The role of GA and ABA in moist chilling-induced effects on germination of scarified seeds of Myrtus commnius L.

Dormancy of Myrtus communis seeds causes problems with the propagation of this plant through seed cultivation. Therefore, in current study firstly interactive effects of various types of scarification (treatment with hot water for 20 min, H_2 SO_4 90% for 5 min, blade and sand paper for 10 min) with moist chilling (0, 15, 30, 45 days) or GA3 concentrations (0, 250, 500, 1000 mg/L) were investigated on seed dormancy breaking in two separate experiments. Results showed that without scarification seed germination less than 3%, but application of various types of scarification achieved final seed germination to 30-67%. The moist chilling and GA3 treatments significantly increased seed germination and seedling growth and vigor in scarified seeds and the best treatment was combination of scarification with blade or sand paper and 30 moist chilling that posed 91% seed germination. In the next experiment, the role of GA and ABA in moist chilling - induced effects on seed dormancy breaking was assessed using inhibitor compounds. Results showed that application of paclobutrazole (as an inhibitor of GA synthesis) as well as treatment with ABA and diniconazole (as an inhibitor of ABA catabolism) reversed the effect of moist chilling on the germination of scarified seeds. In contrast, treatment with fluridone (as an inhibitor of ABA synthesis) increased the velocity and capacity of germination of moist chilled- and scarified seeds. These results suggested that myrtle seeds in addition to physical dormancy possess physiological dormancy that moist chilling can attenuate it by increasing GA/ABA ratio in seeds.