Clonally propagated orchardgrass (Dactylis glomerata L.) ramets were transplanted 10cm (100 ramets/m^2, LD) or 5cm (400 ramets/m^2, HD) apart in plastic containers (L×W×D=60cm×40cm×30cm) in autumn of 1978, and used experimentally in 1979 and 1980 (1st and 2 nd harvesting year, respectively). These simulated swards in both plant densities were fertilized at a rate equivalent to 60g/m^2/year (HN) or 20g/m^2/year (LN) of each N, P_2O_5 and K_2O. Each fertilization level was combined with 9 to 10 (FC) or 5 (SC) harvestings in every year (Table 1). Life histories of tillers which originated during different period of seasons were traced on each combined treatment being classified with colored plastic rings during two harvesting years. Yields of several bunches of differentially originated tillers were also measured seperately on each harvesting time in the 2nd harvesting year. Seasonal changes of tiller population in orchardgrass swards showed a similar pattern under different management regimes in both 1st and 2nd harvesting years expecting those in spring time in the 1st year (Fig. 1, 2). That is, the most pronounced tiller number increase was occurred in autumn in every nutrient and harvesting treatment examined, although a pretty amount of tillers also arose during a limited period after 1st cutting. On the contrary, tiller number gradually decreased during a period from early summer until the beginning of autumn in each year, most severely under HN nutrient and SC harvesting conditions. In early spring of 2nd harvesting year, when the density was the highest in each nutrient and harvesting treatment, tiller number tended to decrease continuously prior to the heading, but adversely, a tiller increment was observed in 1st year spring while tiller density was still in low level in each sward. Tillering acceleration after 1st cutting of reproductive canopy was most pronounced under HN・SC treatment in both LD and HD swards, but these newly emerged tillers were rather infirm and short-lived for the most part, so that the most of them died and disappeared during hot and drought summer time (Table 2, 3). On the other hand, those tillers originated in the preceding year partly continued vegetative regrowth after 1st cutting, and a fair amount of tillers remained alive until the autumn when most active tillering was commenced under each management treatment examined. This autumn tillering was extremely enhanced under HN condition, approaching the level of 10,000 tillers/m^2. The 1st harvesting in the 2nd year was almost entirely composed of leaves and culms of tillers which had originated in the preceding year (Table 5, 6). Yield composition formed by the biennial tillers was kept at high level in aftermass cuttings until summer; it still remained over 50% in September, thus highly contributing the forage production as compared with that of tillers emerged after 1st cutting. The yield of abundantly emerged tillers after 1st cutting in sward of HN・SC were also below that of older tillers because of their lighter weight and gradual senescence during regrowing period (Table 4). In autumn, the yield made from recently emerged tillers ascended fairly high and the density of these new tillers got near to the level with the older tillers in HN swards, while it still remained extremely low level in LN swards (Table 5). Above mentioned evidences suggest that the acceleration of autumn tiller formation is much important for both preserving denser tiller population and harvesting higher forage production in orchardgrass swards over longer years.

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Napiergrass, Pennisetum purpureum Schumach, cv. Merkeron, was grown with a relatively heavy fertilizer input including a total nitrogen application of 500kg/ha, under two planting density regimes, i.e., 4.0 plants/m^2, low density plot (LDP) and 8.2 plants/m^2, high density plot (HDP). No cutting was done during the growing period. Growth parameters and the other some plant factors relating to dry matter production were compared between two plots during the period from May 9 in 1987, when the shoots with 7-10 leaves were planted, to the final harvest on October 22. Shoot numbers, leaf area and dry weight of various plant parts per unit field area were higher in HDP than in LDP throughout the growing period. Leaf area indices (LAIs) attained to the maximum in late September with the values of 12.5 in LDP and 15.3 in HDP. Dry matter weights of whole plant at the final harvest were 42.8ton/ha in LDP and 5.0ton/ha in HDP. The relations between LAI and light extinction coefficient (K) in both plots were nearly coincident and Ks were decreased as LAIs increased. Decreases of net assimilation rates (NARs) following the increases of LAIs were slight and crop growth rates (CGRs) increased nearly proportionally to LAIs in both plots before September. After then, NARs and CGRs were lowered by the decreases of temperature and solar radiation intensity. Hence, CGRs were maximum in late August with the values of 53.5g/m^2/day in LDP and 62.3g/m^2/day in HDP. The inter-plot difference in the maximum CGR was mainly brought about by the difference in LAI. It is suggested from the above that the enhancement of increase of LAI by such a practice as high planting density, is effective for increase of dry matter yield of Napiergrass, especially in southern Kyushu where the productive period of tropical grass is limited within a relatively short duration from May to November.

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This study was conducted to know whether competitive advantage of one species over another one continues in subsequent canopies recovered after defoliation. Vegetatively propagated clones of Lolium perenne (PRG) and Festuca arundinacea (TF) were planted separately (S) or in an equiproportional mixture (M) in containers of 41×61×31.5cm at three levels of density, viz. 400,100 and 44 ramets per m^2 (HD, MD and LD). The treatments were duplicated in a randamized block design. The present report describes whether the competitive superiority of PRG to TF in the first year continues to the second year under the infrequent defoliation. The plants were cut at 10cm height on May 8, July 10 and September 10. 1) In mixture plots (M), heading shoot number per plant (Table 2), tiller number per plant (Table 1) of each defoliation, and dry matter yield (Fig. 1) were higher in case of PRG, and lower in case of TF than in monoculture plots (S). 2) In productive structure (Fig. 2), assimilatory organs (g/m^2) of PRG in the third canopies were smaller than the first and the second canopies. The organ of PRG was smaller than TF. 3) With the declining of leaf area index (LAI) (Fig. 3), relative light intensity (RLI) at 10cm height increased to 60% in the third canopy, and the ratio of assimilatory organ for total organs of PRG in mixture decreased in the third canopies (Table 4). 4) In the third canopy, competitive-values (Table 3) of PRG were smaller in HD than in LD or MD. 5) The regrowth of TF was smaller than PRG until the second canopy, but this relationship was reversed in the third canopy (Fig. 1 and 2). From the results described above, it was suggested that competitive ability of PRG over TF tends to decrease by the deterioration of the regrowth of PRG under infrequent defoliation, and the competitive advantage of PRG to TF decreases in HD of the third canopy.

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Two prediction methods were compared to estimate total digestible nutrients (TDN) by near infrared reflectance spectroscopy (NIR). The one was the method by extrapolation of NIR values to TDN calibration equations (indirect method). The calibrations were obtained by Adams method, Martin equation, Donker equation, equation based on enzymatic analysis and ADF method. The other one was estimated by direct calibration of in vivo TDN (direct method). Samples of TDN prediction were including corn silage, sorghum silage, grass silage and grass hay composed mainly of orchard grass, timothy and alfalfa. Digestion trials of these feeds in vivo were carried out with sheep. In the case of direct method, over 0.7 of correlation coefficents (r) and 1.5-3.8% of standard error (Se) were obtained by the equation of Adams, Martin and enzymatic analysis in the test of hay, but they were very low r values, below 0.5, and 0.8-3.8 of Se %, in the test of corn silage. In TDN calibration, it was found that over 0.8 of correlation coefficients of multiple regression analysis using 3 wavelengths and 0.8-3.4% of standard errors for all feed groups.

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Soil microbial biomass and numbers were measured and compared in topsoils (0〜10cm in depth, Thick High-humic Andosols) of paddocks where introduced pasture grasses had been placed to Pleioblastus chino Makino (paddock A) and Dactylis glomerata L. (orchardgrass) remained (paddock C). The soil microbial biomasses determined under the microscope were 189〜197g dry weight m^<-2> in paddock A and 232〜255g in paddock C. The fungal biomass occupied 89% of the total microbial biomass and the half of fungal hyphae was brown-colored in both the two paddocks. As for bacteria, actinomycetes and fungi measured by the dilution plate method, their numbers in paddocks A were about half of them in paddock C. The difference in soil microbial biomasses and numbers related with the amounts of organic matter (2-0.1mm in diameter), those were 9,190mg 100g^<-1> dry soil in paddock A and 14,100mg in paddock C. The estimated amounts of nutrients in the soil microbial biomass in paddock A were 94kg ha^<-1> of nitrogen, 80kg of phosphorus, 71kg of potasium and 9kg of calcium, whereas the content of available P (Bray No. 2) was low and nitrate N was not detected in both of the two paddocks. These results indicate that the productivity of the pasture was limited by inorganic nitrogen and by the amount of nitrogen released from the microbial biomass.

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In order to practice reasonable fertilizer management for grassland, it is required that fertilizers are applied on the basis of soil testing and plant analysis. This studies were carried out to establish a method of phosphorus nutrient diagnosis and to make its criteria for growing orchardgrass, being one of the most important grass species in Japan. This experiment was conducted on a pure sward of orchardgrass sown on a volcanic ash soil in 1976. In 1979, a long-term field experiment with 8 levels of phosphatic fertilizer applied at the rate of 0, 2, 4, 6, 12, 18, 24 and 36 P_2O_5kg/10a, was set out. Phosphorus, as superphosphate, was applied by top dressing at early spring every year. Sufficient amounts of nitrogen and potassium equivalent to 30kg N/10a and 25kg K_2O/10a, respectively, were also applied as split application at early spring and after cutting time every year. These fertilizer treatments had been conducted until 1986. From 1982 to 1986, dry matter yields of the 1st, the 2nd and the 3rd cutting for each plot were determined together with the total- and 2% acetic acid soluble-P contents in whole tops, heading tillers (except leaf blades and ears) and non-heading tillers. The relations of the P contents to the dry matter yields were discussed and summarized as follows: 1) For establishing P nutrient criteria by a diagnostic approach of plant analysis for orchardgrass, judgement by means of P concentration in non-heading tillers of the 1st cutting at heading stage was found to be more accurate than that of P concentration in whole tops of the hay, though the latter has been taken as a standard method to obtain P diagnosis of pasture plants in Hokkaido. 2) In order to evaluate the relation between the dry matter yield and the P content, a regression equation of Y=a+blogX was considered to be the fittest among the several equations examined, where X was total-and/or soluble-P content in non-heading tillers of the 1st cutting and Y was dry matter yield index of the 1st cutting expressed by the relative value to the maximum yield being equal to 100. 3) The use of the estimated curves of Y=a+blogX for the establishment of P nutrient criteria gave higher reproductivity among the years examined than the use of the other curves. 4) When "nutrient range" was divided into (1) Deficient Range: 〜80% yield, (2) Critical Range: 80〜90% yield and (3) Adequate Range: 90〜100% yield, it was concluded that orchardgrass was under P deficient state when total-P concentration in non-heading tillers of the 1st cutting was less than 0.25% (P_2O_5 0.57%), and was under P adequate state when more than 0.30%(P_2O_5 0.69%).

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A diallel cross mated with 26 parental alfalfa (Medicago sativa L.) clones was evaluated for forage yielding ability and combining ability in order to find out the extent of significance of the utilization of specific combining ability (SCA). All of these parental clones had been selected for agronomic traits from introduced varieties and plants grown in old alfalfa fields in Hokkaido through the breeding program of the Hokkaido National Agricultural Experiment Station. Many progenies derived from the elite clones yielded much more than Thor which is the leading variety in Hokkaido. This suggests the possibility to develop high-yielding varieties. Both mean squares of general combining ability (GCA) and SCA were significant, showing that selection for GCA and SCA was effective. The close relationship between yielding ability and SCA effect in the progenies indicated that selection for SCA was effective as a basis for selecting clones to produce high-yielding hybrids or synthetic varieties.

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Variabilities and relationships of lodging resistance and relating characteristics were investigated. In order to get information for the selection of lodging resistant characteristics in Italian ryegrass under the seed production cultivation, two cultivars, Waseaoba and Wasehikari were used in this experiment. Waseaoba is a lodging resistant, upright plant type and early cultivar, while Wasehikari is a poor-lodging resistant, intermediate plant type and early cultivar. One hundred plants of Waseaoba and 54 plants of Wasehikari were investigated on the lodging resistance and the relating 36 characteristics. The characteristics and the observation criteria are shown in Table 1. The results were as follows; 1) Lodging was observed in Waseaoba and Wasehikari at the beginning of heading and its degree increased with the progress of maturity. The degrees of lodging of Waseaoba were always lower than those of Wasehikari. On the other hand, seed yield of Wasehikari was 42.5 per cent higher than that of Waseaoba. 2) Lodging resistance in Waseaoba correlated significantly with heading date, days for flowering from heading, plant type, upper most internode length, thickest internode diameter, stem number, secondary tiller number, ear number, floret number per spikelet and bending resistance. Lodging resistance in Wasehikari correlated significantly with seed weight per ear, droop of leaf, thickest internode diameter, stem number, secondary tiller number, ear weight/culm weight ratio and bending resistance. On the other hand, seed yield in Waseaoba correlated significantly with the lodging resistance on May 26, seed weight per ear, vigor, plant type, plant height at heading, natural height, plant height at the harvesting time, stem number, ear number, spikelet number per ear and ear weight. Seed yield in Wasehikari correlated significantly with the secondary tiller number, ear number and ear weight/culm weight ratio. 3) According to the stepwise multiple regression analysis, upper most internode length, plant height at heading, heading date, plant type and bending resistance were selected as highly correlated characteristics to the lodging resistance in Waseaoba. Similarly, bending resistance, plant height at heading, upper most internode length, secondary tiller number, thickest internode diameter, ear weight/culm weight ratio and leaf length were selected as highly correlated characteristics to the lodging resistance in Wasehikari. On the other hand, seed weight per ear and ear number were selected as highly correlated characteristics to the seed yield in Waseaoba. Seed weight per ear, ear number, plant height at heading, branch number, upper most internode length and internode number were selected as highly correlated characteristics to the seed yield in Wasehikari. Furthermore, in Waseaoba, the lodging resistance and the seed yield per se, in addition to these, spikelet number per ear, upper most internode length, leaf type, heading date and second internode length were selected as highly correlated characteristics to the lodging resistance with high seed yield. Similarly, in Wasehikari, the lodging resistance and the seed yield per se, secondary tiller number were selected as highly correlated characteristics to the lodging resistance with high seed yield. According to above results, it is important to improve the lodging resistance and the seed yield simultaneously, by the selection of higher seed weight per ear and thick bottom part of stem to increase bending resistance to bear increased ear weight.

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Heritabilities and the effects of selection to lodging and relating characteristics to lodging were investigated in order to get information for the selection of resistant Italian ryegrass lines to lodging under seed production cultivation. Two cultivars, Waseaoba and Wasehikari, which were used in the previous report, were also used as the original populations for the selection. Six groups of population were selected for each cultivar on the bases of lodging resistance, seed yield, lodging resistance with high seed yield, compact ear, upright leaf and droop leaf, respectively. Fifteen plants for each group were selected and the seeds of each group were harvested in 1981. Five to six progeny plants of each selected parental plant were established in the middle of August in 1981 and the 41 characteristics were evaluated in 1982. Heritabilities were estimated by means of the standardization of the data of parental plants evaluated in 1981 and their progenies evaluated in 1982. Judging from the regression coefficients, the progenies within one original line seemed to be based on full sib progenies more or less rather than on half sib progenies only. Therefore, regression coefficients of the progenies to their original parents were used as the estimated heritabilities with the non-doubling of regression coefficients. The results were as follows; 1) Among the four estimated heritabilities of the lodging resistance evaluated at the different stages, the highest one was 0.368 and 0.292 in Waseaoba and Wasehikari, respectively. Mean heritability at the four different stages in Waseaoba was 0.263 and that in Wasehikari was 0.220. The heritabilities of seed yield were 0.350 and 0.174 in Waseaoba and Wasehikari, respectively (Table 2). 2) According to the stepwise multiple regression analysis of the progenies to their parental plants, 7 characteristics of the parental plants such as leaf type, node number/main stem, upper most internode weight, plant height at heading, ear type, branch number/main stem and ear weight/culm weight ratio were selected as highly correlated characteristics to the lodging resistance of the progenies in Waseaoba. In the case of Wasehikari, 4 characteristics of the parental plants such as upper most internode strength, plant height at heading, 100-seed weight and thickest internode diameter were selected as highly correlated characteristics to the lodging resistance of progenies. Similarly, 4 characteristics of the parental plants such as ear length, seed weight/plant, second internode length and heading date were selected as highly correlated characteristics to the seed yield of the progenies in Waseaoba. In the case of Wasehikari, 4 characteristics of the parental plants such as leaf length, ear type, second internode strength and ear weight/culm weight ratio were selected as highly correlated characteristics to the seed yield of the progenies. On the other hand, 7 characteristics of the parental plants such as plant type, second internode length, ear weight, droop of leaf, upper most internode weight, plant height at heading and 100-seed weight were selected as highly correlated characteristics to the lodging resistance with high seed yield of the progenies in Waseaoba. In the case of Wasehikari, 4 characteristics of parental plants such as second internode strength, plant height at heading, leaf length and bending resistance were selected as highly correlated characteristics of the parental plants (Table 2). 3) Lodging resistance of the strains selected based on lodging was clearly improved in the both cultivars. Lodging resistance of the selected strains were 69% and 28.3% higher than the original cultivars Waseaoba and Wasehikari, respectively. Seed yield of the selected strains for seed yield was not clearly improved in the both cultivars. According to the results mentioned here, selection for lodging resistance were fairly effective, and on the contra

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In order to get information for the selection of lodging resistant lines under the seed production cultivation in Italian ryegrass, lodging resistance, seed yield and forage yield of the selected strains for lodging resistance and other relating characteristics were evaluated under the solid row condition. Six groups of the plants were selected from Waseaoba and Wasehikari same as in the previous reports. The selection was carried out based on lodging resistance, seed yield, lodging resistance with high seed yield, compact ear, upright leaf and droop leaf, respectively. The seed of the selected strains with the original cultivars was sown in the seed production trial field and the forage production trial field in the middle of September in 1981. The lodging degree was evaluated 5 times from May 4 to June 26 in 1982. Furthermore, selected strains for lodging resistance with the original cultivars were sown again in the middle of September in 1983 and evaluated in 1984. Cultivation and fertilization were the same as those of in 1981 and 1982. The lodging degree was evaluated 5 times from May 11 to June 2 in 1984. The results were as follows; 1) The lodging degree of the selected strains and the original cultivars became large at 10 days to 3 weeks after flowering in Waseaoba and Wasehikari. Differences among the selected strains and the original cultivar were clear in Waseaoba and not so clear in Wasehikari. The strains in Waseaoba selected for lodging resistance, high seed yield and upright leaf were more resistant to lodging, significantly than the original cultivar through May 8 to June 16 in 1982. On the other hand, in Wasehikari the selected strains for lodging resistance and the other characteristics were more resistant to lodging, significantly than the original cultivar at only June 16 in 1982 (Table 1). The selected strains for lodging resistance were always more resistant to lodging, significantly than the original cultivar, excepting data on lodging resistance in Wasehikari on June 2 in 1984 (Table 4). 2) None of the selected strains indicated significantly higher seed yield than the original cultivar in the both, Waseaoba and Wasehikari in 1982 (Table 2). However, the selected strains for lodging resistance in Wasehikari indicated significantly higher seed yield than the original cultivar in 1984 (Table 4). 3) There were no significant differences of the forage yield among the selected strains for the lodging resistance and the other relating characteristics in the both, Waseaoba and Wasehikari in 1982 and 1984. According to the results mentioned above, selection for the lodging resistance is effective in Waseaoba and Wasehikari, while, selection for the seed yield is not so effective. Furthermore, selection for the lodging resistance and the seed yield are not always disadvantageous to improve forage yield.

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As a part of the application of remote sensing technique on grassland management, Landsat Thematic Mapper (TM) data over the Nishinasuno township was analyzed using the principal component analysis for the image processing and land-cover classification. The first principal component score mainly represents the features of bands 1, 2 and 3 (visible), that is, brightness. The second score mainly represents the features of band 4 (near-infrared), that is, greenness. And the third score mainly represents the features of bands 5 and 7 (mid-infrared). By use of the first two or three components, it could involve 91.5 or 98.6% of the total information contained in six TM bands. False color image derived from the first three scores was better than that from the original three bands, because it was easier to discriminate between grassland and forest, between grassland and bare soil, and between meadows before and after mowing. The results of land-cover classification by maximum likelihood method indicated that the principal component scores were better for classification than original bands under the condition that the same amount of data were used. Reduction of variate dimensions by the use of principal component resulted in the merit that analyzers could visually comprehend the classification area.

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Grassland is a unified organism of plants, animals and soil and it changes with time in a manner like a single organism. In the 1960's, systems approach was introduced as a method to study such complicated, unified systems. The systems approach consists of two steps: in the first step, studies deal with the determination by experiments, of how energy and matter flow in the system. In the second step, studies deal with the conversion of the ecosystems to a mathematical system, that is, a system model, and the investigation of the dynamic behaviour of grasslands using a mathematical system, instead of actual grasslands. In this report, the results obtained experimentally, since 1970, on the energy and matter flow in grasslands are discussed. Many data on the energy flow in grassland ecosystems have been accumulated by now, and it was shown that 0.5 to 1% and about 0.01% of the global solar radiation are accumulated in plant tissues and animal bodies on grazed pastures, respectively, where the amounts of global solar radiation is approximately 10^<10>kcal/ha/yr or 4.18×10^<10>kJ/ha/yr in the central part of Japan. Nitrogen flow has been also measured at several sites in Japan. Nitrogen application in a nitrogen-flow process affects considerably herbage production, but the effect on animal body gain is not significant in most cases. These figures suggest that rational connections between nitrogen application, herbage production and grazing schedule are important. Experimental studies on the phosphorus cycle are also limited. As most of the grassland soils in Japan are composed of volcanic ash soil and show a strong acidity, most of the phosphorus in soil is in an inactive form. Some new methods to activate the phosphorus are being developed using soil microorganisms. There are few examples of measurements of the potassium and carbon cycles in grasslands. A study at the National Grassland Research Institute (Nishinasuno, Tochigi, Japan) indicates that grasslands as well as forests have the ability to accumulate carbon in soil, in contrast to cultivated fields. Ecological studies on energy and matter flows have well been documented, and for preservation of the vegetation in semiarid areas and grasslands in tropical rainy areas, studies on energy and matter flows and related budgets are extremely important to provide data on agriculture.

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