutrition.

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The same samples of eleven fresh orchardgrass (St. Hokkaido) as reported previously were used to isolate cell wall materials from forage and faeces by neutral detergent solution. Chemical composition, digestibility and extent of cellulase hydrolysis of these isolated cell wall preparations were determined. The results obtained were as follows: 1. Indigestible cell walls (cell walls in faeces) were composed of crude protein 9%, cellulose 33% hemicellulose 38%, acid detergent lignin 14% and silica 4%. 2. Significant correlations were obtained between contents of organic matter, crude protein, acid detergent fiber (ADF), cellulose, hemicellulose in forage cell walls and contents of those in indigestible cell walls. Among the contents and digestibility of crude protein, ADF, cellulose in forage cell walls, significant correlations were observed. 3. It was observed that hydrolysis of indigestible cell wall was performed slowly the extent of the hydrolysis was small, whereas forage cell walls were hydrolysed in less than an hour. In the case of six hours treatment at one percent cellulase, the rate of decomposition of indigestible cell wall in dry matter loses showed 12% and those of forage cell walls came up to 43% . 4. Holocellulose in faeces from low digestible forage cell wall was highly hydrolysed by cellulase than those from high digestible forage cell wall.

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Variations of nutritive value of baled hay of 1st cut orchardgrass (earing stage) which had been stored in conventional two-story barn since June 1973 were investigated during the three year storage period. The results are summarized as follows ; Moisture contents of the hays after 10, 14, 24 and 36 month storage were lower than that after one month which was 17.0%. Cell wall and acid detergent fiber contents increased at the rate of 1.56 and 0.48% a year respectively. However, DE, DCP, TDN and digestibility of the components of stored hay were not affected by storage period, i.e., all the coefficients of simple linear regression of the nutritive components on storage period were 0 (p>0.05). When the hay prepared in 1973 and stored for 24 months and the new hay made from the same sward at the same growth stage in 1975 were compared, digestibility of crude protein and DCP content were higher with the latter, but no significant difference was found in digestion coefficients of the other components and in the contents of DE and TDN. Voluntary intake by sheep of the hay stored for 36 months since 1973 was not inferior to that of the hay stored for 12 months since 1975.

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The actogram recorded by means of radio-telemetry was investigated for identifying the behaviour patterns of grazing cattle. This method has been used for detection of movements of wild animals. Flexible transmitting antenna attached to an animal body vibrates and changes its direction as the animal moves. The plane of polarization and the direction of the wave change with vibration of the antenna. If a receiving antenna is fixed, input to the receiver varies as the transmitting antenna vibrates. Actogram of the grazing animal is shown by recording the input level continuously. If a given pattern of animal movement corresponds to a given pattern of antenna movement, the actogram will be able to be used as a method for identifying the behaviour. The main part of transmitter used for recording actogram is a crystall-controlled blocking oscillator, which is designed by ANDO. The weight is about fifty grams including batteries. The posture of a grazing animal is detected, in parallel with the actogram, by mercury switch method. The mercury switch differentiates the behaviour in which the animal keeps the head up from its behaviour of the head down as ON or OFF. The pulse interval of blocking oscillator takes two different values according to ON or OFF of the mercury switch. The demodulator (F-V converter) converts the pulse interval to the voltage. The transmitter was attached to the animal by using a neck-ring or a head ban dof cow halter (Plate 1). The transmitting antenna is made of steel wire (0.6mm in diameter and about 30cm in length). The MMB type receiver was used. The output of the receiver was connected to a pen recorder for recording the actogram. The results were summarized as follows ; 1. The patterns of the actogram recorded in grazing animals by radio-telemetry were classified into three types: pattern 1, prickly pattern, it was composed of high amplitude irregular waves (Plate 2-a) ; pattern 2, intermediate pattern, it consisted of low amplitude waves (Plate 2-b) ; pattern 3, flat pattern, intensity of the input was mostly constant (Plate 2-c). 2. Each pattern in the actogram was considered comparing with the pattern of behaviour observed by direct observation (Table 1). The most part of pattern 1 corresponded to grazing behaviour. Pattern 2 corresponded to idling behaviour which mainly consisted of standing and walking. Pattern 3 corresponded to resting behaviour which was mostly equal to lying. However, it was difficult to distinguish a short idling pattern distributed in grazing pattern. 3. When both actogram method (antenna vibration method) and mercury switch method were performed in parallel, the greater part of pattern 1 corresponded to the posture in keeping the head down, and both pattern 2 and 3 corresponed to the posture in keeping head up mainly. Simultaneous performance of the two method confirms the results more clearly, but the use of antenna vibration method only seems to be enough to identify the behaviour pattern of grazing animal.

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The effects of the month of transfer to the raising farm on the reproduction of heifers were examined for 613 Holstein heifers entrusted to Yamaguchi Prefectural Raising Farm. The results are as follows: (1) The age at the first insemination ranged between 12.8 and 27.4 months, with the mean age being 17.5±2.3 months. The body weight at the first insemination ranged between 246 and 385.3kg, with the mean body weight being 308.9±26.9kg. The mean age at conception was 18.6±2.9 months. The number of services required per conception was ; 1-54%, 2-23.2%, 3-11.4% and 4 or more-11.4%. The estrous cycle was 6 days in the shortest case and 211 days in the longest case. The mean span of estrous cycle was 36.2±30.8 days. In 52.6% of heifers, the estrous cycle ranged between 18 and 24 days, with the mean of 20.3±3.6 days. The peaks of estrous cycle length appeared at the multiple of 20, i.e., at 40, 60 and 80 days. (2) The seasonal distribution showed that the number of heifers inseminated was the greatest in spring both in terms of the number of heifers receiving first insemination and the number of heifers inseminated per month. The number tended to decrease in winter. Furthermore, longer estrous cycles exceeding 35 days were more often seen in winter. The estrous was found to be difficult to confirm in winter. (3) The conception rate was the lowest in September and the highest in December. A temporary decline in the conception rate was observed in April and May. Such a temporary decline in the conception rate seemed to be attributable to the difference in the month of transfer, with greatest cause being the low conception rate of those heifers transferred to the raising farm in May. The compensatory growth observed in the months of April and May also seemed to be one of the cause. (4) The effects of the month of transfer on the reproduction efficiency was also evaluated. The highest age at the first insemination was 20 months of heifers transferred in February. The lowest age was 16.5 months of heifers transferred in September. The rate of conception was extremely low-40%-for those transferred in May. Evaluating the effects of the month of transfer on the reproduction efficiency in terms of age at insemination and conception rate, it can be concluded that the best reproduction efficiency was obtained when the heifers were transferred in summer and early autumn.

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