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Volume 45, Issue 4
Displaying 1-12 of 12 articles from this issue
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Hirakazu SEKI, Tomoaki KOMORI1990 Volume 45 Issue 4 Pages 217-226
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn warming the soil bed for the protected cultivation of a typical water retentivity by circulating warm water, changes of temperature and moisture content distributions of the soil with time were predicted theoretically by applying Philip and deVries' model. Heat and moisture transport properties were estimated systematically, on the basis of the matric potential of soil water expressed by an approximate function of temperature and moisture content, and of the several empirical constants. Temperature and moisture content distributions were calculated by finite difference technique for the cases of 30°C, 40°C and 50°C of water temperature Tl, assuming the bare soil. It was shown that the drying rate of the soil around the warm water pipe becomes larger as Tl becomes higher, and that the dry out would be limited within an extremely narrow region around the pipe. The calculated results shown here would become useful information on planning the soil warming system in a greenhouse.View full abstractDownload PDF (1125K) -
Tetsuya HASEBA, Kenji AIBARA, Koji MORIYA, Atsushi NISHIKAWA, Daijiro ...1990 Volume 45 Issue 4 Pages 227-234
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSAir flow generated by thermal convection was used in a low-speed wind tunnel to evaluate leaf boundary-layer transfer coefficients. The 20cm long test section had a 25cm×25cm square cross-section over which a stable laminar air flow with turbulence intensities of less than 0.02 was produced under a range of flow speed from 10 to 130cm·sec-1.
By applying this wind tunnel, water-vapor transfer coefficients were evaluated for heated leaf models with various temperature differences between the model surface and the air. Transfer coefficients were also evaluated for non-heated leaf models of various lengths and widths both between 1 and 16cm. From the experimental results, the effect of buoyancy on the coefficient was investigated.
Transfer coefficients obtained from the present experiments were larger than the theoretical laminar forced-convection ones. The ratio of the transfer coefficients to the theoretical forced-convection ones was represented as a function of the aspect ratio, the Grashof and Reynolds numbers.
It is concluded that, in light winds, the free-convection over the leaf surface and the advection around the edge produce a larger boundary-layer transfer than the pure forced-convection one.View full abstractDownload PDF (904K) -
Takeharu BOKURA1990 Volume 45 Issue 4 Pages 235-242
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe meteorological observation has been conducted in order to figure out the actual situation of fog and stratus spread under the inversion layer of Yamase.
Since the advective flow from the Pacific Ocean is intercepted by Mt. Hachiman (1022m high) in Aomori Prefecture, the grazing land which is located on the slope of its eastern side was selected and two fixed observation points were set up: one (100m) is in the grazing land and the other is at the mountain district (880m).
Travelling observations between these two points were also carried out by the car to measure solar radiation and dry and wet bulb temperatures.
During the observation period (June 24-July 2, 1988), one or two layers inversion were recognized under the height of 1, 500m from the aerological data at Misawa.
There is a good correspondence between the vertical profile of air temperature at Misawa and the data of air temperature obtained at two fixed points.
When the depth of the inversion layer is shallow, the most part of the grazing land is above the layer and it has been found out that not only air temperature but also solar radiation is enough to vegetate.
When the depth of inversion layer is deep and the land is in the layer, the solar irradiation is higher along with the altitude, because the radiation path through the fog and stratus is shorter.View full abstractDownload PDF (4868K) -
Yasuyuki AONO, Yukio OMOTO1990 Volume 45 Issue 4 Pages 243-249
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSBlooming dates of Prunus yedoensis at 38 sites are estimated by using “the number of days transformed to standard temperature (hereafter referred as DTS)” for the 25 year period starting 1961. The sites are all located at or in the vicinity of the meteorological observatories of Japan Meteorological Agency. The standard temperature for DTS in this study is chosen 25°C, for the temperature characteristic Ea, a value [71.1kJ mol-1] is used for all stations. Both of these values are the same as those in our previous paper, although CGS unit was used before.
It is shown that by this first estimation RMS errors of estimated blooming dates fell within a range 1-3 days except for stations in regions of southern coasts of Kyushu Is. and Izu Is. An attempt of reducing errors, in the first place, readjustment of accumulated DTS was made. This enable us to reduce RMS error up to 0.5 days from the previous computations. But this approach was not very effective at southern stations. Large RMS error in these warm regions seemed to be due to incomplete transition of rest break or large interannual variation of this process. An adjustment of estimation of blooming date at southern sites is made by applying the concept of chill-unit which is the weighted hour corresponding to the effectiveness of chilling to rest completion. It is shown that this procedure reduced RMS error of blooming dates to 2.32 days from 6.64 days at Hachijo Is., and at all stations in warm regions the error reduced to about 2 days.View full abstractDownload PDF (2262K) -
1990 Volume 45 Issue 4 Pages 250
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (177K) -
Responses to Air PollutantsKenji OMASA1990 Volume 45 Issue 4 Pages 251-257
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe effects of air pollutants on stomatal aperture and epidermal cells of attached sunflower leaves were observed with a remote-control light microscope system that permitted continuous observation of stomatal responses over periods of several hours. The relationship between actual stomatal opening and the stomatal conductance, measured with a porometer, was examined at different leaf ages.
The stomatal closure was observed during the exposure of SO2+NO2+O3 in low concentrations (0.1 to 0.2μl·l-1). There was a tendency for the extent of closure to increase in rise of concentration and mixture of these pollutants. The stomatal response to high concentration O3(1.0μl·l-1) fluctuated in the region at a distance from veinlet because of stomatal opening induced by water-soaking. The transient opening was less common in stomata near veins and veinlets.
There was a good correlation between actual stomatal opening and stomatal conductance in the same area of the leaf. However, the regression curves varied with the leaf age.
The results of these experiments indicate the necessity of continuous observation of individual stomata under the microscope to understand the effects of air pollutants on stomatal behavior.View full abstractDownload PDF (6120K) -
Responses to Changes in Water Absorption Through RootsKenji OMASA, Sachio MARUYAMA1990 Volume 45 Issue 4 Pages 259-264
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe effects of water stress on stomatal aperture and epidermal cells of attached sunflower leaves, were observed with a remote-control light microscope system. The relationships between stomatal movements and changes in water potential, turgor potential and osmotic potential of attached leaves were examined.
The leaf water deficit was caused by ice water perfusion to roots and the recovery was performed by 20°C water perfusion. After the ice water perfusion the stomata immediately opened with severe turgor loss and hollow of epidermal cells, and then it rapidly closed. The severe water deficit (leaf water potential: -0.5 to -1.3MPa) produced complete closure of stomata but the slight water deficit (-0.5 to -0.8MPa) caused incomplete closure and immediate recovery after 20°C water perfusion. The hollow of epidermal cells indicated a time point of 0MPa turgor potential.
Changes in leaf water potential above -0.8MPa during water deficit and its recovery were regulated by turgor potential and those below -1.0MPa were caused by osmotic potential. In the range of -0.5 to -0.7MPa leaf water potential and 0.4 to 0.15MPa leaf turgor potential, the stomatal movements were controlled by changes in turgor potential in epidermal cells as well as that in guard cells relating to K+ transport.
The results of these experiments indicate the necessity of continuous observation of individual stomata by the microscope under the measurement of water potential, turgor potential and osmotic potential to understand the effects of water stress on stomatal behavior.View full abstractDownload PDF (4175K) -
Hiroshi HAMAMOTO, Hiroshi NAKAMURA1990 Volume 45 Issue 4 Pages 265-269
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe present study was conducted to understand how large extent the row cover by the fabrics made of spunbonded polypropylene improves surface soil conditions (temperature, water content and hardness) for crop seed germination and emergence. Soil temperature at 5cm depth, water content in 2cm thick surface soil layer and penetration resistance of 1cm thick layer were measured.
On clear days, the row cover maintained the soil temperature 1-3.5°C higher than under the non covered condition, but its effect was smaller on cloudy days. The water content was also higher in the covered row, and this tendency was more significant on clear days. Under the row cover the surface soil structure was protected from raindrop impacts and crusts were not formed.The penetration resistance was maintained almost zero in the covered row, whereas that in the non covered row increased to 2.6kg/cm2.
The row cover promoted the emergence of spinach in November, especially when clear days continued after sowing. This is because the effects of the row cover on soil conditions are large on clear days.View full abstractDownload PDF (4037K) -
Zelkova Trees in Sendai CityKenji OMASA, Akira TAJIMA, Kayoko MIYASAKA1990 Volume 45 Issue 4 Pages 271-275
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThermography, which is a method for obtaining surface temperature, was used to diagnose street trees. Leaf temperature provides physiological information about processes such as stomatal movement, transpiration, CO2 uptake, and air pollutant absorption under steady-state thermal environments. Actually, the effect of environmental stress on zelkova trees on Aobadori St. in Sendai city was evaluated from the difference between temperatures of trees. Also, the recovery after pruning branches, and painting with mud and injecting nutrition to the trunk of a damaged tree was diagnosed from the spatial difference of leaf temperature. The use of both thermography and portable porometer makes a precise diagnosis of street trees possible.View full abstractDownload PDF (2285K) -
Tetsuo SAKURATANI1990 Volume 45 Issue 4 Pages 277-280
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn order to apply, to rice plant, a stem heat balance method for measuring the mass flow rate of sap in the stem of plants, we improved our original gauge in the sensitivity. In the reformed gauge, we used a heater of 8mm in width which was shorter by 2mm than that of the original one and a miniaturized heat flow sensor in which the thermal resistance was provided by an element consisting of a double side tape and an aluminum foil.
The accuracy and the reliability of the reformed gauge were tested by comparing sap flow rate of a potted rice plant measured by the gauge and transpiration rate by the weighing method. The results indicated that the heat balance method was able to be applied to the stem of rice plant with accuracy of the order of ±10% under medium or high flow, using the modified gauge.View full abstractDownload PDF (393K) -
Gui Ging YANG, Shou De GAN1990 Volume 45 Issue 4 Pages 281-285
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (587K) -
Yoshinori SUZUKI, Seiji HAYAKAWA, Tatsuro KUSAKA, Hiroshi UTSUNOMIYA, ...1990 Volume 45 Issue 4 Pages 287-290
Published: March 10, 1990
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (566K)
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