Seasonal change and inter-specific difference in the growth of turf were studied on two species, bentgrass (C₃ type) and manilagrass (C₄ type) . Both turfs were grown with annually around 30 times mowing under the adequately irrigated and fertilized conditions at the experimental field of Kyushu University, Fukuoka (33°35'N, 130°33'E), in 1990 and 1991. The results obtained were as follows;
(1) The growth of manilagrass was limited to the period of April to November. The seasonal change in dry matter production of this species had a mono-peaked curve with the highest value, over 120 g/m²/month, in summer (July and August) .
(2) In bentgrass turf established by sodding, the dry matter production rapidly increased in spring and then gradually decreased towards summer. The species was not able to survive the summer of 1990 with unusually high solar radiation and long lasting high temperature. While the turf established by seed-sowing in October 1990 was able to survive through the summer of next year, the dry matter production considerably reduced. In the turf established by seed-sowing, the root system was well developed.
(3) Nitrogen content in leaf blade was 3-4% in bentgrass and around 2% in manilagrass.
(4) Aboveground growth rates (AGR) of both species were significantly related in multiple regression with four climatic factors, daily maximum and minimum air temperatures, daily mean air temperature and solar radiation. Precipitation volume and frequency influenced the AGR of bentgrass.

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In recent years, the amount of sludges issued from water purification process is increasing with high demand of city water. Since the sludges are mainly composed of soil particles and fine organic debris floated in row water, effective utilization on plant production is desirable. The purpose of this experiment is to investigate the utilization methods of the used sand scraped from slow water filtration pool and the pressed sludge issued from precipitation pond. The results obtained are as follows.
1. Turfgrass grew well in the lysimeter filled with the used sand from slow water filtration pool than in the lysimeter filled with river sand for horticulture as top soil.
2. Turbidity and phosphorus concentration of the leached water from lysimeter markedly decreased by packing the sludge from water purification process as subsoil in the lysimeter. In seme manner, the leaching of chemicals foliar-sprayed also decreased by packing of the sludge as subsoil in lysimeter.
3. However, the pucking of sludge did not reduce the potassium leaching. Besides, it increased nitrate nitrogen concentration in leached water from lysimeter.
It was considered from this investigation that the used sand from slow filtration pool was useful as culture sand for turf, and that the sludge from water purification process was available as absorbent material for phosphorus leached from turf green.

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Recently, the phenomenon of localized dry spots (LDS) occurring on bentgrass sand greens of golf courses has caused serious problems in Japan. In this study, we surveyed various districts of Japan and occurrences of LDS in certain golf courses. Using a question-nair, followed by several experiments and observations, we attempted to find the possible cause (s) of LDS on bentgrass golf greens. Regardless of the season, spot sites occurred in areas with low soil moisture and high soil temperature. Treatment with a wetting agent was effective in diminishing dry spot areas.
By examining the soil temperature and soil moisture, it might be possible to predict potential LDS sites before they occur.
Preliminary treatment of sites that have high soil temperature and low soil moisture with wetting agents might be an effective way to avoid the occurrence of LDS.

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This study presents a field examination (Experiment- I) and a pot examination (Experiment- II ) pursued in order to examine the effects of some soil conditioners on the growth of grasses and soil improvement of lawns.
Experiment- I was done on the Zoysia green of Takamatsu Public Golf Course. Each soil conditioners were mixed into the green soil in the proportion of 20% by volume, and the experiment had been pursued for 2 years.
Soil physical properties such as three phase ratio were somewhat different among the experimental plots, but we could not find any differences of the growth of the grass among the plots. It seems to depend on the very careful maintenance there.
In the Experiment-II, each soil conditioners were mixed with Masa-soil (decomposed granite soil) in the proportion of 20% and 40% by volume, and the soil mixes were put into Wagner pots, then bentgrass seeds were sown. The germination rate in each pot was influenced by the infiltration rate of the soil.
The growth of the grass depended on the nitrogen content of the soil. However, lawns are trampled very often, so soil compaction is one of the greatest problem. The resistance to compaction was very different among the siol conditioners.
It is important to understand the characte-ristics of the soil conditioners before using them.

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Differences in external form of normal stems and stolons of Gramineae plants were compared using seven species; Zoysia japonica Steud., Cynodon dactylon Pers. (bermuda-grass), Eremochloa ophiuroides Hack. (centi-pedegrass ), Stenotaphrum secundatum O. Kuntze. (St. Augustine grass), Chloris gayana Kunth. (Rhodesgrass ), Digitaria decumbens Stent. (pangolagrass) and Paspalum distichum L. (knotgrass) .
The following tendencies were recognized with regard to their rates of leaf emergence and morphological characteristics.
1. The leaf emergence rate in stolon in each species was 2.2 to 5.5 times as much as that in normal stem. Also, the elongation rates of stolon itself in bermudagrass, Rhodes-grass and pangolagrass were higher than those of normal stem, being ranged 1.8 to 3.0 times.
2. Morphological characteristics of stolon varied among species. In spite of this, stolon had a tendency to decrease the length of leaf blade and to increase the leaf width and stem thickness compared with normal stem.
3. Considering their morphological charac-teristics, development of leaf internode unit (LIU, Sharman, 1942) of normal stems begins generally from the initial LIU consisted of undifferentiated leaf blade, leaf sheath and short internode, and proceeds by stages to the fully developed LIU with leaf blade specific to the species and long internode, further stages from LIU carring boot leaf to LIU forming reproductive organ.
However, stolons of centipedegrass, pangola-grass and P. distichum L. were shown to interrupt their processes temporarily and to simply repeat certain stages during development of LIU.
On the contrary to these species, stolons of Z. japonica Steud., Rhodesgrass and St. Augustine grass were shown to dedifferentiation three to four stages backward from certain stage through development of LIU, and then proceed again the same stages periodically.
Based on the repeating types of LIU during developmental stages in stolons, the authors classified stolons of tested species into four types.

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