EFFECT OF MINERAL CONCENTRATION ON TISSUE-CULTURED WALNUT (JUGLANS REGIA VAR. ZEIABADI) GROWTH

In vitro proliferation of walnut (Juglans regia var. Zeiabadi) was studied in response to the four levels (1/3X, 1/2X, 1.0X and 1.5X) of macrominerals of DKW (Driver and Kunjyukj, 1984) medium. Macrominerals can be a limiting factor for growth and development of walnut explants. Addition of 0.5X macrominerals to the basal DKW medium in which containing 4.0 µM 6-benzylaminopurine (BA) and 12 µM indole-3-butyric acid (IBA), significantly (P=0.5) improved the proliferation. Better response of was found with 1.5X macrominerals concentration in respect of growth and proliferation. In contrary, the decrease in mineral availability observed in the depressed growth in the low macrominerals supply treatments (1/3X and 1/2X), (the restricted mineral availability was the main cause of the inhibition of the growth). However, root formation was worsted by supplemented additional minerals. For example, low mineral concentration treatment exhibit high rooting ability (75%) and high mineral concentration showed low (13%).