Sugar concentration and activity of related enzymes in different parts of satsuma mandarin fruit as affected by foliar spray of ethychlozate

摘要

Changes in sugar concentration and activity of related enzymes including sucrose phosphate synthase (SPS) and sucrose synthase (SS) in juice at fruit maturing stage were examined for 15-year-old satsuma mandarin trees (Citrus unshiu Marc. cv. Miyagawa Wase) grafted on Poncints trifoliata as affected by the foliar spray of ethyl 5-chloro-1H-3-indazolylacetate (ethychlozate). Twice spray of 100 mg centre dot L~(-1) ethychlozate on July 9 and 22 increased sucrose concentration, and SS activity. Higherfructose and glucose concentration, lower sucrose concentration, and lower SS activity were observed in the fruit with upward fruit apex artificially arranged by bending of fruiting branch with wire. Blossom half of fruit showed significantly higher concentrations of fructose, glucose, and sucrose, and higher SS activity than those in stem half. SPS activity was not singnificantly affected by the above treatments. These results suggest that SS is a predominant factor in sucrose accumulation in the juice of satsuma mandarin fruit.