关键词: 苹果, 冠层, 光合作用, 蒸腾作用, 水分利用效率

Abstract: It is very important for trimming, fruit bearing, and accurate irrigation with the study of canopy photosynthesis and transpiration dynamic to fruit tree. So that we studied the ‘Fuji’apple (Malus pumila Mill. ‘Red Fuji’) canopy photosynthesis and transpiration rate in different positions from 2002 - 2004 in
‘Richuan’orchard ( longitude 116°13′east, latitude 40°13′north) which training as an open-center system. It had been measured of radiation distribution, the diurnal course of stomatal conductance, photosynthesis and
transpiration rate with random sampling in different positions of canopy. It was found that the radiation flux in exterior was bigger than interior and midst positions, and the ability of photosynthesis of single leaf was so on. The maximal photosynthesis rate of interior, midst positions and exterior leaves were 13.46, 14.69 and 15.98 μmol·m^{- 2} ·s^{- 1}. The diurnal course of stomatal conductance, photosynthesis, WUE (water use efficiency) had two peaks in clear day. And exterior leaves had bigger fluctuate than other. Transpiration diurnal course had one peak, which was decrease in noon. The photosynthesis rate of interior, midst position and exterior leaves in clear day were 4.53, 6.63 and 6.54 μmol·m^-2 ·s^-1 , and transpiration rate were 3.36, 4.06 and 4.40 μmol·m^{- 2} ·s^{- 1}. There were some differences in different positions in canopy of the ability to photosynthesis and transpiration. The value of photosynthesis and WUE in midst position was the most. And the value of transpiration rate in exterior was the most, but interior was the least.

Key words: Apple, Canopy, Photosynthesis, Transp iration, Water use efficiency