Effects of Plant Growth Regulators on the Endogenous Hormone Content of Calyx Development in ‘Korla’ Fragrant Pear

The development of calyxes in ‘Korla’ fragrant pear is influenced by hormones. This study was conducted to investigate the effects of different plant growth regulators on the endogenous hormone content of young ‘Korla’ fragrant pear fruit. The hormone contents [indoleacetic acid (IAA), gibberellin acid (GA3), and abscisic acid (ABA)] of young ‘Korla’ pear fruits treated with water, IAA, and triiodobenzoic acid (TIBA) were determined by high-performance liquid chromatography, and the relationship between the content and ratio of endogenous hormones and calyx abscission in ‘Korla’ fragrant pear was explored. The results showed that the rate of calyx abscission in the ‘Korla’ pear fruits treated with TIBA was significantly higher than that of fruits treated with water and IAA, and that of fruits treated with water was significantly higher than that of fruits treated with IAA. The GA3 content was higher than the IAA and ABA contents during each period. The IAA content of the stalk was higher than that of the calyx tube and flesh. The GA3 and ABA contents of the calyx tube were higher than those of the stalk and flesh. The IAA and GA3 contents of the first order were higher than those of the fourth order. The ABA content of the fourth-order fruit was higher than that of the first order. The (IAA+GA3)/ABA in the calyx tube was significantly higher than that in the flesh and fruit stalk. After IAA treatment, the IAA, GA3, and ABA contents of the first-order calyx tube increased by 47.7%, 17%, and 31.6%, respectively, whereas those of the fourth-order calyx tube increased by 65.3%, 39.9%, and 33.2%, respectively. After TIBA treatment, the IAA, GA3, and ABA contents of the first-order calyx tube increased by 46.1%, 36.5%, and 50.0%, respectively, the IAA content of the fourth-order tube decreased by 25.5%, and the GA3 and ABA contents increased by 22.0% and 12.2%, respectively. The IAA, GA3, and ABA contents of the flesh and fruit stalk did not significantly differ from those in the calyx tube. The results indicated that spraying IAA during flowering promoted calyx persistence, whereas spraying TIBA promoted calyx abscission. These findings provide certain theoretical references and practical criteria for improving the quality of ‘Korla’ fragrant pear.