Arbuscular mycorrhizal (AM) fungi in the order of Glomales (Zygomycetes) maintain a symbiotic association with plant roots of several species. We compared the nested PCR technique utilizing published primers to detect AM fungal DNA from field-collected mycorrhizal roots to the direct PCR technique which has been used for the evaluation of laboratory-grown plant roots or AM fungal spores. The first reaction of nested PCR was performed with a universal primer pair SS38-NS21, and the subsequent reaction was performed with the Glomales-specific primer VANS 1 in conjunction with taxon-specific primer VAGLO (Glomaceae), VAACAU (Acaulosporaceae) or VAGIGA (Gigasporaceae). The nested PCR method was capable of detecting amplified products from the DNA of four plant species roots obtained in the field, while direct PCR utilizing primers VANS 1-VAGLO, VANS 1-VAACAU and VANS 1-VAGIGA did not. To ascertain whether nested PCR end-products were derived from corresponding families of AM fungi, the PCR products were sequenced. The amplified sequences utilizing the VANS 1-VAGLO and the VANS 1-VAACAU were the most similar to sequences representative of the Glomaceae species and the Acaulosporaceae species found in the DDBJ database, respectively. However, most sequences amplified with the VANS 1-VAGIGA were not similar to the Gigasporaceae species, but appeared more similar to some Ascomycetes species. These results indicate that use of these specific primers have limitation in the detection of AM fungi in the field, though the nested PCR method itself was an effective and labor-saving technique when amplifying low amounts of fungal DNA from field-collected roots.

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In a grazed pasture in the steppe of Northeast Chiha, we investigated spatial distribution of plant communities and relationship between the distributions of communities and the soil environments. The investigative site (10m×10m) was divided 100 different plots (1m×1m). The vegetation factors (i.e., vegetation coverage, number of species, and diversity index H') of the divisions were found to relate negatively with their surface soil factors (i.e., pH and electric conductivity (EC) of the soil). The divisions were classified into three types using a similarity analysis of vegetation. The dominant species of vegetation types I, II, and III were Kochia sieversiana, Leymus chinensis, and Arundinella hirta, respectively. oH and EC (mS cm^<-1>) of the surface soil were 10.81 and 1.44 in the type I, 9.93 and 0.46 in the type II, and 8.46 and 0.15 in the type III classifications, and differed significantly among the three vegetation types. The spatial distributions of the vegetation types were primarily affected by the degrees of saline-alkalization in the surface soil.

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To determine energy flows in the growth of suckling Japanese Brown calves, the energy intake that the calves derive from both milk and herbage were investigated, as were their rates of energy retention from these sources. The gross energy intake per live weight basis from milk (GEMILK) decreased exponentially according to the calves' age in days. The GE intake from herbage (GEHERB) was observed from 40 days of age and increased as a quadratic function of age. The crude efficiency of retained GEMILK was 39% on average during the period when the calves ingested only milk. The estimated value of retained energy originating from milk (REMILK), during the first 40 days from the birth, agreed with the retained energy (RE) calculated by live weight, but differences arose between these two values after the calves reached 60 days of age. These differences were considered to be the RE originating from herbage (REHERB). The REHERB exceeded the REMILK after 170 days of age.

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This study analyzed the frequency of defecation and urination by Japanese Black Cattle in a daytime grazing system utilizing a bahiagrass (Paspalum notatum Flugge) pasture to obtain some information about the factors influencing the frequency and examine the possibility of developing empirical, deterministic models for predicting the frequency. The number of defecations and urinations was respectively 8-22 and 2-16 times/head/d (mean=15.4 and 8.5) in individual animals, and 11.0-17.2 and 5.5-12.0 times/head/d (mean=15.1 and 8.2) for the herd. The defecation frequency for the herd was positively correlated with feed DM intake and fecal DM output. A broken-line function employing the intake or fecal output as a predictor explained 53-71% of the variation in the frequency. The urination frequency for the herd was positively correlated with feed DM intake, fecal output as FW and fecal water output. A straight-line function using these variables as a predictor explained 23-29% of the variation in the frequency. The correlation between the defecation and urination frequencies was low or non-significant. The frequency of defecation and urination may be empirically predicted with acceptable errors from some variables commonly dealt with in models of grazing systems.

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The experiment aimed at examining the relation between growth and distribution pattern of starch particles found in stem base in makarikarigrass during the recovering time after drought stress, to evaluate its recovering ability in growth. At the thirteenth day after the initial treatment (DAT) started, the watering regimes were changed to identify the direct- and after-effects of drought stress. The increasing rate in top dry matter weight (TDMW) tended to be smaller with the increase in the drought stress. However, the suppressing rate was the smallest in semi-drought (SD)-SD plot (at the initial-the second period), resulting in the non-significant difference in TDMW between SD-SD and drought (D)-control plot. The leaves began wilting after 13 DAT and the mean starch particle diameter (MSPD) found in the stem base decreased. The decrease in MSPD was promoted by drought treatments as the direct effect. The starch particle distributed preferentially at the smaller side under the drought conditions, except under SD conditions where it distributed normally over the whole range of diameter. The MSPD was positively correlated with both mean tiller dry matter weight and TDMW at the late stage of drought treatments, suggesting that starch particle formation might relate to shoot growth acclimated to various ranges of drought stress.

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Two orchardgrass cultivars, Natsumidori and Aberystwyth S 143 (S-143), were subjected to salt stress by adding NaCl plus CaCl_2 (molar ratio 5.7 : 1, first 3 days 50 mM : next 5 days 100 mM : last 5 days 150 mM) to Hoagland solution for 13 days during the vegetative growth stage. Salinity reduced the growth of plant. Based on the percentage of reduction in relative dry weight, Natsumidori was found to be more tolerant than S-143. Natsumidori had a higher relative water content than S-143 under salt stress. Osmotic potential at full turgor (OP_<100>) was decreased by salt stress in both cultivars, but the rate of decrease was higher in Natsumidori than in S-143. In Natsumidori, the concentration of soluble sugars, glycinebetaine and K^+ of cell sap was increased more by salinity than in S-143. Natsumidori also accumulated more K^+, Ca^<2+> and Mg^<2+> and less Na+ under salinity compared to S-143. The concentration of Na^+, and K^+/Na^+ and Ca^<2+>/Na^+ ratios were correlated with salinity-induced growth reduction. The results suggested that the greater tolerance to salinity demonstrated by Natsumidori is related to differences in specific-ion effects and/or osmotic adjustment.

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Diallel analysis of the resistance to sheath blight was performed using 5×5 reciprocal crosses of lines belonging to the grain type by a field inoculation test to clarify the inheritance of the resistance to sheath blight. The mean additive effect, mean dominance and remaining dominance appearing in a specific combination were significant for relative lesion height : RLH at the 1% level of probability. The results of the analysis for RLH could fit the additive and dominant model without epistasis effect. The heritability was high in a narrow (0.773) and broad sense (0.935). Additive effect for height of lesion on the sheath : HL was significant at the 1% level, while the dominant effect was not. The results of the analysis for the height of flag leaf : HF did not fit the additive and dominant model. There was a significant correlation between the average RLH of better resistant and mid parent ((BP+MP)/2) and that of the hybrids (r=0.942, p<0.001). The additive effect was stronger than dominant effect for RLH. Therefore, the selection for RLH in early generation is effective to develop inbred lines rapidly.

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This study examined the effects of fertilizer application and plant density on the yield of the first and second-cut forage sorghum. The tiller development (tiller numbers and mean tiller weight) of two different cultivars, one has few large tillers (FS401 R) and the other has many small tillers (SX 11) was compared. The dry matter (DM) yield of the first-cut sorghum increased with high-density plot (14.28 plants m^<-1>) under high fertilizer application (360 kg N, 360 kg P_2O_5, 360 kg K_2O ha^<-1>) in cultivar FS 401 R, but DM yield incultivar SX 11 was not affected by density. In cv. FS401 R, the mean tiller weight of main stem in high-density plot was not different from that in low-density plot (4.76 plants m^<-2>), in spite of having more tiller numbers. In cv. SX11, the decrease in mean tiller weight occurred largely by an increase in the tiller numbers with high-density plot and higher fertilizer application. These results showed that the mean tiller weight of main stem affected on the DM yield of the first-cut sorghum. DM yield of the second-cut sorghum was higher in low-density plot than high-density plot in both cultivars. Much of the tiller in the low-density plot consisted of tillers originating from the lateral buds of daughter tillers in the stubble, and these survived tillers contributed to yield by increasing the mean tiller weight. On the other hand, much of the tillers in the high-density plot were of tillers originating from the lateral buds of main stem. More of these lateral buds were released at early period of regrowth, but most of them died before 43 days after cutting. The second-cut DM yield in the high-density plot was less than that in low-density plot. Therefore, the second-cut DM yield depended on the productivity of tillers originating from the lateral buds of daughter tillers in stubble. We considered that low density planting under high fertilizer application produced a higher yield in the forage sorghum's ratoon.

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An experiment was conducted to investigate the growth characteristics and nutritional value of various proportions (stems, leaves and sheaths) of reed canarygrass (RCG). The dry matter (DM) yield of the first crop increased rapidly after the middle of May, and the increase was most remarkable in the stems. The DM yield of the second crop also increased linearly, but the main increase was in the leaves, and even at maximum the stems made up only 30% of the total. In the first crop, the crude protein (CP) yield reached its maximum of 102 g/m^2 at the beginning of June. In the second crop the CP yield reached its maximum at the end of July, but the yield was only 30% of that of the first crop. As regards to the yield of digestible dry matter (DDM), in the first crop the value for the leaves at the middle of May was 102 g/m^2, and this increased to 170 g/m^2 in June. In June the yield of DDM was 170 g/m^2 for the stems and 100 g/m^2 for the sheaths, which represented a substantial increase over the values for the middle of May. However, the yield of DDM dropped in proportion to the decrease in the ratio of leaves. In the second crop, the amount of DDM increased in proportion to the growth of the plant, but it was always less than that of the first crop. These results indicated that the DM yield of RCG in the first crop reached its maximum at the heading stage, but the amounts of CP and DDM were lower than that of the pre-heading one.

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We prepared laboratory-scale silages of alfalfa (Medicago sativa L.), orchardgrass (Dactylis glomerata L.), maize (Zea ,mays L.) and sorghum (Sorghum bicolor Moench), irradiated them with gamma rays prior to storage and examined microflora and fermentation quality of them. Spore-forming anaerobic bacteria, which can cause butyric fermentation of silage, were eliminated from the silages with an 8 kGy dose. Molds and yeasts, which can cause aerobic deterioration of silage, were eliminated from the silages with doses of 4kGy and 16 kGy, respectively, whereas 10^2 cfu/g of aerobic bacteria were still detected from the silages exposed to a 16 kGy dose. The silages which were exposed to a dose of more than 6.6 kGy contained only less than 10^4 cfu/g of lactic acid bacteria and little lactic acid and they were of near neutral pH. These results suggested that at least a 16 kGy dose is necessary to inhibit butyric fermentation and aerobic deterioration of silage.

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'Dioxins' is the generic term given to polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar-PCB. Dioxins are produced during various combustion processes and also unwanted by-products of the manufacture of certain chlorinated compounds. As a result, dioxins are ubiquitous environmental contaminants and are generally present in very low concentrations in all foods including cows' milk and beef. It is currently considered that food is the primary source of human exposure to dioxins. The pathways of entry into food chains include the atomospheric transport of emissions and their subsequent deposition on plants, soil, and water. The major food sources seem to be fat-containing animal products in Europe and America, and seafoods in Japan, where animal products are the second important source. Dioxin concentration in retail cow's milk in Japan seems to be as same as that in England. Generally, dioxins and other lipophilic compounds are not little absorbed and translocated by plants, so residues in foods and feeds derived from seeds should be negligible. Animals that ingest high-roughage diets are the most likely to accumulate dioxins from the environment. Still, however, there are many unclear points on dioxins. So, the conclusion that forage is a maior source of animal exposure to dioxins requires verification by appropriate forage sampling and field investigation. We must appeal to society for reductions in the gross discharge of dioxins, while at the same time attempt our own technological innovation.

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In order to predict the changes of the natural grassland vegetation in global warming, it is necessary for us to clarify the relationship between the natural grassland vegetation zones and the climate. But that relationship has not been argued out in Japan. Therefore we investigated which of the vegetation types are appropriate to clarify that relationship from the first. We concluded that the short-grass type vegetation established under the artiGcial and natUral pressures in the process of the grass-land succession was the most appropriate for the above purpose. As the results, we separated the temperate vegetation from the subarctic one with Zoysia japonica-type grassland. The cool-temperate vegetation was separated from the warm-temperate vegetation with the ranges of Sasa and Pleioblastus.

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Our previous paper showed that the zoning of the Japanese grassland vegetation based upon the climate corresponds to the range of Zoysia japonica-type grasslands, Sasa-type grasslands, Pleioblastus chino-type grasslands. In the present paper we examined the relationships between these types of grassland and the climate factors. The border between the subarctic zone and the cool-temperate zone corresponded to the northern limit of Zoysia japonica type grasslands. In latitudinal distribution, this border corresponded roughly with the line that the coldness index is -35℃・month and that the average minimum temperature of the warmest month is 17℃. However, in altitudinal distribution, this border transferred to the cooler and higher-latitude zone. Futher investigation on the climate index of the altitudinal border is needed. The border between the warm-temperate zone and the subtropical zone corresponded to the southern limit of Zoysia japonica-type grassland and the northern limit of Zoysia tenuifolia-type grassland. This border corresponded roughly with the line that the warmth index is 170℃・month or that the annual mean temperature is 19℃. It was indicated that the border between the cool-temperate zone and warm-temperate zone was the southern limit of Sect. Macrochlamys Nakai, Sect. Sasa (Eusasa Nakai) and Sect. Grassinodi Nakai and the northern limit of Pleioblastus chino. This border was suggested to correspond to the line that the warmth index is 80-85℃・month and that the maximum snow depth is 40 cm. According to the distribution of grassland vegetation based upon the climatic factors in the present study, the distribution of the cool-temperate zone grassalnd including the subalpine zone was expressed to be wider than that of the actual grassland. This can be corrected by taking account the growth limit of Zoysia japonica-type grasslands in higher altitude at each latitude into consideration.The relationship withthe climaticfactors still remaines to be solved.

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We sampled some grassland vegetation types, whose the distributions were ditermind based upon the climatic environment factors in Japan, from the Vegetation Files of National Survey on the Natural Environment published by the Environment Agency. As the result, Zoysia japonica-type grassland, Sasa-type grassland (Sect. Macrochlamys Nakai, Sect. Sasa (Eusasa Nakai) and Sect. Grassinodi Nakai), Pleioblastus chino-type grassland and Zoysia japonica-type grassland, were found to be appropriate for dividing the grassland vegetation zones in Japan as stated in the prvious papers. Furthermore, Pleioblastus linearis-type grassland, Deschampasia-t6ype grassland and so forth were also found to be appropriate for the division. When Zoysia japonica-type grassland vegetation was defined as the temperate grassland in Japan, the subtropical natural grassland vegetation was defined as Zoysia tenuifolia-type grassland and Pleioblastus linearis-type grassland. If the temperate zone was divided into the cold-temperate zone and the warm-temperate zone, Sasa-type grassland and Pleioblastus chino-type grassland were appropriate for dividing them. The subarctic grassland vegetation type, however, was not determined because the vegetation did not appear enough in the files. Incidentally, Miscunthus sinensis and Imperata cylindrica communities adapted to the wide range of the temperature so that these could not be considered as appropriate for the division of the vegetations.

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We predicted how natural grassland vegetation in Japan will change in response to the global warming. We divided the Japanese grassland vegetations into four vegetation zones ; the subarctic, the cool-temperate, the warm-temperate and the subtropical grassland vegetation zones according to Zoysia japonica-type grassland and Z. tenuifolia-type grassland, Sasa-type grassland and Pleioblastus chino-type grassland. According to our results, the distribution in natural grassland vegetation will not change within the next 50 to 60 years. After that, however, the temperature will rise so rapidly and the maximum snow depth will decrease rapidly. One hundred years from now later, the temperature will rise around 3.3 to 3.8 degrees Celsius and the natural vegetation zones in Japan will greatly change. In Hokkaido, the subarctic natural grassland vegetation zone in lowland area will disappear. And the warm-temperate natural grassland vegetation zone in the lowland will spread to Shimokita and Tsugaru peninsula, the northernmost of the mainland, and will also appear even in the plains around Abashiri and Tokachi district in Hokkaido. The cool-temperate natural grassland vegetation zone in Shikoku, Kyusyu and Kii peninsula were predicted to have mostly disappear. On the other hand, the subtropical natural grassland vegetation zones in lowlands of Kyusyu and Shikoku were predicted to spread over Boso peninsula, the south part of Kanto, and the southern Izu peninsula.

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