The objective of this experiment was to determine varieties of orchardgrass (Dactylis glomerata L.) suitable for the intensive grassland in Northern Kanto district (Latitude : 36-37°N.). Nine varieties were evaluated for the forage productivity and competitive ability to Ladino white clover (Trifolium repens L.) under two levels of manuring (standard application and heavy application) and two different clipping frequencies (five and seven times per year). The sward was sown with a mixture of orchardgrass and Ladino clover and a randomized split-split-plot design with three replications was used. The nine varieties of orchardgrass used were selected by time of heading and plant type, such as early maturing varieties viz. Nakei-1, Tottori-yasei and Hokkaido-common, medium maturing varieties viz. Aonami, Frode and S-143, and late maturing varieties viz. Latar, Nakei-6 and Pennlate. This study was carried out in 1965-1966 and results summarized were as follow : 1. There were significant difference for the amount of fertilizer applied and difference of varieties. The highest forage yield was achieved at 2, 440kg per are and the average forage yields of nine orchardgrass varieties were shown at 2, 340kg per are under intensive management (heavy manuring with seven cuts annually) during each of experimental two years. Therefore, the results of this experiment were satisfied with initial aim which should be gain a great deal of forage production. 2. According to these experimental results, it is obvious that the high yielding varieties are, in general, correlated with early heading varieties of Japanese origin, those varieties characterized by the long-culm type, of disease-resistant and of high fertilizer response. However, some of introduced varieties are deficient in summer and fall vigor as well as disease resistance as compared with domestic material. 3. It is difficult to maintain good balance of grass and clover under the heavy application and close clipping. Perhaps Ladino clover would often prevail aginst orchardgrass in Japan. The following characters are considered to be correlated with competitive ability e. g. time of heading, growth habit (erect or prostrate), susceptiblity to summer depression, resistance to disease and some morphological characters (width of leaf, thickness of midrib and plant height). The least competitive varieties such as Nakei-6 and Pennlate are characterized of late-maturity, short stem, prostrate type, narrow leaves, thin midrib and poor summer growth. Therefore, each of them almost looked a clover sward by the rainy season of the 1st hervest year and showed poor grass productivity. 4. It is concluded that Tottori-yasei, Nakei-1, Frode and Aonami are recommended and suited for as a high yielding variety under the intensive managements. Hokkaido-common is found of lenient utilization and Latar is tended to promote forage production. year after year. However, Pennlate, Nakei-6 and S-143 perform a poor forage production because of its lack of commpetitive ability, summer vigor and late maturity.

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In white clover sward, penetration of the adventitious roots to the soil is severely disturbed in summer season under south-western Japanese condition. Cutting-, soil temperature-, and soil moisture-treatments were applied to the stolons of Ladino clover in order to determine which environmental factor relates with disturbing root penetration. Cutting treatment or clipping of newly developed leaves did not disturb the penetration of the root produced from the treated node. Low soil temperature depressed the root formation as well as root penetration to the soil, but in the range of temperature from 15℃ to 30℃, there was not observed so much difference in root penetration. The most detrimental treatment on the root penetration was dry condition of the soil surface. When the soil surface was kept fairly wet through the experiment, the rate of the nodes possessing the penetrated adventitious root was 90% of the total nodes, whereas that of dried soil was 40%. Also, the distance between location of rooting and soil surface seemed to affect the root penetration. The longer the distance was, the more the disturbance they suffered. So far as the root system was concerned, it was important for root penetration to keep the soil surface wet and make the stolon contact to the soil surface as near as possible.

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In Chiba prefecture, a new leaf spot of velvet grass, meadow fescue and rye was observed. From inoculation tests and some morphological studies, they were identified as Helminthosporium sorokinianum Sacc. ex Sorokin (=H. sativum P.K. et B.). This seems the first odservation of the fungus infecting velvet grass (Holcus lanatus L.) in the field. In inoculation tests, tall fescue was observed to have some resistance to the fungus from meadow fescue.

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A study was conducted to obtain informations on the competitive ability of the different types of white clover when introduced into the grass swards. Four types of white clover, i. e., wild, common, ladino and polyploid ladino (octaploid) were used. Propagules of the four types were transplanted into the fields which were broadcasted with orchardgrass and with redtop. Pure stands of each clover type were also established. Yields of clovers and grasses were recorded separately at each clippings over two years. Severe summer drought was experienced in both years of the experiment. Under the condition of low clipping frequency of the experiment, wild and common type white clovers in orchardgrass and in redtop swards were smothered out at the end of the first harvest year by the competitive pressure of the companion grasses and by summer drought (Fig. 1). Ladino and polyploid ladino types in the first harvest year maintained appropriate clover density in the swards and increased the grass yields. In the 2nd harvest year, the growth of polyploid ladino was so vigorous that it overwhelmed the companion grasses and lowered the yield of grass component in the swards. Ladino type behaved in the similar manner to the polyploid up to the 2nd clipping, but disappeared at the end of the year partly because of the competition with the grasses and partly because of summer drought (Fig. 2). Agressiveness of the polyploid type of ladino clover may be largely due to its advantage in plant height which makes it possible to receive more solar energy in the swards compared with the other smaller types. It will be of worth to point out the fact that the polyploid type survived well under severe summer drought of two years. Differential response of the clovers to the two companion grasses was not detected in the present experiment.

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