Masatoshi Aoki

Studies on the carbon dioxide enrichment for plant growth, VII. Changes in dry matter production and photosynthetic rate of cucumber during carbon dioxide enrichment

Abstract The dry matter production and the rate of photosynthesis of cucumber under CO2-enrichment were measured. The effect of CO2-enrichment on the growth was great at 1,200 ppm and 2,400 ppm with the growth of 1.5–1.8 times greater than that of the control plot. The effect of 5,500 ppm enrichment, however, decreased with the duration of enrichment. The most effective CO2 concentration for the growth varied from the higher to the lower concentration as the enrichment continued. This was because the effect of enrichment on the growth rate changed with the duration. The CO2-enrichment was effective on the rate of net photosynthesis of cucumber leaves at the beginning. As the enrichment continued, however, the rates at the higher CO2 concentrations rapidly decreased to below that at the normal CO2 concentration. The decrement in net photosynthetic rate was greater when the concentration was higher and the duration of enrichment was longer. The reduction in the effect of enrichment on photosynthetic rate during enrichment accounted for the change in the most effective concentration on the growth rate with the duration.

The individual and combined effects of ozone and simulated acid rain on growth, gas exchange rate and water-use efficiency of Pinus armandi Franch.

The seedlings of Pinus armandi Franch. were exposed to ozone (O(3)) at 300 ppb for 8 h a day, 6 days a week, and simulated acid rain of pH 3.0 or 2.3, 6 times a week, alone or in combination, for 14 weeks from 15 June to 20 September 1993. The control seedlings were exposed to charcoal-filtered air and simulated rain of pH 6.8 during the same period. Significant interactive effects of O(3) and simulated acid rain on whole plant net photosynthetic rate were observed, but not on other determined parameters. The exposure of the seedlings to O(3) caused the reductions in the dry weight growth, root dry weight relative to the whole plant dry weight, net photosynthetic rate, transpiration rate in light, water-use efficiency and root respiration activity, and increases in shoot/root ratio, and leaf dry weight relative to the whole plant dry weight without an appearance of acute visible foliar injury, but did not affect the dark respiration rate and transpiration rate in the darkness. The decreased net photosynthetic rate was considered to be the major cause for the growth reduction of the seedlings exposed to O(3). On the other hand, the exposure of the seedlings to simulated acid rain reduced the net photosynthetic rate per unit chlorophyll a + b content, but did not induce the significant change in other determined parameters.

Effects of O3 and soil acidification, alone and in combination, on growth, gas exchange rate and chlorophyll content of red pine seedlings

One-year-old seedlings of red pine (Pinus densiflora Sieb. and Zucc.) were grown in typic red-yellow forest soil (Typic Hapludults) artificially adjusted to pH (H2O) 3.15, 3.60 or 3.90 by adding H2SO4 solution to the soil (pH 4.60), and exposed to ozone (03) at 150±10 ppb (nl·L−1) for 8 h a day, 6 days a week, for 16 weeks from June 5 to October 5, 1994. The control seedlings were exposed to charcoal-filtered air (CF) and grown in the soil without the additional supply of H+ as H2SO4 solution during the same period.No significant interactive effects of O3 and soil acidification were observed for the determined seedling parameters in this study. However, O3 caused a reduction in needle dry weight, net photosynthetic rate and chlorophyll contents in the needle tip or on whole-needle weight basis, and stimulated rates of dark respiration and photorespiration. There were no significant effects of O3 on chlorophyll contents in the needle middle and basal parts, transpiration rate or water use efficiency (WUE). On the other hand, the seedlings grown in the soil adjusted to pH 3.60 or 3.90 showed a reduction in needle dry weight, net photosynthetic rate, chlorophyll contents in all the needle parts and WUE, and an increase in the rates of dark respiration and photorespiration. The transpiration rate of the seedlings was not significantly affected by soil acidification. All the seedlings grown in the soil adjusted to pH 3.15 died during the first 4 weeks. Soil and needle analysis suggested that high concentrations of Al and low Ca/Al ratios in the acidified soil were stressors.

The individual and combined effects of ozone and simulated acid rain on chlorophyll contents, carbon allocation and biomass accumulation of Armand pine seedlings

The seedlings of armand pine (Pinus armand Franch.) were applied to exposure, alone or in combination, to charcoal filtered air (CF) or ozone (O3) at 300±15 nl/l(ppb) for 8 h a day, 6 days a week, and simulated rain of pH 6.8, 3.0 or 2.3, six times a week, alone and in combination, for 14 weeks from June 15 to September 20, 1993. No significant interactive effects of O3 and simulated acid rain were observed on chlorophyll contents, carbon allocation and biomass accumulation of the seedlings in the present study. The O3 caused reductions in biomass accumulation of whole-plant and below-ground parts, but not that of above-ground parts without an acute visible foliar injury. At the same time, the O3 reduced R/S ratio, but raised F/C ratio. Therefore, O3 also altered carbon allocation pattern. On the other hand, chlorophyll contents were increased by simulated acid rain, but other determined parameters were not altered.

Some Measurement Results on Sulfate Aerosol Concentration in and above a Pine Canopy

Profile of sulfate aerosol (SO42−) concentration was measured for four days at six heights in and above a 15m-high canopy of pine plantation during 6th and 10th August. 1999. The concentration was the lowest (about 2 nmol/m3) on 6th, and gradually increased to 9th showing the maximum values of about 13 nmol/m3, and then decreased to 2 nmol/m3 on 10th. The vertical profiles of SO42− concentration showed mostly higher in the canopy than above the canopy. As for the vertical profiles above the canopy on 8th and 10th, the minimum was observed just above the canopy (16m), showing SO42− transport from the upper air layer to the canopy. While on 9th the profiles that are higher concentration just above the canopy and lower at the upper air layer were observed, suggesting SO42− emission from the canopy to the upper air layer.

Primary liver tumor associated with Werner syndrome (adult progeria)

A 57‐year‐old woman was admitted to our hospital with characteristic aging of the face and thin body. Before admission, she had been treated for diabetes mellitus type 2 and had undergone amputation of the right leg due to ischemic disease. Abdominal computed tomography revealed primary liver tumor. Biopsy of the liver mass revealed poorly differentiated adenocarcinoma, not hepatocellular carcinoma. Genetic sequencing indicated a homozygous mutation in the Werner syndrome gene (WRN) and she was diagnosed with Werner syndrome with primary liver tumor. She declined medications for the liver tumor and eventually died 6 months after diagnosis. Werner syndrome is a rare autosomal recessive disorder associated with premature aging, and most cases of Werner syndrome have been reported from Japan. The main causes of death with Werner syndrome are malignancy and atherosclerotic vascular disease. With respect to malignancy, non‐epithelial tumors are more common in Werner syndrome patients than in the general population. Some cases also show complications of epithelial tumors, as in the present case. When a liver tumor of unknown etiology is accompanied by characteristic aging of the face, Werner syndrome should be suspected and a comprehensive search for other tumors and complications of metabolic disorders undertaken.

Fine Particle Dry Deposition onto a Cropland — a Trial to Estimate Deposition Velocity

The dry deposition velocity of fine particles is usually on the order of several tenths of cm s−1, and accordingly, the concentration gradient of particles above the surface is very small. This makes the application of the gradient method to the determination of the particle deposition velocity very difficult. This study is a trial to find a way around this difficulty. The idea is to evaluate the thickness of the molecular diffusion layer, zb by simultaneously measuring the concentration gradient of gaseous species such as SO2 ; zb is obtained by combining the turbulent and molecular transport equations for the gas. Then the particle deposition velocity is estimated on the basis of zb and the Brownian diffusion coefficient with an assumption that zb is equal to the thickness of the Brownian diffusion layer. By applying this method to the data collected in a field observation, the velocity of deposition onto a cropland was estimated for submicron particles.