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Volume 49, Issue 2
Displaying 1-8 of 8 articles from this issue
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Masuyuki TAKAICHI, Tsutomu YONETANI1993 Volume 49 Issue 2 Pages 81-90
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThe relationship between temperature distribution around a mature tea bush and its freeze-thaw process was studied in winter. The coldest parts of a bush in nighttime were the top or the lee shoulder for a horizontal plot and the down-slope side shoulder for the row across the contour line on a slope in many cases. Temperature difference (ΔT) between the bush top leaves (TlTOP) and air at 150cm height (Ta150) could be expressed as a following simple equation:
ΔT=TlTOP-Ta150=AU150-0.5Rn
where A: an empirical constant, U150: wind speed at 150cm height, Rn: net radiation above tea bushes. Values of A were 0.0320 (J-1°Cm2.5s0.5) for the bush with few elongated shoots above the plucking table and 0.0227 for the one with many of them, respectively.
The times required for freeze to spread over the aboveground part of the bush were from about 20 to 90 minutes. The freezing of the bush top leaves were initiated nearly at the dew-point temperatures around them (TdewTOP) when TdewTOP were about -2°C to -4°C. For lower humidity (TdewTOP<-4°C), the freezing initiated without dew or frost formation on leaves. These results were almost the same as those of young tea plants reported previously.
The latest thawing of the bush was at the bottom trunk and this part occasionally kept frozen to the following nights. In daytime a situation that the bottom trunk was still in freeze while the bush top leaves were already thawed was observed. This status might increase the water deficit stress if there were high transpiration demands.
Among simple methods to estimate the initiation of the freezing, the ones using TlTOP and TdewTOP could make relatively good estimates with about 20-30 minutes of root mean square error for the samples.View full abstractDownload PDF (1358K) -
Daizou IGARASHI, Keiichi NAKAYAMA, Eisuke SAKAMOTO, Kisei ITOU, Nobuo ...1993 Volume 49 Issue 2 Pages 91-98
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIt has been known that the occurrence of head rot is due to the multiplication of bacteria on cabbage which is pre-disposed by cold injury.
Relations among the bacterial head rot on cabbage harvesting in winter at the Miura Peninsula and the meteorological elements in growing period were investigated from 1983 to 1992 except 1987. Percentage or index of head rot occurrence were determined using from 500 cabbage plants in each year. The meteorological data were obtained from AMeDAS (automated meteorological data acquisition system) data observing in Miura city.
The cold hardiness of the third leaf from outside of the head was investigated during harvesting time for 2 years. Cold hardiness, using ‘LT50’ (equation 2 and 3) which determines the frost-killing temperature required to kill 50% of the cells of cabbage leaves which were under the condition of low temperatures (-5, -7.5 and -10°C) for 2 hours in low temperature water bath were calculated.
The results obtained as follows:
1. There were high correlations between the air temperature in the middle of November and the head rot occurrence in cabbage. The higher the mean air temperature in the middle of November than the normal, the higher the head rot occurrence.
2. There were no relation between the duration of sunshine or the amount of precipitation and the head rot occurrence in cabbage.
3. The time of increased cold hardiness of cabbage leaves was not the same. However, the lowest ‘LT50’ was about -10°C in each year.
4. There were correlations between ‘LT50’ and the accumulated daily mean air temperature for over 4 days. The difference of ‘LT50’ was more than 4°C during harvesting time, because of the differences in the mean daily air temperature when the cabbage were harvested.
5. These results indicates that if the mean air temperature in the middle of November was higher than normal, the countermeasure by covering cabbage is necessary.View full abstractDownload PDF (1038K) -
Mayumi YOSHIMOTO, Yoshinobu HARAZONO1993 Volume 49 Issue 2 Pages 99-104
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
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Yuji INOMATA, Hideaki YAEGAKI, Kunihiko SUZUKI1993 Volume 49 Issue 2 Pages 105-109
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
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Eiji GOTO1993 Volume 49 Issue 2 Pages 111-113
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (313K) -
Working Group of Meteorological Improvement Studie1993 Volume 49 Issue 2 Pages 115-118
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (517K) -
[in Japanese]1993 Volume 49 Issue 2 Pages 119-120
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (169K) -
1993 Volume 49 Issue 2 Pages 121-127
Published: September 10, 1993
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (1085K)
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