A rapid screening method for salt stress tolerance of onion genotypes

Abstract: Salinity is one of the major limitations for onion growth and productivity all over the world. There are several methods to determine of salt stress tolerance of plants such as germination tests, pots trials, in vitro experiments etc. This study was conducted for optimisation of rapid and practical method to compare onion genotypes under salinity conditions. In the first stage of the study, three explant types and twenty one combinations of plant growth regulators were tested for optimization of callus protocol. Callus indicate percentage (%), callus fresh weight (mg) and callus dry weight (mg) were measured on the 31^st day. According to results, the best medium (MS + 2 mg/L 2,4-D + 0,5 mg/L BAP) and explant type (mature zygotic embryo) for the proliferation of callus were determined. After choosing the best hormone and explant type, the effect of salinity on callus induction was tested using different level of NaCl. Akgun-12 consistently performed the best in callus culture. Responses of onion cultivars were different for different parameters. The proposed method was simple to perform, as no long time is required, and offers a possibility to screen genotypes in any time of year.