Initial growth potential and biomass production of field established guayule (Parthenium argentatum Gray.) cultivars
The initial growth potential and biomass production of four guayule cultivars under dryland conditions were investigated at different localities in South Africa. Growth (plant survival, height, canopy diameter, stem diameter) and biomass (wet and dry mass) were recorded for (1) one-year old plantings established in April 2001 at Elsenburg, Graaff-Reinet and Oudtshoorn, and (2) six-month old plantings established in October 2001 at Bethulie, Glen and Upington. For one year old plantings, significant area x cultivar interactions were observed for plant survival and height, while canopy diameter and stem diameter only differed between areas and cultivars. For six month old plantings interaction between area and cultivar was significant for plant height, but not for plant survival, canopy diameter and stem diameter. There were, however, significant differences in terms of stem- and canopy diameter and dry mass production between production areas. Growth potential and biomass production of guayule was influenced by the availability of water during the growth season.