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Volume 39 (2001)
- Issue 4 Pages 235-
- Issue 3 Pages 139-
- Issue 2 Pages 75-
- Issue 1 Pages 1-
Volume 39, Issue 1
Displaying 1-9 of 9 articles from this issue
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Jincai LI, Shichiro MATSUI, Siaw ONWONA-AGYEMAN2001 Volume 39 Issue 1 Pages 1-7
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSOrchids of Brassolaeliocattleya Chian-Tzy Emperor (Cattleya) and Cymbidium Sazanami were cultured at 32/20°C, 30/15°C, and 28/8°C (maximum/minimum temperature) for 2 months. It was found in Cattleya leaves that superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activities were lower than in Cymbidium leaves, while polyphenol oxidase (PPO) and ascorbate oxidase (AOX) activities were higher. The high cultural temperature enhanced activities in all enzymes in Cattleya and in four enzymes except CAT in Cymbidium, indicating that it greatly affects scavenging enzyme activities compared to the low temperatures which induced only an increase in APX activity in Cattleya and a decrease in CAT activity in Cymbidium. PPO activity increased and AOX decreased in both orchids at the low temperature. Cattleya leaves at both high and low cultural temperatures decreased ascorbic acid, while Cymbidium increased it. Cattleya at the low temperature increased markedly SH-containig substances but the latter at the high temperature decreased these substances. Lipid peroxides increased in Cymbidium leaves under both high and low temperatures, but for Cattleya neither temperature conditions affected lipid peroxides.View full abstractDownload PDF (831K) -
—Environmental Analysis of Decrease Light Intensity and Temperature in the Summer—Masahisa ISHII, Toru MARUO, Tadashi ITO, Sadanori SASE, Rimi OKUSHIMA2001 Volume 39 Issue 1 Pages 9-16
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThis paper investigates the improvement of human thermal comfort while working in protected horticulture. Shading materials are used in order to decrease light intensity and air temperature in greenhouses in summer. Lettuce (Lactuca sativa L.) plants were grown under two environmental conditions : clear (high light intensity and high temperature) and under shading (low light intensity and low temperature) together with four human working patterns; whole day clear (control), AM shading (morning work), midday shading (midday work) and PM shading (afternoon work) . Plants that were grown under control and midday work conditions had increased numbers of leaves, dry weight, chlorophyll content and photosynthetic activity, as compared to those grown under morning and afternoon work conditions. There was an inferior thermal environment and poorer crop qualities were observed in the plants grown under the control condition. The present experiment suggests that midday work may be a suitable working time for lettuce production in shaded greenhouses during summer.View full abstractDownload PDF (907K) -
Takashi SHIMOMACHI, Nancy K. OKAMURA, Takehiro TAKEMASA, Tadashi TAKAK ...2001 Volume 39 Issue 1 Pages 17-25
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSEnvironmental stress can induce changes in physiological and physical conditions of a plant, and these changes influence the dielectric properties of the plant, which can be detected by measuring microwave transmission characteristics (scattering“S”parameter, S21) through the plant and its surrounding space. Therefore, experiments were conducted with tomato plants to examine the potential of using measurements of microwave transmission characteristics for real-time and non-contact monitoring of changes in plants caused by environmental stress. Tomato plants were subjected to water stress in the following environment : 12 h d-1 light period, 26°C/ 19°C (light/dark periods), and 200±10μmol m-2 s-1 PPF at the height of leaves used for measurements of stomatal conductance and photosynthetic rate. Time course changes in the microwave transmission parameter S21 were measured for a tomato plant during water stress, as well as changes in stomatal conductance and photosynthetic rate, which reflect the physiological condition of the plants. S21 parameter measurements were taken over the 1 000 to 3 000 MHz frequency range. Results showed that low frequencies near 1200 MHz were effective for detecting mild levels of water stress while frequencies above 2 400 MHz were effective for detecting moderate to severe levels of water stress.View full abstractDownload PDF (1019K) -
Nancy K. OKAMURA, Kenji KURATA, Tadashi TAKAKURA2001 Volume 39 Issue 1 Pages 27-34
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSA method is needed to detect water stress in greenhouse grown muskmelon plants (Cucumis melo L.) for irrigation management. Expert growers observe indicators such as color changes of the youngest leaf to judge the optimum level of stress ; i.e., time for irrigation. In this research, color changes in leaves of muskmelon plants under water stress were analyzed by machine vision to determine indicators of stress. Color images of the youngest leaf were taken under diffuse sunlight in 30-min intervals throughout the day with a still-video camera and then digitized into RGB images. The average green color normalized for luminance (termed chromaticity, g) was found for each leaf image, and two methods of analysis were considered. First, the green chromaticity of the youngest leaf for five plants was averaged and time course changes were examined. Second, the relationship between initial leaf color under non-stress conditions and the leaf color at the stress point judged by the expert grower was examined. Based on this relationship, a machine vision algorithm was developed to estimate the stress time. The second method showed greater potential for practical application. The difference in stress time judged by the expert and machine vision was approximately 30 min to 1 h for plants which reached stress point within 1 d.View full abstractDownload PDF (1978K) -
Toshio SHIBUYA, Toyoki KOZAI2001 Volume 39 Issue 1 Pages 35-41
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThe light-use and water-use efficiencies of tomato plug sheets in the greenhouse were estimated continuously for 15d based on micrometeorological and weighing methods. The light-use efficiency, defined as chemical-energy transformation rate by photosynthesis per unit shortwave radiation flux density, increased with increases in leaf area index and then remained stable at about 2×10-2 - 4×10-2 J J-1 when leaf area index was higher than about 1.0. The light-use efficiency decreased with increases in shortwave radiation flux density. The water-use efficiency, defined as dry matter production rate per unit evapotranspiration rate, also increased with increases in leaf area index and then remained stable at about 3×10-3 - 4×10-3 g dry matter g-1 H2O when leaf area index was higher than about 0.5. The accumulated light-use and water-use efficiencies for 15d were 1.8×10-2 J J-1 and 2.7×10-3 g dry matter g-1 H2O, respectively.View full abstractDownload PDF (887K) -
—Analysis of Phloem Sap and Xylem Sap Fluxes and Fruit Water Balance—Masaharu KITANO, Takuya ARAKI2001 Volume 39 Issue 1 Pages 43-51
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSWater balance in a growing fruit of tomato (Lycopersicon esculentum Mill.) as affected by irradiance and air temperature was analyzed with special reference to phloem and xylem transport. Separate evaluations of phloem sap and xylem sap fluxes through the pedicel were enabled by the cooperative application of the multiple chamber system for measuring rates of expansive growth and gas exchange in the fruits and the heat-ring method for inhibiting phloem transport through the pedicel. A little more than 80% of sap flux through the pedicel contributed to fruit expansive growth, and the residual (i.e. a little less than 20%) was lost by transpiration from the fruit with calyx and pedicel. The most dominant component of fruit water balance was phloem sap flux, and about 70% of sap accumulated into the fruit was brought by phloem transport, which was significantly accelerated with leaf photosynthesis and fruit respiration activated by lighting and rise in air temperature after the start of the light period. Xylem sap flux found to be a minor component in fruit water balance and less sensitive to the temperature rise as compared with phloem sap flux. Thus, the separate evaluations of phloem sap and xylem sap fluxes through a pedicel can be considered to give useful information on mass accumulation into tomato fruits.View full abstractDownload PDF (1132K) -
—Effect of Salt Stress—Takuya ARAKI, Masaharu KITANO, Kunio OKANO, Satoshi YOSHIDA, Toshihiko ...2001 Volume 39 Issue 1 Pages 53-58
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSEffects of salt stress on dynamics of expansive growth and water balance in a growing fruit of tomato (Lycopersicon esculentum Mill.) were analyzed by evaluating components of fruit water balance such as phloem sap and xylem sap fluxes through the pedicel. Salt stress was induced by adding NaCl to the hydroponic nutrient solution. The major part of sap flux into the fruit through the pedicel was brought by phloem sap flux, which was scarcely affected by the salt stress. On the other hand, 34% depression was found in xylem sap flux under the salt stress. These responses of phloem sap and xylem sap fluxes resulted in 25% depression in fruit expansive growth and the higher contribution of phloem sap flux under salt stress, where 83% of sap accumulated into the fruit was phloem sap and the contribution of xylem sap was only 17%. Thus, the separate evaluations of phloem sap and xylem sap fluxes into the fruit can suggest quantitatively that salt stress results in smaller tomato fruits with higher sugar concentrations and higher incidence of blossom-end rot.View full abstractDownload PDF (738K) -
Satoru KONDO, Yasuyoshi HAYATA, Masahiko TAMAKI2001 Volume 39 Issue 1 Pages 59-65
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSThe net photosynthetic rate of the current shoot leaves of sweet cherries (Prunus avium L.) at 40d after full bloom (DAFB) in the field peaked at 9 A.M. at 17.2, μmol CO2 m-2 s-1, and then decreased gradually, probably due to the increase in leaf temperature and the decrease of relative humidity. The net photosynthetic rate in leaves on spurs with fruit on fruiting trees was higher than the rate in leaves on spurs without fruit on fruiting trees and non-fruiting trees. Chlorophyll concentration in spur leaves with fruit on fruiting trees was also higher than that in spur leaves without fruit on fruiting trees. Therefore, the effect of fruiting in cherry trees may appear locally rather than wholly in the trees. The net photosynthetic rate in the current shoot leaves was higher than that in the spur leaves. 13C-photosynthates in both current shoot and spur leaves tended to translocate abundantly closer to the fruit from 13C-fed leaves. Whereas when all leaves were defoliated except for 13C-fed leaves, 13C-photosynthates were translocated almost uniformly to each fruit irrespective of the fruiting position because the source for each fruit was limited by the defoliation.View full abstractDownload PDF (806K) -
Teruhiko KOMORI, Kazuo YONEDA2001 Volume 39 Issue 1 Pages 67-70
Published: March 31, 2001
Released on J-STAGE: June 22, 2010
JOURNAL FREE ACCESSTo establish the optimal temperature control for Miltonia‘Second Love’culture at the highland (955 m above the sea level) in Yamanashi Prefecture, plants were cultivated in greenhouses from autumn to spring by raising night temperature. In the plot where the minimum temperature was kept at 5°C before the night temperature was raised, the emergence of flowering stalk was less than 90%. In the plot where the minimum temperature was kept at 15°C, it was elevated to 100% irrespective of the time of raising temperature. The earliest flowering was obtained when the minimum temperature was kept at 15°C before the night temperature was raised and the minimum temperature was then kept at 18°C from December 29. The numbers of flower stalks and pseudobulbs did not differ among the treatments when the minimum temperature was kept at 15°C.View full abstractDownload PDF (342K)
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