Response of gas exchange rates in <Emphasis Type="Italic">Abies firma</Emphasis> seedlings to various additional stresses under chronic acid fog stress

In order to clarify the chronic influence of acid fog on the gas exchange rates of momi fir (Abies firma Sieb. et Zucc.) trees, we exposed them to simulated acid fog (pH 3) for 3 years. The composition of the acid fog was similar to that observed in a region where momi fir trees have been declining, and it contained organic acids. We then treated the firs with various additional stresses, such as drought, low temperature, fine root cutting, ozone exposure, soil acidification, nitrogen load, and rhizosphere aluminum stress. Under chronic exposure to acid fog, the momi fir seedlings exhibited a pattern of stomatal behavior whereby they excessively opened in summer and closed in winter. Furthermore, the stomata of these seedlings tended to open during drought stress, and their needles were visibly injured after ozone exposure. The net photosynthesis rates of the seedlings exposed to acid fog were regulated by their stomatal aperture, rather than directly by acid fog. These results suggest that acid fog exposure disturbs the control of stomatal function in the momi fir seedlings. In addition, we found that chronic acid fog exposure suppressed the decrease in net photosynthesis rate, due to its nitrogen load.     

Chemical structures of the condensed tannins in the fruits of Diospyros species

The structural variety of the condensed tannins (proanthocyanidins) in the fruits of 16Diospyros species are reported. Eleven species contained condensed tannins mostly consisting of a mixture of catechin (CA) and gallocatechin (GCA) repeating units; the other five species did not. The GCA content in the CA-GCA total varied from 0.3% to 84.6%. The number of esterified gallic acid per one flavan repeating unit (degree of galloylation, DG) ranged from 0.01 to 0.89. The GCA content was found to be proportional to the DG values. Thus, 16Diospyros species tested may be classified into five groups by the analytical data of their condensed tannins. It may be interesting to compare their structural characteristics with those of the condensed tannins in other fruits, leaves, woods, and barks from the viewpoint of their biosynthesis and function in the plants.Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1995     

Mass propagation method from the cutting of three dipterocarp species

We developed a vegetative propagation system for mass-producing three dipterocarps species,Shorea selanica Bl.,Shorea leprosula Mig., andShorea platyclados Sloot. This system uses fog evaporative cooling inside a greenhouse to reduce the leaf-to-air vapor pressure deficit (leaf-to-air VPD) inside the propagator, even under high irradiance conditions. This cooling method has no negative influence on medium conditions such as overwetting. A plastic tent propagator combined with this cooling method was used for vegetative propagation experiments. In mass-production experiments, the annual rooting percentages from the cuttings were low in the first 2 years (1997–1998) due to operational problems of the tent propagator (S. selanica, 48–51%;S. leprosula, 56–59%;S. platyclados: 50–63%). A hard cover propagator improved the rooting percentages in the mass-production experiments in 1999 because it made operations easier (S. selanica, 70%;S. leprosula, 77%;S. platyclados, 77%). This system, which uses a combination of fog evaporative cooling and a hard plastic propagator, should be useful for the mass propagation of these dipterocarp planting stocks. This study was carried out under a joint project of the Ministry of Forestry, Indonesia and Komatsu Ltd. The project was supported by Research Association for Reforestation of Tropical Forest (RETROF) organized by Japanese Forestry Agency.     

Heterotrophic respiration causes seasonal hysteresis in soil respiration in a warm-temperate forest

To assess the effect of changes in organic litter stock on seasonal changes in heterotrophic respiration (R _H), soil respiration (R _S), and total ecosystem respiration (R _E), we measured seasonal changes in leaf litter respiration (R _LL) by the chamber method and estimated the seasonal change in total R _H using the RothC model in a warm-temperate mixed deciduous?Cevergreen forest in Japan. Both R _E and R _S had seasonal hysteresis and were higher in spring than at the same temperature during autumn. Under warm and humid conditions, the rate of decomposition of newly supplied leaf litter in one?year was high (60% loss). Consequently, R _LL and R _H were higher in spring after leaf drop, when more fresh material was available, than in autumn. In this study, 42 and 88% of the difference in R _E and R _S between spring and autumn (soil temperature 16?C18°C) could be accounted for by the difference in R _H, respectively, and 71% of the difference in R _H could be accounted for by the difference in R _LL. This study showed that seasonal changes in heterotrophic respiration (R _LL and R _H) could be a major factor in the seasonal hysteresis of R _E and R _S.     

Behavior of four broad-leaved tree species used to revegetate eroded granite hill slopes

Information on primary growth behavior after planting is required for mixed-plantation revegetation using broad-leaved species. To estimate primary growth, especially from the perspective of crown coverage and changing growth rates, we examined the growth and survival of four broad-leaved species that are frequently used in erosion-control plantations in Japan. The species studied were Myrica rubra Sieb. et Zucc., Alnus pendula Matsum., Quercus glauca Thunb., and Q. serrata Thunb. The survival, height, and basal diameter of planted trees were measured over a 4-year period, and crown area was calculated over a 3-year period. We found a negative relationship between relative growth rate (RGR) and survival rate, suggesting that fast growth may be fatal when resources are severely limited. The relative height growth rate (RHGR) of A. pendula was especially high during the early period of the study (1997–1999) and then drastically declined, whereas the opposite tendency was observed in Q. glauca. The results of stem allometry analyses conformed to the specific relationships between height growth and diameter growth of the four species; increases in stem thickness based on height increments were smaller in the pioneer species A. pendula. Between-species differences in coverage per planted tree (mean crown area multiplied by survival rate) were small as a result of the negative relationship between coverage area and survival rate.     

Effects of chronic acid fog exposure with soil acidification or nitrogen loading on nutrient status in Abies firma seedlings

To clarify the nutrient status in momi fir (Abies firma Sieb. et Zucc.) seedlings under complex stress conditions of acid fog with soil acidification or nitrogen loading, we exposed seedling shoots to simulated acid fog (pH 3) and simultaneously loaded the soil with acid or excess nitrogen for 17 months. Proton and nitrogen loading reduced K concentration in soil, but these treatments had little effect on the nutrient status of fine roots in momi fir seedlings. Acid fog exposure resulted in reduced concentrations of Mg, Al, and Fe in current-year needles and Mg, Al, Cu, Fe, and Zn in 1-year-old needles. The complex effects of acid fog exposure with proton or nitrogen loading on nutrient status were relatively slight. However, elements such as Al and Cu notably reflect the effects of proton loading. These results show that the nutrient status of trace elements, rather than major elements, in needles of momi fir seedlings is sensitive to exposure to acid fog or proton loading.     

Characterisation of starch properties and physical characteristics in buckwheat (Fagopyrum esculentum Moench.) mutant lacking accumulation of ‘granule-bound starch synthase a’

The concentration of amylose, which is synthesised using granule-bound starch synthase, affects the physical properties of food. However, no studies have focused on starch properties and physical characteristics of low-amylose buckwheat. Here, we hypothesised that low-amylose buckwheat would be useful to produce new buckwheat products because low-amylose characteristics change the texture of buckwheat food. In this study, we bred relatively low-amylose buckwheat compared to wild type and investigated the causative genes of the traits, starch properties and physical properties of noodles. In the GBSSa mutant, the amylose concentration was lower than that in the wild type. Compared with the wild type, the mutant exhibited the following traits: Amylose concentration decreased by approximately 2%, setback in the Rapid Visco Analyzer decreased by 30 points and the physical characteristics of noodles in the sensory analysis were soft and sticky. These results suggest that this trait may be useful for changing the texture of foods. In addition, the mutant is promising for producing new foods with physical characteristics that are different from those of the wild type.     

Characterization of zinc adsorption sites in two mineral soils

The adsorption of Zn, as compared with Mg, on two mineral soils, which differed in their major cation-exchange materials and with and without Ca-saturation, was measured in the presence of free CaCl₂.

The adsorption of Zn as well as Mg occurred on cation-exchange sites. The Zn adsorption data conformed to a two-term Langmuir equation. The presence of two kinds of adsorption sites and their numbers and bonding energies were deduced. However, the Langmuir approach was not adopted on the basis of comparison between the total number of the adsorption sites for Zn deduced and the CEC of the soils.

As an alternative approach, the selectivity coefficient as defined by the equation:

was calculated for each adsorption equilibrium and plotted against the amount of Zn adsorbed. This [Zn]_soil plot was used to estimate the capacities of the soil to adsorb Zn with specified affinities. The value varied between 1 and 1,000, whereas the corresponding value varied only between 0.5 and 1. The value was dependent upon the amount of Zn adsorbed, the status of exchangeable cations, and the major cation-exchange materials (montmorillonite VS. allophane-imogolite) in the soils. The importance of surface OH groups in allophane-imogolite as specific adsorption sites for Zn was suggested.     

Investigation of the prevalence of neurologic equine herpes virus type 1 (EHV-1) in a 23-year retrospective analysis (1984–2007)

A single nucleotide polymorphism in the equine herpesvirus 1 (EHV-1) DNA polymerase gene (ORF30 A₂₂₅₄ to G) has been associated with clinical signs of equine herpes myeloencephalopathy (EHM). The purpose of our study was to determine the odds ratio for this genetic marker and EHM using a panel of field isolates from North America collected over the past twenty-three years. EHV-1 isolates cultured at the Cornell University Animal Health Diagnostic Laboratory from 1984 to 2007 were retrieved along with their clinical histories. DNA was extracted from these EHV-1 cultures and allelic discrimination was performed using real-time PCR. The results were confirmed by sequencing of the target region in ORF30. PCR and sequencing were in 100% agreement and showed that 19 out of the 176 isolates had the ORF30 G₂₂₅₄ allele (11%), of which16 were EHM cases and 3 respiratory or abortion cases. The odds of having neurologic disease with the ORF30 G₂₂₅₄ genotype were computed as 162 times greater than those with the opposite allele ORF30 A₂₂₅₄ (95% confidence interval: 35–742). Despite this strong statistical significance, 24% (5/21) of horses with neurologic disease in our study population harbored the “non-neurologic” form of the allele (ORF30 A₂₂₅₄), suggesting that other factors may also contribute to the onset of EHM.