Establishment of guayule plants in a limed bark medium at low phosphate levels

Seedlings of guayule (Parthenium argentatum Gray) were successfully grown on a milled and composted pine bark medium. Liming and saturation of the medium was carried out for a 4-week period, prior to the addition of a VAM fungal inoculum and guayule seeds. This was done to permit an increase and stabilization of pH. Rock phosphate was incorporated into the medium at levels of 1.5, 3, 6 and 12mgdm−3, while other nutrients were provided by a modified Hoagland’s solution (lacking phosphate) with a nitrogen level of 70mgdm−3. Although poor seedling growth was recorded, it is suggested that seedlings may be pre-adapted to transplantation in a potentially hostile environment