Decrease of yield from synthetic 1 to synthetic 2 is undesirable feature in synthetic variety method. The optimum number of composite clone or inbred in synthetic varieties among species or materials. A breeder needs the information about the optimum number. This report exemplify an optimum number of composite clone in alfalfa synthetic. Sixty four plants were selected on the basis of disease resistance, plant type and fall vigor from the 5, 300 individuals which were introduced in 1967 and 1968 from over seas. The selected individuals were propagated into 10 to 12 propagules in 1970 and these clones were evaluated in 1971 and 1972. Based on the clonal evaluations, 35 clones were selected and transplanted into polycross field in 1972 with 10 replications. The polycross seeds were harvested in 1973 and polycross progeny test were carried out from 1974 to 1976. Two-clone synthetic, 4-clone synthetic, 8-clone synthetic and 16-clone synthetic were composed of high yielding 2-, 4-, 8- and 16- clones, respectively based on polycross progeny test. The seeds of synthetic 1 (Syn-1, afterwards) were harvested in the glass house in the spring of 1976 by using alfalfa leaf cutter bees. The seeds of synthetic 2 (Syn-2, afterwards) were harvested in the isolation fields in 1978. Syn-1 and Syn-2 seeds of 2-, 4-, 8- and 16-clone synthetics were sown in 1978 and yielding performance and changes of characteristics were observed from 1978 to 1980. The results were as follows ; 1. The yields of the synthetics were the most in the second year and the least in the first year. The ratio of the yield of the lowest clone to the highest clone in 2-, 4-, 8- and 16-clone synthetics were 98.0, 91.4, 86.7 and 85.6%, respectively, in the polycross progeny test. 2. The observed yields of 2-, 4-, 8- and 16-clone Syn-1 were close to the estimated yields. The yield of 8-clone Syn-2 was the highest and followed by 16-clone Syn-2. On the other hand, the yields of 2-clone Syn-2 and 4-clone Syn-2 were low. The yields of 8-clone and 16-clone Syn-2 were more or less higher than those of Syn-1. On the other hand, the yields of 2-clone and 4-clone Syn-2 were much lower than those of Syn-1. 3. Plant heights in the third year of 2-clone and 4-clone Syn-2 were significantly lower than those of the Syn-1. Stem number of 2-clone Syn-2 was less than that of Syn-1. The proportion of plants with variegated flower color in 4-clone Syn-2 was higher than that of Syn-1. These changes of the characteristics in 2-clone and 4-clone synthetics seem to be the factors of yield decrease in Syn-2. From the above results, 8-clone synthetic seems to be the best in terms of high yielding ability and least yield decrease in the advanced generation in alfalfa.

View full abstract

Occurence of damage in orchardgrass cultivars by continued freezing was investigated. In the first trial, the seedlings of 3 cultivars in pots were hardened at 3℃ for 3 weeks with 8 hours daylength. Thereafter, they were removed from the pots and their crown parts were packed with aluminum foil. The packages were stored in a freezer at -3℃ for 8 weeks. The hardiness of the hardy cultivar increased markedly in an early stage of the storage and was maintained in a high level during 8 weeks, so that no killing was observed. On the contrary, this was not true in the susceptible cultivar and the killing began at 2 weeks after the start of storage. In the second trial, the seedlings of 12 cultivars were treated according to the procedures similar to the first trial and stored at -4℃ for 6 weeks. The tolerance to such a storage condition differed remarkably among the cultivars. Also, a close relationship was found between the percentages of plant survival of the cultivars in the artificial freezing test (-10℃ and -12℃, 16 hours) and those after 2, 4, and 6 weeks of storage. From these results, it was suggested that a prolonged exposure to freezing temperature such as -3℃ or -4℃ was one of the probable reasons why the freezing injury of orchardgrass occured in this area, and that hardier cultivars were more tolerant to such a freezing condition than susceptible ones.

View full abstract

A mixed culture experiment in which each of two sorghum varieties was associated with two soybean varieties respectively was conducted in Fukuoka, Japan, to evaluate the effects on the dry matter production, efficiency of light energy utilization and other growth factors. 1) Though the dry matter yields in the mixed cultures did not over-yield the sorghum pure cultures, the relative yield total in all the mixed cultures was over 1.0. The efficiency of light energy utilization in all the mixed cultures was higher than the each pure culture especially at the later growth stage. The different combination in mixed cultures had little effects on the dry matter yield and efficiency of light energy utilization. 2) The CGR of sorghum in the mixed cultures were higher as compared with the sorghum pure cultures in the later growth stage, which was brought about by the high NAR of sorghum in the mixed cultures. The higher NAR in the mixed cultures was explained by the increase in the estimated net photosynthesis per unit leaf area and lower SLA of sorghum in the mixed cultures. 3) In the mixed culture of sorghum and soybean, no paticular change in the competitive relationship between both species was recognized in any of the different combinations.

View full abstract

S.guianensis cv. Schofield and cv. Endeavour, D.uncinatum cv. Silverleaf, C.pubescens, L.bainesii cv. Miles, T.semipirosum cv. Safari, M.sativa cv. Hunter river, and L.purpureus cv. Dolichos were grown with C.gayana cv. Pioneer (Rhodes grass) under two levels of clipping intensities. DM data were analyzed in relation to the prevailing temperature conditions in southern parts of South-Western Islands of Japan. Schofield, Endeavour, Centrocema, and Lotononis showed higher percent legume and increased legume effect on increased dry matter production, hence, outyielded annual dry matter of other legume-Rhodes grass combinations. Schofield, Endeavour and Centrocema increased dry matter production at around 27℃, whereas Lotononis and Silverleaf at around 22℃. Those results suggested that Schofield, Endeavour and Centrocema are suitable for growing in the area. Data concerning clipping treatments showed that the bunch type or the creeping type of legume such as Schofield, Endeavour and Lotonois is more lasting in the mixture receiving higher clipping intensities comparing with the climbing type of legume such as Centrocema.

View full abstract

This investigation was carried out on 758 cutting swards in Nemuro district in order to clarify the factors affecting the yield of the swards. Among the results obtained from the investigation, it was especially studied in this paper to verify the difference of the yield of the swards and its causes between regosolic andosol and cumulic andsol. The latter soil was greater in cation exchange capacity, buffering capacity for acidification and nitrogen supplying power than the former soil. The results obtained were as follows ; 1) The decrease of yield with the years in the swards corresponded to the unfavourable change of botanical composition such as the decrease of timothy and the increase of Kentucky bluegrass and red top. 2) Since the above change of botanical composition in the swards on regosolic andosol occurred more rapidly than that on cumulic andosol, the decrease of the yield with the years in the swards on former soil was more remarkable than that on latter soil. Therefore, it appeared that the unfavourable change of botanical composition was influenced by the difference in chemical properties of the soils described above. 3) From the results, it was recognized that the main factor which caused the decrease of yield with the years in the swards was worse response to fertilization, because of the unfavourable change of botanical composition.

View full abstract

An experiment of foundation work was attempted to establish pasture on Ando soil in mountainous area which was located in the northeast of Lake Towada, Aomori Prefecture. Cutting and banking were carried out only at the limited part of steep slope for reducing scales and costs. The edges of banking land were consolidated by the compaction using a bulldozer for preventing soil erosion and landslides. Then, pasture establishment was attempted on both cutting and banking lands. Herein are reported the results that pasture establishment was carried out on the banking land. The banking land consisted of the mixture of two different kinds of undesirable subsoil ; one part of "Ao-ban" (bluish platy layer) and two parts of "Akatsuchi" (reddish friable layer), according to their poor physical and chemical properties. Despite of their undesirable properties, a good pasture of orchard grass-ladino clover mixture was made by the following applications of fertilizers and seed mixture ; basal fertilizers (kg/ha): hydrated dolomitic lime 1000-1500, P_2O_5 300, N 50, K_2O 50, additional fertilizers: N 50, P_2O_5 50, K_2O 50, and seed mixture (kg/ha): Italian ryegrass 15, orchardgrass 15, ladino clover 10, with reseeding of Italian ryegrass 20, orchardgrass 20, ladino clover 20, respectively.

View full abstract

An experiment of foundation work was attempted to establish pasture on Ando soil in mountainous area which was located in the northeast of Lake Towada, Aomori Prefecture. Herein are reported the results that pasture establishment was carried out on the cutting land of pumice gravel layer. On the surface where pumice gravels were exposed, forage seedlings were susceptible to drought just after germination because moisture was hardly held by hard and large pumice gravel. This suggested that such a gravel layer should not be exposed in foundation work for pasture establishment. When cutting surface was covered with finer soil materials after seeding, however, forage was successfully established by the following applications of fertilizers and seed mixture ; basal fertilizers (kg/ha): hydrated dolomitic lime 2800, P_2O_5 300, N 50, K_2O 50, additional fertilizers: N 50, P_2O_5 50, K_2O 50, and seed mixture (kg/ha): Italian ryegrass 15, orchardgrass 15, ladino clover 10, with reseeding of Italian ryegrass 20, orchardgrass 20, ladino clover 20, respectively.

View full abstract

The present trial was carried out in order to determine chemical compositions, neutral detergent fiber (NDF), the constituents of the NDF and in vitro dry matter disappearance of the leaves and the stems with sheath of napier grass as affected by nitrogen which was applied at the levels of 0, 30, 60, and 90kg per 10 are per year. The results obtained were summarized as follows: 1. The contents of crude protein and crude fat increased significantly in accordance with the amounts of nitrogen applied, but the nitrogen free extract and crude ash contents decreased in the leaves and the stems with sheath. There was no significant difference in the crude fiber contents of the leaves but significant difference in those of the stems with sheath between the plot with and without nitrogen treatments. 2 In the leaves the lignin content was increased significantly but the silica content was decreased according to the nitrogen fertilization. No significant difference was found in contents of NDF, hemicellulose, acid detergent fiber (ADF) and cellulose of the leaves by the nitrogen treatments. In the stems with sheath the contents of ADF, cellulose and lignin were increased significantly but hemicellulose content was decreased by the nitrogen treatments. There was no significant difference in the NDF and silica contents of the stems with sheath. 3. The dry matter disappearance of both the leaves and stems with sheath decreased as the nitrogen application increased. That of leaves was significantly different between the plots with and without nitrogen application, and that of the stems with sheath was significantly different between the plots with nitrogen, and also between the 30kg and 60or 90kg plot. From the results in this experiment, the crude protein and crude fat contents of napier grass were increased by fertilizations with nitrogen, whereas the various constituents which have high negative correlations to in vitro dry matter disapperance were increased and in vitro dry matter disapperance was decreased by the application of greater amount of nitrogen. Consequently the nutritive value of napier grass tended to be decreased by the application of greater amounts of nitrogen.

View full abstract

Comparison was made between early (Wasehomare, C 535), medium (Hokuyu, Jx92) and late (Jx162, P3390) varieties on nutritive value of corn stover from 1980 through 1982 in Sorachi district Hokkaido. The stovers of late varieties were higher in dry matter and nonstructural carbohydrate content than early and medium varieties, however, no significant differences were shown in the crude protein, acid detergent lignin, TDN and digestible energy (DE) content among the varieties. As the stage of maturity advanced, digestibilities of crude protein, cell wall (CW) and cell contents (CC) decreased significantly. Value for DCP, TDN and DE in milk, doughdent, glaze and flint stages were 2.4, 1.4, 1.1 and 0.9%, 62.6, 59.6, 57.9 and 52.7% and 2.7, 2.6, 2.4 and 2.2Kcal/g.DM, respectively. The changes in the amount of digestible dry matter in corn stover was related to the amount of digestible CC and indigestible CW, however, digestible CW was observed to have less relation.

View full abstract

The black cutworm, Agrotis ipsilon HUFNAGEL, is an immigrant pest harmful to newly sown grasses and other crop plants in Tohoku district. Numbers of the trapped adults fluctuated rather irregularly, presumably because of their migratory habit. The outbreak records accumulated since 1966 however suggested that there might be some regularity in the seasonal oviposition trend, although the outbreaks due to the mass invasion were always local. The oviposition period was estimated to extend from April to August with three peaks in late April to early May, around early June and in mid to late July, respectively. The remarkable larval occurrence was found in spring in the southwestern plain of Tohoku district, being spread over the whole district thereafter. The outbreaks in tame grasslands mainly established in higher lands were referred to the oviposition in June to August, and were more frequent in Aomori, Iwate and Miyagi prefectures, where the grasses were sown continuously during summer, than those in Akita, Yamagata and Fukushima prefectures, where sown in late August or later usually. The delayed sowing was thus recommended to escape the heavy cutworm attack on young grasses. The oviposition prevalence was discussed in conjunction with the synoptic trend of the seasonal adult migration.

View full abstract

The present study was conducted to determine the appropriate cellulase concentration and the digestion period for predicting digestibility of unground dried sorghum leaves by using a simple digestion methodz. The nearly isogenic sorghum lines, bloomless and Bloom Combine Kafir 60 (bloomless and Bloom, hereafter) were grown, the fully expanded top leaves from each line were taken at the 4th, 7th and flag leaf stages, respectively and each of these leaf samples were dried. IVDMD (in vitro dry matter digestibility) values of the fully expanded top leaves using a simple digestion method were measured in cellulase concentrations of 0.1, 0.2, 0.5, 1.0, 2.0 and 4.0% after 24 hours at 40℃. IVDMD values of bloomles were larger than those of Bloom for each cellulase concentration. IVDMD values of each line increased with increasing cellulase concentration, but increase of cellulase concentration had little effect on IVDMD values at the seventh and flag leaf stages above a 1.0% cellulase concentration (Fig.1). From these results, a 1.0% cellulase concentration was concluded as being a reasonable concentration for comparing IVDMD values among different sorghum lines. At the 1.0% cellulase concentrations, IVDMD values for digestion periods of 6, 12, 24, 48, 72, 96 and 120 hours were measured. IVDMD values of bloomless were larger than those of Bloom for each of the digestion periods. IVDMD values of dried leaves were increased with longer digestion periods at each stage, but the distinct differences between IVDMD values of bloomless and Bloom were observed after 6 hours of digestion and IVDMD values almost reached their plateau at 48 to 72 hours of digestion (Fig.2). The powder-like slurry which was difficult to separate quickly from indigestible leaf parts occurred after 72 hours of digestion (Fig.3). From these results, a 48 hour digestion period was considered to be a reasonable digestion period for accurate and quick comparison of IVDMD values among different sorghum lines. Consequently, it is proposed that a 1% cellulase concentration and a 48 hour digestion period at 40℃ are suitable conditions for using a simple digestion method. Furthermore, the procedure shown in Table 1 is proposed as "the simple cellulase digestion method" for comparing IVDMD values of differing sorghum lines.

View full abstract

Two rusts, Puccinia sorghi SCHWEIN. and P.polysora UNDERW., recently attacked corn in Japan. P.sorghi occurred in Shiribeshi and Iburi districts of Hokkaido, the most northern part of Japan, 1981. Again, it was found over the broader area of Hokkaido, 1982. The occurrence of this rust over two years in cold area of Japan is an uncommon case. P.polysora was observed on dried leaves of corn sent from Okinawa prefecture, 1982. This is the first record of P.polysora in Japan.

View full abstract