Effect of CaCl2, paclobutrazol and salicylic acid on in vitro rooting of walnut (Juglans regia L.)
Although protocols are available for micropropagation of walnuts Juglans spp., poor rooting is still one of the main factors limiting their micropropagation. Microcuttings of J. regia 'Chandler' were transferred to a rooting medium consisting of DKW salts and organics, 4 mg L‑1 IBA, 30 g L‑1 sucrose, 6 g L‑1 agar (Sigma) and supplied, in three different experiments, with a) 69 mg L‑1 salicylic acid, b) increased CaCl2 content (1.5×) in respect to DKW salt standard composition, and c) 1 mg L‑1 paclobutrazol. Microcuttings were maintained for 5 days in darkness and then transferred to a hormone free rooting medium and in the light. Rooting medium was used as control in all the experiments. After 40 days from the beginning of the experiments, percentage of explants producing roots, number of roots produced per plant and root length were recorded. Salicylic acid completely inhibited rooting in respect to the control. Similar rooting percentage (59.3 and 55.6%) and root number were obtained in 'Chandler' with standard or increased CaCl2 contents. Rooting response was improved (76.9%), in respect to the control, when paclobutrazol was applied.
Gentile, A., Frattarelli, A., Urbinati, G. and Caboni, E. (2020). Effect of CaCl2, paclobutrazol and salicylic acid on in vitro rooting of walnut (Juglans regia L.). Acta Hortic. 1285, 1-8
adventitious rooting, 'Chandler', indole-3-butyric acid, Persian walnut