OGURA, S.and M.HIRATA (2001):Two-dimensional monitoring of spatial distribution of herbage mass in a bahiagrass (Paspalum notatum Flugge) pasture grazed with cattle. Grassland Science 47, 453-459. Spatial distribution of herbage mass (HM) was monitored two-dimensionally during the grazing season (from May to November) in a bahiagrass pasture (1.06ha) rotationally grazed by cattle. An electronic capacitance probe was used to estimate HM in 1464 permanent positions (50×50cm) whose centers formed 1.5×1.5m grids in the central 90×34.5m area of the pasture. The two-dimensional charting of HM showed almost stable spatial patterns throughout the grazing season, with some patches of high HM appearing and disappearing. The development of new patches was considered to be partly due to the avoidance of areas affected by newly deposited dung pats, and the extinction of patches to the grazing down of areas where dung pats were disappearing or had disappeared. Spatial pattern analysis proposed by DALE and MACISAAC (1989) for HM along a 90m permanent line transect showed larger patch and gap sizes than the grid interval in the two-dimensional monitoring (1.5m). It is concluded that the technique is useful for monitoring the spatial pattern of HM, herbage production and consumption, and for relating consumption to the ingestive behavior of grazing animals.

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KOBAYASHI, K. and Y.YOKOI(2001):Decreasing shoot density of isolated Miscanthus sinensis patches in the warmtemperate region of Japan. Grassland Science 47, 460-470. In terms of clonal persistence of Miscanthus sinensis Anderss., the density of live shoots within a patch ("intrapatch density";no. cm^<-2>) and the cause of its density dynamics were investigated on the basis of the following measurements:the basal area of clonal patches ("patch area";cm^2) and number and configuration (mapping) of their aerial shoots. The intrapatch densities of five patches that were observed over a period of 10 years decreased year by year. Most patches with orthotropic (vertical) shoots had higher densities of live shoots at the periphery than the interior, and were hollow-centred as the central densities further decreased with areal expansion. However, the peripheral densities also declined with the central densities. The vacant inner areas intrinsically occurred even in young patches. In the last four years of the study period, three of the five patches showed considerable decreases in intrapatch densities. (The decreasing densities during this period might be at least partly due to the influence of the other patches.) It was also found that the number of shoots within a patch tended to attain the maximum when the patch area approached 2, 000-3, 000cm^2, and then level off through the areal expansion. From these results, the unexpectedly marked declines in intrapatch density ("patch decay") can be attributed to the small number of peripheral shoots as well as the continued development of vacant inner areas.

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INOUE, N.(2001):Defecation pattern in goats fed maize or sorghum silage as analyzed by near-infrared spectroscopy. Grassland Science 47, 471-477. Goats were fed silages at 4.9% of metabolic body weight per day. As test signal, rye hay treated with ammonia gas was fed for analyzing the continuous defecation stream at 1% of metabolic body weight together with the silage once. The feces were sampled 55 times at 3 hour intervals after feeding rye hay, and near-infrared spectra were obtained. For data compression, correlation coefficients were calculated between the spectrum of the first sample and that of the samples collected thereafter. The change in the correlation coefficient with time was considered to show the defecation pattern of rye hay in the feces. The increase in the proportion of indigestible organic matter in the rye hay is mainly responsible for the decrease in the correlation coefficient. The correlation coefficient fluctuated with the time of sorghum silage feeding, but not with that of the maize silage feeding. In the sorghum silage, the lowest correlation coefficient was observed at 3 days after rye hay feeding. A circadian rhythmicity in the chemical composition of feces was detected by spectrum analysis. The defecation pattern of rye hay varied with the kind of silage fed together with it.

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SAIGA, S., A.MAEJIMA, S.YOSHIDA and M.TSUIKI(2001):Changes of endophyte infection frequency in turf of northeastern Honshu, Japan. Grassland Science 47, 478-483. This study follows the change of endophyte infection frequency in turf sown with endophyte-infected perennial ryegrass and tall fescue seed from fall in 1998 to fall in 2000. Three golf courses (GC) and two sports grounds (SG) were selected for an investigation of the incidence of endophyte in Iwate prefecture. At each site 50 plants were taken along a 50m line transect and endophyte presence at the interior epidermis of a leaf sheath was determined microscopically. In perennial ryegrass, the incidence of endophyte infection varied greatly amongst the different sites. The incidence of endophyte infection at two sites did not change greatly and remained as low level. However, the incidence of infection at Mizusawa GC and Miyako SG increased rapidly up to 90% in 2000. The incidence of endophyte infection of tall fescue was lower than that of perennial ryegrass, but at Miyako SG the incidence of endophyte infection frequency increased in the fall of 2000. The difference in changing the incidence of infection among sites seems to have caused by soil structure. In conclusion, endophyte-infected plants can survive and retain a high incidence of endophyte in dry and hot conditions even in northeastern Honshu, Japan.

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Sunao UOZUMI, Yoshinori YOSHIMURA and Shunji KUROKAWA (2001):Effect of Air Temperature on the Some Characters Related to Heading in Sorghum (Sorghum bicolor Moench). Grassland Science, 47, 484-490. As a part of the study concerning the heading characteristics of sorghum species, the effects of air temperature on the rate of leaf initiation and leaf emergence, the time of panicle initiation and heading and the final leaf number were examined on five cultivars with different thermosensitivity grown in pots under 15.5h day length and four levels of air temperature in glasshouse. In cultivars of high thermosensitivity, the rate of leaf initiation and the days from sowing to panicle initiation increased as temperature was raised, and these responses caused a remarkable increase in the final leaf number under the high temperature condition. Because of this increase in the leaf number, raised temperature had no hastening effect on heading although caused an increase in the rate of leaf emergence. In cultivars of low thermosensitivity, the rate of leaf initiation increased as temperature was raised, but the days to panicle initiation decreased with raised temperature. In consequence, the influence of higher temperature on the final leaf number was considerably less than that in high thermosensitive cultivars. The rate of leaf emergence of low thermosensitive cultivars was hastened with raised temperature, and this response caused a decrease in the days to heading under the high temperature condition. There were varietal differences among high thermosensitive cultivars for the response of the days to heading and among low sensitive cultivars for the response of the final leaf number although both of these differences were not so considerable as that between high sensitives and low sensitives.

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Akihisa YAMADA, Madoka SUTOH and Tsuyoshi IMURA (2001) The Changes of Rumen Temperature with Grazing Behavior in the Daytime. Grassland Science 47, 491-493. An experiment to study the relation between rumen temperature and grazing behavior was conducted using three rumen-fistulated Holstein steers numbered 706, 708, and 709. These animals were grazed in a 1-ha pasture in which orchardgrass was dominant. For the thermometry, a data logger with a thermistor sensor was used. The average rumen temperature was 38.7℃ (min. 33.1℃-max. 39.2℃) in No.706;38.8℃ (min. 34.2℃-max.39.3℃) in No.708;and 38.6℃ (min. 32.6℃-max39.2℃) in No.709. Significant differences (P<0.05) were observed between the average rumen temperature with eating and the average temperature with ruminating in each animal, though the difference was only 0.16℃-0.19℃. Notably, the behavior most affective on rumen temperature was drinking, during which the rumen temperature was decreased by about 6℃ within two minutes. Subsequently, the rumen temperature was returned to basal level after twenty minutes.

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Yoshiyuki MAEDA, Hiroki UNNO, Shigeru HIRANO and Hiroshi TAKENAGA (2001):Relationship between Salt Tolerance and Photosynthesis or Leaf Water Potential in Several Temperate Grasses. Grassland Science 47, 494-501. Salt tolerance in several temperate grasses was investigated from leaf photosynthetic rate in intact plant, oxygen-evolving activity in isolated thylakoid membrane, leaf water and osmotic potential, and Na, K and free Proline (Pro) contents. Four seedlings derived from commercial seeds (tall fescue;TF, Italian ryegrass;IRG, reed canarygrass;RCG, alfalfa; ALF), and RCG seedlings grown on soil perfused with cattle urine (P-RCG) and on soil not perfused (C-RCG) were treated with NaCl for 10 days. Salt tolerance was the strongest in P-RCG, followed by TF, C-RCG, IRG, RCG and ALF under 100 mM NaCl stress. Both leaf photosynthetic rate in intact plants and oxygen production in thylakoid membranes were decreased under a saline condition. Salt tolerance became stronger in the grasses with lower decrease rates of photosynthesis under salt stress. No clear relationship was recognized between change rates in Na, K and free Pro contents of plant tops and decrease rates in leaf osmotic potential. Except for ALF, salt tolerance was stronger in the grasses with lower decrease rates in leaf water potential under salt stress. On the other hand, ALF had the weakest tolerance in spite of showing low decrease rate in leaf water potential, which suggested the direct salt damage caused by ion excess.

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Teruo MATSUNAKA and Hikaru TAKAHASHI (2001):Root Weight as a Principal Factor Responsible for Difference in Nitrogen Absorption among Orchardgrass (Dacthlis glomerata L.), Meadow Fescue (Festuca pratensis Huds.) and Timothy (Phleum pratense L.) during First Growing Period. Grassland Science 47, 502-508. Three temperate grass species (orchardgrass;OG, meadow fescue;MF, and timothy;TY) were grown under solution culture condition from beginning of re-growth in spring to heading stage (first growing period) in order to elucidate the role of root mass and its activity in nitrogen (N) absorption. We used dry root weight per plant (RW) and root length per plant (RL) as parameters for root mass and also N uptake per unit RW (NRW) and N uptake per unit RL (NRL) as parameters for root activity. Dry matter production, leaf area and the amount of N absorbed by the grass showed significantly positive correlation with each other, indicating that N accumulation in the grass increased leaf area and resulted in increasing dry weight of the grass. All grass species tended to have similar relationships to those described above. Nitrogen absorption is, therefore, the most important factor for the control of dry matter production of grasses during the growing period. The amount of N absorbed by TY was the greatest among the three grass species and that of MF, the least. Since NRW and NRL of MF proved almost equal to those of TY during the growing period, the difference in the N absorption between TY and MF was due to the difference in the parameters of root mass, particularly, in RW. The amount of N absorbed by OG during the first half of the growing period was almost the same as that of TY. In this first half of the growing period, N absorption by OG was supported by higher root activity, NRW and NRL, compared with those of TY. During the second half, however, the amount of N absorbed by OG was less than that of TY, although the higher root activity of OG continued until the time of first cutting. This was mainly caused by smaller RW of OG compared with that of TY. From the results we conclude that RW, one of the parameters of root mass, is the principal factor responsible for difference in the N absorption among OG, MF and TY grown under solution culture condition.

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