Abstract

This study was conducted to find out the influence of elevated atmospheric CO2 concentrations and air temperature on photosynthesis and fruit quality of ‘Fuji’/M.9 apple trees and to investigate these to the effects of climate change during the last four years (2009-2012). The treatments employed were: ‘Ambient’ (ambient temperature + ambient CO2 concentration); ‘High CO2’ (ambient temperature + elevated CO2 concentration); ‘High Temp.’ (elevated temperature + ambient CO2 concentration); and ‘High CO2 + High Temp.’ (elevated temperature + elevated CO2 concentration). The elevated temperature plots were maintained at 4 o C higher than ambient air temperature, while the elevated CO2 plots were maintained at 700 µmol·mol �1 . Annual treatment period was applied from end of April to beginning of November for four years. Results showed that elevated CO2 decreased stomatal conductance and leaf SPAD value, but increased photosynthetic rate, intercellular CO2 concentration (Ci), and starch content of mesophyll tissue. In the vegetative growth, elevated temperature increased total number of shoot and total shoot growth per tree, but elevated CO2 decreased average shoot length. In the fruit quality, elevated CO2 increased soluble solid content, fruit red color, and ethylene production. In conclusion, elevated CO2 increased photosynthetic rate of apples during the early growth, but effect of increased photosynthetic rate due to elevated CO2 was decreased during latter growth stage. Elevated temperature, on the other hand, tended to decrease photosynthetic rate of apples during the early growth, but that tended to increase during latter growth stage. Both elevated CO2 and temperature tended to decrease the degree of decreased photosynthetic rate due to each factor.

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