DRYLAND FIELD PERFORMANCE OF CALIFORNIA AND ARIZONA GUAYULE GENOTYPESIN SOUTH TEXAS

Guayule (Parthenium argentatum Gray, Asteraceae) is an alternative sou rce of natural rubber and latex. Seedling establishment and percent ru bber and resin production are important determinants of commercial suc cess of guayule crop production in semi-arid regions, such as south Te xas. Field studies were conducted from 1990-1992 to evaluate the perfo rmance and suitability of selected Arizona and California guayule geno types for rubber production in south Texas. Plant survivorship, biomas s and rubber yields were measured for ten guayule genotypes (PI # 016- 1, N6-5, N9-5 and P3-1 from Arizona, Ca16, Ca17, UC101 and UC102 from California) and two USDA standard lines (P1 # 11605 and N576) planted in Starr County, Texas, where annual rainfall is < 50 cm. The genotype s showed significant differences (p less than or equal to 0.05) for al l traits measured. The highest yield (576 kg.ha(-1), on dry weight bas is) was obtained from UC 101. Genotypes N6-5 and UC101 had the highest biomass production (8859 and 8663 kg.ha(-1).year(-1), respectively). Only five of the ten genotypes tested (11605, Ca16, Ca17, N576 and P3- 1) had survival rates > 50%, but generally < 65%. Survival rate is a t rait that requires improvement in order to sustain long-term guayule p roduction in semi-arid regions. (C) 1996 Academic Press Limited