A PRACTICAL METHOD FOR ALLEVIATING SHOOT-TIP NECROSIS SYMPTOMS IN IN-VITRO SHOOT CULTURES OF PISTACIA-VERA CV MATEUR

Efforts were made to reduce the incidence of shoot-tip necrosis (STN), a frequent and persistent problem in shoot cultures of Pistacia, by supplementation of a standard Murashige and Skoog (1962) medium with raised levels of either boron or calcium. Experimental evidence was obtained to support previous reports that STN is a calcium related physiological disorder aggravated by low vapour pressure deficits inside in vitro culture vessels. Supplementation of liquid culture media with either 100-1000 muM boron or raised levels of calcium as calcium gluconate (0.3-30 mM) significantly reduced the development of STN symptoms supported on filter paper bridges but did not prevent STN. A practical solution to preventing STN in Pistacia vera cv. Mateur shoot cultures, derived from four year old mother trees, was developed subsequently whereby periodic inversion of culture tubes (once every 7 d) containing a liquid modified MS medium (Murashige and Skoog, 1962) supplemented with 15 mM calcium gluconate completely prevented STN development in these cultures.