If the semi-natural Miscanthus sward should be utilized for livestock feeding without renovation, the most efficient management practice may be fertilization, since the productivity was effectively increased by it, although the increment was progressively decreased as the level of fertilization was increased. With or without fertilization, the sward production was sharply declined with increased cutting frequency, resulting in a bracken (Pteridium aquilinum) prominent sward, at which the growth of Miscanthus plant decreased and the growth of other available grasses (Arundinella hirta, Spodiopogon sibiricus) increased. One cutting at heading time of Miscanthus plant could maintain the sward persistence with a high level of dry matter production (12 tons per ha) for many years because of vigorous growth of Miscanthus plant, whereas the herbage may not be used efficiently for feed since the plant was too matured with low digestibility and palatability. The productivity in terms of dry matter and crude protein yield of feed herbage of the renovated orchardgrass-ladino clover mixture was always higher than that of the Miscanthus sward cut 2 or 3 times during a season. When the latter sward is grazed, the productivity difference between the two swards may be far more increased, because the cattle may intake the palatable plants selectively and their regrowth may be depressed under the canopy of unpalatable plants, thus resulting in the lesser production of available herbage than that obtained by cuttings. Therefore it may be concluded that the Miscanthus sward should be renovated to appropriate artificial sward as far as the feed production is concerned.

View full abstract

Relatively few attempts have been made to define the relationships between stage of seed development and germination capacity in pasture grasses. In the second report of this series, the germination behaviour in relation to seed development of Rumex obtusifolius L. was investigated and three developmental phases could be recognized during seed development after flowering. The present experiment was carried out to make clear the changes in dry weight, % moisture content and germination behaviour during seed development of Aonami orchardgrass (Dactylis glomerata L.), and moreover to evaluate the effect of prechilling treatment on the dormancy-breaking of the seeds at various stages of the development. The results obtained were as follows ; 1. Immediately after harvest of mature orchardgrass seeds, the germination rate under continuous light condition was high in low temperature range (18℃-23℃), but decreased in high temperature range (28℃). Under continuous dark condition, the germination scarcely occurred at any constant temperature. Such light-sensitive and temperature-dependent germination was induced regardless of the varieties and the locations where the seeds were harvested. 2. Three developmental phases during seed maturation could be recognized as follows ; The first phase lasted for about 7 days after flowering. During this stage, dry weight increased gradually and moisture content was above 60%. The seeds harvested during this stage were not viable. The second phase lasted for end of the first phase to 28 days. During this period, dry weight increased rapidly and moisture content decreased gradually. The seeds during this stage could not germinate immediately after removing from plant. However, with the lapse of the period of air-drying at room temperature, the light-dependent germination occurred within the limited range of temperature (18℃ to 23℃). Especially, the seeds stored at laboratory conditions for 2 to 3 months after harvesting showed almost the same germination behaviour as the seeds at the third phase. The third phase covered the period after 28 days. From this time on, dry weight and moisture content became equilibrium and the appearance of the seeds got complete. During this stage, immediately after harvesting, the light-dependent germination within the limited range of temperature occurred apparently, and scarcely changed during air-drying period following the harvest. 3. The dormancy of the seeds harvested on the 30th day from flowering could not be broken by any period of prechilling treatment when the moisture content was high (39.5%) immediately after removing from plant. The dormancy, however, was noticiably broken by prechilling for 10 days when the moisture content decreased to 9.7% after air-drying at room temperature for 7 days. After air-drying for 3 to 4 months following the harvest, the seeds in any developmental phase, except the first phase, markedly responded to prechilling treatment, and consequently high germination occurred even in high temperature range under continuous light condition.

View full abstract

Indole-3-acetic acid (IAA) production from L-tryptophan (L-Try) and IAA destruction were examined using Rhizobium meliloti. Nitrate did not affect the rate of L-Try decomposition by this bacterium. IAA was decomposed under non-aseptic condition, but not under aseptic condition irrespective of the presence of this bacterium. It is therefore concluded that a strain of R. meliloti used in this experiment can not decompose IAA.

View full abstract

The effects of coumarins on the germination and growth of white clover, red clover, timothy and orchardgrass were examined in this study. Coumarin at 10^<-3>M inhibited considerably the germination of white clover, timothy and orchardgrass, but not red clover. 4-Hydroxycoumarin, 7-hydroxycoumarin and trans-o-coumaric acid inhibited to a great extent the germination of timothy, but the other three species were comparatively resistant against these coumarin analogs. The germination of white clover, timothy and orchardgrass was inhibited even by coumarin at 10^<-4>M and that of orchardgrass was slightly promoted by coumarin at 10^<-6>M. The elongation of white clover hypocotyl and orchardgrass coleoptile was inhibited with increasing coumarin concentrations. This was also true for red clover and timothy at higher concentrations of coumarin. The elongation of red clover hypocotyl and timothy coleoptile was promoted by coumarin at low concentrations. The thickening of white clover and red clover hypocotyls, and of timothy and orchardgrass coleoptiles in the transversal direction was evoked by coumarin treatment.

View full abstract

A new method of pelleting seeds with pelleter machine is described. The mixtures of pelleting agent are 38% lime, 37-38% talc, 19% bentonite, 1% Yogros, a commercial organic fertilizer, 3% potato starch, 1% avicel, a microcrystalline cellulose with 1-2% seeds by adding water to 22-26% of the mixture in weight. Mixtures are kneaded carefully by adding cupful of water for five minutes to make viscosity ready for pelleting, when seeds are added and kneaded again for half a minute before passing through the pelleter machine. The pelleted seeds are then dried in a ventilating drier for over one hour to reduce the moisture content to less than 5% that is good for storage and transport. Pellets are 3 to 4mm in diameter, 11.1 to 17.6mm in length, 159 to 420mg in weight and the hardness being 4.06 to 5.22kg/cm^2 with smooth surface of excellent texture. Pellets can absorb adequate moisture in one hour on wet filter paper and promote germination of timothy, Italian ryegrass, red clover and white clover seeds and later growth of the four species, e.g. in grass height, root length, number of leaves and tillers. Pelleted seeds of this type are applicable for farm mechanization as their characteristics resemble those of the conventional pelleted fertilizers.

View full abstract

Phytotoxic substances were extracted from sawdust with boiling water. The ether soluble substances from the water extract were separated into acidic, neutral and basic fractions. Acidic fraction exhibited the highest phytotoxicity, followed by neutral fraction. Basic fraction showed only slight toxicity. The acidic materials in acidic fraction described above were fractionated into eight fractions on a alumina column using a solvent elution series. Six fractions of them showed inhibitory effect on the growth of wheat seedlings, of which the benzene, the methanol, the water and the sulfuric acid fractions had intensively inhibitory effect. The toxicity of the ethylacetate and the formic acid fractions were weak. Six fractions described above contained acidic substances and phenolic acid which gave a positive reaction with chlorophenolred or diazotized sulfanilic acid, respectively. The significant correlation was not recognized between phytotoxic activities and total amounts of phenolic acids in each fraction. It was found that the greater parts of phytotoxic activities are located at the Rf regions corresponding to non-phenolic acids by paperchromatography. The chromatographycally separated acids were not identified.

View full abstract

NO_3-N and NO_2-N concentrations of green-chopped forage sorghum harvested at the various stages were determined and physiological responses of the cow fed this sorghum were investigated, and furthermore nitrate poisoning was occurred by a dose of NaNO_3. These results were summarized as follows. 1. Comparing the stem with the leaf blade, NO_3-N concentration in the stem was much higher than that in the leaf blade, and the concentrations in both the stem and the leaf blade appeared to decrease with growing. There seemed to be no difference between NO_2-N concentration in the stem and that in the leaf blade, and the concentrations were very low. For that reason, the concentrations appeared to be neglected from the standpoint of nitrate poisoning. 2. In the case of feeding 50kg/day of green-chopped forage sorghum (300mg/100g dry weight, as NO_3-N) to the cows, various responses were observed. Blood NO_3-N was observed in all cows, and then it appeared to be excreted into urine. Methemoglobin was not observed in all cases. Clinically this degree of the amount of green-chopped forage sorghum didn't remarkably affect the cows. 3. When dosed 150g of NaNO_3 to the cow (body weight 480kg) at 9.00a.m. and. 5.00p.m., nitrate poisoning occurred after second dose. This amount of NaNO_3 was equivalent to the feeding of 10kg (dry matter basis) of green-chopped forage sorghum containing 500mg/100g dry weight as NO_3-N. However, when taken account of other reports and the individual difference of cow, the amount of approximately 400mg/100g dry weight appeared to be danger.

View full abstract

In order to clarify the effects of various conditions for management (scale of grassland, scale of dairy cattle number, and labor power) on the utilization of grassland and the yield, a typical analysis was executed by use of the parametric linear programing method. The place for investigation object was Toyotomi Town under the administration of Soya Branch Office of Hokkaido. The method of analysis was to divide the stereotypes of management for a planning model into the types of employed labor power utilization, domestic labor power utilization and machine union utilization, to establish twelve stereotypes for grassland utilization, and to calculate the optimam grassland utilization on each grassland scale. Results obtained are as follows: 1) Supposing that the labor power and the condition for equipment of labor means are constant, the grassland utilization becomes rough by the enlargement of grassland area and the yield of pasture utilization per ha (Nutrient quantity) decreases. Furthermore, there s a limit of intensiveness by the labor power in the type of domestic labor power utilization. Accordingly, the yield of pasture utilization per ha is lower than that in the type of employed labor power utilization, and it is shown that the rate of decrease according to the scale of grassland is large. 2) Supposing that the grassland area and the condition for equipment of labor means are constant, the grassland utilization becomes intensive by the increase of labor power, and the yield of pasture utilization per ha indicates a trend of slight increase. 3) From the above-mentioned facts, by the enlargement of grassland area per person, the grassland utilization is transferred from the intensive grassland utilization to the extensive grassland utilization. Accordingly, supposing that the quantity of pasture supply (utilized fresh grass quantity) per dairy cattle is constant, the scale of dairy cattle breeding number decreases relatively by the enlargement of grassland area. 4) From these results, it was estimated that the largest grassland area in the case of two family labor powers with three stereotypes is 40.0ha of grassland area (dairy cattle: 65 head; agricultural income: 6,000,000yen) for the type of employed labor power utilization, 20.0ha (35 head; 3,400,000yen) for the type of domestic labor power utilization, and 30.0ha (45 head; 4,000,000yen) for the type of machine union utilization. This conclusion could be introduced from the presumption of a constant self-supply rate of feed and adoption of the present systematized techniques, and the examination on the change of self-supply rate and the discussion in the case of introducing the improved systematized techniques remain as future problems.

View full abstract

Maximum crop growth rate (_<max>CGR) was examined for seasonal regrowth in the pure swards of alfalfa (Medicago sativa L., Du Puits) and ladino clover (Trifolium repens L., Pajbjerg Milka), grown under well fertilized and managed conditions with four times of defoliations, and the correlations of _<max>CGR and net assimilation rate (NAR) with several growth attributes in optimal LAI (_<opt>L) period were determined. NAR was expressed as the following equation revised from those of IWAKI (1958). NAR=(a-γ)-γ_n/SLA-R・(C/F)・(1/SLA)…equation (3), in the text. Here, (a-γ) is apparent photosynthetic rate of canopy leaves on leaf area basis in the daytime, γ_n respiratory rate during night canopy leaves on dry weight basis and R respiratory rate of non-photosynthetic organs on dry weight basis. Other symbols are given in the explanation of table 1. The methods for measurements of dry matter production, stratified clipping for light attenuation (extinction) coefficient (K), solar radiant flux density (S) are the same as OKUBO et al (1969). For measurement of chlorophyll content on leaf area basis (ChA), the canopy was cut with the stratified clip method into four or five layers from the top to the bottom and weighd for fresh leaf weight. Duplicate fresh materials of 2-4g were samlped for chlorophyll content, 10g for moisture content and about 10g for leaf area measurement, from which the chlorophyll content on leaf area basis (ChA), that on dry weight basis (ChW) and specific leaf area (SLA) were calculated for each of leaf layers of a canopy. For the calculation of CI, the chlorolpyll amount of each leaf layer was once determined individually, summed it to the total chlorophyll amount of leaves per unit ground area (CIL ; leaf part of CI), and added stalk chlorophll (CIS ; stalk part of CI) to the CIL into the CI for a whole canopy. The average ChA of a whole canopy leaves was determined by dividing the CIL by the LAI. Other procedures were approximately the same as BROUGHAM (1960), but the equations for chlorophyll determination by ARNON (1949) were corrected as the equation 1 in the text because there were found some slight mistakes in ARNON's equations. 1._<max>CGR attained to the highest in spring growth (exactly in June) in alfalfa and in midsummer growth in ladino clover at the value of 20 and 21g/m^2/day, respectively, among those of four seasons. _<max>CGR during autumn growth period was the lowest in both species at the value of 12.1 and 5.8g/m^2/day in alfalfa and ladino clover swards, respectively. These variations in _<max>CGR depended more on the NAR than on the _<opt>L in the growth of four seasons. Since the solar radiation for the period of _<opt>L in autumn growth was very low, one thirds of that in spring, the low values in _<max>CGR, NAR and _<opt>L also might be partly caused by the low level of the solar radiation. 2. The highest ChA among the four seasonal growth was observed in June for alfalfa sward at the value of 4.68mg/dm^2 of leaf surface and in August for ladino clover of 4.68mg/dm^2 also. The lowest was found in autumn sward at 2.94 and 2.96mg/dm for each species. This variation in ChA was closely proportional to the _<max>CGR and the NAR. 3. The _<max>CGR significantly correlated positively to ChA (r=0.93), S (0.74) and T (0.81) and negatively to C/F ratio (-0.75). The correlation coefficient of NAR with ChA only attained to significant level among the several growth attributes (table 2). Partial correlation of the _<max>CGR showed a significant value to ChA and K, and the correlation of the NAR was significant only in case with ChA (table 3). ChA showed a simple correlation significantly with S, T and C/F, and a partial correlation with S and K. 4. Photosynthetic rate under saturated light for a single leaf, taken from various depth within a canopy around _<opt>L

(View PDF for the rest of the abstract.)

View full abstract

To ascertain the dependence of maximum crop growth rate (_<max>CGR) and net assimilation rate (NAR) upon chlorophyll content of leaf surface in the canopy having a nealy optimal LAI, as seen in the previous investigation, crop growth rate was measured in the alfalfa swards (Medicago sativa L., Du Puits) with four plant densities. The plots with four different level of density were coded as D1>D2>D3>D4 (see the explanation of fig.1). Several times of the measurements of dry matter growth both for the top and underground organ were set out when the canopy attained to 80% light interception at the ground level and continued at one-week intervals for each of the densities. Around the optimal LAI, two times of the measurements with stratified clip method were also carried at the intervals of a week at each density plot in order to determine the light extinction coefficient (K). The vertical changes in chlorophyll content and specific leaf area within a canopy, which was divided into 4〜5 leaf layers, were also measured. Other details in the method for CGR and chlorophyll measurements were the same as the previous papers (OKUBO et al, 1969, 1975a). Changes in photosynthetic rate under dim light (55, 100, and 150cal/dm^2/hr, 400〜700mμ) with leaf age were also determined for alfalfa leaves (Du Puits). The leaf materials were taken from various positions of the plants grown in artificial community, which were planted individually on a peat soil pot and arranged with space of 25×25cm in a glasshouse, and they had been marked on the day of leaf unfolding as leaf age zero. Initial slope of light-photosynthesis curve was calculated as the ratio of gross photosynthesis to incident visible light on energy basis ; the maximum energy efficiency (φ0). Apparatus used was the same as those in the work by GABRIELSEN et al (1959). Chlorophyll determination method was seen in the previous papers (OKUBO et al, 1964, 1975a) Symbols used were given in the explanation of fig.1. 1. Variation in _<max>CGR was observed among the different levels of plant density of alfalfa sward, and it obviously depended more on CI than on _<opt>L (fig.2). Since the CI at this stage can be shown as Cl=_<opt>L×ChA+stalk's chlorophyll and there was not so much difference among the values of _<opt>L, this dependence on CI means that the _<max>CGR and the NAR had close relations with chlorophyll content on leaf area basis (ChA per LAI) at the stage of _<opt>L for each canopy at each density, although solar radiation and C/F ratio showed relations more or less to the _<max>CGR or the NAR (fig.3). 2. ChA of a canopy leaves increased with growth and attained once to the highest level at the growth stage of _<opt>L (at 90〜95% light interception, exactly) followed by a decrease again at excess LAI. ChA measured for each leaf layer with different depth in a canopy showed at most 4.0〜5.0mg/dm^2 at the period of _<opt>L and were mostly below 4.0mg/dm^2 in the canopies before the _<opt>L (fig.4). 3. Photosynthetic rate under dim light increased with leaf age to the highest on 15-20th day from unfolding and decreased. ChA of the leaf showed approximately the same time course as the photosynthesis. The initial slope of the light-photosynthesis curve on energy basis (φ0) showed a close correlation with ChA in the range of 1.0〜5.0mg/dm^2 (fig.5, fig.6). 4. The dependence of _<max>CGR and NAR on ChA shown in the previous paper (OKUBO et al, 1975a) would be caused by the facts that the variation of photosynthetic activity occurred with aging and mutual shading of canopy leaves followed by changes in microenvironmental condition, especially in light, and that the change of the activity was apparently observed in terms of ChA in the canopy at _<opt>L. But the ChA as a weak light factor also must have contribute partly to the close correlation among _

(View PDF for the rest of the abstract.)

View full abstract