Critical factors limiting pistachio micropropagation

Resumen del trabajo presentado en el VI International Symposium on Almonds and Pistachios, celebrado en Murcia (España), del 27 al 31 de mayo de 2013During micropropagation of Pistacia vera cultivars we have faced different problems that limit their culture at different stages. Culture initiation: the establishment of the cultures from mature field-grown trees showed problems in pistachio as excessive browning of the explants and culture medium that could cause the death of the cultures. The use of antioxidants during explants preparation and processing, as well as in the culture medium resulted beneficial in our cultures. In spite of that, frequent transfers to fresh medium were needed to keep cultures healthy. Multiplication: During shoot culture, the appearance of shoot tip necrosis was detrimental to obtain good shoots for rooting. Different treatments were assayed including plant growth regulators, culture media composition, bottom cooling, and explant density, all affecting shoot necrosis rates, being PGR the most effective. Rooting: Lack of rooting or a scarce root number per shoot was frequent in pistachio propagation. Rooting improved after long culture periods. In addition, among the different factors tested, plant growth regulators, culture media composition, and pH showed stronger effect on rooting. Acclimatization: High survival rates during acclimatization were hampered by the lack of visual symptoms of wilting. A protocol based on short exposures to low RH that increased with time is proposed. The final protocol needs to be adapted for each cultivar, since there is a cultivar-dependent response.Este trabajo ha sido financiado en parte por el proyecto RTA2010-00053-C03-03 y por la ayuda recibida del Gobierno de Aragón como Grupo de Excelencia A-43