Effect of the ethylene inhibitors silver nitrate, silver sulfate, and cobaltchloride on micropropagation and biochemical parameters in the cherryrootstocks CAB-6P and Gisela 6

In the present study, the effects of three ethylene inhibitors, silver nitrate (AgNO3), silver sulfate (Ag2SO4), and cobalt chloride (CoCl2), on the morphogenic and biochemical responses in CAB-6P and Gisela 6 cherry rootstocks were investigated. In both rootstocks, AgNO3 and Ag2SO4 promoted shoot regeneration while CoCl2 had such an effect only in Gisela 6. The rooting percentage of CAB-6P and Gisela 6 explants was diminished with AgNO3, Ag2SO4, and CoCl2. AgNO3 increased root number (40 μM) and root length (50 μM) in the CAB-6P rootstock while it had an inhibitory effect in Gisela 6. Ag2SO4 and CoCl2 enhanced root length of Gisela 6 explants whereas Ag2SO4 decreased root number and root length of CAB-6P explants. CoCl2 at 10 μM in both rootstocks augmented root number whereas 20 μM CoCl2 increased root length of CAB-6P microshoots. AgNO3, Ag2SO4, and CoCl2 decreased leaf chlorophyll and carbohydrate content in CAB-6P rootstock. On the other hand, in Gisela 6, 10 μM AgNO3 gave elevated chlorophyll levels and 20 μM AgNO3 or 10-50 μM CoCl2 raised leaf carbohydrate content. The three ethylene inhibitors led to elevated leaf proline levels in the CAB-6P rootstock, whereas in Gisela 6 the increase or decrease in leaf proline content was dependent on both type and concentration of ethylene inhibitor. An efficient micropropagation protocol was established for the CAB-6P and Gisela 6 cherry rootstocks using ethylene inhibitors.