抄録
The effects of NaCl salinity and low solution temperature on the leaf wilting and transpiration rate of snap bean (Phaseolus vulgaris L.) plantlets grown hydroponically were examined. The image of a plant was recorded every 5 min after the start of the treatment. From the plant images, leaf curling could be detected almost unambiguously by the human eye. The decline in leaf blades was evaluated by the relative change in the y coordinate of the center of gravity of the leaf region in a plant image (wilting index). The response of the wilting index to salinity was close to that of transpiration rate and continuous. The ratio of plants with curled leaves was the most sensitive indicator of plant response to stresses in the range of 50 to 100 mM NaCl. Its response was close to all-or-none. It showed a marked interaction of the effects of salinity shock and temperature shock of the nutrient solution. Combined with 60 mM NaCl, solution temperature even at 20°C caused marked leaf curling whereas 60 mM NaCl combined with solution temperature at 25°C did not cause leaf curling.
