Land consolidation involving the joining of small paddy fields to form a large-size field has been promoted recently in Japan in order to increase the efficiency of rice production. However, the variability in soil fertility within a large-size field causes problems for rice production such as late heading, lodging, and deterioration of rice quality. To address these problems, a site-specific nitrogen management system for paddy rice was developed. In this paper, we briefly review the concept and the achievement of precision agriculture, outline the site-specific management system which we developed, and present the results of the application of this system in a farmer’s field.
The role of sugars in the prolongation of the vase life of cut flowers was reviewed. Beneficial effect of sugars on the supply of substrates for respiration and, therefore, on longer life of cut flowers is generally recognized. This widely accepted role of sugars as providers of additional substrates for respiration has perhaps largely over-shadowed other important roles. In this review, attempts were made to study the role of sugars in the prolongation of the vase life of cut flowers in general, and in the delay in ethylene biosynthesis or decrease in sensitivity to ethylene in particular.
A digoxigenin (DIG)-based amplified fragment length polymorphism (AFLP) method was developed to distinguish three closely related citrus cultivars, ‘Kishu’, ‘Mukaku-Kishu’ and ‘Hira-Kishu’. In particular, ‘Mukaku-Kishu’ characterized by seedless fruit is very important for breeding purposes. Initial attempts at using the DIG-based RAPD procedure failed to detect ‘Mukaku-Kishu’-specific bands. However, the DIG-based AFLP method enabled to detect such bands, indicating that this method is more sensitive than the DIG-based RAPD procedure. The detailed protocol for the DIG-based AFLP methods is presented in this paper.
Potato extract (PE), corn extract (CE) and papaya extract (PAE) at concentrations of 25, 50 and 100 mL L-1enhanced callus growth on New Phalaenopsis (NP) medium containing sucrose. Among the various concentrations, 100 mL L-1 PE or PAE and 200 mL L-1 CE significantly promoted callus growth compared to the control. Regeneration of protocorm-like bodies (PLBs) from calli was optimum when NP medium (sometimes referred to as BM) was supplemented with 100 mL L-1 CE, followed by PE and PAE at the same concentration. Most plantlets also regenerated from PLBs with one 100 mL L-1 CE.
This study was conducted in Tan Phu Thanh Village in the Mekong Delta, Vietnam in order to determine the prevalence of Salmonella spp. in the water system, and to reveal the exchange of Salmonella spp. occurring between the water system and livestock in this village. A total of 142 water samples were collected from 40 farms in this village from February to March, 2001. Thirty (21.1%) samples out of the 142 water samples analyzed were positive for Salmonella spp. in culture, based on biochemical tests. A total of 19 different serovars were observed among the 36 isolates from the positive water samples. Serovars Derby (n = 6), O3,10: r :- (n = 4), Anatum (n = 3), Bardo (n = 3), Javiana (n = 3), London (n = 2), Bovismorbificans (n = 2), and Dessau (n = 2) were isolated from more than one water sample. Serovars Derby and Javiana had been observed among the strains isolated from swine in Tan Phu Thanh Village in 2000 (Phan et al., in preparation). Consequently, we attempted to compare these strains of water and animal origins by pulsed-field gel electrophoresis. The difference in the number of bands between the isolates from water and swine was less than 4 in part of the S. Derby and Javiana isolates. These data provide indirect evidence for an exchange of Salmonella between the water system and swine population in this area. Moreover, 3 (6.1%) out of the 49 samples of stored water used for animal watering were positive for Salmonella spp. including the serovar Javiana. Sterilization of stored water is essential to prevent the spread of infection in this area.
TDR (Time-domain reflectometry) is an advanced method for monitoring the water content in fields. TDR measurements can provide accurate information about vegetation effects on both spatial and temporal soil water distribution. The objective of this study was to examine the effects of vegetation conditions on the distribution of the soil water content. Soil water content was measured to express the spatial distribution in the surface layer (0-0.2 m) in grass, corn, and non-planted fields. Additionally, using the TDR method with multiple probes with different lengths, the measurements were conducted on a temporal basis at 4 depths (0-0.1, 0.1-0.2, 0.2-0.3 and 0.3-0.5 m) to determine the soil-water content profiles in the 3 fields. A significantly higher water content in both the grass and cornfields was found, compared to the non-planted field. Moreover, in the cornfield, we observed that microtopographic features significantly affected the spatial water distribution. The lower the soil water content, the higher the coefficient of variation of the soil moisture content. These results indicated that the effects of the vegetation conditions on the soil water distribution in the fields were significant. From the observation of the temporal soil water profiles in the 3 fields, it was found that soil management, i.e. tillage or no-tillage, was a major factor affecting the profiles.
The objective of this study was to elucidate the chemical composition of essential oil from Cymbopogon nardus (citronella oil) and its antifungal activity. Chemical composition of the citronella oil was determined by capillary gas chromatography (GC) and GC/ mass spectrometry. Major constituents of the oil were geraniol (35.7% of total volatiles), trans-citral (22.7%), cis-citral (14.2%), geranyl acetate (9.7%), citronellal (5.8%) and citronellol (4.6%). The antifungal assay using the vapor-agar contact method showed that the crude essential oil markedly suppressed the growth of several species of Aspergillus, Penicillium and Eurotium at a dose of 250 mg/L in air. The most active compounds among the 16 examined volatiles, consisting of 6 major constituents of the essential oil and 10 other related monoterpenes were citronellal and linalool. Citronellal and linalool completely inhibited the growth of all tested fungal strains at a dose of 112 mg/L. Their minimum inhibitory doses ranged from 14 to 56 mg/L. The α- and β- pinenes showed an inhibitory activity against some fungi, whereas the other 8 volatile compounds lacked this property.
Infestations by stem borers in teak (Tectona grandis) and yemane (Gmelina arborea) plantations were surveyed at seven locations in Sabah, Malaysia in March, 1998. The teak beehole borer (Xyleutes ceramica) and the collar ring borer (Endoclita aroura) were found to attack teak and yemane. X. ceramica accounted for most of the boring attacks in teak plantations, damaging 10.3-65.2% of the planted trees, except at one location where no stem borer attack was detected. The number of past and present attacks per tree ranged from 0.27-1.28 and 0.01-0.62, respectively. In contrast, E. aroura was of minor importance, attacking 6.9% or less of the planted trees. Analysis of spatial distribution of past attacks by the teak beehole borer in young teak stands revealed a contagious pattern. The past attacks were heavier on bigger trees. Both past and present attacks were concentrated in the lower part of the trunk, less than 1 m from the ground level. In young stands of yemane, an unidentified lamiine cerambycid damaged 0.0-14.1% of the trees, whereas the teak beehole borer damaged 7.6-12.2% of the trees.
The purpose of the porosity measurements was to compare the boards made by two different methods: the conventional, hydration curing method and the CO2 injection method, and to find out how their porosity affects water absorption. The specific pore-surface area of the CO2-hardened boards was much smaller than that of the hydrated cement-bonded particleboards. Regarding the pore size distribution diagram, in the case of the CO2-hardened boards, there were two peaks on the graph (one peak at a pore diameter of around 6-8 µm, and a second peak at around 2 µm), and in the case of the conventional boards there was only one peak at 2 µm. The total pore volume of the CO2-hardened boards was larger than that of the hydrated boards. Water absorption of the CO2-hardened boards was lower than that of the hydrated particleboards. There was no relationship between the specific pore-surface area and water absorption, and between the total pore volume and water absorption. The use of CO2 did not affect water absorption and these boards still displayed a higher initial strength.