Types of germinating behavior and adhering strength of tall fescue seed (Festuca arundinacea Schreb., variety "Kentucky 31") sown on the soil surface were investigated at various temperature conditions. Number of coleorhiza hairs per seed and length of the longest hair grown under submerged condition were also investigated. The seeds were allowed to germinate under constant temperatures ranging from 5 to 35℃ at 5-degree increments in both experiments. Germinating behaviors were classified into following three types : Type I ; Coleorhiza hairs of the seed adhered to the soil surface and well anchored, and the seed germinated in the same posture where it had been placed (lying type). Type II ; Coleorhiza hairs grasped the soil well to make the seeds rise up (rising type). Type III ; Coleorhiza hairs failed to grasp the soil particles of surface. Seminal root could not penetrate directly into the soil. Among rising seeds, most of seminal roots were exposed to atmosphere (exposed root type). 1) In the 15-30℃ treatments, coleorhiza hairs had a strong adhering strength ranging from 2.7 to 3.0 g, and more than 70% were observed as type II. Here germinating process was favorable. In 5℃ treatment, where seeds required longer germination period than the 15-30℃ treatments, half of seed were observed as type II and the rest was type III. The 35℃ treatment showed poor germination and most seeds were type III because of weak adhering strength around 1.10 g. The rate of the type I was less than 10% in all temperature treatments (Fig. 1, Tables 1 and 2). 2) In 15-30℃, number of coleorhiza hair were about 120-130 per seed when grown under water and mean of the longest hair of each seed were grew about 2 mm at one day after the protrusion of the coleorhiza. About 110 hairs were formed 7 days after coleorhiza appeared at 5℃, whereas fewer and shorter hairs grew at 35℃ (Table 3). 3) Adhering strength of coleorhiza hairs was closely correlated with number of hairs, length of hairs, and ratio of rising seed (Figs. 2, 4 and 5). 4) There were very few seeds of type I throughout germinating processes. Since long and many coleorhiza hairs adhered strongly to the soil surface, large number of seeds rose up and germinating process passed well at favorable temperatures, such as 15-25℃. In unfavorable temperatures, such as 5 or 35℃, type III was dominant because of weak adhesion owing to few and short hairs.

View full abstract

Germinating behavior and adhering strength of tall fescue seed (Festuca arundinacea Schreb., variety "Kenkucky 31") under various soil moistures of four soil types were investigated to evaluate the favorable moisture content and hardness of soil for attaining good establishment of seed. Yellow soil (Takanoo paddy field soil) and three kind of Kuroboku soil(Takanoo non-volcanic ash soil, Kawatabi and Nishinasuno volcanic ash soil) were used in the experiment. Yellow soil was arranged 7 levels of soil moisture ranging from 40 to 90 percent of water holding capacity at 5 or 10 degree increments, and each Kuroboku soil was 6 levels from 55 to 90 percent, respectively. The seeds were allowed to germinate under constant temperature of 25℃. The adhering strength of coleorhiza hairs which is defined as maximum tensile load to pull out a seed from soil surface, was measured by using rising seed at the soil moisture treatment in which the maximum rising percentage was obtained. The germinating behaviors were classified into three types ; Type I (lying type), Type II (rising type) and Type III (exposed root type). 1) The maximum germination percentage of type II, 80%,was obtained at 40 percent soil moisture content for paddy field soil ; the average of adhering strength indicated 3 g. In the Kuroboku soils, the maximum germination percentage of type II, about 40%, was obtained in the 85 percent treatment, and the adhering strength ranged 0.4-0.8 g (Fig. 1, Tables 3 and 5). 2) When the hardness values of Kuroboku soil surface measured by the silk-needle method rose up greater than 5 g, germinating behavior of type III increased extremely. On the contrary, type II in paddy field soil was more dominant than type III in harder than 10 g conditions (Fig. 2). 3) In all soils, type I was observed under the condition that soil surface hardness were lower than 3 g (Fig. 2). 4) There were evident differences between paddy field soil and Kuroboku soil as regards the percentage of germinating behavior type which was governed by the adherring strength of coleorhiza hairs.

View full abstract

For establishing tissue culture methods of Rhodesgrass (Chloris gay ana Kunth. cv. Katambora), callus induction and plant regeneration from mesocotyl-explants were investigated. The most effective medium for callus induction was MURASHIGE and SKOOG'S medium modified with 1.0 mg/l 2,4-dichloro-phenoxyacetic acid (2,4-D), 200 mg/l myo-inositol and 1.0 mg/l thiaminef HCl. The mesocotyl-explants for callus induction were incubated in a growth chamber controlled at 25℃ under the darkness. A high frequency of plantlet formation was obtained from the yellowish compact-friable calli with the nodular structures. The most effective medium for plant regeneration was MURASHIGE and SKOOG'S hormone-free medium. The effects of added activated charcoal and yeast extract for plant regeneration were not recognized. The calli for plant regeneration were incubated in a growth chamber controlled at 25℃ under the about 3000 lux light intensity and 12-hour day length.

View full abstract

Dominance in vegetation by Japanese lawngrass was observed in such areas of pasture as those with application of low level of fertilizer. As a result, the pasture come to be composed of two areas with different types of vegetation : one dominated by temperate grasses (TG area), and the other dominated by Japanese lawngrass (JL area). To analyse the cause of the differentiation into two types of vegetation, the following five parameters were measured in the TG and the JL areas : (1) Amount of nitrogen and potassium in soil. (2) Number of dung lumps, (3) Total treading time by cattle (total standing, walking and grazing time), (4) Amount of grazed herbage of standing crop, and (5) Soil water content. The results of these examination showed that Japanese lawngrass invaded the area where nitrogen amount in the soil and number of dung lumps were small. Cattle ate temperate grasses more than Japanese lawngrass in the area. Then the proportion of Japanese lawngrass increased, and the area dominated by Japanese lawngrass became to appear in the pasture. In the area where the nitrogen amount in the soil and the number of dung lumps were large, dominance in vagetation by temperate grasses continued. These result suggested that it was necessary to apply more amount of nitrogen fertilizer than those application so far in order to maintain a vegetation dominated by temperate grasses in the pasture.

View full abstract

The yearly changes in energy conversion efficiency of solar radiation in the period of transition from a vegetation dominated by temperate grasses to a vegetation dominated by Japanese lawngrass were investigated in a pasture. The pasture was divided into two areas with different vegetation types : an area dominated by temperate grasses (TG area) and an area dominated by Japanese lawngrass (JL area). 1) The amount of standing crop in the pasture which was largest in May and/or June in 1983 and 1984, became largest in September in 1986. 2) Yearly energy conversion efficiency from solar radiation (E0) to net primary production (E1) in the TG area decreased from 0.66% to 0.46% over a period of four years, while in the JL area it increased from 0.42% to 0.56% over the four year period. 3) Yearly energy conversion efficiency from E1 to the grazed amount (E2) ranged from 29.5% to 32.0% in the TG area, and from 34.2% to 35.3% in the JL area over the four year period. 4) Yearly energy conversion efficiency from E1 to the amount of energy of decomposed dead plant parts in the above- and underground plant parts (E3) in the TG area increased from 64.4% to 77.3% over the four year period whereas in the JL area it decreased from 72.7% to 41.8% over the four year period. 5) The amount of energy accumulated in temperate grasses decreased in the TG area year by year over the four year period. In contrast the amount of energy accumulated in Japanese lawngrass increased in the JL area over the four year period.

View full abstract

Relationships between heat temperature and degradation of ruminal nitrogenous compounds in various roughages were discussed on the basis of proportion of nitrogen disappearance from a nylon bag placed in a rumen. First cutting Italian ryegrass (Lolium multiflorum, Lam.) dried at four levels of temperature (freeze, 40℃, 80℃ and 120℃) and ensiled at two levels of temperature (20℃ and 60℃) were prepared, and described as dried materials and ensiled materials, respectively. The materials were put into the rumen by an in situ nylon bag technique and taken out after 2, 4, 6 and 8 hr. rumen exposures. The residual nitrogen content in the bag was measured to determine the proportion of nitrogen disappearance. In order to classify degradation pattern of nitrogenous compounds by a simple and mathematical way, the obtained results were simulated to a logistic equation :Y = M/ (1 + Ke^<-ax>) or Y = M/ (1 + Ke^<-a√<X>>), where Y = proportion of nitrogen disappearance; X = ruminal exposure hours ; K, M and a = coefficients. 1. The proportion of nitrogen disappearance in the rumen of freeze-and 40℃-dried materials and 20℃-ensiled materials showed more than 70% after 2 hr. rumen exposure. While those of 80℃- and 120℃-dried materials showed only 45% and 30%, respectively, after 2 hr. rumen exposure, those values increased up to 85% and 80%, respectively, after 8 hr. rumen exposure. Those of the materials ensiled at 60℃ for 6 and 12 days showed 60% and 45%, respectively, after 2 hr. rumen exposure. The values of 60℃-ensiled materials showed lower throughout 8 hr. rumen exposure than those of 20℃-ensiled materials. 2. Degradation pattern of nitrogenous compounds in the rumen differed between the materials treated under 40℃ and the one over 60℃. It seemed to be reasonable that the pattern could be shown as Y = 100/ (1 + Ke^<-aX>) for freeze-dried, 40℃-dried and 20℃-ensiled materials, and Y = 100/ (1 + Ke^<-a√<X>>) for 80℃-dried, 120℃-dried and 60℃-ensiled materials. 3. On the basis of the speed of nitrogen disappearance in the rumen, total nitrogenous compounds in the materials were grouped into three fractions containing soluble, insoluble-degraded and undegraded nitrogen. In the materials heat-treated over 60℃, the amount of soluble nitrogen fraction was smaller and that of undegraded nitrogen fraction was larger as compared to those heat-treated under 40℃. However, the disappearance speed of insoluble-degraded fraction in the rumen was low and almost constant throughout the rumen exposure.

View full abstract

A 3-year study was conducted in Chushin dist., Nagano, Central Japan to examine the varietal differences in stover digestibility of forage hybrid maize determined at yellow ripe stage desirable for ensiling, and to examine the relationships among digestibility and other agronomic traits. The test was performed on 35 commercial hybrids at 556 plants/a in both 1984 and '85, and 144 hybrids at 741 plants/a in 1986. Stover digestibility parameters analyzed include organic cellular contents (OCC), organic cell wall (OCW), high digestible fraction in OCW (Oa) hydrolysed by cellulase and low digestible one (Ob) resisted to cellulase digestion, according to the enzymatic analysis developed by ABE. Digestible organic matter (DOM) was calculated by using the contents of OCC, Oa and Ob and these in vivo digestiblities. The results were as follows : For the 2-year trial in 1984 and '85, the significant differences (P <0.01) among hybrids and years were found in OCW, DOM, maturity and mean top growth rate from seeding to harvesting, but not significantly in the proportion of ear to whole-crop dry matter. For the trial in 1986, there were manifest variations among 144 hybrids for all characters of stover digestibility. Especially, Ob ranged 24% among the hybrids. The coefficients of variability (C.V.) in OCC, Oa and Ob were larger than C.V. in the proportion of ear. The OCC and DOM contents were negatively correlated with OCW and Ob, and the varieties which highly contented OCW and Ob tended to have large proportion of ear or high top growth rate or late maturing in each trials. It was found that the Ob content was closely correlated with whole-crop DOM in each year, compared with the proportion of ear, but not found that the digestibility of OCW increased while the field resistances to lodging and disease decreased. It is concluded that there are fairly differences in digestibility of stover among the varieties of forage maize, and that the stover digestibility does not have less important role in nutritive value of whole-crop than the proportion of ear : grain content. The varietal differences in digestibility of stover may be considerably affected by the "source-sink" relationship, maturity and the indirect selection with assessing grain yielding ability.

View full abstract