The field experiment was conducted to evaluate the effect of harvesting interval (20, 30, 40, 50, 60 and 70 days) on the dry matter productivity of guineagrass (Panicum maximum Jarq. cv. Gatton) and setaria (Setaria sphacelata var. sericea cv. Kazungula). The annual dry matter yield of guineagrass increased with the longer harvesting interval up to 60 days and decreased at the 70-day interval. The significant quadratic regression was obtained with average CGR as criterion variables and with harvesting interval as explanatory variables (p<0.01). The equation presented that average CGR value was the maximum at the 50-day interval and decreased with the longer harvesting interval. On the other hand, average CGR and annual dry matter yield of setaria increased with the longer harvesting interval and maximized at the 70-day interval. Leaf/stem ratio decreased with the longer harvesting interval for both species. This tendency was remarkable in summer period. Though the extension of harvesting period for both species cause higher productivity, however, it is recommended for harvesting interval of 40-50 days, considering with leaf/stem ratio and leaf yield. Comparing with dry matter production of both species under an assumed drought condition, guineagrass is more tolerant than setaria.

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In the timothy sward of the early cultivar "Nosappu" and the late cultivar "Hokushuu" both of which are cut twice a year, a steep change in tiller generations was assumed to occur at the time of first cutting in late June or early July (the heading stage). It is thought that most tillers that lead to aftermath yield from summer onward (Aug. to Oct.) had emerged from after the first cutting until around September. Most of them continued to grow as vegetative tillers through winter, and developed as main shoots that contribute to foliage production of the first cutting (Jun. to Jul.) in the next year. With regard to the seasonal growth process of the timothy tiller population, one cycle corresponds to about a year and is divided into 3 terms as follows: a1, the term wherein many new tillers emerge (after the cutting in Jun. or Jul.) and continue to grow as vegetative tillers until before wintering; a2, wintering that lasts for 6 months; and a3, the term wherein most tillers change their growth phase from vegetative to reproductive and accomplish high dry matter production.

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NonGM corn and its near isogenic line of glyphosate-resistant genetically modified corn were cultivated for 4 years from 2001 to 2004. We treated the GM corn with glyphosate (GM+G) and conventional herbicides (GM) and compared them with the nonGM corn treated with conventional herbicides (nonGM). GM+G corn showed differences in weed vegetation, soil microflora, and growth of crops, but there was no difference in the arthropod fauna in the farm. Therefore, with regard to biota, there is no difference between glyphosate-tolerant GM corn and non-GM corn. The difference in biota was attituted to the herbicides.

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We have established an efficient method for obtaining dwarf mutants from cogongrass (Imperata cylindrica L.) through induced heavy-ion beam irradiation with tissue culture techniques. Young shoots of cogongrass were collected by detaching from field-grown native plant. The shoots with apical meristems were cut into about 5cm segments in length, and the surface was sterilized. Murashige and Skoog's (MS) medium supplemented with various compositions of 2,4-D and BAP were used in this study. The highest frequency of multiple-shoot formation was observed on MS medium containing 0.1mg/L 2,4-D and 2.0mg/L BAP. Subsequently, multiple-shoot clumps were transferred to a fresh hormone-free MS medium for inducing shoot elongations. Elongated shoots were divided from multiple-shoot clumps, and then transferred to a fresh hormone-free 1/2MS medium for the induction of roots. The multiple-shoot clumps were periodically subcultured to a fresh medium every month and proliferated with primary multiple shoots, which developed as crowded shoot clumps. The multiple-shoot formation from seed-derived shoot apical meristems of cogongrass were irradiated with heavy-ion beams 5, 10, 20, 50 and 100Gy (135-MeV/nucleon <20>^Ne and <12>^C ions). Although some albino plants regenerated, green plants produced 507 plantlets in total. All regenerated plantlets were transplanted into individual small pots, and then placed in the field. Only one plantlet out of 507 regenerated plantlets showed the lowest plant height during the first two years, when evaluated morphological characteristics.

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In order to find Japonica-Indica hybrid rice strains suitable for both soiling and whole-crop silages, 36 strains were investigated for dry matter yield and silage fermentation quality. Rice plants were harvested at the before-heading stage (Aug. 1, first cut of the twice-cut treatment) and at the yellow-ripe to full-ripe stage, depending on strains (Oct. 2, second cut of the twice-cut treatment and first cut of the once-cut treatment). Total dry matter yield calculated from dry matter weight per plant was greater than 2000g/m^2 for 2 strains (Areum byo and Milyang #42) in the twice-cut treatment and for 3 strains (Choopoong byo, Samgang byo and Yushin) in the once-cut treatment. Grain yield calculated from grain weight per plant was greater than 1300g/m^2 for 2 strains (Choopoong byo and Samgang byo) in the once-cut treatment. Silage with a higher dry matter content showed higher fermentation quality. The silages ensiled at the yellow-ripe to the full-ripe stage had a high V2-SCORE (above 60 points) for 3 strains (Namyeong byo, Taebaek byo and Yongiu byo) in the once-cut treatment. There was a high correlation (p<0.001) between dry matter content of materials and V2-SCORE of there silages.

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In Japan, the use of abandoned cultivated lands for cattle (mainly breeding cattle) grazing has been increasing. However, the feeding value of wild plants at there has been little investigated according to vegetation types, and corresponding information available for native pastures is also insufficient. Hence we determined the feeding value in terms of total digestible nutrients (TDN) and crude protein (CP) of the wild plants in abandoned cultivated lands (20 sites) and native pastures (14 sites) in western Japan. We determined the feeding value of mixed wild plants in different plots, each dominated by 1 of the 6 main species (4 grasses, 1 forb and 1 vine), as well as that of the dominant species. Most of the data indicated that the TDN content of mixed wild plants was more than 50%, which is the optimal value recommended for the maintenance of beef cows. With the exception of Miscanthus sinensis-dominant plots, the CP content of mixed wild plants was more than 8%, which is the value recommended the maintenance of beef cows. The feeding value of the mixed wild plants in grass-dominated plots was greater than that of each dominant species, although contrary results were observed in the case of Pueraria lobata-dominant plots.

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