Mohadeseh Meysami - Department of Ecology, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
Mohammad Javad Arvin - Institute of Science and High Technology and Environmental Sciences,Graduate University of Advanced Technology, Kerman, Iran, Plant Products Division, Shahid Bahonar University, Kerman, Iran
Hakimeh Oloumi - Department of Ecology, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran

The cultivation of Watermelon (Citrullus lanatus,Cucurbitaceae) has long been considered in Iran due to its nutritional and health importance. The main issue in Japanese watermelon cultivation in Iran is the low seed yield per hectare. In this project, the effect of some plant growth regulators on the sex determination and fruit set of a citrus population were studied under field condition. An experiment was conducted in a completely randomized block design with three replications at the Research Farm of the Graduate University of Advanced Technology, Kerman, Iran in May-June 2017. Treatments were applied during the vegetative phase of plant growth. One month after cultivation, plants sprayed with 200 and 100 ppm of benzylaminopurine (BAP), 50 ppm gibberellin (GA) and 0.75 ppm brassinosteroid (Br). After the appearance of the first flowers, the number of male, female and bisexual flowers was daily counted for three weeks, the total number of fruits was also accounted until the end of crop vegetation. Based on the results, GA treatment resulted in the highest number of male, female and bisexual flowers production in comparison with other treatments. The mean of male flowers per plant was 173.97 in GA, 116.68 in BAP-200 ppm, 107.16 in Br, and 53.33 in BAP-100 ppm. BAP treatment in both concentrations produced the highest number of female flowers. The number of fruit set per plant was similarly raised in BAP-200 ppm and GA 50 ppm compared to other groups. From our results, it can be concluded that benzyl amino-purine has considerably promoted feminine and increased female flower production in watermelon. Gibberellin treatment encourages androgenesis as well as bisexual flower development and yield production. Therefore, applications of plant growth regulators are recommended for agricultural usages and breeding experiments.

Plant growth regulators, Bisexual flowers, Watermelon population, Yield production