Endogenous Hormone Contents in Standard and Dwarf Persimmon (Diospyros kaki Linn. cv.)

`Xiao Fang Shi' is a rare, dwarf cultivar of persimmon ( Diospyros kaki Linn cv.) recently found north of Shanghai, China. The tree starts to bear fruit at 2 years of age, while standard trees start fruiting at 5 or 6 years of age. Dwarf and standard cultivars have about equal spring shoot growth, but the dwarf cultivar has little fall growth. To determine the mechanisms of dwarfness and early fruiting, enzyme-linked immunosorbant assay (ELISA) was used to analyze the endogenous indoleacetic acid (IAA), gibberellic acid (GA 1+3 ) and abscicic acid (ABA) contents in leaves and shoot tips of dwarf (`Xiao Fang Shi') and standard (`Da Fang Shi' and `Zhu Sha Hong') persimmon. The measurement was done during the entire growing season. The results showed that IAA, GA 1+3 , and ABA contents were influenced by cultivars, ages of trees, and phenophases. The dwarf cultivar `Xiao Fang Shi' has lower IAA and GA 1+3 but higher ABA contents than the two standard cultivars during the growing season. These correlations are especially evident when the fruit is ripening. The correlation coefficiency between contents of IAA and GA 1+3 and tree height was 0.9704, while that between ABA content and tree height is –0.9697. The low IAA and GA, and high ABA contents may be responsible for little shoot growth of the dwarf cultivar in the fall.