Rubber and Resin Yield Performance of New Guayule Selections

Abstract

AbstractGuayule (Parthenium argentatum Gray) is a promising alternative to the rubber tree (Hevea brasiliensis Muell. Arg.) for domestic production of natural rubber in semiarid regions. Guayule is not yet a crop and its commercialization will depend on the development of high rubber‐yielding cultivars. The objectives of this study were to determine if individual plant selection has been effective in improving rubber yield; to determine the suitability of California selections for rubber and resin production in Arizona; and to examine the extent of genotype‐by‐environment (G ✕ E) interactions in improved guayule selections. Plant height, width, dry weight, rubber content, resin content, rubber plus resin content, rubber yield, resin yield, and rubber‐plus–resin yield were measured for 24 guayule genotypes planted at Riverside and Palmdale, CA, and Maricopa, AZ, from 1986 to 1989. Genotypes were significantly different for all traits except for plant width and dry weight at Maricopa. The highest rubber yields were 743 kg ha−1 yr−1 at Riverside, 172 at Palmdale, and 564 at Maricopa. Genotype A9 at Riverside and Genotype A22 at Maricopa exceeded the mean rubber yield of two standard varieties by 163 and 66%, respectively, indicating that selection for increased rubber yield within heterogeneous germplasm has been successful. The highest resin yield was 1405 kg ha−1 yr−1 at Riverside, 668 at Palmdale, and 1006 at Maricopa. With rubber plus resin yields of 2085 and 1579 kg ha−1 yr−1, Genotypes A4 and A22 appear acceptable for large‐scale production at Riverside and Maricopa, provided economic markets are found for guayule resin. The G ✕ E interaction effects were significant for all traits. Analyses of data suggested that both quantitative and qualitative differences in performance of genotypes in different locations were responsible for the observed G ✕ E interactions.