Dryland field performance of California and Arizona guayule genotypes in south Texas

Guayule (Parthenium argentatumGray, Asteraceae) is an alternative source of natural rubber and latex. Seedling establishment and percent rubber and resin production are important determinants of commercial success of guayule crop production in semi-arid regions, such as south Texas. Field studies were conducted from 1990–1992 to evaluate the performance and suitability of selected Arizona and California guayule genotypes for rubber production in south Texas. Plant survivorship, biomass and rubber yields were measured for ten guayule genotypes (PI # 016-1, N6-5, N9-5 and P3-1 from Arizona, Ca/6, Ca/7, 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 genotypes showed significant differences (p≤0•05) for all traits measured. The highest yield (576 kg.ha−1, on dry weight basis) was obtained from UC101. 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, Ca/6, Ca/7, N576 and P3-1) had survival rates >50%, but generally <65%. Survival rate is a trait that requires improvement in order to sustain long-term guayule production in semi-arid regions.