This study examined the effects of intraspecific genetic variation on botanical structure of mixed swards by comparing the performances in two-species mixtures among different cultivars (cultivated populations) in three grass species : Lolium perenne L., Dactylis glomerata L. and Festuca arundinacea Schreb. There were significant differences in botanical composition of the grass-grass mixtures among the cultivars. The relative contribution to the total biomass (relative dominance) of the mixtures ranged from 54 to 90% between L. perenne cultivars, from 45 to 85% between D. glomerata cultivars and 11 to 43% between F. arundinacea cultivars. The relative dominance in the mixtures showed a close relationship with tiller size of the monoculture swards in the three species. However, the relationship differed among the three species : a positive linear relationship in L. perenne, a positive quadratic relationship in D. glomerata, and a negative quadratic relationship in F. arundinacea. The following hypothesis was proposed to explain the results: the differences in relative dominance of mixtures among the cultivars are determined by the relative balance between potential growth and regrowth ability after defoliation, both of which are closely associated with tiller size, and that the three species differed in the relative importance between them.

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To investigate the effects of foaming in the rumen with white clover ingestion on the microbial digestion of sheep, an experiment using three treatments - white clover sole feeding (WC), white clover sole feeding with an antifoaming agent (Ruminon^<【○!R】> 5ml/day) (WR), and white clover and orchardgrass (1:1 on a dry matter basis) feeding (WO) - was carried out with 3×3 Latin square design using three lambs. Ruminal fermentation was investigated in 2, 4, 6 and 12 hr after feeding under restricted feeding (30 g of dry matter/kg of body weight/day, 08:00 and 29:00). The foam stability of ruminal fluid was remarkably high 2 and 4hr after feeding in WC, while the ruminal fluid in WR formed little foam at any stage after feeding. Protozoal density of ruminal fluid was significantly small in WR compared with that in WC and WO (P<0.05), particularly 4 and 6 hr after feeding. Total volatile fatty acid concentration was 23-26 m mol/l higher in WR than in WC and WO 2hr after feeding. Scanning electron micrographs revealed a large bacterial population on leaf particles and extensive disintegration of leaf tissues in WR compared with that in WC.

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Carbohydrate metabolism in stem bases of timothy and orchardgrass in winter was studied under snow in eastern region of Hokkaido in Japan. Phlein concentration in both grasses decreased during winter, especially in frigid winter (January) and early spring. The decrease in phlein in frigid winter proceeded under increase in phleinase activity with concomitant increase in low molecular sugars. The decrease in early spring occurred under decrease in phleinase activity, but increase in low molecular sugars was not detected. Molecular size of phlein was larger in timothy than in orchardgrass throughout winter as measured by gel chromatography. Division of the carbohydrate metabolism in winter according to the changes in the nonstructural carbohydrate concentrations and phleinase activity was discussed.

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Twenty-three populations of Medicago arabica collected from western Japan and foreign countries were evaluated in nitrogen fixation capacity, represented by acetylene reduction activity and plant dry matter production, under inoculation with four strains of Rhizobium meliloti collected in western Japan. Significant differences of nitrogen fixation capacity among populations of M. arabica were recognized. Of the five geographical groups of plant populations, the foreign group was very different from the Gifu, Aichi and Nara groups of Japan, but similar to the Japanese Okayarea group in the response to the R. meliloti strains. Plant populations were clustered into three groups based on the response to the four strains of R. meliloti, by principal component analysis; group I included the foreign and the Okayarea populations, and group II was composed of the other Japanese populations except one, which was clustered into group III. Three strains of R. meliloti had similar response to the plant populations and can be clustered into the same group (group B), but GRC5K16 was different from the former three strains, and can be clustered into another group (group A). The plant population group I tended to show high compatibility with the strain group A and the population group II with the strain group B, suggesting that compatibility between local populations of M. arabica and strains of R. meliloti was symbiotically differentiated. The strain group isolated from the population group showed high compatibility with the host population group. It implies that a new symbiotic relationship, which is new connection of plant populations with R. meliloti strains, is developing within the species.

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Pleioblastus chino var. viridis can dominate under severe grazing conditions. To understand the reason of this dominance, we investigated the maintenance mechanism of stem density of P. chino var. viridis in three plots; grazed, 1-year-ungrazed and ungrazed ones. The stem weight was ranked, grazed< 1-year-ungrazed<ungrazed plots. On the contrary, the stem density was in the reverse order, because there are differences in both the rhizome bud density and the bud utility ratio among plots. The rhizome bud density was ranked, grazed (8619/m^2)>1-year-ungrazed (6303/m^2)> ungrazed (789/m^2) plots. The bud utility ratio was also ranked, grazed (47%)<1-year-ungrazed (35%)>ungrazed (17%) plots. These traits were considered to be responsible for the enhanced dominance of P. chino var. viridis under severe grazing conditions. In both 1-year-ungrazed and ungrazed plots, the relationship between mean aboveground weight per stem and stem density seemed to follow a thinning line with a gradient of -3/2. This density regulation of P. chino Var. viridis was caused by intraclonal controls of rhizome as well as by both intraclonal and interclonal competitions.

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Decrement of the β-carotene contents with advancing growth stages has been well-known in forage crops. The experiment was carried out to clarify the effects of β-carotene content and the weight ratio of leaf, stem and head on the β-carotene decrement in the whole plant of Italian ryegrass. β-carotene content of the whole plant decreased as the plant advanced through its growth stages, and the decrement depended on the stem, head, and especially the leaf weight ratios, but didn't depend on the β-carotene contents of the plant parts. β-carotene contents in whole plants at each growth stage could be estimated from the overall means of β-carotene content in plant part through the growth stages and the weight ratio of each plant part, with values from estimation being very close to those from chemical analysis. β-carotene content of whole plant can be accurately and easily estimated from leaf weight ratio irrespective of the plant's growth stages.

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A change of vegetation and soil of the deseritfied grasslands in the process of recovery have been studied at Keerqin Sand Land, Inner Mongolia, China. Two sites were selected for survey, one was at the sand dune (No. 1), the other was at the flat sand land (No. 2). At site No. 1, three pastures of different years after planting Caragana microphylla were surveyed: 14 years (plot B), 17 years (plot C) and 19 years (plot D), and no planted (plot A). At site No. 2, three pastures of different years of corn cultivation and of light grazing were surveyed: 14 years cultivation-one year grazing (plot A), 5 years cultivatlon-10 years grazing (plot B) and 15 years continuously grazing (plot C). Results obtained were as follows: 1. In the site No. 1, plant height of Caragana microphylla and number of species of vegetation increased corresponding to years after planting Caragana. Content of the organic matter, available N, P, K and total amount of N and P in surface soil were higher in the plots of longer years after planting than these of shorter years. 2. In the site No.2, dominant species in plot B was Pennisetum flaccidum, a perennial rhizomous grass, whereas in plot A it was Setaria viridis, an annual species, and in plot C it was Cleistogenes squarrosa, a perennial bunch type grass. The soil in plot A had the smallest amount of the organic matter, available N, P and K among three plots. This indicated that soil where the corn cultivated was severely degraded. On the contrary, the soil in C plot where continuously grazed for 15 years had the highest amount of the organic matter, and available N, P and K among three plots. The soil in plot B had intermediate amount of the organic matter and nutrients between Plot A and B. This suggested that ecosystem of pasture 10 years grazing recovered somewhat but not completely. 3. In the process of recovering from the desertified pastures it is considered that the vegetation development coincide with the improvement of soil fertility and that once degraded pastures take a long time for recovery, especially in the moving sand dune where no plant cover, and the soil organic matter and nutrients are scarce.

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Performance of steers and heifers (Aberdeen Angus) was investigated under the intensive grazing system on timothy (Hokushu, TY) swards (2.4ha×2 replications) in 1988 and 1989. Each experiment sward was divided into 35 paddocks, and grazed rotationally during 168 days from May to October in both years. During May- mid June, 14 or 15 paddocks were used for grazing and the other paddocks were harvested for ensiling at the early June. During late June-October, all paddocks were used for grazing. Grazing animals were divided into three herds, herd of steers that grazed through the grazing season and herd of steers and herd of heifers, those grazed temporally in both years. Results obtained were as follows (1) The averages of sward height were maintained about 30 cm high throughout the grazing seasons. On the other hand, herbage allowances were kept the sufficient level of over 3 kg DM/100 kg BW throughout the grazing seasons, by adjusting grazing area to demand of animals. (2) Dry matter digestibilities (DMD) of TY were also kept relatively high (73-81%) through the grazing seasons except in summer. The lowest DMD was 65% in summer of 1988, due to the lack of precipitation. (3) The average daily gains of steers that grazed through the grazing season were high (0.70-0.75 kg/day). Cumulative body weight gains per unit land area over grazing season were high in both of two years (614-721 kg/ha).

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The effects of adding formic acid, bacterial inoculant or a mixture of bacterial inoculant and enzymes on the fermentation quality of wilted grass silage were investigated using first and second cuts of timothy (Phleum pratense L.), orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) with laboratory silos. Both the first and second cut grass were harvested at 3 cutting dates. Within the first cut, the water-soluble carbohydrate (WSC) contents of timothy, orchardgrass and alfalfa were 3.6-6.8, 4.8-8.1 and 4.0-4.7% on a dry matter basis, respectively. The WSC contents of orchardgrass and alfalfa at the second cut were lower than that those at the first cut. The fermentation quality of the silages was influenced by the cutting date of the grass. The extent of fermentation variation were dependent on the species of grass material, the cutting frequency and the additives. There was a marked variation in the untreated and inoculant-treated silages of the second cut orchardgrass and the inoculant and enzyme-treated silages of the second cut alfalfa, the extent of fermentation variation was markedly increased. There was a slight variation in the formic acid-treated silage in all species of grass. The fermentation quality of formic acid-treated silages of timothy, orchardgrass and alfalfa silages were better than that of the untreated each silage,irrespective of cutting date. The formic acid treatment was markedly effective for the improvement of the fermentation quality of alfalfa silages. The fermentation quality of the inoculant-treated first and second cut timothy silages were good, while the fermentation quality of the second cut orchardgrass silage was improved less than that of the first cut silage. The first and second cut alfalfa silages were not improved with the inoculant treatment. The fermentation quality of the first and second cut timothy silages and first cut orchardgrass silage was increased with treatments of inoculant and enzymes. However, the fermentation quality of second cut orchardgrass silage and first and second alfalfa silages was not different from those of the inoculant silages. There were no significant differences between the inoculant and enzyme-treated silages and the untreated silage. From the above results, the effectiveness of additives on the silage quality depended on the species of herbage materials used, the cutting frequency and the cutting date.

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Soluble carbohydrate composition of phasey bean (Macroptilium lathgroides (L.) Urb.) was compared with those of some tropical forages. Siratro (Macroptilium atropurpureum (DC.) Urb.), tropical kudzu (Pueraria phaseoloides (Roxb.) Benth.), cook stylo (Stylosanthes guianensis (AubL) Sw. cv. Cook) and greenleaf desmodium (Desmodium intortum (Mill.) Urb.) were used as legume species, and gatton panic (Panicum maximum Jacq. var. maximum cv. Gatton) and napiergrass (Pennisetum purpureum Schumach) were used as grass sepcies. Phasey bean, legumes and grasses were sampled at 3, 6 and 9 weeks of regrowth after they all were cut on August 23. 1996, and measured water soluble carbohydrate (WSC), fructose and glucose concentrations using the Anthrone method and HPLC. The following results were obtained. The concentration of WSC of seven tropical forages were ranged from 1.3 to 9.4% DM. Maximum fructose and glucose concentrations were 2.4% DM and 1.3% DM, respectively. WSC concentrations of phasey bean were from 4.1 to 7.8% DM and higher than those of other legumes at all sampling dates. WSC content of phasey bean was lower than that of napiergrass at 6 week of regrowth (7.8% DM versus 9.4% DM). The concentrations of fructose and glucose in phasey bean were 0.2 to 0.5% DM and 0.8 to 1.2% DM, respectively. When compared with other tropical forages, the composition of monosaccharides in phasey bean was characterized by high glucose concentration and high glucose/fructose ratio.

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Productivity and efficiency of Sudangrass production under minimum tillage cultivation was surveyed at dairy farm. Sudangrass produced under minimum tillage seeding with applying slurry barnyard manure at early growing stage was harvested and processed as roll bale. In this system, tillage, fertilizing, seeding, covering and tamping were done in the single operation process. Dry weight yield of Sudangrass was about 500 kg/10 a at summer planting after corn harvesting. The total working hours consumed in this cropping system was about 90 min/10a, of which 30 minutes for seeding, 20 minutes for slurry applying and 40 minutes for harvesting. Sudangrass planted in spring after Italian ryegrass harvesting, also showed a high yield of 1,200 DM kg/10a and was higher than the yield of conventional cultivation method. And it took about 140 min/10a. The production cost of Sudangrass in this cultivation system after Italian yegrass was about \38/DM kg, and about \10/DM kg lower than the cost of conventional cultivation method. In conclusion, Sudangrass production under minimum tillage could be very efficient and less time consuming system for dairy farmers.

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A field experiment was conducted in orchardgrass (Dactylis glomerata L.), timothy (Phleum praterise L.) and meadow fescue (Festuca elatior L.) after the first cutting to investigate the effects of applied nitrogen on the relationships among the leaf area index (LAI), the net assimilation rate (NAR) and the crop growth rate (CGR), and to assess the interactions between nitrogen absorption and those three parameters. Two treatment levels of nitrogen (0 g m^<-2> and 6 gm^<-2>) were used in this study. The dry matter yield was the greatest in orchardgrass, followed by meadow fescue and timothy in the treatment applied nitrogen. This ranking was derived from the CGR responses to nitrogen applied in the three grasses tested. Nitrogen application increased the LAI, but had no great influence on the NAR. The CGR rose according to the increased LAI, resulting in a higher yield of dry matter at the time of second cutting. It appeared that the differences among timothy and other two grasses in the CGR after nitrogen application were attributable to the differences in the characteristics of nitrogen uptake and translocation of absorbed nitrogen during this growing period. The difference in the CGR between orchardgrass and meadow rescue was due to the difference in the increasing efficiency of leaf area per unit absorbed nitrogen.

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