An old, deteriorated and weedy pasture, with remains of orchardgrass and red top, was resown naturally by deferred defoliation in two methods and compared with control during two grazing seasons of 1984 and '85. Treatment were: R1. Cutting in early August after deferring from spring in 1984, then followed two grazings in September and October (plot size 12.5a). R2. The same treatment as R1 except no grazing in September (plot size 12.5a). C. Conventional grazing (plot size 25a). In the following year, all experimental plots were grazed simultaneously after removing fences among the plots. The results obtained were summarized as follows: 1. The seed production and the quantities of fallen seeds in early August per m^2 in R1 pasture were 91.1g and 59.3g, respectively. 2. Soil moisture contents in R1 and R2 pastures in August and September, when plenty of fallen orchardgrass-seeds began to germinate, were distinctly higher than that in C pasture. Soil hardness in R1 and R2 pastures at the same months was significantly softer than that in C pasture. 3. The death-rates of adult orchardgrass from April to October in 1984 were higher in naturally reseeded pastures then in C pasture (R1: 74%, R2: 68%, C: 39%). 4. The vegetation after natural reseeding in R1 pasture was remarkably improved by the marked increase of individual density due to a large number of plants naturally-reseeded, especially by orchardgrass. On the contrary, in R2 and C pastures the invasion of aggressive weeds, particularly Digitaria adscendens Henr., made those vegetational status worse. It seems that the success of natural reseeding method in R1 pasture might be due to the plentiful fallen orchardgrass-seeds in addition with the good environmental condition (i.e. soil moisture, soil hardness, the competition between new seedlings naturally-reseeded and other plants, …) for the germination and establishment of fallen seeds.

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The process of the freezing injury in the crown of the seedlings of orchardgrass (cv. Kitamidori) was studied using by paraffin sections made at thawing and by observing regrowth of seedlings after two freezing treatments ; 1. Freezing at -3℃, -6℃, -9℃ and -14℃ for 16 hrs (Short time freezing), 2. Freezing at -3℃ and -6℃ with several durations up to 12 weeks (Long time freezing). In short time freezing, the percentage of survival plants, their fresh weight and their plant height decreased with the decreasing of temperature. The regrowth of the main shoot was less than that of tillers. The damage of the organs and tissues both of the main shoot and the tillers increased with the decreasing of temperature. The damage was heavier younger leaves (Y) followed by transitional region (T), shoot apex (S), basal part of the leaf sheath (B), lateral bud (L) and root primodia (R). The main shoot was injured more than the tillers. In long time freezing at -3℃, the number of leaves which developed from the main shoot started to decrease at 2 weeks, and the killing of plants began at 6 weeks. The damage of the organs and the tisses both of the main shoots and the tillers was increased as the freezing was prolonged. The main shoots were injured more than the tillers. The decreasing order of the degree of damage was Y≧S>L>B>T≧R. In long time freezing at -6℃, almost all the plants died at 2 weeks. The main shoots of ten cultivars which were differed in frost hardiness were injured more than their tillers during the short time freezing of -3℃, -10℃ and -12℃. Their shoot apices were injured more than their lateral buds. The younger leaves and the shoot apices of larger tillers were more damaged than those of the smaller tillers (the primary tiller from the larger tiller) within a plant which were collected from several pastures in Obihiro at the end of snow cover. These results indicated the importance of freezing injury which causes the death of younger leaves and shoot apices of vigorous tillers and finally decreases the number of ears at first cut in every year in the pastures of soil freezing area, eastern Hokkaido.

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Lucerne leaf protein concentrate (LP) was prepared at the pilot plant at Bidkin in India by the following procedure. Extracted lucerne juice was heated to 90℃, poured into filter tubes and pressed to recover LP. The LP was resuspended in water. The suspension was adjusted to pH4 to coagulate the LP again and filtered as before. The wet LP was dried in the shade. Nutritive values of LP, 1:3.8 mixture of LP and a wheat flour (LP: WF) and a calf milk replacer containing LP at 10% (MR) were studied using rats. True digestibility of protein, nitrogen retention and biological value of LP were 83, 44 and 71%, respectively. By supplementing methionine, the nitrogen retention and the biological value of LP were significantly improved to 60 and 89%, respectively. Supplementation of lysine in combination with methionine was not effective in improving the nutritive value of LP. These results are superior to those reported on LP prepared by oven-drying without washing and similar to those reported on freeze-dried LP suggesting that the nutritive value of LP is affected by the remaining brown juice rather than the drying method. True digestibility of protein in LP: WF and MR was better than that of LP. Biological value was similar in the three preparations. The supplemetary effect of methionine alone was significant only in LP. Supplementation of lysine alone was effective only in LP: WF. The nutritive value of MR was significantly improved by adding both methionine and lysine. The improved biological value was the highest in LP (89) followed by LP: WF (85) and MR (81) in that order. While improved nitrogen retention was the highest in LP: WF (69) followed by LP (61) and MR (58). The Ca and P contents of MR were a little shorter than those recommended by NRC. LP contained more than a half of the reguirements of Ca and P of monogastric animals. But, LP was a good source of Mg. The concentration of Na and K in LP was very low. The high Fe content of LP might be derived from rust of plantmachine and/or water.

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This study was carried out to investigate the possibility of regeneration of pasture by natural reseeding of orchardgrass. In order to know the realities of natural reseeding and to explain it's necessity, vegetational changes which involved density, coverage, stand frequency and buried seeds of various species, stand diameters and distances between stands of orchardgrass were determined in the pastures established at 1976, 1977, 1978, 1979, 1981 and 1982 in Yachiyo public pasture, Obihiro. The frequency of pasture plants, weeds, and self-sown orchardgrass seedlings in lightly grazed pasture were compared with those in conventionally grazed pasture. Changes of density of self-sown orchardgrass seedlings were surveyed at lightly grazed pasture before and after winter (1983-1984). The results obtained were summarized as follows: 1) It was remarkable that SDR_3 of orchardgrass tended to decrease and that of weeds tended to increase with increasing of pasture age. 2) Accompanied with increasing of the distance between orchardgrass individuals, the diameter of orchardgrass plants increased sharply from 7th year. It was shown that the vegetation change of pasture could be caused by the formation of bunchy plant of orchardgrass. 3) The results 1) and 2) suggested that a suitable density of pasture plant was very important to maintain vegetation continuity, but the formation of bunchy plant and decrease of density of orchardgrass is usually followed with conventional utility. In the sense of this fact, the necessity of natural reseeding was brought forward. 4) The density of self-sown orchardgrass seedlings in lightly grazed pasture amounted to 220 plants/m^2. This result proved the reason why the frequency of orchardgrass in lightly grazed area was higher than that in conventionally grazed area. 5) According to the results above-stated, it was assumed that natural reseeding should be applied at 6-9th year after pasture establishment.

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In the first and second reports, we confirmed varietal difference in resistance of alfalfa to southern blight, Corticium rolfsii, and discussed injury and evidence of the resistance for southern blight in selected strains for one generation. In the present paper we examined the increase of the resistance to southern blight based on the selection which was continued to 5th generation. Resistant plants of alfalfa to southern blight were selected in the inoculated field by maternal-line selection method and synthetic variety method. Selected resistant strains to southern blight showed more resistance than Natsuwakabe which was the main breeding stock. Synthetic strain CRSY 572-1 selected by maternal-line seletion method after passing four generations was the most resistant among all selected strains, and the strain CR 4871-5 selected by maternal-line selection method for five generations and the strain CRSY 541-1 selected by synthetic variety method after two generations followed them. As for the relation between the number of selection generation and the resistance to southern blight, the effectiveness of selection on the infected plant percentage increased slowly and linearly, but the effectiveness of the dead plant percentage was high in the early selection generations and low in the later ones. It becomes clear that the effect of selection for southern blight resistance was closely related to be the cumulative selection differential regardless of selection methods. And the heritability for southern blight resistance is relatively high (20.1〜58.4%) at the early and low (4.2〜12.0%) at the later selection generations. When rearranging these results, it is considered that effect of the selection for southern blight resistance is high at the early selection generations for fast gathering of the genes take part in the resistance. But, it is necessary that we select with a higher accuracy for more higher gathering of genes at the later selection generations.

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This study was carried out to clarify the allocation of photosynthetic product in white clover with both organs of seed and vegetative propagation. The relationship between the reproductive effort of seed propagation in wild white clover and the environmental factors of its habitats were investigated in Satsunai River valley. The other transplanting experiment with three populations collected from distinctly different habitats was conducted in order to estimate the genetic variations of their reproductive effort. The reproductive effort of seed propagation in white clover at habitats tended to decrease successively from river-side toward river-bed, and it correlated negatively with the degree of plant succession and the soil fertility. At river-side where the plant succession is in early stage and the soil fertility is low, 35% of total dry weight above ground were allocated into seed propagative organs and a great deal of seeds were produced. However, at river-bed where the plant succession is progressive and the soil fertility is high, only 4% of total dry weight above ground were allocated into seed propagative organs and the proportion of vegetative organs was extremely high. On the other hand, the transplanting experiment showed that the difference of reproductive effort among populations was not statistically significant. These results indicate that white clover is endowed with a remarkable plasticity on the allocation strategy against the differences of its habitats. The ecological significance of such strategy in white clover was also discussed.

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Investigations at six different habitats and a transplanting experiment were conducted in order to clarify the environmental and genetic variation of the reproductive strategy in spontaneous and cultivated white clover. Reproductive effort of seed propagative organs at different habitats was ranged widely from 38% at riverside to 5% at lawn and pasture. Thus reproductive effort was closely related to the environmental conditions of each habitat, such as the types of vegetation and defoliation regime. In the transplanting experiment, the genetic difference on reproductive effort was significant among plant groups obtained from different habitats, and it varied from a maximum of 22% at at riverside to a minimum of 5% at meadow and lawn. The relationship between habitats and transplanting experiment on reproductive effort was extremely low as compared with other characters. Therefore white clover seems to adapt itself to different environments through the plastic reproductive strategy in addition to the genetic variation.

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To clarify the role of nonstructural carbohydrate in the snow endurance of winter annual forage crops, two varieties each of barley and rye were grown at four nitrogen application rates (4, 8, 16 and 24kg/10 a). Contents of nonstructural carbohydrate, yield in autumn and the snow damage just after the thawing of snow were measured. Increased nitrogen (N) application rates markedly decreased the concentration of NSC. The rate of decrease of the NSC concentration was higher in barley than in rye, and in the low snow endurance varieties than in the high ones in the both species. The snow damage became greater as the nitrogen application rates increased in every species and variety. Significant interaction was also found between varieties and nitrogen application rates. This indicates that varietal traits in the snow endurance are not absolute but could be altered by environmental factors. The amount of the snow damage tends to relate inversely to the NSC concentration. The regression lines between the snow damage and NSC concentration, however, lie apart distinctly between the varieties in each species. We consider that the snow endurance is not only affected by the carbohydrate status but also some unknown factors.

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In greenhouse experiments, 4 tropical forage crops: Chloris gayana Kunth. cv. Katambora, Sorghum bicolor L. Moench. cv. Sweet Soix IV, Pennisetum typhoides (Burmf.) stapf and Coix lacryma-jobi L. var mayuem (Roman) stapf were grown in low pH nutrient solution (pH 4.2) containing 0, 5, 20ppm aluminum (Al) and in high pH nurient solution without Al (pH 5.0) for 15 days and assesed for Al tolerance in terms of shoot and root lenght, root and shoot dry weight, Al and nutrinet (Ca, Mg, K, P) uptake. The pH of nutrinet solution was adjusted intitially to 5.0 and 4.2 with H_2SO_4 and NaOH and adjusted by the automatic pH adjusted controller through the experiment period. Both of root and shoot growth were depressed in 4 species grown with Al. Relative values of root dry weight (rate of dry weight of roots grown in low pH with 20ppm Al to that of roots in high pH without Al) was very high in C. lacryma-jobi, P. typhoides and low in S. bicolor and C. gayana. As aluminum-affected roots in aluminum sensitive species, the roots of C. gayana and S. bicolor were relatively short and thick and had many stunted laterals. And also, in C. gayana and S. bicolor, leaves showed chlorosis resembling to Al-induced magnesium deficiency, and reduced the growth of tillering. The absorption amount of all nutrients of C. gayana tended to be depressed severly by Al treatments, however, in other 3 species, the absorption of calcium (Ca) and magnesium (Mg) were more severely decreased than that of potassium (K) and phosphorus (P). C. gayana and S. bicolor that are aluminum sensitive species contained excess K and were deficient Ca and Mg, especially Mg. K/Ca+Mg (meq) ratios of C. gayana and S. bicolor in high pH culture medium without Al was 1.31 and 2.33, respectively. However, these ratios increased remarkably up to 5.85 and 5.55 in low pH culture medium contained 20ppm Al. Although the Al concentration of root increased by Al treatment, there were no differences among the species. It is conculuded from results obtained that Al tolerances among the species of tropical forage crops might be related to the ability of plant roots to absorb Ca and Mg, especially Mg, from culture medium containing high Al.

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The surveying method for quantitative determination of the population density of ticks was considered. 1. The Tullgren and the improved Tullgren apparatus were compared for the recovery percentage of Haemaphysalis longicornis larvae which were mixed into fresh grass and soil. The improved Tullgren apparatus was equipped with a holey plate which covered over samples and obstructed a radiant heat from the electric bulb. The recovery percentage of ticks by the Tullgren apparatus was about 25%. On the other hand, the recovery percentage by the improved Tullgren apparatus was about 90%, but it decreased with increasing sample volume. The collection time of ticks from soil was about two times as compared to that from grass. 2. The ticks in the pot cultured grass was separately collected from cutting plant and surface soil by the using of the improved Tullgren apparatus. The total recovery percentage was 76.4%. But the recovery percentage of ticks from surface soil was only 4.4%. 3. The improved Tullgren apparatus and the Flannel method, which was rubbing vegetation with a piece of flannel (1m×1m), were compared for the recovery percentage of ticks in artificially released plots in grassland. The improved Tullgren apparatus showed a higher recovery percentage, about 52%, than the Flannel method, about 23%, for the ticks in grassland. The mean recovery percentage by the improved Tullgren+Flannel method, which collected the ticks on plant by the improved Tullgren apparatus and the rest on the ground surface by the Flannel method, was about 57%. These results indicated that the method used both the improved Tullgren apparatus and the Flannel method in combination was the most suitable surveying method for determination of the quantitative population density of ticks, and the improved Tullgren apparatus was also suitable for collecting the wintering ticks.

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Structure of before-grazing canopy and herbage consumption were investigated on bahiagrass pasture grazed by Holstein heifers under rotational system. Outlines of results are as follows. 1. Before-grazing herbage mass of total aboveground changed in the range of 467-669g/m^2. Consumed herbage changed greatly in the range of 21-150g/m^2. Consequently, percentage utilization of total aboveground herbage was in the range of 4-30% with a large fluctuation. 2. Percentage utilization of total aboveground, which was suggested to be related to grazing intensity, was found to be raised by grazing down to the lower strata of the canopy. 3. Cattle grazed the canopy from the upper strata down to the lower ones in principle. But there found a tendency that leaf was consumed preferentially than stem and standing dead.

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[in Japanese]

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