This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Photoperiod is one of the factors affecting productivity of cucumber plant by inducing ethylene hormone production and so triggering flower sex differentiation into female flower.

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... r, only few studies have been perfomed in order to reveal the effect of photoperiod in molecular level in relation to the flower differentiation. Therefore, in this study, Mercy cultivar of cucumber (andromonoecious) was treated with photoperiod of 8, 12, 16 hours of light, while control received no treatment of additional light. Photoperiod of 8 hours was achieved by blocking the sunlight with shade net and 16 hours by giving longer light exposure using white LEDs. Cucumber's flowers were quantified and the apical and lateral shoots were extracted to evaluate the gene profile related to the photoperiod, ethylene production, and female flower differentiation, which were CsACS2, CsETR1, CsCaN, and CsPIF4 using PCR method. Photoperiod of 8 hours affected the production of female flower with average number of 6.7 flowers in main stem and 8.0 flowers in lateral stem, compared to photoperiod of 12 and 16 hours which produced 3.7 and 2.0 flowers in main stem with 7.0 and 11.3 in lateral stem, respectively. In silico studies in this experiment resulted in proposed model of signal transduction that showed the connection between ethylene production and flower differentiation. PCR analysis confirmed the expression of CsACS2, CsETR1, and CsCaN, that was positively correlated with numbers of female flowers in cucumber, but the expression of CsPIF4 that represent photoperiod haven't been confirmed correlated with the ethylene production and flower differentiation.