To investigate the suitability of a hand-held spectroradiometer for estimating grassland productive functions such as aboveground biomass, plant coverage and plant height, spectral characteristics were measured in three Italian ryegrass (Lolium multiflorum L.) meadows in Gifu prefecture. Spectral reflectance in six wavelengths ranging from the visible to the near infrared was measured, and nine vegetation indices were calculated from combinations of spectral data. Leaves in a meadow strongly absorbed blue and red sunlight in the chlorophyll absorption ranges, while strongly reflecting light in the near infrared range. Soil surface conditions as well as vegetation conditions affected these spectral characteristics. It was suggested that grassland productive functions show specific spectral characteristics depending on their location and growth stage. The correlation and regression analyses showed that the aboveground biomass (g DM/m^2) was linearly related to the Difference Vegetation Index with r^2=0.95 and the K-Vegetation Index with r^2=0.95, while plant coverage (%) was linearly related to the Normalized Difference Vegetation Index with r^2= 0.97. The results suggest that spectral characteristics are suitable for rapidly qualifying vegetation in grassland.

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In grazing pastures, a mosaic or patch vegetation pattern resulting from selective grazing by livestock animals is often observed. This heterogeneous structure contributes to the maintenance of species richness in grassland communities. The patch pattern of a grazing grassland and the distribution of component species in the grassland community were surveyed in order to elucidate the effect of selective grazing of cattle on the maintenance of species diversity. By comparison of the fioristic composition among the plots in tall ungrazed patches with those in short grazed turf, plots in the patches were revealed to have higher diversity within and among plots than those in the turf. Most of the autumn-flowering species showed higher stem densities in the patches than in the turf. Based on these results, the ungrazed patches should be evaluated in terms of their positive effect on maintaining species diversity. The function of the patches was discussed from this viewpoint.

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To investigate the effects of foaming in the rumen with white clover ingestion on ruminal digestion and nutrient flow, two experiments were conducted. Experiment 1 was carried out with 3x3 random block design using three rams and three treatments;white clover sole feeding (WC), white clover sole feeding with dosing a non-ionic surfactant (Ruminon^【○!R】 4ml/day) (WR), and white clover and orchardgrass (1:1 on a dry matter basis) feeding (WO). Voluntary intake, foam stability of ruminal fluid, ruminal fermentation characteristics, ruminal dilution rate and in situ degradability were examined. In experiment 2, non-am monia nitrogen (NAN) and RNA entering duodenum was measured by using two rams with duodenal cannula under WC and WR treatments. The treatments did not differ in intake of dry matter and nitrogen (P>0.1). The foam stability of ruminal fluid greatly decreased (P<0.05) by dosing of a surfactant throughout the experiment. The propionate proportion of total volatile fatty acids was higher (P<0.05) in WR and butyrate proportion and protozoal density were higher (P<0.05) in WC than other treatments. Furthermore, both duodenal NAN and RNA per ingested nitrogen were greater in WC than in WR. Foam formation in the rumen indicated the beneficial effect on nutrient utilization in ruminants owing to the increase of bypass protein and of microbial flow to the duodenum.

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The effects of wilting and added enzymes on fermentation and in vitro digestion of rhodesgrass and guineagrass silages were examined. First cuts of the two forages were ensiled in laboratory silos directly or after being wilted for 4 h with or without cell wall degrading enzymes (0.2 g kg^<-1>). Silos were opened after 45 d and the chemical composition and the fermentation quality were determined. The silages were subjected to in vitro rumen incubation and the degradation of NDF was determined. Without enzymes rhodesgrass silage failed to achieve lactate type fermentation, while guineagrass silage had high proportion of lactate even without any of the treatments. Wilting inhibited the organic acid production but decreased the proportion of lactate in rhodesgrass silage. Use of enzymes improved the preservation of both the silages, as evidenced by the increase of lactate and the decrease of pH value and NH3-N. The contents of NDF and ADF were reduced by enzyme treatment, but the reduction was considerably suppressed when forages were wilted before ensiling. In vitro degradation of NDF was low in direct-cut rather than wilted silage. Addition of enzymes also lowered the degradation, but this effect was restrictedly found in guineagrass silage incubated for 72h. These results indicate that although added cell wall degrading enzymes can promise an improved fermentation of tropical grass silage, the benefit would be less pronounced when treated with low moisture material.

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To search for genetic resources of resistance to sorghum sheath blight, we examined the varietal difference of the resistance by a field inoculation test. The materials used were 72 varieties and lines, which were classified into grain, dual purpose (F_1) and sorgo types, including the Indian-type varieties selected for grain yield from grain type, Korean varieties and male-sterile lines. Field inoculation tests were carried out in 1984 and 1985. Barley grains were inoculated with anastomosis group 1 (AG-1), which was the most pathogenic to sorghum, and the grains were spread on the hill and covered with soil two months after the seeding of the test plants. Resistance to the disease was evaluated by the relative lesion height (RLH), which is the ratio of the height of lesion on the sheath (HL) to the height of flag leaf collar at maturity (HF). The varietal differences of HL, HF and RLH were similar in both years, and the coefficients between the values obtained in the two years showed a significant correlation (p<0.001). HL showing the degree of invasion and RLH showing the damage of plants closely correlated with each other, and the relationship in each of the three groups, grain type including male sterile lines, dual-purpose type including Korean type and sorgo type including Indian type, was regressed to a linear equation. The correlation between HF and RLH in each of the same three groups was also regressed to a linear equation (p<0.001). A wide variation in RLH was detected among the varieties of grain type with the same plant height. The higher resistant resources were found in every type, and a common criterion of the resistance was considered to be an RLH of less than 20% and HL of less than 20 cm.

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The effectiveness of a breeding system using a field inoculation test was evaluated for producing hybrids resistant to sorghum sheath blight. F_2 plants were obtained from 3 cross combinations using a resistant line as a seed parent. The selection by a field inoculation test was started for 200 lines in the F_2 generation of each combination. Anastomosis group 1, which is the most pathogenic to sorghum, was inoculated to barley grains and the grains were spread on the hill and covered with soil, 2 months after the seeding of the test plants. Resistance to the disease was assessed by the relative lesion height (RLH), the ratio of the height of lesion on the sheath to the height of the flag leaf collar at maturity. The plants with an RLH under 20 were selected from F_2 to F_4. From the F_5 to F_8 generation, the plants with a lesion height under 30 cm on the sheath in addition to RLH under 20 were selected by the head-to-row-testing. The rate of selection was 25% on the average. The RLH of the selected Fs lines was lower than or the same as that of the parents. The RLH of F_1 lines obtained by the cross be- tween Redbine selection 3048A as a seed parent and F_8 lines as a pollen parent was the same as that of the F_8 lines or slightly higher. The value was 15% on the average and relatively lower than that of the commercial variety Suzuho which was derived from the same seed parent, Redbine selection 3048A. Hybrids with resistance to Rhizoctonia sheath blight can be developed by selecting inbred lines based on RLH and the height of the lesion on the sheath at maturity in the field and by evaluating the combining ability of the inbred lines selected.

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Inflorescence position of Anthoxantum odoratum is still low at the beginning of flowering but considerably high at seed dispersal. A. odoratum seems to cope with defoliation stress by this behavior. Details of the behavior, however, have been unknown. We marked a total of 518 inflorescences in an experimental population, and monitored their positions to understand the nature and variation of the behavior. All the inflorescences elevated their position both during and after flowering. The maximum elevation was 52.2cm. Elevation rate was significantly higher during flowering than after that. It also differed among inflorescences within the individual plants, late- flowering inflorescences having the higher rate than early- flowering ones. There was a significant variation in the average elevation among plants, ranging from only 6.2 cm to 33.4 cm. Ecological implications of the behavior were discussed in relation to defoliation avoidance.

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In our previous papers, we suggested that mountainous sloping pasture was characterized by the interactions between inclination of pasture and grazing pressure that means tramping, grazing and excreting. This study was conducted to investigate the relations between those interactions and the yearly and spatial changes in pasture vegetation. The subject pasture was established in 1969 using the unplowed method, and in 1972, 40 examination points were set up in the pasture to observe the shifts in vegetation. With the passage of time, the dominant species in the pasture has changed from orchardgrass (Dactylis glomerata L.) into Kentucky bluegrass (Poa pratensis L.). However, the process of the change on the concave slope site was more complex than the change observed on the convex and linear slopes. The period of shift from one dominant species to another was much longer on the steep sloping site than on the gentle slope, though this did not hold true for the concave slope site. Observations made in 1992 revealed that Kentucky bluegrass covered about 80% area on the pasture. The number of perennial grass species was higher at the steep sloping site than on the gentle slope with the exception of the strong concave slope site. The complexity of plant community composition was increased relative to the increasing the angle of the sloping site. These results suggest that the yearly and spatial changes in the pasture vegetation were caused by the variation of the grazing pressure according to topography.

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Perennial ryegrass (Lolium perenne L.) is used for not only forage but also turf. Recently, since many turf-type cultivars that are artificially infected with endophyte have been marketed, seeds of those cultivars could be sown in grasslands. To compare varietal characteristics of poten- tial endophyte toxicosis, endophyte infection rate and ergovaline and lolitrem B concentrations as alkaloid were investigated for seeds of 28 commercial cultivars of perennial ryegrass. The cultivars consisted of 5 forage-type and 23 turf-type. Endophyte infection rate and ergovaline and lolitrem B concentrations varied among 28 cultivars in the range of 0-96%, 0.0-2.8ppm, 0.0-6.5ppm, respectively. In endophyte infection rate, the cultivars could be roughly divided into two groups, one with the higher value of above 60%, and the other with the lower value of below 20%. All of cultivars in the high-rate group were turf-type and had higher ergovaline and lolitrem B concentrations. On the other hand, any cultivars in the low-rate group did not have ergovaline and lolitrem B. All of forage-type cultivars had 0% of endophyte infection rate and did not have ergovaline and lolitrem B.

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Soil type in Inner Mongolia, China is aeolian sandy soil, which is poor in nutrients. Corn cropping, however, is continued more than 10 years in this region. The objective of this study is to examine the relation between continuous corn cropping and soil fertility, based on nutrient budgets in continuous corn cropping field. We chose 4 corn fields, different in successive periods. Soil samples were taken from each field in May and October, 1998. Corn samples were taken in September, 1998. We analyzed nitrogen (N), phosphors (P), and potassium (K) in soil and in corn samples. Soil fertility was evaluated using data on available phosphorous, inorganic nitrogen, and exchangeable potassium. Nitrogen, P and K contents in whole corn plant were calculated from their contents in each part (ear, stalk, leaf). Application rates of fertilizer N and P were larger than corn uptake. Exceeded P was absorbed on soils in surface layer. In case of K, however, corn uptake exceeded its application rate. Shortage of fertilized K should be derived from exchangeable K in soil. Soil fertility was maintained in our study sites. We speculated that long-term fertilizing contributed to increase in soil fertility and made possible to continuous corn cropping in this region.

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