2021 Volume 20 Issue 2 Pages 179-187
It is necessary to clarify leaf resistance when estimating the transpiration rate of tomato plants. We examined the effect of different conditions with different values of electric conductivity (EC) of the culture solution, cultivars, and media, on the leaf resistance and transpiration rate using a single truss tomato hydroponic system. We measured the real transpiration rate by investigating weight changes, calculated leaf resistance, and estimated the transpiration rate using leaf resistance and environmental factors. When tomato plants grew under different EC conditions, the total transpiration varied significantly and the transpiration rate decreased as the EC increased. The solution absorption and root bleeding rate under the EC8 condition were significantly lower than under EC1.35 in ‘Managua’ and ‘CF Momotaro York’. When tomato plants grew with D-tray, rock wool slab, and deep water culture under EC1.35 and EC8 conditions, there was no significant difference in root bleeding rates among media and that under EC8 was lower than EC1.35. The amount of transpiration was highest under EC 1.35 with deep water culture and lowest under EC 8 with rockwool slab. The leaf resistance affected EC of the culture solution, being different among cultivars. The leaf resistance was not changed among D-tray, rock wool slab, and deep water culture. The leaf resistance changed with time: it was high in the early morning and after 15:00 and low at noon. It was clarified that the leaf resistance was affected by different EC values of the culture solution and cultivars, and changed with time.
