To assess ozone impacts on vegetation, the stomatal flux-based method is more appropriate than ozone concentration based indices. The flux-based method recently developed in Europe would also be useful for ozone risk assessment in East Asia. However, it should be modified to apply to the assessment in East Asia because of an interaction between regional climate and species-specific stomatal response on stomatal ozone uptake. For deciduous forest, the length of growing season, when ozone uptake is estimated, is also one of the determining factors. However, it was defined by a fixed time period in previous studies. The fixed time period may remain uncertainty in the estimation of ozone uptake. Therefore, stomatal response for deciduous forests was initially parameterized from scientific literature in East Asia to estimate stomatal ozone flux to deciduous forest. In addition, we made comparisons of simulated cumulative stomatal ozone flux (F_st) for deciduous forests between the following two cases of the length of growing season: 1) the fixed time period (the start and end of growing season were April 15th and October 15th, respectively) and 2) the period based on a phenological model for leaf development. The results showed significant differences in F_st between both cases of the growing season length (up to 22%). In Case 2, high F_st was estimated not only in highest ozone concentration area but also in the moderately high ozone concentration area, such as western Japan and southern China. This showed that ozone effects might spread wide areas in East Asia.

View full abstract

Leaf area density (LAD) profile of zelkova trees was estimated by combining helicopter-borne and portable lidar data based on voxel-based canopy profiling (VCP) method. In this VCP-method, 3-D point cloud data of the trees in the measurement plot were collected from airborne and portable scanning lidar. These data were registered into a single-point cloud date set with a common coordinate system, and then converted into a voxel-based 3-D model that reproduced the tree precisely, including within the canopy. This precise voxel model allowed the LAD of these trees to be computed by direct counting of the beam-contact frequency in each layer. Afterwards, linear interpolation was applied to the underestimated parts of the LAD profile. Root mean square error of the best LAD estimations was 0.20 m²m^-3.

View full abstract

Field observation was conducted for released red-spotted grouper, Epinephelus akaara, at the protected area near Ibuki-jima Island, Kagawa Prefecture to develop effective techniques for stock enhancement of this fish. On Oct. 20 1977, 4,214 hatchery-produced fingerlings were released to the site. Numbers of the fingerlings within a fixed 20 m × 20 m area (quadrat) were counted for 16 days after releasing, and condition factor and stomach content of the fish at the site were also examined. The number of the released fish in the quadrat decreased from 487 on the released day to 17 on the 16th day with daily decreasing rate of 19%, and the value was lower than previous trials at the same site. However, considerable amount of fish were found behind several rocks, suggesting that simple visual observation is not considered to be effective to examine numbers of this fish in the area. Condition factor of the released juveniles was higher than that of the wild fish just after releasing ; however, it sharply decreased to the level of wild one within 4 days. Percentage of the empty stomach of the released juveniles was significantly higher than that of the natural one suggesting that one month and more is required for released juveniles to acclimate to natural environment.

View full abstract

The concentrated deep seawater, which is highly enriched in not only Na but useful minerals such as Mg, K and Ca, is expected to be applicable to the production of high quality tomatoes enriched in sugar, acid, minerals, etc. In order to establish the suitable application of the concentrated deep seawater to tomato production on the basis of plant physiological responses, root uptake and leaf gas exchange were examined under the salt stress. Tomato plants (Lycopersicon esculentum Mill.) were grown in the NFT system, where the concentrated deep seawater was applied to the nutrient solution at the stage of rapid fruit growth for the short-term salt stress treatment. The water and ion uptake of roots were decreased by the short-term salt stress, but Mg²⁺ uptake was significantly enhanced. This brought the high accumulation of Mg into leaves. Concentrations of NO₃^- and PO₄ ^3- in xylem sap under the salt stress were kept at a high level by active uptake of roots, and these concentrations were remarkably higher than those in the nutrient solution. Transpiration rate and stomatal conductance in leaves were depressed by salt stress. However, there is no significant depression in photosynthetic rate. Therefore, it was verified that the short-term application of the concentrated deep seawater can accelerate the Mg uptake by roots and the accumulation of Mg into leaves, and these contributed to keep the photosynthetic activity moderately under the salt stress.

View full abstract

The effect of photoperiod on the flowering of Tithonia rotundifolia Mill. was studied. Plants were exposed to an 8-hrs photoperiod under natural daylight. The photoperiod was extended with 60 W incandescent lamps to give an 8-to 24-hrs day. Under photoperiods at and under 12-hrs, flower buds were initiated; the days from bud formation to flowering were shortened in plants grown under a 12-hrs photoperiod. No effects of photoperiods at and under 12-hrs on plant height and number of nodes. Tithonia rotundifolia Mill. seems to be an short day plant according to the results of this study.

View full abstract