Clonal propagation of cashew (Anacardium occidentale L.) by tissue culture

A study was conducted to develop in vitro culture techniques relevant to the clonal multiplication of cashew (Anacardium occidentale L.) using the Tanzanian elite clone AC4. Cultural factors affecting shoot proliferation, shoot elongation, and node development were assessed using glasshouse-raised plants of various ages. MS salts medium containing full-strength macroelements was found to be best forshoot proliferation and shoot elongation. Increasing ages of stock plants resulted in drastic decreases in the abilities of axillary buds on nodal explants to sprout and elongate and best performances were obtained from juvenile explants of 1-6 month old explants. Out of six cytokinins compared, 6-benzylamino purine (BAP) applied at 30 muM and zeatin (Zea) at 5 muM were found to be optimal for axillary shoot proliferation and shoot elongation, respectively. Microshoots were rooted in vitro at a frequency of 50-60% when cultured for 3 d in woody plant medium (WPM) with 0.5 mM indole-3-butyric acid (IBA). About 60-65% of rooted microshoots survived weaning and produced healthy vigorously growing plants.