@article{oai:mie-u.repo.nii.ac.jp:00005702,
 author = {森田, 脩 and Morita, Osamu},
 journal = {三重大学生物資源学部紀要 = The bulletin of the Faculty of Bioresources, Mie University},
 month = {Mar},
 note = {application/pdf, Sod- and over-seeding methods have been considerabty employed on grassland development, especially in mountainous area of Japan. On the surface of untilled land, however , seed germination and seedling establishment seem variable depending on the ecosystematically combined conditions of vegetation, soil, and weather. In the present study the germinating process and behavior of surface-
sown seeds of temperate grass species was, on a laboratory scale, investigated in relationship to the
function of coleorhiza hairs in seedling establishment under several different conditions of soil and temperature.
I.  Characteristics of Germination and Establishment of Surface-sown Grass seeds
1)  Germination process and behavior
   In the germination process of tall fescue seed placed embryo downward on the soil of the seed
bed, the coleorhiza appeared at the basal portion of the lemma and developed numerous hairs around the tip of that organ first. The coleorhiza hairs adhered to the soil surface, entered the soil and then
bound soil particles. This anchoring action of the coleorhiza and its hairs was followed by the appearance and penetration of the seminal root. The germination process of the coleorhiza phase was identical for different conditions of soil and environment, while the process of seminal root penetration was variable depending on the adhering strength of coleorhiza hairs equivalent to the maximum tensile load to pull seed out of the soil surface. To measure these values, an apparatus was devised in the present study. Germinating behavior was classified as three different types as follows:
TYPE  I (Lying type); Coleorhiza hairs of the seed adhered to, and were anchored in the soil, and the
seed germinated in the same lying posture as it was placed.
TYPE II  (Rising type); Coleorhiza hairs grasped the soil well, and seed germinated in rising posture.
TYPE Ⅲ (Exposed-root type); Colerohiza hairs failed to grasp the soil particles, and the seminal root could not directly penetrate into the soil adequatly. Seminal roots in most of the seeds were held
up and exposed over the soil surface.
\n2)  The variations in germinating behavior and adhering strength of coleorhiza hairs of six temperate grass species Orchardgrass, tall fescue, and Kentucky bluegrass had a relatively higher percentage of rising type
in germinating behavior and of penetration of seminal root than did meadow fescue, perennial ryegrass and Italian ryegrass. The adhering strength of coleorhiza hairs was higher at the level of 2 gr per seed
for orchardgrass, tall fescue, and Kentucky bluegrass than at that of 1 gr per seed for the other grass species tested. Within each of grass species, the adhering strength of coleorhiza hairs was found to be
closely related to the percentage of rising type in germinating behavior (r=0.96, p<0.01).  Overall six grass species examined, however, there was not relationship between those two measurements, probably reflecting in their differences in the shape and weight of seeds.
   Coleorhiza hairs, and especially their adhering strength, are a very important factor associated with seedling establishment of surface-sown seeds. From this perspective, there were some advantages in
sod- and over-seeding were for tall fescue, orchardgrass and Kentucky bluegass.
   
Ⅱ. Effects of Environmental Conditions of Temperature and Soil on Germinating Behavior and Adhering Strength of Coleorhiza hairs
1) Temperature
    The germinating behavior and the adhering strength of coleorhiza hairs of the surface-sown tall fescue were investigated under different temperature conditions. The best germination process was
observed at the temperatures of 15- 25℃ which have been known as the favorable range of growth
temperatures for temperate grass species. Within that temperature range the coleorhiza hairs
appeared,grew vigorously and adhered strongly to the soil surface,and the percentage of the rising type in germinating behavior was considerably higher as compared with other temperatures, such as
5℃ and 35℃. At the unfavorable temperatures, the exposed root type was observed more frequently, reflecting the weak adherence of coleorhiza hairs which was associated with lower number and
length of the hairs. The lying type was infrequent throughout all temperature conditions tested. The
adhering strength of coleorhiza hairs was closely correlated with number and length of those hairs and with the percentage of rising type (r =0.89, p<0.01 and r=0.92, p<0.01).
\n2)  Soil type, moisture and hardness
    The germinating behavior and the adhering strength of coleorhiza hairs of surface-sown tall fescue
seed in a yellow paddy field soil and in three different types (sampled from Takanoo, Kawatabi, and Nishinasuno areas) of Kuroboku soil treated with 7 or 6 moisture levels (40- 90%) were observed.
With all soil types and moisture levels, the lying type was rernarkably dominant below the hardness value of 3 gr which was determined on the soil surface by the silk needle method. The percentages of the rising type and the exposed-root type were increased with increasing soil hardness related to the 
decreasing moisture content. The highest percentage of the rising type was obtained at 40% and 85%
moisture contents for paddy field soil and for the Kuroboku soils respectivety,indicating that the adhering of coleorhiza hairs was very variable in different physical structures of soil.
\n3) Forms of organic litter on the soil surface
   As for with the germination rate and percentage of tall fescue sown on the soil surface, those
values of that grass were not influenced by three different forms of organic litter placed on the soil surface (the leaf litter layer, the decomposed layer, and the ash layer), except for a lower germination rate
with the leaf litter layer. The rising type tended to be higher for the decomposed matter than the leaf
litter form, although all percentages were considerably higher in the exposed-root type. The adhering
strength of the coleorhiza was, as the result of combining adhering potentiality of the hairs and physical
structure of soil or organic matter, lower with the decomposed matter and ash layers as compared with
the yellow paddy field soils.
\nIII. Effects of Soil Amendment matter and Seed Pressing on the Seed Germination and
    Seedling Establishrnent
1) Application of soil amendment matter
    The germination behavior of surface-sown tall fescue was investigated at the different pH conditions of each of the yellow paddy field soils and the Takanoo Kuroboku soils treated with applications of
soil amendment matter. The rising type in germinating behavior was dominant at the pH values of 5
to 8 in the paddy field soils and at the values of 5 to 6 in the Kuroboku soils. An application of fused magnesium phosphate was more effective in improving the p.H value of the acid Kuroboku soils and the germinating behavior in that soil than was that of superphosphate.
\n2) Seed pressing
   Cattle trampled surface-sown seeds into the soil induced more favorable germination, such as higher percentage and higher initial growth of plant. Without trampling, most of seeds were lost during unsettled conditions.
   The adhering strength of coleorhiza hairs of surface-sown seeds was increased by seed pressing to about 1.4-2.4 times as much as no pressing, showing a higher percentage of the rising type which was superior in the initial growth to the exposed-root type. By inserting the embryo part of the seed into
the soil to about 2 mm depth, or by pressing seeds at the force of about 1 gr, good penetration of the seminal root and good seedling establishment were highly achieved even for the Kuroboku soils in which the exposed-root type was normally dominant.
\n   In the present study adhesion of coleorhiza hairs to the soil surface was found to aid favorable
penetration of the seminal root and thereby to induce favorable seed germination and seedling establish-
ment because such anchoring action could protect seeds from being held by the penetration of the semi-
nal root, The strength of coleorhiza hairs was found to be positively related to the percentage of the
rising type in germinating behavior observed during such initially critical stage of germination. The rising type in germinating behavior resulted in good seedling establishment, while the exposed-root type
did not survive. With the sod- and over-seeding establishment tested here, the percenhge of the rising type was variable depending on grass species, soil type and moisture level, hardness of soil surface,
form of organic litter, application of soil amendment matter, and seed pressing. Frorn the viewpoint of
the adhering function of coleorhiza hairs, application of soil amendment matter and seed pressing were
found to be effective methods to improve seed germination and seedling establishment, especially for
acid Kuroboku soils which weakened the adhering strength of coleorhiza hairs.},
 pages = {1--72},
 title = {不耕起草地造成におけるイネ科牧草の発芽・定着に関する研究},
 volume = {4},
 year = {1990}
}