EFFECT OF REFLECTIVE FILM ON SUGAR ACCUMULATION AND SUCROSE-METABOLIZING ENZYME ACTIVITIES OF 'CUIGUAN' PEAR UNDER PLASTIC TUNNEL CULTURE

We studied effects of covering orchard floors with silvery reflective films (RF) in plastic tunnels on photosynthesis, sugar accumulation and variations of sucrose-metabolizing enzyme activities of ‘Cuiguan’ pear. The results showed that reflective film could significantly increase net photosynthetic rate of leaves in the lower portion of the canopy, but has little significant influence on leaves of the upper portion of the canopy. The contents of sorbitol, fructose, glucose, sucrose and total sugars increased along with the fruit development. The contents of total sugars, especially sucrose were higher in RF treatment than in control. Among the five sucrose metabolizing related enzymes, the sucrose phosphate (SPS) activity of RF in ‘Cuiguan’ pear was higher than that of control. However, the neutral invertase (NI) activity was lower than that of control. The increase in SPS activity and decrease of NI activity may lead to the increase in sucrose content of RF treatment.