Use of high CO 2 atmosphere and medium modifications for the successful micropropagation of pistachio

Abstract

A medium that will support excellent growth of Pistacia vera and hybrid pistachio shoots was developed. Several basal medium preparations were tested and Driver-Kuniyuki-Walnut (DKW) medium was selected. Potassium, nitrogen, boron, and zinc were adjusted to provide optimum growth and multiplication of shoots, some of which were grown and multiplied for more than 2 years. The use of thidiazuron as a growth regulator was tested, but was not beneficial. Initial experiments were hindered by significant systemic bacterial contaminants. Contamination was controlled through the use of a 2% CO 2 atmosphere, increased light level to promote photosynthesis, and the elimination of all carbon sources (sugars) from the substrate. This system gave improved shoot growth, survival when rooting, and acclimation compared with a sucrose based medium. Up to 88% rooting was obtained using 1.2 × 10 −5 M (2.5 mg l −1) IBA rooting medium.