In order to investigate the ecological differentiation of timothy (Phleum pratense L.) in growth response to high temperature, twenty natural populations collected from some areas in Hokkaido (Fig.1) and three cultivars were grown during the summer in Sapporo. Their seedlings were grown in pots in unheated greenhouse (high temperature plot) and outdoor (control plot). Several characters on the main stem and number of tillers were measured on five plants per plot. Based on the principal component analysis of response index ([(mean of high temperature plot-mean of control plot)/mean of control plot]×100) of leaf size (Table 1), twenty natural populations were classified into two groups (groups I and II, Fig.2). In the group I, which consisted of four populations from the area west of Hidaka Mountains, leaf growth was promoted under high temperature conditions (Fig.3). The group II included the other sixteen populations and except for one population they were collected from the area east of Hidaka Mountains. In these populations leaf growth tended to be inhibited by high tem-perature. In cultivars the leaf growth inhibition by high temperature was more evident than in natural populations. While the group I had the more elongated stem and quickened heading date in high temperature plot, the group II did the more shortened ear and delayed heading date (Fig.4). Cultivars showed the most shortened ear among three groups in high temperature plot. These experimental results suggested that populations of the group I had a wider range of tolerance to high temperatures than those of the group II or cultivars. The differences of natural populations in high temperature tolerance were discussed in relation to climatic conditions of their habitats.

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In this study were examined the variations in carbohydrate concentration, and phleinase and invertase activities in the stem base of orchardgrass (Dactylis glomerata L.) during the regrowth after cutting. Phleinase activity increased drastically during the first 2 days and then kept almost constant level until it decreased on the 15th day. The phlein concentration was inversely related to this activity, suggesting the involvement of phleinase in the in vivo metabolism of phlein. The concentration of total mono- and oligosaccharides kept almost unchanged, while that of fructose increased rapidly during the first 2 days. Sucrose concentration, which was almost inversely related to the invertase activity, decreased during the first 2 days and recovered to the initial level on the 15th day. Glucose concentration decreased rapidly during the first 5 days and began to increase on the 11th day. Phlein began to accumulate again as sucrose concentration increased at the late stage of regrowth. The phleinase is considered to hydrolyze phlein endwise from the elution profiles of phlein on Sephadex G-75 and rapid augmentation of fructose immediately after cutting.

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An investigation was conducted to elucidate the process of freezing injury of white clover stolons. The stolons were collected from the frozen field covered with snow during the late Februray and they were exposed artificially at various temperatures. The degree of freezing injury was determined by electrical conductance, the percent survial, and the vigor of recovery growth after freezing. The injury was observed slightly at -3℃ and more clearly at -6℃. The death of stolons occurred initially at -6℃ and increased with the lowering in temperature down to -12℃ at which almost all the stolons died. Also, the injury of the inner tissues was observed microscopically. The disorganization of the tissue originated initially from the large cell mass of central pith of the stolon and extended to parenchyma of cortex, cambial tissue, epidermal tissue and vascular bundle as the degree of injury increased. The shoot primordium and lateral buds more resistant to freezing than the other inner tissues of the stolon. Usually the death of stolon was resulted from the collapse of almost all the vascular bundles in the stolon. Some disorganization of the tissue was observed in more than 70 percent of stolons taken at random from the sward. Although the degree of disorganization of the tissue was smaller in the stolons taken from the sward than those treated artificially, the organization was similar in morphological appearance to freezing injury observed in the artificially frozen stolons. Thirty stolons from each of 30〜40 plants of three cultivars, which were seeded in the previous spring, were sampled during early November and they were frozen at -12℃ for 8 hrs. Marked variations in percent survival of stolons were found among the cultivars and also individual plants within a cultivar. Ladino type tended to be more susceptible to freezing injury than common type. The repeatability of the percent survival of stolon of an individual plant was estimated to be 60 to 81 percent. This suggested that comparatively high proportion of the variation was genotypic in nature.

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The purpose of our research series is to elucidate the individual and varietal differences in concentrations and characteristics of nonstructural carbohydrate (NSC), and the relationships of NSC concentration to some morphological and physiological traits in Italian ryegrass at vegetative phase grown in fall. In the present paper, differences of concentrations and characteristics of nonstructural carbohydrate between 1) tetraploid strains and thier parental diploid varieties and 2) diploid and tetraploid groups each of which is composed of 10 varieties with different maturities and origins, and also relationships between NSC concentrations and some traits were investigated. 1) NSC percentages of dry matter were distinctly higher in tetraploid strains than their parental diploid varieties at the early growth stage in the experiment, i.e. up to about 35 days in stem and 45 days in leaf blade after emergence. But the differences decreased as the time goes and, on the contrary, the diploid varieties showed clearly higher values than their tetraploid strains at the later growth stage in the experiment. 2) Mean NSC percentages of fresh matter was significantly higher in diploid group than tetraploid group. And it is recognized that the result described above was due to the difference in fructosan, especially in percentage of the low molecular weight component of fructosan. No clear inter group difference in mono- and oligosaccharide percentage was obtained. Although no significant difference was obtained, mean NSC percentage of dry matter was also higher in the diploid group than tetraploid group. 3) Under the space-planted condition, NSC percentages of the tetraploid strains were equal to or slightly less than those of their diploid parental varieties. But under the condition of community, NSC percentages were distinctly lower in the tetraploid strains than their diploid parental varieties. It is considered that under the community condition the heavier mutual shading due to more drooping leaf blade of plants resulted in lower NSC percentages in the tetraploid strains. 4) In inducing tetraploid varieties from diploid varieties, it is necessary not only to keep the ability of reserving carbohydrate physiologically but also to improve the canopy form for light-interception morphologically. 5) Highly significant positive linear regressions between dry matter contents and NSC percentages were shown both in diploid and tetraploid groups, which may indicate that the dry matter content is possible to be used as the criterion of NSC concentration. But diploid and tetraploid varieties must be dealt with separately because of their significantly different intercepts.

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In order to establish proper methods of harvesting seeds of Green panic (Panicum maximum var. trichoglume) and Kazungula setaria (Setaria anceps STAPF cv. Kazungula), heading time head length, seed yield, numbers of filled and germinated seeds on the tillers developed at different times were investigated. The results are as follows: 1) In two species, heads did not emerge at the same time even from the tillers developed nearly at the same time but did emerge irregularly over long periods of time. For Green panic, most tillers which constituted peak of heading developed before the 2nd of July (about nine leaf stage of the main stem), while for Kazungula setaria, those developed before the 9th of July (about fifteen leaf stage of the main stem). 2) For Green panic, head length and seed weight per head were more affected by the time of heading than the time of tillering, and were larger in case of early emerged heads. For Kazungula setaria, however, those were affected by both the time of tillering and heading, and were considerably larger in case of early emerged heads of early developed tillers. 3) For Green panic, the numbers of filled and germinated seeds per head were largest in the heads which constituted peak of heading, while for Kazungula setaria, the numbers of those seeds were largest in the heads emerged at the time and during three days before the peak of heading. Therefore, in order to obtain the largest numbers of filled and germinated seeds it is suggested that the harvesting time should be determined with the criteria as measured by these heads.

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For maximizing annual dry matter (DM) yields of Rhodes grass (Chloris gayana cv, Pioneer), Guinea grass (Panicum maximum, OK-73-1040) and Napier grass (Pennisetum pureum), the effects of clipping intervals on the DM production of each grass were compared in relation to the climatic data. The plant length was stopped to grow within 60 days of regrowth periods in Rhodes grass and in Guinea grass, however it continued to grow in Napier grass throughout 90 days of regrowth periods. Annual DM yields appeared to be highest in Napier grass followed by Guinea grass and by Rhodes grass. The highest yield was obtained with two-month clipping in Rhodes grass and in Guinea grass and with three-month clipping interval in Napier grass. Monthly DM yields appeared to be lower from Sep. to Mar. and higher from Apr. to Jun. in Rhodes grass, lower in Jan. and Feb. and higher in Aug. and Sep. in Guinea grass and lower in Nov. and Dec. and higher from Apr. to Aug. in Napier grass. Water concentration in plant was higher in Napier grass than in Guinea grass and Rhodes grass and showed a seasonal variation pattern being higher from Jul. to Oct. and lower from Nov. to May. With the results above, both Rhodes grass and Guinea grass should be clipped in between 30 and 60 days of regrowth and Napier grass after 60 days of regrowth periods for maximizing annual DM yields. Judging from the relations of monthly DM yield with mean monthly temperature or with rain fall, the growth of Rhodes grass will be limited with temperature above 25℃ and very susceptible to water shortage and either Guinea grass or Napier grass grow better with higher temperatures but Napier grass is susceptible to water shortage.

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In order to search apporopriate clipping intervals for maximizing digestible dry matter (DDM) yields of Rhodes grass (Chroris gayana cv. Pioneer), Guinea grass (Panicum maximum, OK-73-1040) and Napier grass (Pennisetum purpureum), annual dry matter (DM) yields, in vitro dry matter digestibility (IVDMD) and leaf/stem ratio which affect digestible dry matter (DDM) yields were compared each other under three different clipping intervals ; one, two, and three month intervals. Annual DM yield increased with longer clipping intervals in Napier grass and Guinea grass but decreased with three-month interval in Rhodes grass. Leaf/stem ratio were reduced with longer clipping intervals in all grasses tested. Leaf/stem ratio of Rhodes grass was raised during cooler seasons and reduced during warmer seasons in all clipping intervals, however a defined trend was not observed with other grasses especially in longer clipping intervals. IVDMD was lowered with longer clipping in tervals in all grasses. Each grass has shown a seasonal variation in IVDMD value showing lower values in warmer seasons and higher values in cooler seasons. IVDMD tended to be higher in leaf than in stem. With longer clipping intervals, annual yields of DDM increased in Napier grass, however it tended to decrease in Guinea grass. The yield became highest with two-month clipping interval followed by one and three-month clippings in Rhodes grass. For maximizing annual DDM yields Napier grass should be clipped with longer intervals and Rhodes grass with shorter intervals but Guinea grass seems to be not affected by clipping intervals. Also, shorter or longer clipping intervals will be recomended in warmer or cooler seasons, respectively, for increasing annual DDM yields in all grasses tested in this experiment.

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Twenty grass accessions were evaluated as annual summer growing forages in subtropical Australia. Eleven were annuals and nine were perennials, but the latter were sown at a higher seeding rate than usual. Grasses were either cut five times throughout the growing season at four weekly intervals or were cut four times with an eight week period before the first cut and with four weekly harvests thereafter. Harvested material was separated into leaf, stem and reproductive heads. In vitro digestibility was measured on the separated components. The two most productive perennial grasses (Chloris gayana cv. Katambora and a Setaria sphacelata×S. splendida hybrid) yielded an average of 11, 000kg/ha with five cuts and 15, 000 with four. However the leaf yield was virtually unchanged at about 6, 000kg/ha. The two most productive annuals, Zulu and Sudax sorghum, averaged 10, 000 and 19, 000kg/ha for the same cutting treatments and leaf yields were 5, 000 and 6, 000kg/ha. Thus less frequent cutting increased yield of stem much more than yield of leaf. The higher stem yields were associated with a depression of 5% in stem digestibility. Digestibility of both leaf and stem was highest at the beginning and end of the growing period. Measurements of plant and tiller density were made after each harvest and were related to changes in yield over the season. The advantages and disadvantages of using either annuals or perennials as annual fodder crops are discussed

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A pot experiment was conducted to determine the effects of fertilization after the autumn final cutting on the contents of N, P, K and TNC (reserve carbohydrates) in all plant parts including part harvested, stubble and root at early winter and on the winter hardiness of dallisgrass, setaria and green panic. The plants grown under natural condition at Fukuoka, Japan were treated with six kinds of application including NPK, NK, N, P, K at the rate of 1kg/a as N, P_2O_5, and K_2O and no fertilizer (control). Each grass under the treatments with N was greater in plant height, number of stems and dry matter weight at early winter than that under treatments without N. There were slightly higher N content and considerably higher K content in the whole plant receiving N, and a significant positive correlation was observed between both element levels. Content of P in plant, which was not always increased by the treatment with P, tended to increase in the part harvested of setaria and green panic under the treatments without N. The higher mineral absorption by the plant and the absorption ratio to fertilized nutrient under the treatments with N indicated that N supply played an important role for the absorption of P and K. The TNC content as well as N and K in the whole plant receiving N tended to increase and a significant positive correlation existed between the contents of TNC and N or K except for setaria. In early winter frost, leaves of green panic showed greater damage in order of P, K and control>N>NPK and NK treatment, associating with the low contents of TNC and K, high content of P and high ratio of P/K in the part harvested (mainly leaves). Survival after winter was observed only in dallisgrass, and the grass had greater regrowth leaves under the treatments with N, associating with higher TNC contents. No clear effect of N application was found in setaria on frost or winter hardiness. In the case of dallisgrass, results indicated that N application accelerated the regrowth after autumn final cutting and consequently, resulted in the greater carbohydrate reserves in all plant parts during the following lower temperature period, in its turn beneficial effect on hardening and winter survival.

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The formation and development pattern of tillers and tiller buds of orchardgrass seedlings, grown under favorable conditions, was investigated anatomically. The results are summarized as follows. 1) Generally, the appearance of leaf n (numbered acropetally) of mother shoot synchronized with that of 1st leaf of tiller Tn-3 which was subtended by leaf n-3, so that most of the tillers appearing in this manner produced "corresponding leaves" at almost constant intervals (Table 2). This phenomenon is supported by Katayama's concept) of tillering systems in cereal crops. 2) In addition to the tillering regularity, it was observed that the corresponding leaves, either expanded or expanding, of different tillers were similar in length to each other as in cereal crops (Table 3). 3) Primordia of corresponding leaves of main shoot and emerged primary tillers were initiated almost simultaneously, and subsequent developments progressed analogously (Table 4, Fig.1, 2, 3). Therefore, the externally visible synchronism in the appearance of any corresponding leaf of each emerged tiller may result from its simultaneous initiation and analogous development occurring at the subapical regions. 4) During the tiller bud development, the initiation of successive leaves at the shoot apices of buds proceeded more quickly than that of emerged tillers (Table 4, Fig.2, 3). 5) After all, the developmental course in tiller bud growth is suposed to be composed of two different morphogenetic phases. The first part defined as the "phase of tiller bud formation" is the process from the initiation of primordial bulge of tiller bud to the completion of bud structure (Fig.1, 2). In this case, the structure of tiller bud bearing its own shoot apex and 3〜4 juvenile leaves is achieved immediately after its subtending leaf "n" has just fully expanded on the mother shoot. The second part of the developmental course starts with rapid elongation of 1st leaf of tiller bud "Tn" being subtended by the leaf "n" and concludes with the tip emergence of the tiller from subtending leaf sheath. This is defined as the "phase of tiller bud elongation".

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The tillering pattern and tiller bud development of orcharadgrass seedlings, grown under various light and nutrient regimes, were observed anatomically. The results are as follows. 1) The tillering regularity was variously disturbed under unfavorable growth conditions such as reduced light intensity, lowered nutrition or combination of both. The course of the tillering disturbance seemed to divide generally into two forms in proportion to the severity of treatments. One was the regular tillering accompanied with some delay of leaf appearances in main shoot and primary tillers, and another was the complete stoppage of tiller emergence (Table 1, 3). 2) The "phase of tiller bud formation" proceeded almost regularly though the buds could not develop into the tillers as the heavy shading treatment had imposed on the seedlings (Fig.2, 3, 4). Namely, the tiller bud primordium was initated at the leaf axil 3〜4 nodes below the first collar-like leaf on the main shoot. Then the bud developed normally in the same manner as in a tiller-bearing seedling and formed itself into a complete tiller bud consisting of a shoot apex and about 3 juvenile leaves as its subtending "n" on mother shoot had fully expanded (Fig, 2, 3, 4). 3) On the contrary, the subsequent elongation of the tiller bud whose structure had been completed at the axil of leaf "n" was wholly suppressed when the seedling was heavily shaded (Fig.2, 4c). Accordingly, the bud turned resting and never synchronized with the growth of mother shoot. The tillering pattern may have a regularity only when the tiller bud formed at the node "n" of mother shoot is promoted and elongated uncheckedly.

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Some of the factors influencing the germination, establishment and survival of Zoysia japonica were investigated on the cultivated field established by broadcasting the cattle dungs containing the seeds. 1. The soil compaction treatments were made with roller. The increase of soil compaction disturbed emergence of Zoysia japonca but did not affect the growth and survival of the seedlings. 2. The applications of soil amendment matter and N, P, K fertilizer had no effect on emergence and survival of Zoysia japonca in the cultivated field. But their application promoted the growth of annual grass weeds, so that the growth of Zoysia japonica seedlings was depressed by severe competition between them. 3. The mortality of the seedlings during winter was lower in vegetation with abundant plant cover than that with poor plant cover, however, the number of erect shoots per unit area after wintering was not different significantly in both vegetations for the reason that the number of erect shoots per plant was less in abundant vegetation. 4. Based on the above results, it was concluded that the soil amendment matter and fertilizer were unnecessary to apply for successful establishment of seedling of Zoysia japonica on the cultivated field.

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The Sasa nipponica community developed after felling forest was suppressed by several disturbing methods, and was oversown with Zoysia japonica seeds contained in the cattle dungs. In the first study, the establishment and survival of Zoysia japonica seedling were examined on the following four disturbance treatment plots: (i) the Sasa community was removed and cultivated ; (ii) burned ; (iii) grazed ; and (iv) undisturbed. 1) In the next year of the treatments, the stands of cultivating plot, burning plot, grazing plot, and undisturbing plot were dominated by Chenopodium album, Erigeron spp., Artemisia princeps and Sasa nipponica, respectively. 2) The establishment of Zoysia japonica seedling on the cultivating plot was better than that on the other plots under the rotational grazing. The numbers of seedling on the undisturbing plot were markedly reduced. 3) Although many seedlings were destroyed by the rotational grazing, the seedlings on the cultivating plot more by the deferred grazing. But on the undisturbed plot, such a deferred grazing was not effective on the survival. In the second study, the Sasa nipponica community was surppressed by heavy and light grazing pressures in the year before sowing of Zoysia japonica. 1) In the next year of the grazing treatments, the stand of light grazing plot was dominated by Sasa nipponica. However, the stand of heavy grazing plot was more invaded by Erigeron spp.. 2) The establishment of seedling on the heavy grazing plot was significantly better than that on the light grazing plot. Such a difference was maintained till the next spring. 3) Although the application of N-P-K fertilizer increased the growth of Chenopodium album or annual grass weeds, it had no effect on the establishment of Zaysia japonica seedling. Based on the above results, it was concluded that for success in the establishment of seedling of Zoysia japonica on the Sasa community developed after felling forest, Zoysia japonica seed shoued be sown after disturbing of the Sasa community allowed waste type weeds such as Erigeron spp. to invade.

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The purpose of this investigation was to find out how the quantitative difference in nutrition for the calf would come out on the lifetime performance of the matured beef cow. During the grazing period (the first year), the heifers were divided into two groups. High-nutrition heifers (H) were fed 1.5kg of concentrates every day and low-nutrition ones (L) were fed no concentrate. In the winter feeding period, they were divided into the following three groups according to TDN intake which were classified on the basis of Japanese feeding standards (1970). H group was continued to give high-nutrition (110%) and this group was named HH group. On the other hand, L group was divided into two groups, the heifers which were given high-nutrition (110%) were named LH group, and heifers which were given low nutrition (90%) were LL group. In the second year, all heifers of every group were grazed on improved pastures with no concentrates. The results obtained from about 9 months old to the first calving time were as follows. 1) H group showed more DM and TDN intake than L group during the graging period, but chiefly, this difference was observed from the beginning up to the second month of grazing. Then in re-grazing period (the second year) feed intake of LL group was much greater than that of HH group. Besides, TDN intake of LL group during the re-grazing period, expressed as the percentage of the requirement for the growing female beef cattle in the Revised Edition of Japanese Feeding Standard, was significantly larger than that during the grazing in the first year. 2) Growth of H group in grazing period (the first year) was significantly faster (p<0.05) than that of L group. Only in winter, the growth of LH group had a tendency to be superior to those of HH and LL groups. Although the growth of LL group was considerably slow in this period, there was a remarkable compensatory growth during the regrazing period. 3) The dialy gains during the grazing period indicated significant multiple correlation with intake of TDN and DCP in the first year (r=0.761, p<0.01). 4) Ages at the first insemination of HH, LH and LL groups were 16.0, 16.6 and 18.6 months, respectively. Corresponding figures for conception were 17.4, 17.8 and 21.2 months. In LL group, four of seven heifers had reproductive disturbance in winter. The first insemination and conception among LL group generally took much time than other two groups. From the facts described above, the level of nutrient intake imposed during early life has a pronounced effect on the state of growth and reproduction.

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Data resported here were obtained from 175 forage samples, including 76 of orchardgrass, 42 of perennial ryegrass, 23 of timothy, 18 of tall fescue and 16 of meadow fescue. Digestion trials with wethers were carried out at both ad libitum and restricted feedings. Grasses of several growth stages including aftermath were used for each species. When expressed as percentage of dry matter, significant positive correlation was found between cell contents (CC) and digestible CC as well as between cell well (CW) digestibility and acid detergent lignin (ADL)+silica. Following regression equation was obtained: Y=a-X_1(b+cX_2), where Y is digestible dry matter, X_1 is CW, X_2 is ADL+silica, and a, b, c are constants depending on species and location. It was observed that CC in grasses was nutritively uniform and contents of digestible CW were relatively constant among the different stages of maturity. Changes in the amount of digestible dry matter in grass related to the amount of digestible CC and indigestible CW.

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The digestion trials of corn silages were carried out using with dairy cows and adult castrated male sheep. The seven silages were used in this experiments, ranging in maturity from the early milk stage to the over-ripening stage, each prepared from the three different corn varieties. The results are summarized as follows. (1) The ratios of the grain fraction in whole dry matter of seven silages ranged from 18.6 to 48.3 percent. Chemical composition of silages ranged as follows ; 6.7-12.2% for crude protein ; 3.1-28.4% for starch ; 25.5-37.7% for acid detergent fiber, respectively. (2) From the results of digestion trials true digestibility of dry matter, crude protein, crude fat, organic matter and gross energy showed little significant differences between the cows and the sheep. However, the starch digestibility obtained from sheep had higher values (about 10%) than those from cows. (3) The values of total digestible nutrient (TDN), digestible energy (DE) and digestible dry matter (DDM) were not recognized significantly different between the dairy cows and the sheep. (4) Highly significant correlations existed between the cows and the sheep as to the values of the TDN (r=0.97), DCP (r=0.99), DE (r=0.96), DMD (r=0.97), digestible crude fat contents (r=0.99). (5) Regression equations were derived to predict the nuritive values of silages for dairy cows from the values obtained through the feeding trials on sheep.

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In Tohoku district, outbreaks of several noctuids have occurred in tame grasslands during the last more than ten years. The following three species may have been immigrants, and the outbreaks were abrupt. The Oriental armyworm, Mythimna separata WALKER, attacked gramineae mainly in early summer. The total area of damaged grasslands markedly fluctuated from year to year. Newly developed grasslands were occasionally brought to total ruin by the black cutworm, Agrotis ipsilon HUFNAGEL, shortly after sprouting of grass. The tabacco cutworm, Spodoptera litura FABRICIUS, rarely injured white clover in the southern region. Among indigenous noctuids, Amphipoea ussuriensis PETERSEN, S. depravata BUTLER and Xestia c-nigrum LINNE caused local outbreaks, the former two feeding on orchardgrass and the last on white clover.

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In Tohoku district, outbreaks of the following pests in artificial grasslands have been recorded during the last eleven years. A scarabaeid grub, Anomala testaceipes MOTSCHULSKY, caused severe deterioration of gramineae in 16 grasslands covering 586 ha, which have been developed by tractor-plowing mainly in woodland sites of volcanic ash soil. The false melon beetle, Atrachya menetriesi FALDERMANN was widely found to feed on white clover, but the extensive outbreaks were rather rare cases. A grasshopper, Parapleurus alliaceus GERMER, caused significant reduction of grass yields in older pastures of the northern region. In contrast, outbreaks of the emma cricket, Teleogryllus emma OHMACHI et MATSUURA, mostly occurred in new grasslands of the southern region. Occurrences of the barley flea beetle, Chaetocnema cylindrica BALY, the rice grasshopper, Oxya japonica WILLEMESE, and the spottedspitttle bug, Atuphora stictica MATSUMURA, in high numbers on orchardgrass were also found locally.

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