Adhering strength of coleorhiza hairs and germinating behavior of surface-sown seed were investigated with six temperate grass species when sown on Yellow (paddy field soil) and Kuroboku (Kawatabi volcanic ash soil) soil, in relation to the differences in establishment. Grass species tested were orchardgrass, tall fescue, meadow fescue, Kentucky bluegrass, perennial ryegrass and Italian ryegrass. 1) Adhering strengths of coleorhiza hairs of orchardgrass, tall fescue and Kentucky bluegrass were higher at the level of 2 gr per seed as compared to that of 1 gr for meadow fescue, perennial ryegrass and Italian ryegrass. The former also had better penetration of seminal root into both types of soil and higher percentage of the rising type in germinating behavior, while the latter root were exposed considerably. Thus, adhering strength of coleorhiza hairs was highly correlated with the percentage of the rising type in germinating behavior (r = 0.96, P <0.01) (Fig. 2, Tables 2, 3). 2) As compared with number and length of coleorhiza hairs under water-germination, tall fescue, perennial ryegrass, meadow fescue and Italian ryegrss had higher hair number than orchardgrass and Kentucky bluegrass. The hair length were in order of tall fescue > orchard- grass, perennial ryegrass and Italian ryegrass > meadow fescue and Kentucky bluegrass. Thus, there were no significant relationship between adhering strength and number or length of coleorhiza hairs throughout six species examined (Fig. 4, Table 4). 3) The growth speed of seminal root was higher for Italian ryegrass and perennial ryegrass, being twice as much as the other species. Diameter of that root in Italian ryegrass and perennial ryegrass were also larger than in orchard grass, meadow fescue and Kentucky bluegrass. However, those characteristics were not significantly related with the percentage of rising type in germinating behavior, reflecting relatively less influence on germinating behavior and establishment (Fig. 5, Table 5). 4) Consequently, adhering strength of coleorhiza hairs is an important factor to control the establishment in case of surface sowing. Tall fescue, orchardgrass and Kentucky bluegrass were supposed to have some advantages in this viewpoint.

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The development of prostrate stems and root systems of first year stands of kudzu-vine was compared among three different plant spacings. Stems and roots were harvested in both the planting site (PS) and the interplant site (IS) eight times at three week intervals from 17 July to 11 December 1986, using a 20 × 20 cm quadrat. At 40 and 80 cm spacings, total stem length per m^2 attained a maximum of 102 m/m^2 on 18 September and 79m/m^2 on 30 October, declining to 55 and 54 m/m^2 at the final harvest, respectively; whereas at 120 cm spacing, total stem length leveled off during the late growing season, with a maximum of 66 m/m^2 on 30 October (mean of PS + IS). The wider spacings had thicker stems. The number of rooted nodes per m^2 and the proportion of rooted nodes to total number of nodes averaged over the growing season were the highest at 80 cm spacing (61.3 rooted nodes/m^2, 8.8%) and the lowest at 40 cm spacing (41.9 rooted nodes/m^2, 6.2%). The proportion of rooted nodes with greater LBD (the basal diameter of the thickest root in each root system) was higher in the wider spacings. Also, the wider spacings had a greater number of roots per rooted node. Fairly large differences existed in the seasonal trends of total stem length and the number of rooted nodes per unit area, percentage of rooted nodes to total number of nodes and the proportion of rooted nodes on the basis of LBD between PS and IS in all spacings. The differences in the former two growth characteristics between sampling sites tended to decrease gradually at 40 cm spacing during the late growing season, while increasing at the other two spacings. As mentioned above, the difference in the development of networks comprised of stems and roots was observed between sampling sites in the same kudzu stand and among stands differing in spacing in the first year of establishment.

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Improvement of nutritive value of maize (Zea mays L.) for silage use is accelerated by employing the simple technique which estimates the digestible organic matter (DOM) of whole crop silage by using fresh crop before ensiling. Our objectives were to assess the use of near infrared reflectance spectroscopy (NIRS) for the determination of chemical constituents of stover and to verify the equation for estimating DOM (EDOM) of whole crop silage as follows. EDOM(%)=87.0×G+(87.3×OCC+84.6×Oa+33.1×Ob)×(1-G) where G was the proportion of grain in total dry matter [g・g^<-1>], and OCC, Oa and Ob were the organic cellular contents, the high digestible fraction in organic cell wall (OCW) and the low digestible fraction in OCW, which were contents in stover at harvest time on dry matter basisfg-g"1], respectively. The 129 samples of stover dried forced-air oven at 80° C for 48 hrs were assayed for the purpose of NIRS calibration and validation. Calibration equations by NIRS were validated on 30 samples. Standard deviation of prediction error (SDP) for Ob, OCW, OCC and CA were less than 1.6%. Evaluation index (El) which evaluated the accuracy of prediction samples ranged from 15.3% for Ob to 9. 896 for OCW. There was a significant correlation between EDOM and in vivo DOM determined by freeze-drying in digestion trials with goat (r=0.94, n= 8, p<0.01). Eliminating material which was damaged by infection of Pythium graminicola S. before harvesting, EDOM closely correlated with in vivo DOM (r=0.99, n=7, p<0.001), and the regression equation was described as follows : DOM=1.06×EDOM-7.01 (F=242.9). When bias was 2.1% and SDP was 0.1%, the range of in vivo DOM nevertheless revealed widely from 76.9% for brown midrib-3 hybrid to 65.0% for genetic sterile hybrid, the bias corrected equation resulted the acceptable error of estimation. We conclude that the NIRS chemical assay and consecutive prediction equation can be used to accurately estimate the DOM of whole crop silage by using fresh crop in breeding purposes.

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This research was carried out to study agronomic performance of F_1 hybrid strains of Italian ryegrass (Lolium multiflorum LAM.) and tall fescue (Festuca arundinacea Schreb.). Early seedling growth and other agronomic characters of the F_1 hybrid strains were compared with those of their parental cultivars. Early seedling growth of the parental cultivars and their F_1 hybrid strains grown in boxes in an unheated greenhouse was scored 30 d after sowing. The Italian ryegrass cultivar, Waseaoba, had significantly taller plant height and more tillers per plant than the tall fescue cultivars and F_1 hybrid strains (Table 1). Most F_1 hybrid strains were shorter than the parental tall fescue cultivars in plant height, but some F_1 hybrid strains had taller plant height than their parental tall fecue cultivars. More than half of the F_1 hybrid strains produced more tillers per plant than their parental cultivars of tall fescue (Table 1). Agronomic characters of the Italian ryegrass and tall fescue cultvars, and their F_1 hybrid strains were measured in the field. The F_1 hybrids tended to have shorter plant height than the parental species. However, dry weight per plant of the F_1 hybrids was higher than that of tall fescue in the first harvest year. In the second harvest year the F_1 hybrids were similar to tall fescue in dry weight per plant (Table 2). Using the 10 traits (first heading date, plant height, flag leaf length, flag leaf width, ear length, fresh weight at first heading stage, fresh weight on 25 July, 13 September and 31 October, and total fresh weight), principal component analysis was employed to detect the overall pattern of variation in the tall fescue cultivars and their F_1 hybrid strains. About 78 % of the variation was extracted by the first and second components (Table 4). The first component represents maturity and forage productivity. The second component appears to be a measure of morphological factors. The tall fescue cultivars and their F_1 hybrid strains were scattered according to their first and second component scores (Fig. 1). The scatter diagram indicated that the forage yields of F_1 hybrid strains tended to be similar to those of their parental cultivars of tall fescue. However, there were some F_1 hybrid strains that were superior to their parental tall fescue cultivars in forage productivity. The results obtained indicate the possibility of producing F_1 hybrids with high agronomic performance.

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Kentucky bluegrass (Poa pratensis L., abbreviate as Kb), Redtop (Agrostis alba L., Rt), Creeping red fescue (Festuca rubra L., Cr) and Japanese lawngrass (Zoysia japonica Steud., Zy) are promising grass species for not only grazing purposes but soil conservation against erosion on the sloped pastures in Japan. We have reported the plant and animal productivity of these grasses and suitable managements for the swards or pastures in regard to interspecific competition in previous paper. In this report, comparisons of growth in underground organs were made on the pure swards treated with the combinations of three levels of fertilizer application and three cutting intervals. Fertilizers were applied at the rates of 50 (low), 150 (medium) and 300 (high) kg, N, P, K/ha, yr., respectively. Experimental swards were cut when the relative light intensity at 3 cm above ground surface reached to 5% (long cutting interval), 20% (medium) and 50% (short), respectively. Underground parts of the swards were sampled in July of the 4th year after sward establishment by a soil sampler which consisted of four cores with 11.3 cm in diameter (equivalent to 100 cm^2) and 2.5 cm or 5 cm in length. The results obtained were as follows : 1) Weights of underground parts of all pure swards of Kb, Rt, Cr and Zy were ranged about 300-1200 DMg/m^2, and the differences in weights among species were far greater than those of either cutting or fertilizer application treatment. Weights of underground parts decreased as the descending order of Cr > Kb > Zy > Rt. In three temperate grasses, Kb, Cr and Rt, the proportions of weight of rhizomes to total underground parts were relatively small, though that of Kb was a little larger (22%) than other two grasses. On the other hand, rhizomes of Zy occupied the greater part of the underground parts (70%). 2) Weights of underground parts increased remarkably as the amount of fertilizer increased in Kb and Rt, but not so much in Cr and Zy. Among organs, fertilizer application increased weights of root and crown in Kb and Rt, and decreased them slightly in Cr and Zy. Contrasting to these, the amount of rhizomes were not affected by fertilizer application in all species, suggesting that the rhizome was a most stable organ to the soil environment surrounding the root system. 3) Sixty five percent of all the roots distributed in 0-2.5 cm soil surface layer in Kb and Cr, and 27% in Zy, showing the concentrated root systems near the surface in Kb and Cr, and the uniform distribution in Zy. However, weight of root of Zy was only 174 g/m^2, being a half to one-fourth of the other species. In regard to the rhizome, 90% existed within 0-2.5 cm layer in Zy, contrasting with rhizomes of Kb and Cr, which distributed not only in near the soil surface but in the deeper layers. From these findings, it was concluded that Japanese lawngrass (Zy) had a markedly rhizomatous and evenly-distributed root system in favor of conserving soil media against erosion and preventing root-mat formation near the soil surface, which seemed to limit air and water infiltrations into the deeper soil.

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Callus cultures were induced from hypocotyl, root and cotyledon sections of 65 species of the genus Trifolium. The callus induction medium was that of Gamborg (B5) containing 3.0 mg / 12, 4-D and 0.5 mg / 1 kinetin. After two subcultures on B5 medium containing 0.5 mg / 12, 4-D and 0.5 mg / 1 kinetin, the growth rate and the nature of calli were examined. There were variations in the growth rate and the nature of the calli among different species and among plants within the same species. The growth rate and the nature of calli derived from different explants of a given species were less variable than between species. Species with slow vegetative growth tended to show slow callus growth in comparison to species with rapid vegetative growth. Further there was a tendency for the callus growth rate of the perennial species to be slower than that of the annual species. After the calli had been transferred to a regeneration medium (B5 medium with 0.2 mg / 1 IAA and 2.0 mg / 12ip), green-pigmented spots were observed on the calli derived from some of the species. In many cases, the calli with green-pigmented spots became brownish without regenerating. Some of the calli in a few of the species produced embryoids. Subsequent plantlet formation occurred on minor modified White medium. Plantlets were obtained in 10 of the 65 species. The present study is the first report on plant regeneration in T, amabile, T. alpestre, T. apertum, T. caucasicum, T. cherleri, T. heldreichianum, or T. montanum. The mode of plant regeneration in these species appeared to be somatic embryogenesis.

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