UC Davis

Protocols for the micropropagation of pistachio rootstock are not well established, and little is knownabout the effect of different plant growth regulators (PGRs) on micropropagation systems of the UCB-1 pistachio rootstock. Two cytokinins, 6-benzylaminopurine (BAP) and meta-Topolin (mT), were tested at three different concentrations (1uM, 5uM, 10uM) to germinate, multiply, and root UCB-1 pistachio seedlings in vitro. UCB-1 seedlings germinated at a rate of 76% in clean culture after being split with bypass pruning shears and a 3hr decontamination treatment in 3000ppm sodium dichloroisocyanurate (NaDCC) solution. Data were collected on cumulative shoot length, weight, and branching of singleshoot descent lines. The 10uM concentration of both tested cytokinins provided the greatest amount of shoot material at the end of three transfer cycles, though no significant difference (P < 0.05) in shoot growth was found between the two cytokinins at that concentration. Mean rooting performance was significantly (P < 0.001) higher for shoots multiplied with BAP (87.2%) as the source of cytokinin compared to mT (57.9%).