To investigate genetic resources suitable for Kitakami highland, perennial ryegrass ecotypes were collected from alpine regions in northeastern Japan and southern Germany and evaluated at an experiment field (970m) near Morioka from 1991 to 1993. As a result of principal component analysis using 13 characters in 1993, cumulative proportion of eigen values of the first and second principal components was 0.73 of total variance. From distribution of eigenvectors of the components, 27 entries were classified into 4 groups which includes two Japanese groups, one of each German ecotype and German cultivar. German ecotypes were better in winter hardiness, higher in percentage of survival plants, earlier in heading date, shorter in plant height and more in number of heads than the other groups. German ecotypes would be one of the promising genetic resources suitable for Kitakami highland. Among Japanese ecotypes, the ecotypes from Iwate showed the latest heading date and the longest in plant height, followed by those collected from Fukushima, from Nagano and from Tochigi. Among Japanese ecotypes, the population collected from Okunakayama (650m) was the best in survival, and exceeded the commercial cv. Friend.

View full abstract

The influence of storage temperatures and periods on the nodule formation of inoculated seeds was investigated. Seeds inoculated with coating, vacuum processing and adhesive were stored at cool or room temperatures. The number of viable rhizobia on seeds was estimated by the dilution-plate method, and nodule formation was examined in solution culture and field cultivation. The numbers of viable rhizobia after 6 months of inoculation declined differently depending on the inoculation method and storage temperature. Vacuum-processed seeds decreased markedly the number of viable rhizobia when stored at room temperature. A similar tendency of these inoculation methods was observed for the number of nodules in solution culture. Coated seeds maintained a high nodulating ability as well as at the start of inoculation, after 12 months' storage under cool conditions. In field cultivation, coated seeds stored for 3 months, regardless of storage temperature, formed large numbers of nodules. However, vacuum-processed and adhesive seeds decreased nodulation even if stored under cool conditions. When stored for 12 months at cool temperatures, coated seeds still possessed high nodulating ability, while adhesive seeds had little effect and vacuum-processed seeds had no effect on nodulation.

View full abstract

Three experiments were made to determine whether formic acid treatment or mixture of bacterial inoculant and enzyme treatment would improve the fermentation properties of unwilted orchardgrass and timothy silages, and unwilted and wilted alfalfa silages. In all experiments, the untreated silages made without additive were badly preserved. In experiments 1 and 2, the formation of butyric acid and volatile basic nitrogen (VBN) were slight in formic acid-treated timothy silage. The formic acid-treated orchardgrass silage was poorly preserved. The pH value of this silage rose to 5.64, accompanying high butyric acid and VBN concentrations. The addition of inoculant and enzyme led to well preserved silages in orchardgrass and timothy. The formic acid-treated timothy silage contained high residual water-soluble carbohydrate (WSC). In experiment 3, all the formic acid-treated alfalfa silages were well preserved except a wilted silage from the second cut. The inoculant and enzyme treatment was effective in improving the silage quality for first cut unwilted alfalfa but was not for other alfalfa materials. The residual crude protein and WSC contents of all the formic acid-treated alfalfa silages were higher than those of the other alfalfa silages. The results of this study indicate that the effectiveness of the formic acid- treatment on the silage quality depends on the herbage materials used and the treatment with the mixture of bacterial inoculant and enzyme is insufficient to produce a satisfactory fermentation in alfalfa silage.

View full abstract

Three year-old napiergrass (Pennisetum purpureum Schumach) stands were subjected to the management conditions consisting of different cutting intensities with or without stubble cover with soil in mid-November. The management effects on the spring regrowth of the plants were mechanistically analyzed mainly in relation to the tiller regrowth processes from tiller buds. The decreasing cutting intensity firstly tended to increase the total number of primary tiller buds (PTBs), which led to the increase in the number of dead PTBs. At the same time, the decreasing cutting intensity tended to increase the emerged percentage of secondary tiller buds (STBs) from dead PTBs. These changes resulted in the increase in the numbers of STBs and regrown tillers from STBs (RTstbs), and consequently in the increase in the regrown percentage of plants (RPplant). The stubble cover with soil decreased the number of regrown tillers from PTBs, but tended to increase the number of daughter tillers of RTstbs (DTstbs). The decrease and the increase almost offset each other, and there was no significant effect of the stubble cover on the RPplant. However, because of the higher proportion of DTstbs, the stubble cover was considered to be an effective practice before colder winters.

View full abstract

This paper deals with the including the tableland of Kirigamine and Utsukushigahara and the volcanos of Joshin-etsu. The area corresponds to the largest diastrophic zone in Japan, and is situated mainly on lava rocks formed by Fossa Magna. The tablelands of Kirigamine and Utsukushigahara originate from largescale pyroclastic lava flows. The rocks have good water permeability, and therefore the decrease in the available water established the grasslands of this area. The grasslands have been used jointly by community farmers as native or sown pastures, without beingprivately-owned and cultivated for forage crops. This contrasts with the fact that most of the Japanese grasslands are located on volcanic ashs have been developed by privately-owned farms that intensively utilize sown pastures and forage crops for dairying orcultivate grain crops and vegetables.

View full abstract

Fossa Magna and the Median Tectonic Line are the largest tectonic lines in Japan. The north Alps, a mountain range upheaved by crustal movements, border the western verge of Fossa Magna, with the Norikura volucanic range. In these mountain ranges, grassy plains have formed on lava plateaus. Highlands near treelines have also formed in a similar condition. In the outer zone of the Median Tectonic Line, grassy plains have formed on Paleozoic Mikabu Green Tuff, which has good water permeability. This line extends to as far as the Shikoku and Kanto districts, and there are mamy grassy plains and golf courses along it. Thus, stable subclimax grasslands of Japan are mostly distributed in the area where the rain water permeability is high and the soil water availability is low because of geographical and geological features.

View full abstract

The eastern verge of Fossa Magna has been defined by-various lines. NAUMANN considered a line connecting Naoetsu, Iwamurata, Wakamiko and Odawara as the verge. Currently, the verge extends to a line connecting Kashiwazaki and Choshi. Among the lines, the Iwamurata-Wakamiko line is a western verge fault of an old crustal block which formed when the sea of Tertiary period divided Honshu. Many grassy plains or grasslands exist along this line. A 30km-diameter plain between Mt. Tairappyousan and Mt, Makihatayama is a roof pendant which was raised by an intrusive granite formed at the intersecting point of Median Upheaval Zone and Fossa Magna. The plain is covered with Molinia japonic and Sasa kurilensis.

View full abstract

To study the effect of cattle grazing on the seed production in Miscanthus sinensis which is a native perennial and wind-pollinated grass, the intra- and inter variation of the seed production and components of seed production were investigated in three native grasslands dominated by M. sinensis with a different years of grazing at Kawatabi farm in Tohoku University. The seed production of M. sinensis decreased with increase of grazing. This was mainly depend on the decrease of inflorescence density and number of flowers per inflorescence. The seed-set ratio of M. sinensis did not suffered definite effect from grazing. There were considerable variations for the seed production, inflorescence density, number of flowers per inflorescence and seed-set ratio in each grassland. The coefficient variances of seed production and inflorescence density increased with increase of grazing. But the coefficient variance of seed-set ratio did not increase with increase of grazing. The effects of grazing on inflorescence density and number of flowers per inflorescence were very remarkable. By contrary, the effect of grazing on seed-set ratio was very small. It is supposed that the variation of seed-set ratio was caused by the probability of cross-pollination and grazing did not effect greatly on pollination.

View full abstract

Minimum-tillage and ditching cultivation method was developed to stabilize the emergence and growth of dent corn (Zea mays L.) on rotational upland field. Tractor attached seeding machine was developed for this method. This machine performs every seeding operations (fertilizing, ditching and stripe seeding) in one process. The results were as follows : 1) Efficiency of the seeding machine was 15.8 are per hour, that was twice as good as the rate of conventional method. Fuel consumption of this machine was 4.9 liter per hour, that was 62% lower than that of conventional method. 2) Soil surface drainage was increaced by ditchs. And penetration resistance was kept large during the period of growth in consequence of limited tillage. 3) Emergence, establishment and growth of dent corn on minimum-tillage and ditching method was beter than those on the conventional cultivation on rainy year. Dry matter yield by this new method was from 1-1.6 ton per 10 are stably, and was 150%-higher than that on the conventional cultivation in 1993 which was large precipitation.

View full abstract

Perennial ryegrass (Lolium perenne L.), one of the most important forage grasses for temperate regions, exhibits lower winter survival than other temperate grasses. Freezing hardiness is one of the primary factors associated with winter survival. The objectives of this study are to elucidate the differentiation in freezing hardiness among cultivar groups of perennial ryegrass, and then to examine the relationships of freezing hardiness with some agronomic characters. Freezing hardiness was assessed for 152 diploid and 25 tetraploid cultivars released in various nations using the crown-freezing test. Survival rate (%) after freezing ranged from 0% to 100% among the cultivars. Diploids overall had higher freezing hardiness compared to the tetraploids. Freezing hardiness also varied among the cultivar groups based on the utility type ; turf-types were the most hardy, the forage-types were the most sensitive to freezing, while the dual-purpose types were intermediate. Hardy cultivars tended to be small in plant height, leaf width and forage yield. It was also diverse among the cultivar groups based on nations of origin ; the cultivars released in U.S.A. were more hardy than the ones released in Europe.

View full abstract

In this study the wintering ability of Italian ryegrass (Lolium multiflorum Lam.) cultivars was evaluated on two characteristics, snow endurance and cold hardiness. Eighteen cultivars were tested from September 1990 to March 1991 in experimental fields located in a heavy snowfall area (Hokuriku Nat. Agric. Agric. Exp. Stn.) and a highland area (Nagano Stn. of Nat. Livestock Bred. Center). As indicators for wintering ability, Snow Endurance Index and Cold Hardiness Index were determined based on the survival ratio and spring growth vigour of plants. There was a significant relationship between these two Indices (r=0.55, p<0.05), but some difference was detected in the individual values among cultivars. For the wintering ability, CV. Miyukiaoba was more dependent on snow endurance than on cold hardiness, while in CV. Tur cold hardiness was more responsible. Both CVs. Ace and Fujiooba were relatively superior in both snow endurance and cold hardiness. The Cold Hardiness Indices obtained for CVs. Miyukiaoba and Niigatakei, both of which were bred at Hokuriku district, were lower than the average of the cultivars used. This suggests that the cultivars selected with strong snow endurance have not always showed a high cold hardiness in this species.

View full abstract

As a part of the study on the adaptability of timothy cultivars to environmental conditions and breeding high quality of timothy, effects of groundwater stress on growth and in vitro dry matter digestibility (DMD) were examined using 5 cultivars. Four clones of each cultivar were transplanted in a 1/5,000 a Wagner pot, and grown in a green house for 50 days. Four levels of groundwater treatment were non (WO), 14cm, 9cm and 4cm. Crop growth rate, net assimilation rate (NAB) and relative growth rate (RGR) in each cultivar decreased with increasing of the groundwater level at the period of 21 to 40 days after the treatment (P 2). The differences between the treatments in leaf area ratio (LAR) were smaller than those in RGR and NAR, and it was assumed that RGR was more greatly affected by NAR than LAR. NAR and LAR at P2 showed highly significant differences between cultivars. NAR was the highest in Kunpu and LAR was the highest in Erecta R.v.P.. The highest DMD was obtained at WO in each cultivar, which decreased due to groundwater treatment. Interactions between groundwater level and cultivar were not significant for RGR, DMD and other characters. Cultivarietal variation was small in groundwater stress on the plant growth, and the reason might be resulted from the materials that most of those were bred at the same station.

View full abstract

This study was carried out to establish suitable screening technique of freezing tolerance in Italian ryegrass (Lolium multiflorum Lam.) with the method modified in terms of freezing treatments of the artificial screening technique for cold hardiness developed by FULLER and EAGLES (1978). Scheme of screening technique of freezing tolerance for Italian ryegrass was as follows : The seedlings were raised in a growth cabinet at day/night temperature of 20/15℃ with 16 h photoperiod for 4 weeks. Raised seedlings at the 3-4 leaf stage were hardened for 14 days in a growth cabinet at 2℃ with 8h photoperiod. Following hardening, the seedlings were subjected to 5 freezing treatments wher,e the temperature was lowered to the fixed temperature of -4 to -12℃ at 2℃ intervals at a cooling rate of 1℃/h followed by 16 h plateaus and thawed at heating rate of 2℃/h, maintained at 2℃ for 24 h. After freezing treatment, seedlings were maintained for 3 weeks under the same condition as the growing condition. Then, plant mortality was recorded and LT50 (Lethal temperature for 50% kill of plants) was estimated by the probit analysis. This technique was applied to assess the change of freezing tolerance during winter.

View full abstract