Osama Hussein Al-Abdullah
General Commission for Scientific Agricultural Research
Agricultural Research Center in Homs
Horticulture Department

Abstract 

The research was carried out during the period (2010- 2013) in the General Commission for Scientific Agricultural Researches (GCSAR) using three garlic varieties; local varieties Kisswani and Yabroudi and the accession Chinese variety. Field and lab experiments were conducted in GCSAR’s Tyba Research Station (Kisswah region) and tissue culture Lab- Biotechnology Department.

The research aimed to:

• Study the effect of three mutagens, gamma rays, Ethyl Methane Sulfonate (EMS), and Sodium Azide (SA), on plants growth and productivity of studied garlic varieties.
• Determine the best mutagen for each of the studied garlic varieties.
• Implement individual clonal selection and follow up of mutant plants’ progeny to segregate the superior mutant clones (super elite).
• Determine the response of studied varieties to in vitro micro-propagation.
• Establish an efficient method for in vitro production of garlic bulblets of studied varieties using tissue culture techniques.

– Healthy uniform garlic cloves were selected and treated with Gamma rays Co⁶⁰ (0, 1, 2.5, 5 and 10 Gray), or by Soaking in the chemical mutagens EMS (0.025, 0.05, 0.10 %) or SA (0.1, 0.2, and 0.3 mg/l) for a period of 6 hrs under room temperature, or in distilled water only as a control.

– As for tissue culture experiments, garlic cloves were sterilized before in vitro culture using sodium hypochloride 20 % (commercially called Chlorax) for 15, 20, 25 and 30 minutes, or mercury dichloride Hgcl2 0.1 % for 5 and 10 minutes. Leaf primordia from the vegetative bud, and root tips were planted on MS medium supplemented with different concentrations of Benzyl adenine (BA) and 2,4-dichlorophenoxy acetic acid (2,4- D) hormones to induce callus formation. The callus was then transplanted to MS medium with different concentrations of kinetin (Kin), Naphthalene acetic acid (NAA), and BA to induce vegetative growth. Thereafter, these shoots were then transplanted to MS medium free of growth regulators and contain different concentrations of sucrose (3, 7, 9, and 12 %) or to ½ MS medium free of growth regulators with 3 % sucrose.

-The randomized complete block design and the factorial design were used for field and Lab experiments and analysis of variance conducted with Mstat-c and Genstat,12.1 statistical programs, respectively. Consequently, means were compared using LSD _0.05.

     -Conclusions:

• The different genotypes of studied garlic varieties resulted in varied response toward the different doses Gamma rays, and different concentrations of the chemical mutagens (EMS, SA).
• It was possible to determine the lethal dose of gamma rays to garlic plants of studied varieties (LD₁₀₀), as well as the gamma dose and the different concentrations of chemical the mutagens EMS and SA that were close to (LD₅₀), which creates the possibility to obtain higher ratio of potential mutations.
• It was possible to determine the gamma rays dose and the different concentrations of the chemical mutagens (EMS, SA) which positively affected in emergence, growth and productivity of all studied varieties of garlic.
• The best mutagen that positively affected production indicators of garlic plants.
• Gamma rays was the most effective mutagen inducing positive mutations in studied varieties, followed by the chemical mutagen SA, and then EMS.
• The physical (gamma rays) and chemical (EMS and SA) mutagens induced positive mutations in garlic plants of studied varieties and enabled selection 11 of promising clones (super elite) from all studied garlic varieties; of which 4 clones belonged to Kisswani, 3 clones to Yabroudi, and 4 clones to the Chinese variety using superiority in of the bulb and clove weight characteristics.
• Studied varieties varied in their response to bulblet formation of in-vitro; Kisswani was significantly better than Yabroudi and Chinese.
• Tissue culture experiments contributed to setting up an efficient system of in- vitro bulblet production of studied garlic varieties.