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Volume 29 (1991)
- Issue 4 Pages 153-
- Issue 3 Pages 97-
- Issue 2 Pages 59-
- Issue 1 Pages 1-
Volume 29, Issue 1
Displaying 1-8 of 8 articles from this issue
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Performance of the System in a Model-Sized GreenhouseKazuo KOJIMA, Herry SUHARDIYANTO1991 Volume 29 Issue 1 Pages 1-10
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSA zone cooling system employing cool air blowing was tested in a model-sized greenhouse. Cool air was provided by a spot cooler, and blown continuously into the lower layer in the greenhouse. The ratio of spot cooler capacity to floor area was about 0.14 kW⋅m-2. The cooling system was tested under dry and wet soil conditions in combination with shading application. The test began on August 18 and terminated on September 12, 1989. In wet soil condition, the cooling system was capable of reducing air temperature at the lower layer in the greenhouse at noon to about 35°C. The system was capable of maintaining air temperature at the lower layer in the greenhouse under dry soil condition to about 1.0°C lower than outside air temperature only during the nighttime (from 18: 00 to 06: 00 JST) . However, under wet soil condition, decreasing air temperature at the lower layer to about 2.7°C lower than that of the outside air was recorded from 17: 00 to 09: 00 JST. The daytime air temperature at the lower layer was about 1.3°C and 2.4°C lower than that of the middle or upper layer under dry and wet soil conditions, respectively. The overall coefficient of heat transfer (U) through single layer cover of vinyl chloride panel was about 15.7 W⋅m-2⋅°C-1 during the daytime, and about 3.6 W⋅m-2⋅°C-1 during the nighttime.View full abstractDownload PDF (951K) -
The Typical Characteristics of Daily Variation of Stem- and Fruit-Diameter of Vine Trees in Several Fruit Developmental StagesShunji IMAI, Kenzo IWAO, Tamio FUJIWARA1991 Volume 29 Issue 1 Pages 11-17
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThis paper reports the typical characteristics of daily variation of cane and fruit diameter of vine tree in several fruit developmental stages.
The results of this study are as following.
(1) The fruit diameter shrunk in the day time and swelled at night just like the daily variation of cane diameter in the young, fruit-developmental stage. It was estimated that these phenomena were caused by the deficit of water content in the day time.
(2) The characteristics of the daily changes of the diameter of cane and fruit, varied depending upon the several stages of development. This shows there is competition of water between the fruit and other organs even in a vine tree.
(3) It was thought that the water did not easily come out of the ripening fruit and not was delivered to the other organs. Cane diameter shrinkage lasted continuously after the II stage of fruit development.View full abstractDownload PDF (634K) -
Influence of Soil Moisture on Daily Variation-Characteristics of Stem and Fruit Diameter of Vine TreesSunji IMAI, Kenzo IWAO, Tamio FUJIWARA1991 Volume 29 Issue 1 Pages 19-26
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThis paper reports the study on desirable soil methods of soil-water control for the restricted-root-area cultivation of vine tree. The results of the measurement are as following.
(1) According to the measurement of cane (one year old) and fruit diameter strinkage, the water stress appeared when the soil drying increased over pF 2.3 in tension of soil moisture.
(2) The increment of fruit diameter strinkage in the fruit development at the I stage was linear to the increment of tension of soil moisture. The upper limit of soil drying was regarded as pF 2.3.
(3) The fruit continued to swell even under the condition of soil drying, but the cane strunk significantly over pF2.2 in the veraison stage of fruit development.
(4) In the ripend stage, fruit swelling was affected conspicuously by soil drying. The upper limit at this stage of tension of soil moisture was regarded as pF 2.1.
(5) The daily changes of cane diameter in the post-harvest stage was very small and the upper limit was regarded as pF 2.1.View full abstractDownload PDF (791K) -
Soung Han CHI, Yutaka SHINOHARA, Yoshio SUZUKI1991 Volume 29 Issue 1 Pages 27-33
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThe Effect of concentration of nutrient solution and aeration on growth and dry matter partitioning in hydroponieally grown young tomato plants (Lycopersicon escurentum M., cv. Ogatazuikou) was investigated.
The plant growth increased with increasing concentration of nutrient solution, except under the highest nutrient concentration. These plants grown with 8 times strength of the standard solution showed temporary wilting and lower dry matter production. As the concentration of nutrient solution increased, the dry matter partitioning in the stem was increased but that in the root was significantly reduced. The total nitrogen content in each organ was the lowest at 1/4 time strength. The total nitrogen content in the leaves was highly correlated to the crop growth rate (CGR, γ=0.97*) and leaf area index (LAI, γ=0.99**) .
The growth of tomato seedlings was accelerated by aeration except for night aeration. This suggests that the aeration during the day time is more effective to the dry matter production than that during the night. The day time aeration and continuous aeration decreased dry matter accumulation in the stem but increased that in the root. The total nitrogen content in the tissue was not influenced by aeration treatments.
In conclusion, low concentration of nutrient solution which resulted in lower shoot: root ratio is thought to be suitable for controlling the vegetative growth in hydroponically grown young tomato plants.View full abstractDownload PDF (868K) -
Kazuo TANAKA, Yosiaki ISIGURO, Hideo YASUI1991 Volume 29 Issue 1 Pages 35-38
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThis study was carried out in order to develop a moisture sensor for rockwool culture. The moisture sensor consists of a small cylindrical plastic probe (50×4×4 mm), in which a thermocouple and nichrome wire were buried and isolated from each other by a plastic resin. The probe was placed in the rockwool block, heated by the nichrome wire during 3 min, and the temperature was measured just before and after heating by the thermocouple. When the heat was transmitted to the rockwool block, the difference between the two measured values decreased in proportion to the thermal conductivity which depended directly on the degree of water saturation in the block. This difference was indicated as mV by the controller. Consequently, the reciprocal of the mV value showed a close linear correlation with the degree of water saturation. It was essential for standard monitoring in the rockwool culture that the probe remained in close with the lower part of the rockwool mat. The degree of water saturation which was measured automatically gave adequate information for the irrigation control system of rockwool culture.View full abstractDownload PDF (497K) -
Kazuo TANAKA, Hideo YASUI1991 Volume 29 Issue 1 Pages 39-43
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThis study was carried out in order to develop electro-conductivity (EC) sensor for rock-wool culture. The EC sensor was developed according to the method of Ito (1982) . The sensor consisted of a ceramic plate (1×10×30mm), on which two electro-conductive pastes were printed as electrodes. The power of the EC sensor, measured by the standard EC measuring amplifier, was 1/3 of that of a conventional one, and the dead time in the measurement was approximately 15 min. The linearity between the measured value of each sensor was maintained in the range of 1.0 to 8.0 mS/cm. The degree of water saturation in the rockwool mat surrounding the ceramic plate affected the power of the EC sensor. However the effect was negligible for practical use when the ceramic plate was placed in the lower layer of the .rockwool mat.
The EC value was measured automatically early in the morning when the fluctuations of the temperature and nutrient solution in the mat were minimal. The values obtained gave adequate information for the irrigation control system of rockwool culture.View full abstractDownload PDF (525K) -
Toshihide NAGANO1991 Volume 29 Issue 1 Pages 45-50
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSDestruction of the Mangrove forests is deteriorating rapidly under unplanned timber felling and land development in Southeast Asia. Recently, it has been realized that reservation and reforestation of the Mangrove forests is necessary for the maintenance of our natural ecosystems.
For performing reservation and reforestation of the Mangrove forests, it is important to understand environmental conditions regarding the natural Mangrove forest. Environmental measurements were carried out at the Mangrove forest in Phang-nga, Thailand.
The following results were summarized.
1) The soil texture of the Mangrove forest is heavy clay which contains above 45% clay. The permeability of the soil is between 1C-4 and 1 G-7cm/sec.
2) Chemical properties of the underground water are influenced considerably by climatic conditions.
During the dry season period, salinity of the underground water has a concentration of 1.1 to 1.7 times that of sea water. As for the rainy season, the concentration of salt is 0.6 to 1.2 times that of sea water.
3) There are many pores made by small animals and dead roots in the soil of the Mangrove forests. It seems that these pores and dead roots contribute considerably to the movement of the underground water and to the discharge of the harmful substances generated in the underground.View full abstractDownload PDF (554K) -
(2) Diagnostic Expert System (DES) for NFT-HydroponicKenji HATOU, Yasushi HASHIMOTO1991 Volume 29 Issue 1 Pages 51-55
Published: March 31, 1991
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSDiagnostic expert system (DES) for NFT-hydroponic culture is designed and examined based on a computer integrated cultivation system (CICS) .
DES is composed of four frames of knowledge referred to as“searched out mechanical and electric error functions on sensors, ”“searched out error functions on controllers, ”“continuous control”and“searched out error functions caused on crops, ”and these frames consist of production rules. Measurement data are compared with simulated data from system identification on autoregressive (AR) model. In case of these differences increasing, DES will search out error functions and continuously control.
In this paper, DES diagnosed trouble caused by an ion-sensor. DES searched out an error function on the ion-sensor, and continuously controlled ion-concentrations.
DES uses not only ion concentration control but also other applications. For automation of cultivation and control in NFT-hydroponic culture, CICS as proposed in this paper is the most suitable system at the moment.View full abstractDownload PDF (388K)
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