International Journal of Agricultural and Natural Sciences, cilt.15, sa.3, ss.319-335, 2022 (Hakemli Dergi)
An unfertilized ovary culture is an effective approach for inducing haploid plants that can significantly reduce breeding time. The present study aimed to investigate the effect of plant growth regulators (PGRs), floral stages, and heat pre-treatments on the formation of embryo-like structures (ELS) and calli in watermelon using the unfertilized ovary culture method. This method has already been used effectively for breeding across many species, but observations of it being used for watermelon breeding are limited. Three different watermelon varieties (‘Ersin’, ‘Silva’, ‘Üstün’) were used as plant materials. Ovaries were collected from plant materials at three floral stages (12 h before anthesis, at anthesis, and 12 h after anthesis). Different concentrations and combinations of 2,4-D (2,4 Dichlorophenoxy acetic acid), BAP (6-Benzylaminopurine), and NAA (Naphthaleneacetic acid) PGRs were used to induce callus and ELS. Ovaries were kept on induction media in the dark at either 25 °C or 35° C for 3 days followed by 25°C for 30 days, and then transferred to three different differentiation media. Different levels of callus and ELS formations were observed at different rates among varieties. Based on the results ‘Üstün’ variety had the highest rate of callus formation and ELS development among all varieties. I3 combination of plant growth regulation (3 mg/l 2,4D+ 2mg/l 6-BA+0.5mg/l NAA) had the highest rate of callus formation with a rate of 97%, and M3 had the highest rate of ELS at a rate of 6.94%. Anthesis time of ovaries also had the highest callus formation rate of all stages, at 85%, and 25°C was the best temperature for callus formation overall, at 79%.