The existence of juvenile stage is well known in orchardgrass ; that is, the imbibed seed and the seedling immediately after germination are not responsive to short day-length and/or low temperature which later promote flowering. However, inconsistent results have been reported about the duration of juvenile stage. The present studies were carried out to clarify the influence of planting density, fertility-level, and seedling-age on the responsiveness to floral-induction treatment. Seedlings were grown under continuous light in a warm (25℃ in day/15℃ at night) glasshouse for several weeks after sowing. Thereafter, they were subjected to floral-induction treatment of natural short-day-lengths and low temperatures for 2 to 6 weeks in spring and autumn. After the treatments, their heading behaviour was observed under continuous light in a warm glasshouse (Fig.1 and Table 2). The results are summarized as follows: In Experiment I, 7-weeks-old seedlings of "Aonami" and "Latar" grown at different four planting densities and two fertility-levels were subjected to floral-induction treatment for 6 weeks. The heading behaviour showed that the responsiveness to floral-induction treatment substantially increased when seedlings were grown at low planting density and at high fertility-level (Table 3). In Experiment II, seedlings of "Aonami" and "Nakei EV-No.1" were subjected to floral-induction treatment from 3-, 4-, 5-, 6- and 7-weeks-old to 9- or 10-weeks-old, respectively. From the heading behaviour, it was certified in both materials that the 5-weeks-old seedlings grown under continuous light in a warm glasshouse were responsive to floral-induction treatment. However, the effects of floral-induction treatment started with the 3- or 4-weesk-old seedlings were lower than those started with the older seedlings, although the seedling-age and plant stage expressed by leaf number of main stem increased equivalently until the end of treatment. When the treatments were started at younger seedling-ages, on the other hand, the plant height of the seedlings remained lower until the end of treatment. From these results, it was suggested that the responsiveness of seedlings to floral-induction treatment was influenced not only by the seedling-age and the plant stage in leaf number but also by the size of the seedlings (Table 4). In Experiment III, 3-, 4-, 5-, 6- and 7-weeks-old seedlings of "Aonami", "Latar", "Aberystwyth S143", "O.S.G. -7", "Nakei EV-No.1" and "Dactylis glomerata ssp. judaica" were subjected to floral-induction treatment for 6 weeks. In all materials tested, the effects of floral-induction treatment increased linearly with the seedling-age up to the 6-weeks-old, but the effects on the 7-weeks-old seedlings were almost the same or a little higher than those on the 6-weeks-old seedlings (Table 6). Therefore, it was concluded that the 6-weeks-old seedlings grown under continuous light in a warm glasshouse were considerably responsive to floral-induction treatment irrespectively of materials.

View full abstract

In the previous paper, it was clarified in orchardgrass that juvenile stage was completed within 5 to 6 weeks after sowing under continuous light and warm temperature. The study reported here was carried out to investigate the influence of plant-age after juvenile stage on the responsiveness to floral-induction treatment. The 7-weeks-old seedlings and the aged tillers were used. Seedlings were grown under continuous light in a warm (25℃ in day/15℃ at night) glasshouse after sowing. Aged tillers were obtained by dividing clonal materials which had been grown under the same condition for about 6 months. These materials of each age were subjected to floral-induction treatments for 2 to 6 weeks. After the treatments, their heading behaviour was observed under continuous light in a warm glasshouse (Fig.1 and Table 1). The results are summarized as follows: In Experiment I, 7-weeks-old seedlings and aged tillers of "Aonami" were subjected to floral-induction treatment of natural short-day-lengths and low temperatures for 2, 3, 4, and 5 weeks. From the heading behaviour, it was clarified that the number of weeks required for floral-induction was considerably shorter in aged tillers than in 7-weeks-old seedlings (Table 2). In Experiment II, 7-weeks-old seedlings of "Aonami", "Aberystwyth S143" and "Nakei EV-No.1" were subjected to floral-induction treatments of continuous light with two different temperatures (natural low temperature and controlled warm temperature) for 6 weeks. The results showed that floral-induction was almost entirely prevented by continuous light independently of temperature conditions in seedling of all materials tested (Table 3). In Experiment III, aged tillers of "Aonami", "Aberystwyth S143" and "EV-700" were subjected to floral-induction treatments of continuous light with the two different temperatures as mentioned in Experiment II for 6 weeks. From the results, it was recognized in all materials tested that floral-induction scarecely occurred under both conditions of continuous light and warm temperature but was brought about only by low temperature even under continuous light in aged tillers (Table 4). From the above results, it was suggested that the responsiveness of orchardgrass to short day-length and low temperature increased with the advance of plant-age after juvenile stage and that the short-day requirement for floral-induction became lower in the aged-plants than in the seedlings immediately after juvenile stage.

View full abstract

Experiments were carried out to develop suitable techniques for testing the resistance of cocksfoot varieties to Typhula ishikariensis and T. incarnata and to study the relationship between winter hardiness and the resistance to the disease. Experimental methods are as follows ; Seedlings were grown in a glasshouse for 10 weeks, followed by artificial hardening for 2 weeks at 3℃ with 8-h photoperiod. Then each plant received 0.37-0.72g of inoculum, and was incubated under a snow cover more than 50cm thick for 65 days to test the resistance to T. ishikariensis and 80 days in the case of T. incarnata. Plants were transferred into a glasshouse after incubation, and tops were clipped. Then the plants were allowed to recover for a month, and plant survival was recorded. The varieties from colder regions were more cold tolerant and were generally resistant to T. ishikariensis except for a few cases. The resistance to T. ishikariensis was closely related to the winter hardiness in Sapporo. On the other hand, the varietal response to T. incarnata did not always coincide with that to T. ishikariensis. Two south European varieties, Dora and Montpellier, were as resistant as the north European ones to T. incarnata. This contributed to a decrease in the overall correlation coefficient with winter hardiness. The highly positive correlation between the resistance to Typhula spp. and winter hardiness suggests that the primary factor for the wintering of cocksfoot in Sapporo is the resistance to Typhula spp.

View full abstract

This experiment was carried out to clarify the inter-population variation of intra-plant variations and to investigate the relationship of intra-plant variation with forage yield in timothy (Phleum pratense L.). Thirteen natural populations collected from the eastern district of Hokkaido and three cultivars were grown under spaced planting conditions for four years. In the seeding year, heading date of each tiller within plant was recorded, and it was found that there was a large variation among natural populations for the inter-tiller variation of heading date. In the second and third years, plants were cut in early July (first cut) and in mid-September (second cut). At each cut, the number of heading tillers and green yield per plant were measured. Heding ratio, which stands for the number of heading tillers in the 2nd cut relative to the total heading tillers of two cuts, and total green yield (1st cut+2nd cut) were closely associated with. For these two characters there were significant differences between natural population and cultivar, and among natural populations. The inter-tiller variation of heading date in the seeding year was correlated positively with heading ratio and negatively with total green yield in the second and third years. In the fourth year, four lines of which two had higher and the other two had lower heading ratio in the previous years were examined on inter-tiller variation within plant for six characters as well as total green yield and heading ratio. Consequently it became evident that the former lines had larger inter-tiller variations on vegetative organs but less total green yield than those of the latter. Experimental results suggested that heading ratio was a reflection of a intraplant variation in tiller elongation and that high heading ratio was a factor which decreased forage yield. Cultivars had more synchronous heading, lower heading ratio and smaller inter-tiller variations on vegetative organs than natural populations.

View full abstract

In order to develop the technique of rasing and stabilizing the corn production in cold climatic districts, the problems related shall be analysed and solved through our research series. As the first step, we compared, in this paper, the difference of climatic conditions and climatic productivities of corn in Hokkaido (the northernmost island of the four main islands in Japan) with those in the Corn Belt of North America so as to clarify the climatic features and evaluate the climatic productivity in Hokkaido as a corn production zone. The results obtained were as follows ; 1) The climatic productivities of corn were calculated, based on two climatic factors, air temperature and solar radiation, from the equation (1). Y={(0.80172 ln R)-3.60842}・(5.445・10^<-5>・T^4-2.13068・10^<-3>・T^3+3.241477・10^<-2>・T^2-0.12469694・T-0.41051959), where R is solar radiation (cal/cm^2・day), T is daily mean air temperature (℃), and Y is the index of climatic productivity. The equation (1) was derived from the relationship between the two climatic factors and CGR (Crop Growth Rate) which was the average CGR of two corn hybrids, Hokuyu and KO No.6, during the early growth stage. From the equation (1), climatic productivities at various air temperatures and solar radiations may be calculated as productivity indices ; Y=1 is obtained at 315cal/cm^2・ day and 17.5℃ (refer to Fig.1). 2) The climatic productivity of corn in Hokkaido was considerably lower than those in the Corn Belt. The productivity at Sapporo (43°03' N.L.) in Hokkaido, for example, was about half that at Moline (41°27' N.L.) in the Corn Belt (Fig.3). The climatic productivity (index) of corn in Hokkaido showed a large regional difference ranging from 30 to 110 (Fig.4). Extremely low indices were shown in the eastern and northern parts of Hokkaido. 3) The air temperature at Sapporo was lower than that at Moline. The period of optimum air temperature (22-26℃) for the corn growth was only about 10 days in summer at Sapporo. While at Moline the optimum air temperature continued as long as three months (Fig.2A). In the seasonal changes of solar radiation at Moline the maximum was shown during the middle stage of corn growth (July) when the corn population had the highest leaf area index (LAI) so that the population could been expected to have a high efficiency in the light utilization and photosynthsis. On the other hand at Sapporo the solar radiation became highest during the early (low LAI) stage (May-June), then decreasing graduately with the growth stage proceeding (Fig.2A). The precipitation at Moline was highest in spring (the season of germination and early growth stage), decreasing in autumn (the harvesting time). While the precipitation at Sapporo had the seasonal change contrary to that at Moline, showing the lowest in spring and the highest in autumn. At Sapporo, the combination between the seasonal change of these climatic factors and growth pattern of corn was not desirable, as compared with that at Moline.

View full abstract

In the cold climatic district the production of silage corn has been often unstabilized by low solar radiation, low air temperature and the other adverse climatic factors. In this paper we analysed the relationship between the productivity of silage corn and the solar radiation, one of the climatic factors which may influence the productivity strongly. Experiments were carried out over three years, 1977-79, with six hybrids of different maturities in 1977, with two hybrids in 1978 and with nine hybrids in 1979. The treatments of three different light intensities, 100% full sunlight (control), 75% of full sunlight (light shading treatment) and 60% of full sunlight (heavy shading treatment) were applied to plants during different growth stages (early, middle and late growth stage, and the whole growth stage). The shading treatments were conducted under the field condition using the iron frames (3.6m×7.2m×3m in height) covered with white and black shading-cloths. The white cloth reduced the light intensity down to 75% fullsunlight (reduction ratio was 25%) and the black one, 60% full sunlight (reduction ratio was 40%). The plants grown at the density of 5, 330 plants/10 are. The amount of N, P_2O_5 and K_2O supplied were 16〜18kg, 22kg and 18kg/10 are, respectively. The results obtained were as follows ; 1) The silage corn production was strongly affected by the whole stage shading treatments, conspicuously by the heavy shading treatments. At the heavy shading treatments, the aboveground and ear weights decreased down to 52〜80% and 32〜80%, respectively, to those (100%) at the control. While at the light shading treatments the aboveground and ear weights also decreased down to 82〜94% and 76〜94%, respectively. 2) Yields were raised a little higher by the early stage shading treatments than those at the control. On the other hand, the middle stage shading treatments were most effective, decreasing yields conspicuously. That is, the heavy shading treatments applied during the middle stage decreased the aboveground and ear weights down to 69〜80% and 57〜60%, respectively, to those (100%) at the control, while the light shading treatments during the middle stage decreased the aboveground and ear weights down to 89〜94% and 87〜90%, respectively. From the view point of the total solar radiation supplied during the whole growth stage, the ratios of solar radiation cut by the middle stage, light and heavy, shading treatments were no more than 15% and 9%, respectively, nevevertheless, the middle stage shading treatments were crucially effective on the silage corn production. Subsequently to the effect of the middle stage shading treatment, the effect of the late stage shading treatment was largest, that is, the heavy shading treatments decreased the aboveground and ear weights down to 74〜75% and 72〜83%, respectively, to those (100%) at the control. Difference among hybrids used may have been found in the effect of shading treatments on the production.

View full abstract

This paper dealt with the increment of silage corn production in Hokkaido, the northernmost main island in Japan, with the high plant-density cultivation. Two hybrids, Caldera 535 (early maturity) and Pioneer 3715 (late maturity), were used as experimental materials. Both hybrids were grown at different thirteen plant-densities ranging from 2,850 plants/10 are up to 19,950 plants/10 are so as to investigate the effects of plant density on the yield and the characters related to the yield. The different plant densities were obtained by changing the inter-row width from 20cm to 140cm with increments of 10cm. While the inter-plant space within each row was constant (25cm). The amount of fertilizer supplied to a plant was constant, N, 3.16g ; P_2O_5, 6.85g ; K_2O, 3.16g (at 6,000 plants/10 are, for example, N supplied was 19kg/10 are). The results obtained were as follows ; 1) The aboveground (stover+ear) weight per plant in both hybrids reduced exponentially with plant density rising, substantially leveling off at the density over 15,000 plants/10 are. The reduction in the ear weight per plant with plant density rising was much more outstanding than that in the aboveground weight (Fig.2). The ear capacity, l×a×b (l, ear length ; a and b, long and short diameters corssing rectangularly at the largest part of ear) decreased with plant density rising, and the decreasing tendency was shown more markedly in Pioneer 3715 than in Caldera 535 (Fig.4). 2) The aboveground yield per unit ground area considerably increased with plant density rising in both hybrids. The ear yield per unit ground area also increased a little with plant density rising. The ear ratio (ear weight/aboveground weight) decreased with plant density rising (Fig.3). 3) The leaf area index (LAI) increased linearly with plant density rising (Fig.5). Since at high densities SLA (Specific Leaf Area, Leaf area per unit leaf weight) increased in both hybrids (Fig.7), high-density populations may have had a large leaf area for the leaf weight of the population. 4) The maximum LAIs at the plant density of 6,000 plants/10 are, which is a standard density of corn cultivation in Hokkaido, showed about 3.0 and 4.5 for Caldera 535 and Pioneer 3715, respectively. The light extenction coefficient (k) of corn populations were 0.55 and 0.45 for Caldera 535 and Pioneer 3715, respectively (Fig.6). The ratios of light interception by plants at the density of 6,000 plants/10 are were 80% and 87% for Caldera 535 (LAI=3.0, k=0.55) and for Pioneer 3715 (LAI=4.5, k=0.45), respectively (Fig.6). Considerably much light (20% and 13% to the incident light) was permitted to pass through without being received, as photosynthetic energy, by leaves. To raise the light utilization efficiency (up to 95% light interception) it was necessary that the plant density of both bybrids should be raised up to 10,000 plants/10 are. 5) Judging from the results obtained in the experiment, the standard plant-density (6,000 plants/10 are) recommended in Hokkaido may be regarded as a little too low. The higher production of silage corn should be expected by raising the plant density up to nearly 10,000 plants/10 are, especially in the central and south-western part of Hokkaido where the corn plant may have a comparably good growth.

View full abstract

We investigated features of growth and productivity in the hybrid corn, pioneer 3715, which was grown under the conditions with different combinations of plant densities, sowing times and fertilizing levels. That is, the experiment was carried out under the conditions with six plant-densities, 3,625, 5,320, 7,254, 8,866, 11,400 and 13,000 plants/10 are ; with two sowing-times, early sowing (on May 20) and late sowing (on June 20) ; and with two ways in fertilizing, namely, one is the way of fertilizing a constant amount to a plant (N, 3.4125g/plant supplied to the early sowing plots and N, 2.5594g/plant to the late sowing plots) and the other was the way of fertilizing a constant amount to an unit ground area (N, 18.0kg/10 are supplied to the early sowing plots and N, 13.6kg/10 are to the late sowing plots) (table 1). The results obtained were as follows ; 1) The aboveground yield and TDN yield had increasing tendencies with plant density rising. The highest yield was obtained under the combination of early sowing, high plant-density and heavy fertilizing (Fig.1 and Table 1). 2) Leaf Area Index riled with plant density rising (Fig.2). <LAI>^^^wholes (mean LAI over the whole growth period) obtained at the highest plant-density (13,300 plants/10 are) were 5.2 and 4.3 at the early and late sowing plots, respectively (Fig.2). The opt-<LAI>^^^whole, at which the Crop Growth Rate in the population shows the largest value, was calculated 5.78, which indicated that the aboveground yield may have increased yet even at higher plant-densities than at the highest plant-density (13,300 plants/10 are) examined in this experiment (Fig.4 and 2). 3) The <LAI>^^^mat. (mean LAI in the maturing stage) at the highest plant-density (13,300 plants/10 are) reached about 9.0 (Fig.2). The opt-LAImat. may have been calculated 6.269, which corresponded to the LAI shown at the plant density of about 8,500 plants/10 are (Fig.4 and 2). The ear yields at the early sowing plots also took the largest value around this density (Fig.1 and Table 1). 4) The aboveground yield at the late sowing plots was 35%-lower than those at the early sowing plots (Fig.1 and Table 1). The <LAI>^^^mat. at the late sowing plots reached as high value as shown at the early sowing plots, while the maturing period at the late sowing plots was considerably shortened (Fig.2 and Table 1). The yield reduction at the late sowing plots was caused by the maturing-period shortening, not by the LAI reduction. 5) The aboveground yields at the final growth-stage, as the plant density rised, increased almost in parallel with the aboveground weight at the flag leaf emergence time (regarded as the final stage of vegetative growth) (Fig.1). This phenomenon demonstrates that the aboveground weight at the flag leaf emergence time is an important determinant to the final yield and the final yield may be increased by rasing the amount of accumulation during the vegetative stage.

View full abstract

We get average parameters of logistic equations for increase in whole tops dry matter, leaf blades dry matter and leaf areas with growth of Italian ryegrass population in experiment of five years for each season respectively. On these equations, the seasonal changes were discussed of the relations between increase in whole top dry matters (W), and that of leaf blade dry matters (L_w) and leaf areas (L_a). Obtained results are as follows. 1. The relationship between whole top dry matters (W) and leaf blade dry matters (L_w) with growth of the population could well be expressed by the following quadratic equation. L_w=μW-νW^2 μ, ν ; relative growth coefficients 2. The relation of relative growth of whole top dry matters (W) to leaf blade dry matters (L_w) in each seasons could be shown by the following approximate equations respectively. in autumn L_w=0.9W-0.000519W^2 50<W<450g・m^<-2> in winter L_w=0.53W-0.000055W^2 100<W<600g・m^<-2> in spring L_w=0.6W-0.000385W^2 120<W<600g・m^<-2> 3. Changes of the leaf area ratio (L_a/W) with growth in each seasons could be shown by the following approximate equations respectively. in autumn L_a/W=430-0.367W 50<W<450g・m^<-2> in winter L_a/W=23572/W+W/3.48 100<W<600g・m^<-2> in spring L_a/W=9728W^<-0.578> 120<W<600g・m^<-2> 4. Changes of the specific leaf area (L_a/L_w) with growth in each seasons could be shown by the following approximate equation respectively. in autumn L_a/L_w=500-0.238W 50<W<450g・m^<-2> in winter L_a/L_w=48142/W+W/1.75 100<W<600g・m^<-2> in spring L_a/L_w=126.34/W^<0.04>-1.092 120<W<600g・m^<-2> 5. In spring, although less distribution is observed in leaves, the leaf area can develop rapidly, as the specific leaf area is quite large. There arises a rapid reduction in the specific leaf area with growth of population, which seems to lead to the persistance of high NAR. Such transition in the specific leaf area in spring indicates a part of the high production mechanism of spring flush. 6. The fact that the specific leaf area is particularly large in spring seems to have more to do with the stage of growth development than the direct influence of the environmental factors.

View full abstract

Effects of lime nitrogen application on the establishments and yields of several warm-season grasses in a serial non-tilled sowing were investigated by pot and field experiments. And another pot and petri dish experiments were also conducted to find out the best condition for controlling the survival of Italian ryegrass (Lolium multiflorum, abbr. as Ir) and for preventing the inhibition of the germination of oversown grasses with the higher rate of lime nitrogen application. 1. In the field, Ir swards were treated with 12, 24kg/10a using lime nitrogen or ammonium sulfate on June 17 and in the pot experiments, 0, 0.2, 0.4, 0.6gN were applied to each pot using lime nitrogen or ammonium sulfate on July 4. Then Sweet sorghum (Sorghum vulgare, abbr. as So), African millet (Eleucine corocana, abbr. as Am), Rhodes grass (Chloris gayana, abbr. as Ro) and Green Panic (Panicum maximum, abbr. as Gp) were oversown on June 20 and July 7 respectively. The residual growth of Ir which received the higher rate of lime nitrogen was extremely suppressed comparing with that treated with the ammonium sulfate. Then the better establishment and growth of So, Am, Ro, Gp were found on the field which received N ; 24kg/10a of lime nitrogen and on the pot received 0.4g/pot N lime nitrogen. However, in the pot experiment, the heavier lime nitrogen application caused the suppression of the germination of oversown grasses. Yields of warm-season grasses were increased with improving their establishment. The establishments and yields of oversown grasses on the lime nitrogen plots were ranked as Am>Ro>Gp. 2. The suppression of the residual growth of Ir was proceeded in case of supplied lime nitrogen to the soil surface or to the root stumps of Ir after cutting of Ir swards. Furthermore, the residual growth of Ir was suppressed by lime nitrogen application in cultural solution. Therefore, it was considered that the residual growth of Ir was more effectively suppressed when Ir swards were cut as lower as possible and treated with lime nitrogen onto the root stumps of Ir and/or the soil surface near to stumps. 3. The effects of the concentration of lime nitrogen on the germination and establishment of Am were investigated under the different soil temperatures and soil moisture contents. The suppression effects of lime nitrogen on the germination and establishment of Am were decreased extremely at the higher soil temperature (above 28℃) and at the middle (18%) or high (25%) soil moisture contents.

View full abstract

A field experiment was conducted in order to investigate the effect of nitrogen on the yields of Napier grass. The grass was grown on a calcareous soil, which is one of the typical soils and called "Jagaru" in Okinawa, for two years from 1976 to 1977. Nitrogen was applied at four levels, namely 0, 30, 60 and 90kg per 10 are per year. The obtained results were summerized as follows ; 1. The grass showed remarkable increase in the yield with the rate of nitrogen up to 60kg in both years. Little difference was recognized in the yield between the nitrogen rates of 60 and 90kg. The grass produced more than 30 tons fresh yield or more than 4.5 tons dry yield per 10 are per year over 60kg of nitrogen applied. 2. The rates of nitrogen did not affect on the number of tillers, but increased on the weight of a tiller. 3. The effect of nitrogen on the grass height was recognized. The grass grew more than 200cm on the plots of 60 and 90kg of nitrogen in the season with high temperature. The number of leaves per tiller was affected by the rate of nitrogen. More than 9 leaves developed per tiller one the plots of 60 and 90kg of nitrogen in the season with high temperature. Also, by the nitrogen rate affected was the leaf area per leaf. The leaf area showed more than 250cm^2 on the plots of 60 and 90kg of nitrogen in the season with high temperature. On the other hand the leaf weigth ratio was highest with the lowest rate of nitrogen and it decreased with the increased rate of nitrogen. 4. With the rate of nitrogen the leaf area index (LAI) increased and showed more than 9 on the plots of 60 and 90kg nitrogen at each cutting except the 4th cutting in 1976 and the 5th cutting in 1977. 5. The net assimilation rate (NAR) ranged from 15 to 50g・m^<-2>・week^<-1> and higher values were obtained from the plots 60 and 90kg of nitrogen in all cuttings. Both of crop growth rate (CGR) and the optimum LAI were strongly affected by the nitrogen application. The maximum CGR at 60 and 90kg of nitrogen yielded more than 200g・m^<-2>・week^<-1> from April to September. The optimum LAI was more than 7 in the plots of 60 and 90kg of nitrogen at each cutting except the 5th cutting of 1977. From the results obtained here the most appropriate amount of nitrogen was considered to be around 60kg per 10 are per year for higher yield of Napier grass on this specific "Jagaru" soil experimented.

View full abstract

Italian ryegrass containing large amounts of nitrate was ensiled in laboratory silos at three moisture levels adjusted by pre-wilting. Effect of these moisture levels on the disappearance of nitrate was investigated. At each moisture level, the following ensiling treatments were applied ; (1) the material was packed heavily and lightly (Expt.II), (2) the material was chopped into 1cm and 5cm in lengths (Expt.III). The silos were kept at 28℃ in the incubator and opened at 3, 7, 15 and 50 days after ensiling. The results obtained were as follows: 1. At high and medium moisture levels, the nitrate contents considerably decreased with advancing period of ensiling. In low moisture silage, the nitrate contents changed little during ensilage process. These silages were chracterized by a high pH value but, large amounts of butyric acid was found at high moisture levels. 2. The high moisture silages were different in the nitrate disappearances and qualities between the silages of the heavy pack and those of the light one in Expt.II, but the qualities of both silages were poor and the nitrate disappearances of these silages were high. There were no marked differences in the nitrate disappearances and qualities between the silages chopped into 1cm and 5cm in lengths, at each moisture level in Expt.III. 3. The high moisture silages were poor in quality and the rate of nitrate disappearance were from 80.1 to 100%. At medium and low moisture levels, the quality of these silages were slightly better than that of the high moisture silages. But there were differences in the rate of nitrate disappearances between the medium and the low moisture level. The rate of nitrate disappearrance was from 91.5 to 98.0% in the silages of medium moisture, and from 4.2 to 30.0% in the silages of low moisture.

View full abstract

The effects of the addition of ammonium propionate to corn silage as an anti-aerobic deterioration agent on rumen fermentation, blood composition, milk yield and milk composition were studied using lactating cows. Twenty cows were assigned to two groups and fed one of two diets ; untreated corn silage and corn silage added with 1.0% of ammonium propionate (conc. of 75%) at feeding. Each cow was fed 20kg of treated or untreated corn silage daily for 25 days. In the molar ratios of VFA in rumen fluid of cows fed treated silage, acetate was lower and propionate and n-valerate were higher than those of cows fed untreated silage. Ammonia in rumen fluid increased in cows fed treated silage. Protozoal numbers were a little higher in the cows fed untreated silage than those fed treated silage. However, no significant differences were observed in concentration of cholesterol, total protein, urea-N and glucose in blood plasma between groups. Milk yield and percentages of fat, protein and lactose in milk were not affected by the addition of ammonium propionate. Moreover, propionate was not detected in milk of cows fed treated silage. Under these conditions that cows ingest 20kg of corn silage daily, the addition of 1.0% of ammonium propionate to corn silage have no influence on the yield and milk composition, and it is assumed that treated corn silage has equal performance for dairy cows with untreated corn silage.

View full abstract

A series of field experiments was undertaken to assess changes in some structure of a pasture ecosystem due to cessation of grazing. This report deals with the changes of the form and function of orchardgrass root system in following three experimental plots ; Control plot: managed by rotational grazing ; Ca-exclosure plot: prohibited grazing from 1976 to 1979, with CaCO_3 (2ton/ha) application at the beginning of excluding; Exclosure plot: with no CaCO_3 application. The experimental results obtained were as follows: 1. The root weight per unit area of the orchardgrass pasture was increased by cessation of grazing. 2. About 70% of roots in control plot were concentrated in the top 5cm soil layer. In both exclosure plots, however, percentage of roots in the top 5cm soil layer decreased and the root pattern was deeper than that in control plot, especially evident in Ca-exclosure plot. 3. The rate of root respiration of orchardgrass in control plot was 200〜300 CO_2mg/m^2. hr from 1977 to 1979. In both exclosure plots, the rate increased with increasing root weight untill the third year of excluding (1978), however it decreased in the fourth year (1979) despite of increasing root weight. From the above results, the role of root pattern is discussed in relation to productivity and stability of permanent pasture.

View full abstract

The possibility of introducing grain maize into Okinawa region as winter crop was investigated at Ishigaki Island in the sub-tropics. Three maize varieties, Wasehomare (very early), Takanewase (early) and Hyugacorn (late), were sown every month from November, 1979 to February, 1980. As a result, the average growing days and heat-unit accumulations were 97 days and 1, 900℃ in Wasehomare, 107 days and 2, 100℃ in Takanewase, and 121 days and 2, 440℃ in Hyugacorn, which showed varietal differences in both characters. However, the most accurate differences related with the earliness were observed in the heat-unit accumulation between germination and silking stage. All plants of every plot produced at least one normal ear, which suggests that grain maize production and setting breeding nursery in winter at this region is likely to be possible.

View full abstract