The control of shoot tip necrosis in Pistacia vera L in vitro

The effect of increased concentrations of calcium (Ca) (3-24 mM) and boron (B) (100-800 mu M) in the medium was studied on the occurrence of shoot tip necrosis (STN) in cultures of Pistacia vera L. STN was significantly reduced by application of Ca or B, however media with more than 200 mu M boron had reduced shoot multiplication. Ca (12-24 mM) supplied as calcium chloride reduced STN without any adverse effect on shoot multiplication or elongation, whereas calcium acetate reduced elongation. It is concluded that STN is a physiological mineral disorder associated with Ca and/or B deficiency in the meristematic regions of actively growing shoots. Application of Ca (up to 24 mM) as calcium chloride to the medium was the best treatment for the control of STN. Reduction of humidity or increased aeration in the culture jars did not have any significant effect on the occurrence of STN.