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These studies were carried out to investigate the relationship between fruit growth and the endogenous hormone content in parthenocarpic fruit induced by plant growth regulators and seeded fruit set by pollination in cucumber. Along with fruit growth, the change of endogenous IAA showed similar tendency in all treatments while the maxinum occurred 6 days after anthesis in the case of N-(2-chloro-4-pyridyl)-N^†-phenylurea (CPPU) and BA treatment and appeared 9 days after anthesis in other treatments, like the fruit increment, and then slowly decreased. The content of ABA was high in the early growth stage of fruit, slowly decreased and again increased with fruit maturation. In particular, the fact that the content of ABA in pollinated fruit 30 days after treatment was two times higher than other treatments suggested that mature seeds were closely related to ABA increment with fruit maturation. The activity of gibberellin-like substances was the highest 6 days after anthesis, except for non-treatment and GA₃ treatment, and then decreased. On the other hand, the activity of gibberellin-like substances in pollinated fruit again increased IS days later and was two times higher than in other treatments. The activity of gibberellin in GA₃ treatment was sixteen times higher 3 days after treatment, then rapidly decreased, resulted in no difference from other treatments 12 days later. As a result, this study indicated that the increment of IAA and gibberellin and the reduction of ABA at the early growth stage of both parthenocarphic fruit and seeded fruit occurred while vice versa at the maturation stage.
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