Showing papers in "Jarq-japan Agricultural Research Quarterly in 1999"

Effects of Various Radiant Sources on Plant Growth (Part 2)

Abstract: In Part 2 of this report, we analyzed the spectrum distribution of several high intensity discharge lamps, in which the spectrum values were multiplied by the average values for 4 different photosynthesis curves developed by McCree(1972) and Inada(1976), and we calculated the photoelectric conversion efficiency expressed as the plant growth radiant efficiency. As a result, we confirmed the high effectiveness of high pressure sodium lamps for plant growth within the PAR range of wavelengths, and concluded that a metal halide lamp 3,500 K (150 W high color rendering index type) was a suitable light source for indoor maintenance of ornamental plants. We also analyzed the light quality within the PAR range of different artificial light sources, by using the R/B and R/FR ratios as a reference to photomorphogenesis. Discipline: Agricultural facilities/Crop production/Horticulture Additional key words: artificial light source, supplemental lighting, plant factory

Distribution of Antimutagenic Components in Colored Sweetpotatoes

Abstract: Antimutagenicity of the water extracts prepared from the outer or inner portion of storage roots (hereafter referred to as ‘outer and/or inner portion’) of 4 varieties of sweetpotato differing in the flesh color was investigated using Salmonella typhimurium TA 98 to determine the distribution of the antimutagenic components. Analysis of anthocyanin pigments in both portions revealed a large distribution of anthocyanin pigments in the outer portion and showed that the content of cyanidin in the outer portion was higher than in the inner one. The strong antimutagenicity of Ayamurasaki outer portion was attributed chiefly to the high concentration of cyanidin. The extracts from the outer portions of Koganesengan, Sunny Red, and Joy White varieties showed an antimutagenic activity unlike the inner ones, suggesting that the antimutagenic component in the outer portions of these varieties was mainly associated with phenolics. Discipline: Food Additional key words: antimutagenicity, anthocyanin, phenolics JARQ 33, 143-148 (1999)

Effects of Various Radiant Sources on Plant Growth (Part 1)

Abstract: In Part 1 of this report, we introduced fundamental aspects of the use of artificial light in horticulture, giving an outline of a number of different artificial light sources and discussing recent research trends (such as the use of microwave-powered lamps, light-emitting diode and laser diode devices) in Japan. Discipline: Agricultural facilities/Crop production/Horticulture Additional key words: artificial light source, supplemental lighting, plant factory

Identification of DNA Polymorphism Induced by X-Ray and UV Irradiation in Plant Cells

Abstract: Angelonia protoplasts were irradiated with X-rays or UV to obtain a half survival rate. To evaluate the DNA damage, total genomic DNA was prepared from protoplasts irradiated with X-rays or UV and nonirradiated control protoplasts, respectively. An aliquot of DNA was subjected to polymerase chain reaction (PCR) with a decamer arbitrary primer in the presence of radiolabeled nucleotides under annealing conditions of low stringency. Randomly amplified PCR products were analyzed using a denaturing polyacrylamide gel. All the DNA bands detected by autoradiography were compared. The number of DNA bands detected in one lane was approximately ~150. The results indicate that the arbitrarily amplified PCR method is very sensitive for monitoring the DNA polymorphism caused by X-ray and UV irradiation. This novel procedure, designated as RI (radioisotope incorporated)-RAPD, could be applied to detect precise DNA polymorphism in plant cells. Discipline: Biotechnology Additional key words: RI-RAPD, Angelonia salicariefolia JARQ 33, 223226 (1999)

Direct acquisition of organic nitrogen by crops

Abstract: Growth response to organic nitrogen application was observed among various crops. We used rice bran mixed with rice straw as organic nitrogen source with a C/N ratio of 20. Nitrogen was not readily released from the organic matter because of the high C/N ratio. Organic nitrogen was applied with chemical fertilizers in an upland field to various crops such as upland rice, maize, potato, sugar beet and soybean. Inorganic nitrogen level in fallow soil was lower until the middle of the growth stage when organic nitrogen and chemical N-P-K fertilizers were applied, compared to the application of chemical fertilizers, only. In contrast to the inorganic nitrogen level in soil, upland rice grew better with organic nitrogen than chemical fertilizer, and took up more nitrogen than other crops during the first 100 days after amendment with organic nitrogen. These results can be attributed to 2 factors. (1) Higher mineralization rate in the rhizosphere of upland rice compared with other crops. Upland rice may enhance nitrogen mineralization in soil by the secretion of some enzymes such as protease and/or materials promoting microorganism activity. (2) Upland rice has a greater ability to take up organic nitrogen directly. If a crop is capable of taking up organic nitrogen in the form of amino acids, peptides and protein, the crop could absorb nitrogen with less competition for nitrogen with microorganisms compared with a crop which absorbs nitrogen mainly as nitrate. The protease activity in the soil planted with maize and sugar beet was higher than that in the soil planted with upland rice and in fallow soil. These results show that the enhancement of nitrogen mineralization is not essential for upland rice. In relation to hypothesis (2), upland rice took up more amino acids than maize in a solution culture containing some kinds of amino acids. The amino acid and protein contents in the soils from the rhizosphere and non-rhizosphere zones of upland rice (hereafter referred to as “rhizosphere and non-rhizosphere soils”) were lower than those in the case of maize, soybean and fallow soil. We also observed that upland rice took up nitrogen before mineralization based on a 15N-labelled rice bran application test. These results suggest that upland rice may take up organic nitrogen preferentially compared with other crops. We examined the nitrogen uptake mechanism of upland rice and maize. Upland rice takes up nitrogen preferentially in the organic form rather than as nitrate which is the favorite form for maize. Endocytosis is one of the mechanisms for organic nitrogen uptake by upland rice. Discipline: Soils, fertilizers and plant nutrition Additional key words: maize, nitrogen uptake, rice bran, upland rice JARQ 33, 15 -21 (1999)

Preliminary Report on Stable Isotope Ratio Analysis for Samples from Matang Mangrove Brackish Water Ecosystems

Abstract: The stable carbon and nitrogen isotope ratios of mangrove leaves, particulate organic matter (POM), shrimps and crabs, squids and fishes were studied for tracing the actual food web structure in the Matang mangrove brackish water ecosystems. Carbon isotope ratio of POM showed a positive correlation with the level of salinity, suggesting that POM around the mouth to mudflat areas of the river may consist of phytoplankton-derived detritus from the sea, whereas POM from mid-to upstream areas of the river may consist of mangrove-derived detritus. 6 13C-6 15N map showed a C-N isotope ratio gradient with the lowest value with mean (±SD) of 6 13C (-28.74±0.031%0) and 6 15N (4.36±0. 15%0) for a mangrove leaf (Rhizophora apiculata), the highest value of 6 13C (-20.45±0.026%0) for a squid (Loligo duvaucelii) and of 6 15N (13.63±0.021%0) for a fish (Stolephorus commersonii). Penaeid shrimps (Penaeus merguiensis, Metapenaeus brevicornis and M. ensis) and mangrove crabs (Scylla serrata) showed intermediate C-N values between those of mangrove leaves and fish/squid. Discipline: Fisheries resources Additional keywords: mangrove litter, food-chain, energy flow

Papaya Ring Spot, Banana Bunchy Top, and Citrus Greening in the Asia and Pacific Region : Occurrence and Control Strategy

Abstract: Results obtained in a special project on insect-borne virus/virus-like diseases of tropical fruit trees implemented during the period 1991-1995 are presented. Incidence of papaya ring spot virus (PRSV), papaya leaf-distortion mosaic virus (PLDMV), banana bunchy top virus (BBTV), cucumber mosaic virus (CMV), citrus greening and citrus tristeza virus (CTV) was examined by ELISA tests for virus diseases of papaya, banana and citrus, and by DNA probes for citrus greening. The FFTC survey teams visited countries in the Asia and Pacific region including Fiji, Guam, Indonesia, Japan (Okinawa), Korea (Cheju), Mainland China, Peninsular Malaysia (West Malaysia), Sabah and Sarawak (East Malaysia), New Caledonia, Palau, the Philippines, Pohnpei, Saipan, Taiwan, Thailand, Tonga, Vietnam and Western Samoa. The distribution of PRSV and PLDMV diseases is expanding. A large area covering East Malaysia, Mindanao, Fiji, Indonesia, New Caledonia, Palau, Pohnpei, Tonga, Western Samoa was found to be free from these diseases. In Okinawa, Taiwan and Saipan which are located in the northern marginal area of distribution of PRSV, the incidence of PLDMV was also observed. BBTV used to occur together with CMV. BBTV had a wider distribution than had been previously assumed, because banana plants did not show lesions when infected with the symptomless mild strain of BBTV. Except for some Pacific islands including those in Micronesia and New Caledonia, all the countries visited were found to be infected with both BBTV and CMV. Citrus was affected by the greening disease and CTV except for some islands in Micronesia. The distribution of a new greening strain which infects pomelo is now expanding. In addition to Taiwan and Mainland China, Okinawa, Mindanao, Palau and Thailand, citrus trees including pomelo are likely to be destroyed unless appropriate control measures are taken. Integrated management system of insect-borne diseases of fruit trees was analyzed in terms of the development of a production system for virus-free seedlings, protection of seedlings from attacks of viruliferous vectors and the elimination of virus sources. Discipline: Plant disease/Insect pest Additional key words: insect-borne diseases, IPM, fruit tree, aphids, citrus psyllids

Effects of Medium Conditions on Adventitious Bud Formation in Immature Mulberry Leaves

Abstract: Immature mulberry leaves isolated from winter buds were cultured on MS media7) differing in the nitrogen source, sugar(s) or pH, or containing various kinds and concentrations of plant hormones, antibiotics or a herbicide. The ratio of the concentration of nitrate ion to that of ammonium ion remarkably affected the frequency of adventitious bud formation (FABF) and ratios in the ranges of 1:1 and 3:1 were optimum. The most suitable sugars for adventitious bud formation were sucrose, glucose and fructose among the tested sugars. The highest FABF was usually observed in the medium containing 1 μM thidiazuron and the addition of 1 μM abscisic acid further enhanced FABF. Changes of pH and addition of other plant hormones did not produce better results than in the control. Kanamycin, geneticin, hygromycin and bialaphos suppressed adventitious bud formation, showing that the antibiotics and the herbicide may be effective for the selection of transgenic plantlets of mulberry. Discipline: Biotechnology Additional key words: nitrogen source, sugar, thidiazuron, abscisic acid, antibiotic JARQ 33, 267274 (1999)

Evaporation and Percolation Control in Small Farm Ponds in Thailand

Abstract: In savanna and tropical monsoon areas where the dry and rainy seasons can be clearly distinguished, it is important for farmers to secure as much irrigation water as possible in the dry season in order to produce fruits and vegetables. Though the Department of Land Development, Ministry of Agriculture and Cooperatives, Thailand recommends that farmers excavate small farm ponds for the purpose mentioned above, the irrigation water stored in the farm ponds in the rainy season is not effectively used in the dry season because of evaporation from the surface of water and percolation from the bottom and lateral parts of the ponds. Therefore, the authors developed methods to control the evaporation and percolation in small farm ponds. They selected 4 methods mentioned below, based on the results of experiments carried out in the eastern region of Thailand by Kobayashi. They developed low cost and sustainable methods which farmers can apply themselves as follows: (1) Covering the surface of water with floating materials. (2) Management of irrigation water using several ponds. (3) Changes in the pond shape. (4) Compaction of the bottom of the pond after crushing. The authors confirmed the effectiveness of the 4 methods through field experiments and model calculations. Discipline: Irrigation, drainage and reclamation Additional key words: floating materials

Raising and transplanting technology for long mat with hydroponically grown rice seedlings

Abstract: Long mat with hydroponically grown rice seedlings (hereafter referred to as LMHS) with a mat size of 6 m in length and 28 cm in width, was designed to develop a labor-saving rice transplanting system. The rice seedlings were grown in a newly developed nursery device for about 2 weeks and the plant length reached 10 to 15 cm. The seedling mat was composed of entangled plant roots and nonwoven cloth and it was strong enough to be handled. LMHS were transformed into roll type seedlings by rolling up. The weight of a mat with roll type seedlings was about 12 kg and approximately 1/5 of that of a conventional mat with young seedlings raised in a soil bed (hereafter referred to as CMSS). A rice transplanter was designed and tested to transplant the roll type seedlings in paddy fields. The rate of damaged seedlings immediately after transplanting was 30 to 50%. However, the minimum rate of missing hills after rooting was 3%, when the number of plants per hill ranged from 7 to 8. Working rate of the transplanter was approximately 0.5 ha/h for a working speed of 1.13 m/s and a working width of 1.8 m. Rice yield in the case of LMHS was assumed to be equal to that of CMSS. Discipline: Agricultural machinery Additional key words: nonwoven cloth

Technique for Deep Placement of Coated Urea Fertilizer in Soybean Cultivation

Abstract: The objective of this study was to increase the productivity of soybean seeds by the application of controlled release nitrogen fertilizers (coated urea). Based on the results obtained in field experiments carried out for 3 years (1989-1991), deep placement of coated urea consistently enabled to increase the seed yield by about 10-20% over the conventional treatment. Deep placement of coated urea did not depress the N2 fixation activity throughout the growth stages until maturity, though N from fertilizer was actively absorbed. The basal deep placement of coated urea for soybean cultivation enabled to supply N from the lower part of roots without concomitant depression of N2 fixation, and consequently seed yield increased. High recovery rate (over 60%) of fertilizer N was also advantageous from economical viewpoints. Discipline: Soils, fertilizers and plant nutrition/Crop production Additional key words: N2 fixation, ureide, root growth, Rb uptake

Estimation of Flowering Date and Temperature Characteristics of Fruit Trees by DTS Method

Abstract: A theory and a method were developed for obtaining temperature characteristics for the flowering period of deciduous and citrus fruit trees from the number of days transformed to standard temperature (DTS) based on the Arrhenius law. Three temperature characteristics, i.e. (1) starting date of calculation (ST day), (2) temperature sensitivity (Ea) or temperature coefficient of growth rate (K) and (3) DTS from ST day to flowering time, were determined in a total of 186 cultivars from 11 species on the Main Island of Japan (Honshu) based on the daily mean air temperature and flowering date recorded over a period of at least 10 years. These temperature characteristics differed among cultivated species and may enable to estimate the flowering date. Discipline: Horticulture Additional key words: temperature sensitivity, Arrhenius law, deciduous and citrus fruit trees

Use of soil animals as bioindicators of various kinds of soil management in northern japan

Abstract: As the soil invertebrate fauna is expected to modify several properties of upland soils in agriculture, the effect of the soil fauna on the soil properties and soybean growth under several kinds of soil management depending on the soil type, nitrogen source, tillage, insecticide and herbicide was investigated. Number of hand-sorted earthworms was positively correlated with the amount of soil aggregates (>diam. 2 mm) (r=0.85, p<0.01), and that of oribatid mites (Acari: Cryptostigmata) extracted by using modified Tullgren funnels was positively correlated with the nitrate nitrogen concentration in the soil (r=0.89, p<0.01). Number of oribatid mites was positively correlated with the content of total nitrogen and the content of total soil carbon in a Gray Lowland soil (both: r=0.99, p<0.01) and a Brown Forest soil (not significant), but negatively in an Andosol. The stem length of soybean cultivated on those soils showed a positive correlation with the number of earthworms (r=0.54, p<0.05) and oribatid mites (r=0.62, p<0.05), while the stem weight of soybean with the number of macrofauna organisms (r=0.61, p<0.05) and earthworms (r =0.8, p<0.01), respectively. The correlations between the number of soil invertebrates and yield or quality of soybean were not significant in this survey. Discipline: Soils, fertilizers and plant nutrition Additional key words: soil invertebrates, earthworms, oribatid mites

Analysis of the Interaction between Surface Water and Groundwater Using Radon-222

Abstract: It is essential to analyze the interaction between surface water and groundwater in order to use water effectively and predict water quality. The conventional method of analysis, however, measures only the flow of a stream and can not determine groundwater seepage accurately. Since the concentration of Radon-222 (222Rn) in groundwater is much higher than in surface water, the use of 222Rn was examined as an indicator for the analysis of the interaction between surface water and groundwater. Measurement of the 222Rn concentration in surface water was conducted to detect groundwater seepage into a stream. Furthermore, the simultaneous movement of water both into and out of a stream from the underlying strata was quantified by solving the 222Rn and water balance equations. Discipline: Irrigation, drainage and reclamation Additional key words: 222Rn balance, water balance JARQ 33, 261 265 CJ999)

Gamma-Ray-Induced Mutation Breeding in Fruit Trees : Breeding of Mutant Cultivars Resistant to Black Spot Disease in Japanese Pear

Abstract: Black spot disease, caused by Alternaria alternata Japanese pear pathotype, is the most important and serious disease of the susceptible cultivars of Japanese pear. The fungus produces a host-specific toxin (AK-toxin) which is highly toxic to the susceptible cultivars. Susceptibility to this disease is controlled by a single dominant gene, and all the susceptible cultivars are heterozygous. Mutants resistant to black spot disease were induced by irradiation of susceptible cultivars with gamma-rays. Nine resistant mutants were selected from chronically irradiated ‘Nijisseiki’. One of these mutants was registered as ‘Gold Nijisseiki’. A resistant mutant derived from acutely irradiated dormant scions of ‘Shinsui’ was registered as ‘Kotobuki Shinsui’. One resistant mutant, which was induced from acutely irradiated dormant scions of ‘Osanijisseiki’, displayed unfavorable characteristics. Four resistant mutants were selected from chronically irradiated ‘Osanijisseiki’. One of them was registered as ‘Osa Gold’. A list of these resistant mutants is shown in Table 4. It was confirmed that all of the mutants showed an intermediate resistance to black spot disease and conferred various levels of resistance. Moreover, mutations with a higher level of resistance than that of ‘Gold Nijisseiki’ were induced from ‘Gold Nijisseiki’ by acute and chronic gamma-ray irradiation. The reason why various levels of resistance were induced could not be elucidated. Discipline: Plant breeding Additional key words: gamma-ray irradiation, Alternaria alternata, AK-toxin, intermediate resistance JARQ 33, 227234 (1999)

Pathology of Acute Necrotizing Mastitis Caused by Staphylococcus aureus in a Dairy Cow

Abstract: Acute necrotizing mastitis in a cow was investigated pathologically. The udder was firmly enlarged to twice the size of a basketball. Histologically, the epithelium of the interlobular duct of the mammary glands was displaced by necrotic debris and bacterial clumps (Grampositive cocci). The intralobular ducts were also necrotic. The alveoli showed scattered necrotic foci varying in size and containing bacterial clumps. The vascular walls of the interlobular stroma exhibited fibrinous necrosis with fibrinous thrombi. The liver showed centrolobular fatty and droplet degeneration of the hepatocytes. Extramedullary hematopoiesis was observed in the liver, spleen, adrenal glands, lungs and kidneys. The bacteria observed in the lesions of the mammary glands were stained positively with immunoperoxidase using an antibody against Staphylococcus aureus. Ultrastructurally, the bacteria were round or oval in shape and had thick cellular walls. Capsule-like fibrous material was present around the surface of the bacteria. Bacteriologically, Staph. aureus was isolated in pure culture from the mammary gland. These findings suggest that Staph. aureus caused the acute necrotizing mastitis. The pathogenesis of the disease was examined. Discipline: Animal health Additional key words: bovine mastitis

Determination of Optimum Spraying Time for Chemical Control of Mulberry Scale, Pseudaulacaspis pentagona(Targioni)(Hemiptera: Diaspididae) in Tea Fields

Abstract: Monitoring methods of mulberry scale larvae, Pseudaulacaspis pentagona, were evaluated for determining the spraying time of effective chemical control. Among them, the calculation of the ratio of “more than half hatched egg batches” which was found to be suitable due to its accuracy, is however, time-consuming. Optimum spraying time is defined as the duration of the period required to achieve a ratio of more than half hatched eggs in egg batches (60 to 90%), which is referred to as “more than half hatched egg batches.” The use of sticky traps set inside a tea bush to capture crawlers of the mulberry scale is a simple and accurate monitoring method. The optimum spraying time occurs 2 to 5 days after the peak capture of the crawlers by the traps. The traps should be set up from the beginning of the egg hatching period, and should be examined daily or every other day to determine the peak capture of the crawlers. The use of sticky traps for monitoring is suitable for only the first generation of mulberry scale. Thus observations of “more than half hatched egg batches” are needed to determine the optimum spraying time for the second and third generations of the mulberry scale. Discipline: Insect pest / Tea industry Additional key words: sticky trap, crawler, egg batch JARQ 33, 155-161 (1999)

Groundwater Pollution by Cattle Slurry Stored in Unlined Lagoon

Abstract: The influence of dairy wastes stored in an unlined lagoon on the total nitrogen concentration of shallow groundwater was investigated in western Hokkaido. The lagoon was constructed in a meadow consisting of an Andosol with a high water table. Increase of the total nitrogen concentration in groundwater was observed at a distance of 75 m from the lagoon within 4 days after a low concentration dairy slurry was loaded into the lagoon. At a distance of 15 m from the lagoon, higher total nitrogen concentration was still observed 85 days after slurry loading. These facts clearly indicate that groundwater contamination by cattle slurry stored in the unlined lagoon occurs very quickly and persists for a very long period of time. Discipline: Agricultural environment Additional key words: nitrogen leaching, Andosols

Helminths and helminthiosis of pigs in the Mekong Delta, Vietnam with special reference to ascariosis and Fasciolopsis buski infection

Abstract: To demonstrate the infection of pigs with helminths in the Mekong Delta, an investigation into the actual conditions was carried out in the area. A total of 87 pigs from 38 farms were examined for the presence of the helminths. Eggs of common nematodes (Ascaris suum, Metastrongylus spp., Oesophagostomum spp., Trichuris suis and Strongyloides ransomi) present in Japan, were detected. Especially, since the morbidity rate of A. suum infection was very high, the effect of the Ascaris infection on pig growth was investigated. As a result, economic loss was estimated at US$2.0/head. In addition, infection with Fasciolopsis buski, which dose not occur in Japan, was detected in 4 pigs from 4 small farms. These 4 pigs were given water spinach as a supplemental feed. It was suggested that this vegetable played an important role in F. buski infection and that the fluke infection was one of the zoonoses. Infection with this fluke in human can be anticipated, because most of the inhabitants ate this vegetable in the Mekong Delta. Discipline: Animal health Additional key words: Ascaris suum, zoonosis, anthelmintic, economic loss JARQ 33, 193-199 (1999)

Mechanism of off-flavor production in brassica vegetables under anaerobic conditions

Abstract: Mechanism of the production of off-flavor in Brassica vegetables, mainly broccoli stored under anaerobic conditions was studied. Methanethiol and dimethyl disulfide were identified as the volatile sulfur compounds in the headspace of anaerobically stored Brassica vegetables, including broccoli. When the activity of C-S lyase, a key enzyme for the formation of volatile sulfur compounds, was measured, no significant changes were observed in the C-S lyase activity in broccoli kept under anaerobic and aerobic conditions. The most obvious difference between anaerobically and aerobically kept broccoli was the degradation of the cell membranes. These results suggest that under anaerobic conditions volatile sulfur compounds are formed by the degradation of cellular membrane lipids and loss of intracellular compartmentation, allowing the enzyme-substrate reaction to proceed. Furthermore, the factors which affect the production of the volatile sulfur compounds, under anaerobic conditions were also investigated. Methanethiol which was one of the first compounds formed under anaerobic conditions appears to be primarily responsible for the off-flavor. Therefore, the chemical nature of the formation processes of methanethiol was also analyzed. Discipline: Postharvest technology Additional key words: broccoli, storage, volatile sulfur compounds JARQ 33, 109 -114 (1999)

Discrimination of Basidiomycete Species and Strains by Random Amplified Polymorphic DNA (RAPD) Analysis

Abstract: To develop a method for the discrimination of basidiomycete species and strains with vegetative mycelia, DNAs isolated from the mycelia of Coprinus and Tricholoma strains, were subjected to random amplified polymorphic DNA (RAPD) analysis. Seven Coprinus species could be distinguished, clearly showing species-specific DNA patterns in the RAPD analysis. One specimen of unknown Coprinus strain was identified as C. cinereus by this method. Six strains of C. cinereus and 4 of C. angulatus could also be distinguished by the presence of strain-specific RAPD fragments. Five members of the Tricholoma family, T. matsutake and related 4 species, also showed species-specific DNA patterns in the RAPD analysis. The discrimination of Tricholoma species was confirmed by cluster analysis based on 192 RAPD fragments. The 5 species could be clearly divided into 5 groups in complete agreement with the taxonomic classification. RAPD analysis of mycelial DNA, as shown in these studies, is a suitable method for distinguishing basidiomycete species and strains. Discipline: Genetic resources Additional key words: Coprinus, Tricholoma JARQ 33, 149154 (1999)

Distribution and RFLP Mapping of Complementary Genes Causing Hybrid Breakdown in Asian Cultivated Rice, Oryza sativa L.

Abstract: Weak plants were found in the BC1F1 generation in a backcrossing program aimed at introducing the wx gene from a Thai cultivar, Col. No. 15, into a Japanese cultivar, Sasanishiki, in Asian cultivated rice. These weak plants were characterized by poor growth and discoloration at the tillering stage, but they were fertile. Hybrid breakdown, which is defined as hybrid weakness and sterility detected in the F2 and later inbred generations from varietal crosses, is controlled by a pair of complementary recessive genes, hwd1 and hwd2, at unlinked loci. Two dominant genes at either the same or different loci, Hwd1/Hwd1 hwd2/hwd2, hwd1/hwd1 Hwd2/Hwd2 or Hwd1/hwd1 Hwd2/hwd2 are needed for normal growth. Using tester lines homozygous for a pair of complementary recessive genes selected in the BC1F3, the genotypes for hybrid breakdown of 100 Asian rice cultivars were tested based on the phenotype of F1 plants. Clinal variation for hybrid breakdown was observed. Cultivars with 2 dominant alleles at either hwd1 or hwd2 locus, were mainly found in insular Asia (Japan, Philippines and Indonesia), while the frequency of cultivars with 4 dominant alleles was more common in cultivars from continental Asia. Linkage analysis using RFLP markers mapped over 12 rice chromosomes indicated that hwd1 from Col.No.15 was located between RFLP markers, C701 and R2309, on chromosome 10, and hwd2 of Sasanishiki was tightly linked to 4 RFLP markers on chromosome 7. Role of hybrid breakdown in genetic differentiation of Asian cultivated rice is discussed. Discipline: Plant breeding/Genetic resources Additional key words: reproductive barrier, hybrid weakness, geographical differentiation, RFLP markers

Summer-Sown Cultivation of Forage Oats and Breeding in Japan

Abstract: Oats are mainly used as forage in Japan. A new cultivation type, in which oats are sown in late summer and harvested as silage or hay in December or later, has been adopted in the warm region of Japan. This type which is referred to as “summer-sown cultivation” enables to make good use of the field from late summer to early winter. However, this system is not satisfactory for oats, because high temperatures persist until mid-September, the day-length shifts from long to short, and the temperature from high to low. We have been engaged in the breeding of oats for summer-sown cultivation to overcome such adverse conditions. Therefore we focused on early heading habit in fall. Based on the evaluation of introduced varieties and lines for heading habit, we observed that some Mexican varieties headed early in summer-sown cultivation. Then we released ‘Haeibuki’ which is a progeny from a cross between a Mexican cultivar, ‘Guelatao’ and an old Japanese one, ‘Hayate’. Haeibuki is characterized by very early heading in summer-sown cultivation and a high dry matter percentage at harvest. Through field trials in the breeding process, we observed differences among cultivars in germination under summer-sown conditions, presumably associated with high temperature. Discipline: Plant breeding Additional key words: Avena sativa L., heading, germination JARQ 33, 57 63 (1999)

Resource-recycling system for domestic wastewater treatment using biogeofilter ditches planted with useful plants

Abstract: It is necessary to develop an energy-saving and resource-recycling system for water purification in rural and mountainous areas. This paper outlines the development of a resourcerecycling system for water purification. The purification system consisted of a combination of an anaerobic/aerobic treatment plant and biogeofilter (BGF) ditches filled with zeolite and Kanuma soil as bed filter materials. The BGF ditches were planted with useful aquatic and terrestrial plants. The average rates of total nitrogen (T-N) and total phosphorus (T-P) removal by the aquatic plants were 1.34 g m-2 d-1 and 0.34 g m-2 d-1, respectively. The water purification system decreased the average T-N concentration to 0.31 mg L-1 and average T-P concentration to 0.22 mg L-1 from domestic wastewater in summer. The useful plants planted in the BGF ditches grew vigorously and were more productive indicating that the secondary effluent of the domestic wastewater contains essential nutrient elements. Thus, the use of this effluent for water culture of useful plants enables to purify the domestic wastewater and is also an effective means of nutrient recycling. Discipline: Agricultural environment/Horticulture Additional key words: domestic wastewater purification, nitrogen, phosphorus

Infection and development of nosema sp. nis h5 (microsporida : protozoa) in several lepidopteran insects

Abstract: Infection and development of Nosema sp. NIS H5, a microsporidian parasite isolated from Antheraea pernyi, in the cell line of Antheraea eucalypti were investigated, compared with those of Nosema bombycis isolated from the silkworm, Bombyx mori. No differences in the infection rate of A. eucalypti cells were observed by 48 h postinoculation between the two species of Nosema. However, the spread of infection in the cell culture with Nosema sp. became slower than that with Nosema bombycis from 96 h postinoculation onward, resulting in 16% of cell infection with Nosema sp. and 22% of cell infection with N. bombycis at 120 h postinoculation. Morphological changes in the sequence of development were almost the same in both Nosema species, but from 96 h postinoculation onward, the sporogenesis of Nosema sp. was slower than that of N. bombycis. Infectivity test to 13 lepidopteran species revealed that N. bombycis was infectious to Bombyx mori, Bombyx mandarina, Antheraea pernyi, Antheraea yamamai, Hemerophila atrilineata, Spilarctia imparilis, Hyphantria cunea, Glyphodes pyroalis, Leucania separata, Spodoptera litura and Pieris rapae crucivora, but not infectious to Lymantria dispar and Euproctis similis. On the contrary, Nosema sp. was infectious to these 12 lepidopteran species except for B. mori, and highly infectious to L. separata, inducing a lethal infection. Thus, it is concluded that Nosema sp. is not infectious to B. mori and has a wide host range of lepidopteran species, suggesting that Nosema sp. could become a very promising agent for the microbial control of insect pests, especially in sericultural areas. Discipline: Sericulture/Pathology Additional key words: silkworm, Nosema Bombycis, host range, lepidopteran species

Use of lacZ and gusA reporter genes to trace the infection process of nitrogen-fixing bacteria

Abstract: To determine whether the gusA gene, which encodes β-glucuronidase (GUS) and lacZ gene, which encodes β-galactosidase are suitable for tracing nitrogen-fixing bacteria in the infection process, Bradyrhizobium japonicum strains labelled with each gene were constructed. Both introduced genes were expressed in rhizobia, but it was difficult to specify the sites where lacZ-labelled bacteria were present, since endogenous β-galactosidase levels were high in soybean root tissues. On the other hand, endogenous β-glucuronidase activity has not been detected in soybean root tissues. The gusA-marked Bradyhizobium, Rhizobium and Azospirillum strains were constructed for assessing the use of their GUS-marked bacteria to trace the presence of introduced bacteria manifested by colonization on the root surface, as well as infection sites, invasion modes and nodulation competitiveness between bacteria. Bradyrhizobium japonicum inoculated to soybean colonized in the form of spots on the root surface. In the spots, curling roots with infection threads were observed. In this report, we describe only the gusA-marked (Brady)rhizobium and Azospirillum strains which we constructed. Discipline: Biotechnology Additional key words: β-glucuronidase, β-galactosidase, Azospirillum, nitrogen fixation JARQ 33, 77-84 (1999)

Operation of a diesel engine using unrefined rapeseed oil as fuel

Abstract: This report deals with experiments carried out to examine the possibility of using unrefined rapeseed oil as a substitute for light oil in a small diesel engine. The authors carried out tests on short-term performance, long-term operation and no-load continuous operation using various kinds of unrefined rapeseed oil (deacidified oil, degummed oil and crude oil) produced in the process of refining, and refined rapeseed oil and light oil for comparison. Specific fuel consumption, thermal efficiency, exhaust-gas temperature, and density of black smoke in exhaust-gas were examined in tests on short-term performance and long-term operation. The amount of deposits in the precombustion chamber and on the injection nozzle was determined in tests on no-load continuous operation. As a result, it was considered that deacidified rapeseed oil can be used as fuel for a diesel engine. Degummed oil and crude rapeseed oil were found to be unsuitable for use as fuel due to the high level of incombustible materials in oil. Discipline: Agricultural machinery Additional key words: substitute fuel, deacidified oil, degummed oil, crude oil, incombusti bility