In vitrobacterial decontamination ofKelussia odoratissimaseed during dormancy breaking

Abstract

Kelussia odoratissima (Apiaceae) is an endangered medicinal plant indigenous to Iran. Seeds of this plant have a long-term dormancy. This study aimed at obtaining in vitro method to reduce microbial contamination, overcome seed dormancy and to disclose the type of classification system of seed dormancy. After using completely randomized design and Duncan's Multiple Range Test, the significance of between individual group's means was assessed. Results revealed that only one gram negative bacterium strain, Klebsiella sp., was isolated from the contaminated culture. Applying 500 mg/l copper sulphate for 6 min during seed sterilization, the contamination was eradicated. During cold stratification, to estimate the effect of exogenous application of cytikinin hormones, N6-furfurylaninopurine (Kin) and 6-benzylaminopurine (BAP) alone or in combination with each other, pre-soaking treatment with tioureae as a nitrogen compound and seed osmopriming with polyethylene glycole (PEG 6000), alone or in combination with BAP, the highest final seed germination (92.5%) was obtained on medium containing 1 mg/l BAP combined with 1 mg/l Kin. The lowest mean germination time (45.81 days) was also obtained on medium containing 0.25 mg/l BAP. Since using tiourea was simple and economical, with 80% final seed germination (using 0.2% thiourea) this can be an excellent way to promote seed germination of this plant. Considering the efficacy of treatments and growing of zygotic embryo without cold temperature exposure, seed dormancy mechanism identified as non-deep physiological dormancy and particularly chemical dormancy classification.