In order to evaluate the drought resistance of warm season forage species, Paspalum dilatatum cv. Kyushu 5 (dallisgrass), Chloris gayana cv. Katambora (rhodesgrass), Sorghum birolor cv. Sweet siox IV (sweet sorghum), Zea mays cv. Snowdent 1 (corn), Coix lacryma Jobi (job's tears) were grown on the pots, of which soil moisture was adjusted to pF 1.7-2.0, pF 2.3-2.5, pF 2.8-3.0 and their photosynthetic rates, leaf water potentials, leaf resistances were examined. And, rhodesgrass being the most tolerant, sweet sorghum and job's tears being sensitive species to water stress, were grown at the graded level of soil moisture, and the distribution of ^<14>C assimilated among their various organs and organic constituents were determined. The results obtained are summarized as follows ; 1) The apparent photosynthetic rates of species decreased by water stress, and especially, these decreases were remarkable in the sensitive species. 2) The disadvantage of root development of the sensitive species by water stress was particularly due to the lowering of translocation of assimilated carbohydrate from leaves to roots. 3) Under the water stress condition, species had enhanced incorporation of assimilated ^<14>C into low molecular constitutes such as amino acids, and soluble sugar fractions, but not much into high molecular constitutes such as starch, protein and lignin-cellulose fractions. 4) ^<14>C incorporation into lignin-cellulose and protein fractions of job's tears root was apparently suppresed by water stress, but that of rhodes-grass was not much as job's tears. It is concluded from these results that drought resistant species might maintain their dry matter production ability greater through maintaining higher photosynthetic rate, and also their root development well by the efficient distribution of assimilates into roots or high molecular root constitutes such as lignin-cellulose.

View full abstract

The internode composition, based on the number of vascular bundle rings of the overwintering stem, and the length and the fresh weight of overwintering aboveground parts (overwintering stem+crown) of individual plants were examined in order to clarify the ranges of kudzu plants which made up a natural kudzu population. Kudzu plants were collected from a natural population in Kitabata, Motoyamacho, Nada-ku, Kobe, at the foot of the Rokko mountains. Individual plants were classified into 25 groups based on the internode composition of overwintering stems. The length and fresh weight of overwintering aboveground parts (OAP) ranged from 1.0cm to 62.7m and 0.5g to 4, 231g, respectively. About 53% of kudzu plants sampled were less than 1m in length and about 60% had less than 100g fresh weight of the OAP. Frequency distributions of the length and the fresh weight of the OAP were skewed with the highest numbers at the lowest size class. It is considered that the great diversity of internode composition is due to the variation among plants in the detachment of rooted nodes from the parent plants as well as in the dying and regrowth of stems. Also, the high proportion of plants which were classified into small size groups can be attributed to frequent detachment of individual rooted nodes from parent stumps.

View full abstract

Regrowing process and changes in chlorophyll, nitrogen fractions, phosphate fractions and carbohydrate fractions concerning photosynthesis in the leaves were measured on orchard grass during 3 week regrowth periods after cutting. In the early stage of regrowth, most of the new tissues regrown were dependent on the expansion of the cut-leaves which had been expanding in the lower leaf sheaths. The acquirement of photosynthetic activity on their cut-leaves contributes much to the physiological recovery of the plant after cutting. The chlorophyll concentrations in cut-leaves increased immediately after cutting and attaind to the maximum on 12th days and decreased slowly after that. TCA-insoluble nitrogen did not change so much for first 5 days after cutting and went up the maximum concentration on 9th day and decreased after that. Consequently, the ratio of chlorophyll to TCA-insoluble nitrogen cotents revealed a loose slope in curve at the phase of 5th to 7th day and on and after 15th day. These were suggest that the former impressed the time when a steep accumulation of leaf protein was caused by greening of cut-leaves which grew out from lower leaf sheaths, the latter when the decrease of leaf protein, on whole plant, appeared to be caused by the senescence of the regrowing leaves. The concentration of TCA-soluble phosphate and soluble carbohydrates, especially 85% ethanol soluble fraction, changed similarly in that of the chlorophyll and TCA-insoluble nitrogen.

View full abstract

In order to clarify the factors affecting sward conditions and grassland managements, the data obtained by the postal questionnaire survey of well managed pastures and deteriorated ones from a total of 653 co-operative livestock farms were analyzed by the quantificatin II method, a kind of discriminant function method. This analysis dealt with 13 items consisting of 72 categories as follows ; pasture establishment method, shape of pasture against contour line, shelter and shade woods, topographical condition, distance from farm center to pasture concerned-road condition in farm, direction of slope, age of pasture, annual amount of nitrogenous fertilizer, trimming, pasture utilization purpose, cattle breed, grazing frequency and stocking rate. The results obtained are as follows ; 1. The major criteria for judging pastures as in good condition were high forage production, high population density of forage. For pastures as in bad condition, weed infestation, poor population density and bare ground were pointed out. 2. The most significant factors discriminating pastures in good condition, were inclination-undulation condition, followed in order by distance from farm center to pasture and road condition in farm, pasture utilization purpose, annual amount of nitrogenous fertilizer, direction of slope, grazing frequency and stocking rate. 3. Pastures giving both high forage production and high utility of forage were apt to be maintained well. Such pastures were characterlized with factors as follows ; gently inclination, flatter slope, locating near farm center, well maintained farm's road, utilizing for both as grazing and cutting, higher amount of nitrogen applied and frequent grazings.

View full abstract

To study the demography of timothy (Phleum pratense L.) in the process of the various establishing swards, both the simulated swards and the monoculture swards experiments were carried out. In the simulated swards, seeds were hand-broadcasted on plastic flats (41.5×26.5×8.0cm). The monoculture, the mixed culture with orchard grass, the one with kentucky-bluegrass, the one with white clover, and the one with these three species were set up. They were grown under uncutting (control), cutting and waterlogging conditions. We observed the demography of all species, and measured the number of tillers and height of timothy plants for a half year in both experiments. The results were as follows: In the simulated swards, both the number of timothy plants and total number of plants over all species decreased rapidly during first three months in control and cutting plots, but this tendency was not conspicuous in waterlogging plots. The survivorships in the final observation decreased in the order of waterlogging, cutting, and control plots. The dominance-suppression relationships between timothy and orchard grass varied among the various environments. Timothy showed high mortality in the plots mixed with orchardgrass under control and cutting conditions, but low mortality under waterlogging one. Timothy plants increased their tiller number only by one or two in all plots, particularly almost none in cutting plots. Plant height was higher in control than in waterlogging plots. In the monoculture swards of timothy established in field, the number of plants decreased rapidly, but the mean number of tillers per plant increased continuously during the course of the experiment. The plants with many tillers and tall height had higher survival rate, more tillers and taller height than those with few tillers and short height as time passed. These results might suggest that the population dynamics of timothy in the establishing swards varied among the various environments, and that the relationships of dominance and suppression among the members in a monoculture population of timothy are established during the early growing stage.

View full abstract

Red clover has a shortage, i.e. its yield greatly decreases within a few years in single or grass-red clover mixtures. We report here that the application of the insecticide isoxathion, lengthened the persistence of red clover included in the swards. Four single and mixed swards, i.e. O (orchardgrass single), R (red clover single), O-R (orchardgrass and red clover were sown in alternate rows) and O/R (orchardgrass and red clover mixture, broadcasted) were made in October of 1976. The forage was cut four times each year. The insecticide was applied from 1978 through 1980. The insecticide application increased the total dry matter yield for 4 years in every sward. This yield increment was greater in the swards which included red clover. It was also greater in the 3rd and 4th year. In the 4th year, the ratio of the forage yield of the swards applied with insecticide to that of the control swards (water application) was 1.1 in O, 2.7 in R, 3.1 in O/R and 1.6 in O-R, respectively. Insecticide application produced both a higher yield of red clover and a higher percentage of the red clover to the total yield in the swards. In the control swards, the red clover yield and the percentage of the red clover to the total yield were greatly decreased during the 3rd and 4th year. After the final harvest of the 4th year, the larvae of cupreous chafer (Anomala cuprea Hope) were counted. It was found that the larvae population was very high in the red clover control sward and very low in all swards applied with the insecticide.

View full abstract

It is seemed that the cattle may escape from where the tipped corner posts, one of the pasture fence defects caused by the snow settling load in the snowy area, slackened the barbed wire. The purpose of this investigation is to make a study on the factors affecting the tipping of corner posts, from the standpoints of structural changes of pasture fences with the years and various conditions of soil bearing capacity especially. The results obtained are as follows ; 1) The small soil hardness showed a tendency to be tipped corner posts near the heaped stumps remarkably (Fig.5). 2) It was confirmed that the tipping of corner posts made the slack of the barbed wire greater as the plane angle in the corner fences became acute gradually. It is necessary to pay attention to the method of hanging the wire on the posts or the pasture fence maintenance because the tipping of corner posts was caused mainly by the action of the snow settling load to the wire (Fig.7). 3) Although the investigated 13 corners of the pasture fences were not sufficient number, the extended angle's rate per year of plane angle in the corner fences, stood in high correlation with the tipping of corner posts, was concerned with the plane angle of the corner fences, the cone index as a soil bearing capacity and the snow depth mutually. 4) It was supposed that the tipping corner posts was affected mutually by the plane angle where the corner fences were installed, the soil bearing capacity and the snow depth.

View full abstract

The comparison were made on R^2 value of the regressions of the various plant parameters (Panicum maximum cv. Gatton) against P-levels obtained in the acid soil and in the alkali soil with six P-tests ; Bray-1, Bray-2, Truog, Truog modified, Olsen, and Ion exchange resine methods. The P-tests which showed higher R^2 value in the regressions of P-levels against rates of P-fertilizer applications, relative plant top DM yields, and relative plant P-uptake were Bray-2, Truog, Truog modified and IER methods, Truog, Truog modified and IER methods, and Bray-2, Truog modified and IER methods, respectively. With the above results, Truog, Truog modified and IER methods were judged as suitable methods for estimating available-P in the soils of South-Western Islands of Japan. However, in view of the range and coefficients of covariation of soil available-P obtained with above three methods, Truog modified method was considered to be the most convinient for evaluating P-response of various pasture plants and for predicting a precise rate of P-application required for the optimum plant growth.

View full abstract

Deficiencies of Zn and Fe were found in Dark-Red alkali soil showing that the optimal application levels were 2-3kg/ha for Fe and not less than 8kg/ha for Zn. A significant defeciency of Mo for the legume growth was found in Red-Yellow acid soil in the following order ; Siratro>Greenleaf desmodium>Cooper neonotonia・Miles lotononis>Endeavour stylo・Centroeema. The positive effects of Mo application became greatest at 300-400g/ha of Mo application and at about 6t/ha of liming being attributed to the increased levels of nitrogen fixation by the root nodules. A deficiency of Mn was also found in the acid soil.

View full abstract

A field study was conducted to clarify the effects of subsoil acidity of Andosols on the yield and botanical composition of alfalfa-orchard grass mixture for three years. Two kinds of unreclaimed Andosols were used for the subsoils of experimental plots: very strongly acid Kawatabi soil (non-allophanic) and weakly acid Zao soil (allophanic). Root growth of alfalfa was severely precluded by Al toxicity in non-allophanic subsoil but normal in allophanic subsoil. In contrast, orchard grass showed normal root growth both in allophanic and non-allophanic subsoils. Inorganic nigrogen derived from basal ammonium sulfate moved easily toward subsoils because of high rainfall in autumn. Consequently, in early growing stage, alfalfa grown in non-allophanic soil plot showed severe nitrogen deficiency and drustic reduction of dry matter. During dry summer, the alfalfa in the non-allophanic soil plot showed severe "Wilting" symptom than that in allophanic soil plot when available soil water in the limed surface soil is exhausted. Dry matter yield of alfalfa in non-allophanic soil plot was much less than that in allophanic soil plot. In contrast, the dry matter yield of orchard grass was rather greater in non-allophanic soil plot. The proportion of alfalfa to total yield was higher in allophanic soil plot than in non-allophanic soil plot throughout experimental period. The present study showed that subsoil as well as surface soil plays an important role in supplying both water and nutrient for grasses.

View full abstract

Whole crop maize was applied with fresh poultry manure at levels of 0, 5, 10, 15 or 20t/10a, respectively (Expts 1 and 2) or with urea at levels of 0, 10 or 20kg (or 30kg)/10a, respectively (Expts 3 and 4) as a basal dressing. They were harvested at silking or yellow-ripe stages and ensiled in bag silos for about 90 days. Nitrate nitrogen contents were determined both in whole crop maize and their silages, and effects of level of nitrogen fertilizer on nitrate accumulation in whole crop maize and disappearance of nitrate during ensilage were studied. The results obtained were as follows: 1. Nitrate nitrogen contents in whole crop maize harvested at silking stage increased with increasing amounts of nitrogen fertilizer and they reached the maximum of 0.22% of dry matter at levels of 15-20t/10a of poultry manure or 30kg/10a of urea. Nitrate nitrogen contents in yellow-ripe stage materials were entirely much lower than those in silking stage irrespective of levels of nitrogen fertilization. 2. In all silking stage silages except for the controls in each experiment, nitrate nitrogen contents were more than about 0.1% of dry matter. The rates of nitrate disappearance in silages made from materials containing relatively high levels of nitrate nitrogen (more than 0.19%) were 21.1-54.5%. 3. Most of silking stage silages were of fairly good quality characterized by a high lactic acid and a low acetic acid. Most of yellow-ripe stage silages also were of good quality, although contents of lactic and acetic acids were lower than those in silking stage. The qualities of silages were not affected by levels of nitrogen fertilizers.

View full abstract

Two experiments were carried out to evaluate the loss of dry matter in silage occurring during the oven drying. In experiment I, the dry distillation of 27 silages was conducted by an apparatus designed to collect the volatile matters produced during the drying and the volatility of volatile matters in the silages was examined. The Silage samples made from Italian ryegrass were collected from different dairy farms in Okayama prefecture. These samples consisted of various fermentation qualities, ranging in pH value from 3.84 to 5.33 and in the score by Flieg's method from 14 to 100. For the dry distillation, about 100g of each sample chopped to about 5mm length was accurately weighed and then dried in the oven of the apparatus for 16h. During the drying, the oven temperature was maintained at 100℃ and the rate of air flow was kept constant at 12 1 per h. The contents of volatile matter in the silages used and in distillates produced by the dry distillation were analyzed quantitatively. Volatilities of volatile matters and of dry matter during the drying of silages were calculated from the amounts of volatile matters present in the silages and their distillates. In the silages examined, the mean value of volatility of total volatile fatty acids (VFA) was 73.5%, ranging from 15.2 to 111.7%. And mean percentage volatilities of acetic acid, propionic acid, i-butyric acid and n-butyric acid were 70.3, 64.4, 40.0 and 80.4, respectively. Lactic acid was also recovered in the distillates from all the silages and its volatility ranged from 0.5 to 3.7% with a mean value of 2.1%. Furthermore, all silages and their distillates contained considerable amounts of ammonia and ethanol. The volatility of ammonia during the drying process ranged from 0.3 to 99.9% with a mean value of 20.7% and that of ethanol ranged from 15.3 to 109.2% with a mean value of 67.3%. Statistical analysis showed that the volatility of volatile matters was significantly influenced by the fermentation properties of the silages. On the other hand, the mean value of dry matter volatility of the silages by the dry distillation was 3.56%, ranging from 1.10 to 7.80%. And mean values of apparent dry matter and corrected dry matter contents in the samples were 30.34 and 31.39%, respectively. Significantly negative correlations were found between the volatility of dry matter and the fermentation quality or dry matter content of the silages. In experiment II, conditions of drying silage samples were examined for their influences on the volatility of volatile matters in the silages by the dry distillation. Silage samples used for this experiment were made from Italian ryegrass without additive (A), and with the 2% glucose (B). The volatility of volatile matters in each sample was evaluated by drying for 8, 16 and 24h at 100℃, and by drying at 60, 80, 100 and 110℃ for 16h. In general, with the increase in the time and temperature, the volatility of volatile matters in the samples increased. However, each volatile matter had a volatility pattern according to the drying conditions. Namey, ethanol and n-butyric acid indicated a higher volatility, whereas lactic acid and i-butyric acid showed a lower volatility. Furthermore, volatilities of acetic acid and ammonia were highly influenced by the drying conditions. From these experiments, it was confirmed that the considerable loss of dry matter owing to the volatilizing of volatile matters could occur during the oven drying of silage and the extent of the loss could be significantly influenced by the fermentation properties and drying conditions of the silage.

View full abstract