In order to define the proper stocking intensity at the sandy land in a semi-arid region, a grazing experiment using sheep was conducted at Korqin sandy land in Inner Mongolia, China. Three months after the initiation of this experiment (August, 1992), the effects of grazing intensity on the growth of dominant plant species were investigated by vegetation survey. The results obtained are as follows : 1. All seven species investigated were clearly influenced by sheep grazing and especially the plant height was shortened in heavy grazing site. Individual size and biomass of the investigated species except for Aristida adscensionis became remarkably smaller in grazing sites than the ungrazed control site. 2. The grazing preference of grass plant by sheep varied with species : The biomass of Setaria viridis, Digitaria ciliaris and Pennisetum centrasiaticum showed the tendency to decrease with the increasing of grazing intensity. While that of A. adscensionis was scarcely influenced by grazing pressure because of its hard and long awns. The growth of underground part of S. viridis seems to be strongly inhibited by grazing. 3. It was clarified that the range of grazing preference of sheep was wide comparing with cattle and horse: Artemisia scoparia abounded in the degraded pastures, and a small prostrate plant of Euphorbia hurnifusa were well grazed under heavy grazing conditions. Spiny and pioneer plant in shifting sand dune, such as Agriophyllum squarrosum, was also grazed.

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Fifty-four cultivars and strains belonging to several species of genus Lolium were evaluated in a heavy snowfall area and was classified by cluster analysis using twenty-five characteristics. A high degree of correlation was observed between snow endurance and dry matter yield of 1st cutting. It seemed that snow endurance was one of the most important factors influencing forage productivity in a heavy snowfall area. Snow endurance was also correlated significantly to heading date. Plant type tended to be more prostrate in late maturity group than in early one. Degree of summer endurance was much higher in late and very late maturity groups than the other early maturity groups. Fifty-four cultivars and strains were classified into eight clusters by cluster analysis on the basis of twenty-five characteristics. Cluster I consisted of L. multiflorum LAM., which was superior in snow endurance and dry matter yield. Cluster II consisted of L. multiflorum, which was inferior to cluster I in those characteristics but heading date was earlier. Cluster III consisted of L. perenne L., L. hybridum and Festuca-Lolium hybrid, which showed very late heading, rather prostrate in plant type and higher summer endurance. And also, cluster III was similar to cluster I in snow endurance and dry matter yield of 1st cutting. Cluster N consisted of L. multiflorum, ,which showed very early heading and upright in plant type. Cluster V consisted of L. strictum PRESL, L. rigidum GAUD. and L. subulatum VIS., which showed the lowest snow endurance. Cluster VI consisted of L. temulentum L. and L. remotum SCHRANK which showed lower dry matter yield. Cluster VII consisted of L. temulentum, which showed lager thousand kernel weight. Cluster VIII also consisted of L. temulentum, which showed the most upright in plant type of all of cultivars and strains. Clusters I and III were considered to be important from the viewpoint of adaptability to snowfall area. Cultivars and strains of those clusters seemed to be useful as material of snow endurance breeding of Italian ryegrass.

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In order to induce callus efficiently in Festuca spp. and Lolium spp., effects of 2,4-D concentrations on callus formations and their differences among species or varieties were investigated. The calli were induced from mature seeds on the media containing 1, 5, 10 and 15mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) in six, four, seven and five varieties of meadow fescue, tall fescue, perennial ryegrass and Italian ryegrass, respectively. Effects of 2,4-D on callus formation and its size were examined in each species. Significant differences were observed both in callus formation and callus size among species. The callus formation of perennial ryegrass was significantly higher than the other species, and the callus size was larger in Italian ryegrass and smaller in tall fescue than the other species. Significant differences among varieties were observed in callus formation of meadow fescue, tall fescue and Italian ryegrass and also in callus size of tall fescue and perennial ryegrass. The callus formation and its size were influenced by the concentration of 2,4-D except for the callus formation in meadow fescue. The optimal concentration of 2,4D was 5 mg/l for all four species. The regeneration rate of adventitious organ was the highest in perennial ryegrass, and tended to be high at lower levelof 2,4-D in meadow fescue. In four species, adventitious root regenerated from calli very frequently. On the other hand, green or albino adventitious shoot did not regenerate so frequently. In general it was not easy to determine the optimal concentration of 2,4-D for regeneration of green adventitious shoot, but 5 mg/l 2,4-D was considered to be suitable for some varieties of perennial ryegrass. Most of all green adventitious shoots obtained grew into complete plants.

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The flowering phenomenon of Nezasa bamboo occurred in 1992 over a large area of Nezasa type grassland in the Aso Mountains. The growth characteristics of Nezasa bamboo were investigated in 1992 comparing the data with growth parameters obtained in 1991, a year in which the flowering phenomenon did not occur, in heavy and light grazing. Results obtained are as follows ; (1) In 1991, heading culms were not observed and the maximum number of non-heading culms were 2762 m^<-2> and 2894 m^<-2> in heavy and ligt grazing, respectively. The maximum number of heading culms were 2204 m^<-2> and 1420 m^<-2> and of non-heading culms were 74 m^<-2> and 135 m^<-2>, in heavy and light grazing, respectively, in 1992. (2) The maximum dry matter weights of aboveground plant part were 274.4 gDMm^<-2> and 297.5 gDMm^<-2> in 1991, however dry matter accumulation drastically decreased in 1992 with values of 69.8 gDMm^<-2> and 64.5 gDMm^<-2>, in heavy and light grazing, respectively. (3) Dry matter weights of underground plant parts decreased from April to August and increased from August to November in 1991. It decreased again from April to August in 1992, but most of the underground plant parts died from August to November in 1992. As a result, the dry matter weights of live underground plant parts remained only 24 gDMm^<-2> and 60 gDMm^<-2> in November, 1992, in heavy and light grazing, respectively. (4) The amounts of nitrogen uptake from soil were 5.15 gNm^<-2> and 4.40 gNm^<-2> in 1991,but they were -8.29 gNm^<-2> and -10.67 gNm^<-2> in 1992, in heavy and light grazing, respectively. (5) These results showed that in the year in which the flowering occurred, growth was greatly reduced, most of the underground plant parts died during summer and autumn, and a large amount of stored nitrogen in Nezasa bamboo was lost.

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This study was conducted to improve the quality of the water hyacinth silage. Rice bran and wheat bran are the by-product of the agricultural system and may have the potentiality to improve the fermentation and palatability of silage. The fresh water hyacinth material was wilted to about 70 moisture content by sun drying. Then the wilted water hyacinth was mixed with 0, 5, 10, 15 and 20% of rice bran or wheat bran in the polyethylene bottles, respectively. The silage quality was evaluated after 4 weeks of ensiling. The pH value, lactic acid, butyric acid and amrnonia-N/total-N contents of the silage added rice bran ranged 5.2-4.7, 1.3-3.7%, 0.3-0.1% and 5.6-3.1%, respectively. On the other hand, those of the silage added wheat bran were 5.2-4.6, 1.3-4.1%, 0.4-0.2% and 7.8-3.9%, respectively. This result showed that the silage with more than 15% of the additive had high qualities in both rice bran and wheat bran treatment and the addition of wheat bran was slightly better than that added rice bran in silage quality.

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Recently, it has been reported that percent Brix of stalk juice is positively and highly related to stover digestibility in forage corn. In this study, genotypic differences in percent Brix of stalk juice among inbreds and F1 hybrids, its relationship between hybrids and their parental inbreds, and correlation of percent Brix of stalk juice with the traits related to yield in hybrids were investigated. Percent Brix of stalk juice varied significantly among inbreds and also among hybrids. High percent Brix was found more frequently in flint inbreds and dent×flint hybrids than in dent inbreds and dent×dent hybrids. The positively significant correlation between hybrids and mid-parents indicates that percent Brix is genetically controlled and that inbreds with high percent Brix are promising potential of the development of hybrids with high stover digestibility. Percent Brix of stalk juice was not correlated with maturity of hybrids but with dry matter content of stover and yields of stover and whole plant. Considering the negative correlation between percent Brix and dry matter ear content, careful selection for higher percent Brix is required to avoid loss of ear and/or grain yield.

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This study was conducted to clarify the dry matter productivity of winter hardiness cultivar of bermudagrass on its northern growing boundary in Japan. Net primary production (NPP) was compared between 0.047 ha bermudagrass (Ber : cv. Brazos) sward and 0.14 ha Lolium×Festuca hybrid (F1 : cv. Tandem) sward under intensive grazing for two years. Both swards were a part of total 2.0 ha pasture grazed by 12 steers. From April until mid-July, F1 sward was grazed rotationally by all steers. From late July until mid-September, the steers were devided into two herds composed of each six steers ; one herd grazed F1 sward, and the other herd grazed Ber sward. Grazing capacity was 645-938 cow days per ha on F1 sward, and 215-307 cow days per ha on Ber sward. NPP was estimated as the sum of ΔB (accumulation of biomass during the grazing period ), ΣLWL (annual amount of decomposed litter), ΣG ( annual herbage intake) and ΣR (annual production of underground organs). Amount of litter production (LP) was estimated as sum of ΣLWL and dead plant part among ΔB. On F1 sward, NPP was 2,052 g/m^2 on the average of two years. Fifty two % of NPP (1,065 g/m^2) was consumed by the steers (ΣG), and 41% (847g/m^2) was transferred to the soil (LP). On the experimental site, shoot elongation of Ber commenced in early April. Grazing season on Ber sward was two months, from late July until mid-September. On Ber sward, NPP was 1,274g/m^2 on the average of two years. Sixty three % of NPP (799 g/m^2) was consumed by the steers(ΣG), and 16% (206 g/m^2) was transferred to the soil (LP). ΣG on Ber sward was equivalent to as much as 75% of that on F1 sward. Dry matter production of Ber sward predominated during summer, when herbage production on F1 sward was at the lowest level during the grazing period because of summer depression. From these results, we concluded that winter hardiness cultivar of bermudagrass provided relatively high productivity even on the northen limit of the species, and supplemented to summer depression of temperate grasses.

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It was reported that meadow steppe in Wulanaodu, Inner Mongolia had been seriously degraded owing to overgrazing, soil alkalization and moving sand dune. Vegetation of cutting and grazing pastures were compared in order to find out the way of sustainable usage of pasture. The following results were obtained. 1. Seven vegetation types were identified according to their dominant species ; Suaeda, Chloris, Artemisia, Puccinellia, Aneurolepidium, Arundinella and Agropyron. Each type was distributed in small patches corresponding to the relative ground height, maximum value of which was 25 cm. It was observed that bare ground and Suaeda type were distributed at the lowest ground level, while Arundinella type and Agropyron type at the highest ground level. 2. As for the degree of degradation, it was considered that bare ground and Suaeda type were severely degraded, Aneurolepidium type, Arundinella type and Agropyron type were weakly or not degraded. 3. The grazing plot had higher frequencies in bare ground and Suaeda type than the cutting plot, and had not Arundinella type which appeared in the cutting plot. Moreover, growth of Aneurolepidium chinense in the grazing plot was inferior to that in the cutting plot. From these results it is concluded that the grazing plot is more seriously degraded compared to the cutting plot, and that cutting is more favorable usage than grazing from the conservational point of view.

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In order to clarify mechanism of pasture degradation a survey was carried out on distribution of vegetation types in connected with such environmental factors as relative ground level, pH and electric conductivity of soil in Wulanaodu, Inner Mongolia, the same region as the previous report. The results obtained were as follows. 1. It was observed in the grazing plot that Suaeda type distributed around bare ground at the low ground level and Aneurolepidium type disributed around Agropyron type at the highest ground level, and that between these circles Chloris type spread at the medium ground level. 2. Sequence of soil alkalinity of vegetation types was as follows ; bare ground > Suaeda type > Chloris type・Artemisia type・Puccinellia type > Aneurolepidium type > Arundinella type. It was considered that distribution pattern of vegetation types, which adapt to soil alkalinity, corresponding to relative ground level and soil alkali was a phenomenon of "habitat segregation". 3. These results indicate that soil alkalinity as well as over grazing are the main causes of pasture degradation, and suggest that decreasing soil alkali may improve degraded pasture vegetation. As for a measure for decreasing soil alkali, effects of proper use of pasture and the drainage of surface water is discussed.

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Simple logistic model cannot describe the decrease in the plant biomass after biomass has reached a plateau, i.e., carrying capacity. To alleviate this shortcoming, a practical extension of the logistic model was attempted in this study. Suppose that w is the plant biomass at time t, and r and W are constants designated as growth coefficient and carrying capacity of the plant biomass, respectively. Here, the simple logistic model is represented by the following equation : dw/dt=rw (1-w/W). In the new version, r is replaced by a quadratic polynomial equation of time t as follows : dw/dt=(b_1+b_2t+b_3t^2) w (1-w/W). An example for the analysis of the dynamics of aboveground biomass in the Stipa baicalensis plant community is given in this paper.

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A two-year experiment was conducted to investigate the responses of plant and litter dry weights of Pensacola bahiagrass swards to the nitrogen fertilization rates (0-80 g N/m^2/year) and cutting intervals (10.5-42 days). The plant and litter parts differed in the occurrence frequency of the significant responses to the treatments. On the seasonal basis, the significant main effect of the nitrogen rate appeared more frequently in leaf>stem>standing dead>stolon>belowground litter>root>surface litter. The significant main effect of the cutting interval occurred more frequently in leaf>stolon>stem and root>surface litter>standing dead and belowground litter. The significant interaction appeared more frequently in root>leaf>standing dead and belowground litter>stem, stolon and surface litter. The main effect of the nitrogen rate, when it was significant, took a tendency to raise the dry weights with increasing nitrogen rate in leaf, stem, standing dead and stolon, and took a reverse tendency in belowground litter. The main effect of the cutting interval, when it was significant, always took a trend to raise the dry weights with increasing cutting interval in ear, leaf, stem, standing dead and stolon. The present results, together with the results from the previous study which examined the responses to the cutting heights, revealed a diversity of responses of the plant and litter dry weights of bahiagrass swards to the management factors, from which some implications to the future studies were derived.

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^<15>N-labelled cattle urine was applied to small plots (20 cm diameter enclosed in polyvinyl chloride cylinders, 35 cm deep) in bahiagrass (Paspalum notatum Flugge) pasture on 4 June, 24 July and 14 October 1991, to trace the fate of urine-N in the soil-plant system. After one year, recovery of ^<15>N in measured components was similar for each application date. Between 27.5-35.4% of the applied ^<15>N was recovered in the plant parts with a further 8.8 -12.2% remaining in the soil and 1.3-1.6% in litter (both above and below ground). Of the ^<15>N applied, 53.6-59.9% was unaccounted for in the soil-plant system after one year. It was suggested that a bahiagrass pasture in this region (south Kyushu) was a open system for the nitrogen cycle, allowing for above 50% losses of urinary N from soil-plant system.

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