ARS | Publication request: Effects of various treatments on seed germination and growth of carob (Ceratonia siliqua L.)

Submitted to: Pakistan Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2011
Publication Date: June 30, 2011
Citation: Gunes, E., Gubbuk, H., Ayala Silva, T., Gozlekci, S., Ercisli, S. 2011. Effects of various treatments on seed germination and growth of carob (Ceratonia siliqua L.). Pakistan Journal of Botany. 39(1):251-254.

Interpretive Summary: Carob (Ceratonia siliqua L.) is commercially propagated by grafting. Grafting requires the generation of seedlings. Carob seeds are very recalcitrant, therefore, it is necessary to scarify or stratify the seeds before germination. We applied three treatments: mechanical scarification, incubation in hot water and sulfuric acid, to seeds from both a commercial cultivar and wild type carob. The seeds were incubated in pure sulfuric acid (98%) for 20 minutes, in hot water (100 oC) for 5 minutes or scarified with scalpel (1 mm from the hilum). These treatments improved germination and early seedling growth characteristics of carob seeds. All treated seeds were incubated in petri-dishes at 25±1°C. The germination rate of seeds from both the wild and cultivar type was 13.57 % in the control and 70.40 % in the hot water treatment. The highest germination rate 95.07%, in the wild type, was obtained with the sulfuric acid treatment. The highest germination rate (98.77%) in the commercial cultivar was obtained with the mechanical scarification. The hot water treatment although was better than the control, was inferior to the two other treatments. We recommend the sulfuric acid treatment to overcome seed coat dormancy. Keywords: Carob, germination, scarification, sulfuric acid, Ceratonia siliqua

Technical Abstract: Carob (Ceratonia siliqua L.) plays an important role in Mediterranean landscape. It is commercially propagated by grafting which requires the generation of seedlings. However, its seeds are very recalcitrant and need pretreatment for germination. In this study, carob seeds harvested from both wild and cultivated genotypes in Turkey were subjected to mechanical scarification, soaking in hot water and dipping in sulfuric acid, untreated seeds were used as a control. All treatments hastened seed germination and seedling growth of carob. The germination percentage of control seeds were similar for both wild and cultivated types (13%) and it was increased 95% and 93%, respectively, following sulfuric acid treatment. Seed germination percentage of wild and cultivated carobs was similar in all treatments indicating that domestication does not appear to have influenced germination behavior in this species.