The dynamic changes of main endogenous hormone content in leaves during flower bud differentiation of bolting garlic cultivars

In this study, using garlic cultivar ‘Zhengyuezao’, the dynamic changes of IAA, GA3 and ABA content in garlic leaves were analyzed by reversed high performance liquid chromatography to explore the relationship between the changes of endogenous hormones in leaves and flower bud differentiation. IAA content in leaves during the whole growth process of the plant was relatively low, ranging between 0.17~0.21 µg g-1 in vegetative growth period, sharply declining to 0.06 µg g-1 in inflorescence differentiation period, and maintaining steady at lower levels during the flower organ primordium differentiation period and flower organogenesis. GA3 kept high but varied a lot within a wide range during development periods, dropped sharply to 5.5 µg g-1 in inflorescence differentiation period, and reached a peak in flower organ primordium differentiation period with 9.7 µg g-1, which was 24 times the ABA content and 138 times the IAA content in the same period. The ABA content increased in the late vegetative growth period (0.41 µg g-1), and has remained at around this level till flower organ primordium differentiation period, then raised sharply to 0.61 µg g-1 in flower organogenesis, about 2 times the value of the vegetative growth period. And the ratio of ABA/GA3 and ABA/IAA in general showed an upward tendency. While ABA/GA3 has a decrease in flower organ primordium differentiation period, and both moved up sharply from flower organ primordium differentiation period to flower organogenesis. The results suggested that the flower bud differentiation is closely related to the changes of endogenous hormones in garlic leaves. GA3 and IAA content in garlic leaves appeared low during flower bud differentiation(except for GA3 in the flower organ primordium differentiation period), while ABA content showed higher values during the flower bud differentiation period. ABA/GA3 and ABA/IAA both presented higher levels in the process of flower bud differentiation, especially the flower organogenesis than in the previous periods.