To clarify the mechanism for slowing down vegetative growth to reduce withered floral buds occurring in Yuluxiang pear, the length and diameter of the new shoots, the activities of antioxidant enzymes and malondialdehyde （MDA） content in terminal buds of short shoots in a withered bud-occurring orchard in Wei County, Hebei Province and a normal bud-growing orchard of Wei County, and a normal bud-growing orchard in Taigu County, Shanxi Province were measured and com- pared. The results showed that the increases in the length and diameter of new shoots in the withered bud-occurring orchard were very significantly higher than those in the two normal bud-growing orchards, and the shoots in the withered bud- occurring orchard stopped growing later than in the two normal bud-growing or- chards. During the period of floral bud differentiation, the activities of superoxide dis- mutase （SOD）, catalase （CAT）, peroxidase （POD） and the content of MDA in the two normal bud-growing orchards all increased at first and decreased subsequently. But in the withered bud-occurring orchard, the activities of both SOD and POD gradually decreased during the period of floral bud differentiation, while the activity of CAT and the content of MDA increased at first and decreased subsequently. Withered floral buds had significantly lower activities of SOD, CAT and POD, but significantly higher content of MDA than normal buds. The results suggested that vigorous vegetative growth may lead to the occurrence of withered floral buds in Yuluxiang pear; in addition, the occurrence of withered floral buds in Yuluxiang pear may also be associated with the activities of SOD, CAT and POD.
