Seasonal changes in efficiency of solar energy fixed on grazed pasture of tall fascue (Festuca arundinacea SCHREB.) was investigated. Throughout growing season from late March until late October in 1986-1987, 0.78% of incident solar energy (3017 GJ/10 a and 2843 GJ/10 a, respectively) was fixed in herbage available, 0.76% was consumed by grazing Holstein heifers and 0.021% was retained in heifers' body. At every step of energy conversion in plant and animal growth, the values of efficiencies were highest in spring grazing season and lowest in summer grazing season. Relation among herbage energy supply (HA), grazing intensity (GI) based on fasting metabolism, and consumed herbage energy (HCE) was expressed as following equations: in spring and autumn HCE=12.3GI-49.2GI^2/HA-0.709 (R^2=0.94) in summer HCE=-3.58GI+46.7GI^2/HA+3.43 (R^2=0.69) Here, the HA is the sum of HCE and the amount of residual herbage available left uneaten at the end of each grazing period. Fasting metabolism was calculated by ARC (1980)'s method. In vitro dry matter digestibility (IVDMD) of the available herbage measured at every beginning of rotational grazing period was highest in spring, then decreased in summer and recovered in autumn. These seasonal variation in both HCE and IVDMD, which were relating negatively with air temperature, were regarded to be a main caused of the seasonal change in solar energy conversion efficiency for the secondary production of grazing heifers.

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Seasonal changes in energy efficiency from herbage allowance to heifers' gain on tall fascue (Festuca arundinacea SCHREB.) pasture was investigated. Every energy constituent was expressed on the basis of MJ/F/day in this paper, and F was fasting metabolism estimated by ARC (1980)'s method. Herbage energy allowance (DA) and herbage energy intake (DHEI) were measured for every period of rotational grazing, and gross energy intake including subsidiary concentrated feeds (DGEI) was calculated. Heifers' energy retention (DRE) was estimated from body weight gain by ARC (1980)'s method. Heat production (DHP) was estimated from heart rate. Metabolizable energy intake (DMEI) was calculated from DRE + DHP. Relationships between these energy constituents in spring and autumn or in summer were expressed by regression equations. Using these relationships, seasonal changes in efficiencies were investigated. In summer, every energy efficiency was depressed, relating to air temperture. Efficiency of utilization of metabolizable energy for gain in summer (-0.02) was significantly lower than that in spring and autumn (0.47).

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For investigating the influence of digestibility on energy efficiencies for grazing heifers, following energy constituents were estimated from some measurements on Italian ryegrass (Ir) pasture and perennial ryegrass (Pr) pasture. Let available herbage energy supply (HA), grazing intensity based on fasting metabolism (GI) and consumed herbage energy by heifers (HCE) be described usign unit of GJ/10a/grazing period ; and energy retention (DRE ; estimated by ARC's method) and heat prodution (DHP ; estimated from heart rate), metabolizable energy intake (DMEI ; DRE + DHP) be described by unit of MJ/F/day, where F is fasting metabolism estimated by ARC's method. Using GI and HA, HCE was expressed as following equation : HCE = 12.6GI - 70.5GI^2/HA - 0.248 (R^2 = 0.81). The values of HCE estimated from this equation were similar to those estimated on tall fescue pasture in the previous report. Pelationships between DMEI and DRE were expressed as follows : on Ir pasture in spring, DRE = 0.63 DMEI - 1.76 ; on Pr pasture in spring, DRE = 0.65 DMEI - 1.72 + on Ir and Pr pasture in summer, DRE = 0.43 DMEI - 1.04. The regression coefficients in above equations, including those on tall fescue pasture in the previous report, were positively correlated to in vitro dry matter digestibility in each pasture significantly.

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Sustaining or increase in field crop productivity depend on soil and crop managements how to maintain or increase the value of organic matter in soil. In this report, the degradation dynamics of arganic matter in forage crop field were investigated to obtain a simple model for kinetic prediction of soil carbon accumulation. Crop yield, litter and root dry weight, soil carbon content, and carbon dioxide evolution from soil surface were measured in the field of corn-barley cropping system with heavy application of cattle manure (1100 kg/a/year) for two years. Carbondioxide evolution from the manured soil was also measured in vitro at three temperatures (9.0, 22.5 and 37.5℃). Total carbon content in the 0-15 cm soil layer with manure application increased by 375 g・C/m (0.25% dry soil) to 2085 g・C/m^2 (1.39% dry soil) in the first year. This gain of organic matter (375 g・C/m^2) was approximately 40% of the total amount of carbon weight (manure 789 + litter and root 122 g・C/m^2) applied in a year. The time course change in carbondioxide evolution obtain from the incubation experiment of wet soil was well approximated by the simple type model as described below. S=S_0{1-exp (-k・t)}・・・・・・・・・・・・・・・・・・・・(1) The parameters k_1, k_2, k_3 at three temperatures were determined by a simplex method. The relation between degradition rate k and apparent activation energy Ea was presented by the next equation. k=A・exp (-Ea/R・T)・・・・・・・・・・・・・・・・・・・・(2) By substituting the parameters, S_0 and Ea into the equations showed above, the daily changes in carbondioxide evolution rate could be estimated. We recognized that the estimated carbon contents of manured soil were approximately equal with the real values for the two years.

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Fractal dimensions of plant expanding pattern were compared among the ecotypes of Zoysia japonica STEUD. collected at the ten different habitats from Hokkaido (42°33' N) to Okinawa (26°13' N), and the variation in fractal dimension was discussed in relation to some growth parameters. A round stock (5 cm in diameter) of turf was transplanted on May 29, 1989, in pot (65 cm in diameter) filled with sands conventionally fertilized. The mowing treatment (10 mm in height) was made four times from Aug. 25 to Oct. 10. Fractal dimension and several growth parameters were periodically measured on the ten ecotypes. Fractal dimensions of top plant (Ft) and nodes distribution (Fn) were determined by the grid-counting method adopted in the previous paper. The results are as follows ; Ft of each ecotype linealy increased with growth after transplanting, then reached almost constant level in the middle of August. Ft (Aug. 21) of the ten ecptypes ranged from 1.727 to 1.922. The effect of mowing treatment on Ft was different among the ecotypes. Both ecotypes from Miyazaki and Toimisaki maintained higher fractal dimensions under mowing treatment. Fns of the ecotypes from Miyazaki, Toimisaki and Morioka were 1.622 and 1.345, respectively. Fn was closely related with mean Ft obtained during mowing treatment period. Statistically significant relationships existed between Fn and the total length of stolon + rhizome or the total number of nodes. However there was no significant correlation between Fn and dry matter production. Fractal dimension (both Ft and Fn) and elongation rates of stolon and rhizome were regarded as important criteria to select the ecotypes or strains with a high turf-making ability ; the two ecotypes from Miyazaki and Toimisaki having the highest ability among the ten ecotypes ysed here.

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In order to clarify the effect of shading on growth, nutrient contents and their digestibility in orchardgrass and red clover were studied through feeding trial in rabbits. 1) In orchardgrass, the effect of 40% shading rate on dry matter (DM) was reratively small, but at 70% shading rate, on decreased to about 30% of the control. Compared to orchardgrass, the shading effect on growth in red clover was greater. In 40%, and 70% shading rates, DM in red clover was reduced to 20% and 60%, respectively, as compared with the control. 2) The content of crude protein, crude fat, crude fiber, crude ashes, K, Fe and other nutrients in shaded orchardgrass plants, was hihger than those of the control, but decreases in soluble non-nitrogen compounds and Ca were observed. Ca/P rate was lower while K/(Ca + Mg) rate was higher in shaded than in unshaded plants. The digestibility of crude fats and crude protein was higher in the shaded plants, but the digestibility of soluble non-nitrogen compounds was lower and there was no great difference in the digestibility of the organic matter and crude fiber. There was also no significant difference in the content of TDN among the treated plots, plobut TDN tended to decrease in shaded plants. There was no significant difference in the yield per m^2 of TDN in 40% shading rate plants from the control, but in 70% shading rate, TDN of shaded plants decreased to about 40% as compared with the control. In red clover, the content of nutrients, inorganic compounds and TDN, and the digestibility of these nutrients were not significantly affected by shading. As a result, per m^2 TDN showed the same pattern as in dry matter.

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In this study, characteristics of higher nodal-position tillering of festlolium cv. Tandem were compared with those of perennial ryegrass (Lolium perenne L. cv Friend) under intensive grazing condition. Higher nodal-position tillering was observed in both festlolium pasture and perennial ryegrass pasture. The higher nodes elevated by the extension of the lower internode of the tiller formed a propagule with the subsidiary tillers (the higher nodal-position tillers) and advantitious roots. The density of the propagules was 8.3/m^2 and 18.7/m^2 in the examined festlolium pasture and the perennial ryegrass pasture, respectively. In the perennial ryegrass pasture, positive correlation was obtained between the density of the propagules and that of the adult plants each in the examined quadrates. On the other hand, in the festlolium pasture, there was no correlation between the two densities each in the quadrates, and the density of the propagules was higher in a lax grazed part. The avarage length of the extended internodes of festlolium was longer than that of perennial ryegrass. The avarage horizontal angle of the parent tillers of the propagules of festlolium was less (5°) than that of perennial ryegrass (30°). Establishment ratio of the propagules of festlolium was higher (95.9%) than that of perennial ryegrass (63.6%). Since the propagules of festlolium occurred on the almost horizontal tillers, the propagules of festlolium could establish more easily than those of perennial ryegrass. Thus it was concluded that festlolium could spread vegetatively by means of higher nodal-position tillering as well as perennial ryegrass.

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Current year's stems and overwintering stems of kudzu-vine, other plant species and litter were sampled separately, using 1-m^2 quadrats, in a kudzu stand which was established in an abandoned field about 15 years previously. Current year's stem emergence from the buds on overwintering stems, and current year's stem dry matter and leaf area production were examined to compare with results obtained previously by the present authors and another researcher (Athens, Georgia, USA). In the one-ring stems, the number of living current year's stems produced per node (NLCN) was at a maximum of 0.22 in June and was 0.13 or 0.14 from August onward. NLCN of the two-ring stems ranged from 0.03 to 0.07 throughout the growing season. The number of living current year's stems produced per m^2 was highest (21.0) in June and then decreased thereafter to values of 5.0 to 5.7 from October onward. The highest values for growth parameters of current year's stem were as follows : 380 g/m^2 in August for current year's stem dry weight, 131 and 54 g/m^2 in August for leaflet and petiole dry weights respectively, 216 g/m^2 in September for stem dry weight, 50 m in July and August for total stem length per m^2 and 3.7 in July for LAI. Dry matter production of overwintering stems was greater in this study than in Athens, Georgia, USA, while the reverse was true for dry matter and leaf area production of current year's stems. The causes responsible for these results were considered to be more severe drought injury, disease and insect damage, fewer one-ring stems with the greatest number of current year's stems produced per node, and an inferior development of photosynthetic surface area in this study compared tp the study in Georgia.

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A series of trials has been carried out to determine the level of voluntary intake and digestibility of clipped orchardgrass and alfalfa fed at several growth stages to wethers. The rectilinearity of the relationship between digestible cell wall intake (YDCWI : g/kg^<0.75>) and cell wall intake (XCWI : g/kg^<0.75>) : YDCWI=a+bXCWI and the curvilinearity of the relationship between cell wall digestibility (YCWD : %) and cell wall intake (XCWI : g/kg^<0.75>) : YCWD=b+a/XCWI seem be the result of certain interrelationships among the supreme cell wall digestibility (=b) and excretion of delayed residues flow through gastrointestinal tract (=a). The regression equations are shown below : orchardgrass : YDCWI=-9.2+0.88XCWI, (r=0.93,P<0.01, n=102) YCWD=91-1014/XCWI, (r=-0.70, P<0.01) alfalfa : YDCWI=-1.8+0.48XCWI, (r=0.76, P<0.01, n=55) YCWD=47-157/XCWI, (r=-0.13) The fill of cell wall in the gut (CWF : g/kg^<0.75>) would equal the cell wall intake added to (a). The rate of passage (Kp) can be represented by Kp=cell wall excretion/CWF The rate of digestion (Kd) can be represented by Kd=digestible cell wall intake/CWF Estimated average values of total amount of cell wall present in the gut (fill), Kp and Kd are shown below : orchardgrass : fill=43.5g/kg^<0.75>, Kp=0.31, Kd=0.48 alfalfa : fill=32.9g/kg^<0.75>, Kp=0.55, Kd=0.40

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In order to elucidate the genetic differentiation of diploid cultivars in perennial ryegrass (Lolium perenne L.), 137 cultivars released in various nations were assayed by starch gel electrophoresis for seven enzyme systems. From zymogram variation, eight polymorphic loci, Aco 1, Aco 2, Aph 1, Got 3, Pgi 2, Pgm 1, Pox and 6 Pgd 1 were investigated. Isozyme gene diversity of Lolium perenne L. was high for Aph 1 and Pgi 2, and was partitioned into 81% within cultivars and 19% between cultivars. The cultivars of Netherlands and Germany have higher total gene diversity than those of U.S.A. and Denmark. Allelic frequencies were different at some loci among cultivar groups based on nations of origin. Principal component analysis (PCA) was applied to allelic frequencies. About 55% of the total variation was extracted by the first, second and third principal components (PC1, PC2 and PC3). THe characteristic scatter diagrams of PC1 and PC3 showed that the cultivars of Netherlands, Germany and U.S.A. were indentically distrubuted on their nation bases. Cultivars of several nations in Western Europe were close in genetic distance and formed a cluster. Western Europe cluster was also close to the cultivars released in U.S.A., but farther from the cultivars released in Eastern, Northern Europe and Italy. The cultivars released in Oceania were independent from Western Europe cluster and other cultivars. These results were discussed in relation to the cultivar differentiation among the nation.

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[in Japanese]

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Allelopathic characteristics of Lolium perenne L. have been previously reported in sand culture. The objectives of this study were : (i) to confirm if allelopathic interference of Trifolium repens by Lolium perenne might exist under soil culture condition, and (ii) to determine the toxic effects of soil previously planted with Lolium perenne. The result obtained are summarized as follows : 1. In intercropping experiment on soil (red-yellow color clay loam), plant growth of Trifolium repens was apparently inhibited by associating with Lolium perenne, showing the greater inhibition at the higher proportion of Lolium in mixture. Lolium perenne showed the oppositeresponse, growing better in association with Trifolium repens (experiment 1). 2. Growth of Lolium perenne and Trifolium repens was generally found to be reduced in soil in which Lolium plants had been grown previously (Lolium-soil) ; whereas in the soil where Trifolium plants had been planted (Trifolium-soil), there was benefit effect in stimulating the plant growths of both species (experiment 2). 3. Methanol extracts from Lolium soil and Trifolium soil caused a reduction in seedling growth of Trifolium repens in bioassay ; showing the greater inhibition in Lolium soil compared with Trifolium soil (experiment 3). 4. Form these results, it is suggested that allelopathic mechanism may occur in the interference of Trifolium repens by Lolium perenne in soil culture that involves the exudation of allelochemics from root of Lolium plants.

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A three-year experiment was conducted to investigate the response of bahiagrass sward to cutting height. The sward were cut to the heights of 2, 7, 12, 17 and 22 cm at the 2-4 week intervals from May to November. In all the plant and litter parts, significant effect of the cutting height on the dry weight per unit area appeared in the first season after the treatment initiation, and usually continued throughout the experiment. The pattern of response, however, varied with the plant and litter parts, season, year and the time after the treatment initiation. Response of leaf and stem ddry weights to cutting height varied with the season and year. Low cutting height decreased leaf weight from summer to early winter, and stem weight from summer to winter. In spring, however, lower cutting heights did not always result in lower leaf and stem weights than higher cutting heights. Dry weight of standing dead consistently took and increasing tendency as the cutting height increased. Response of stolon and root dry weights changed with the time after the treatment initiation. The cutting height for the maximum weights of stolon and root shifted from the 22 cm side to 2 cm side. Dry weight of surface litter was always smallest under the lowest cutting height. Response of belowground litter varied with the season and year without any definite trends. The results were compared with those from other swards to characterize the bahiagrass response, and possible factors influencing the responses were discussed.

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The race horse ranches are historically located and developed in specific regions in Japan. This study has been made on localization of the race horse ranches, mainly from the view point of topographical and geological aspects and make clear common conditions of these localized ranches. Results obtained are as follows. A. Almost all the ranches located and developed regions are classified four lotations as follows ; 1. Dissected plateau covered with volcanic ash soils. 2. Frequently flovd suffered areas. 3. Tectonic terrace e.g. large coastal terrace zone. 4. As recently developed region, hilly or at the foot volcano regions covered with volcanic ash soils. B. Agricultural conditions common to above mentioned four locations, all of them are histrically unproductive and barren lands.

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