RESIN PRODUCTION OF GRINDELIA ACCESSIONS UNDER CULTIVATION

In the early 1980's, Grindelia camporum (Asteraceae) was proposed as a potential resin crop for arid lands. A field experiment was conducted in Arizona to evaluate eight Grindelia accessions that included two a ccessions of G. camporum (native to California's Central Valley, and k nown to differ in earliness of flowering), Grindelia stricta var. plat yphylla and G. stricta var. stricta (both native to saline estuaries i n northern California), and four accessions of Grindelia chiloensis fr om the coastal region of southern Argentina. Two plots were establishe d in September 1994, with a total of 2176 plants. Crude resin (CR) con tent was highest for all four accessions of G. chiloensis, with the te traploid accessions having the highest CR contents. G. camporum and G. stricta var. platyphylla were intermediate in CR content. CR content in G. stricta var. stricta was 3.3%. In general, CR contents were lowe r than previously found for these species. A possible explanation for this is a reduction in resin production due to high water and nutrient availability. Biomass production was significantly different among ac cessions. The highest biomass production for the first harvest was fou nd for G. stricta var. platyphylla (517 g/plant). The two tetraploid a ccessions of G. chiloensis (accessions 333 and 336) yielded around 200 g/plant. Biomass production of the tetraploid accessions of G. chiloe nsis was significantly higher than that of the diploid accessions of t he same species. This yield was about one-half of that for G. camporum . Grindelia stricta var. stricta biomass production was the lowest of the eight accessions (119 g/plant). At second harvest (November 1995), individual plant biomass was equal to or smaller than the first harve st for most accessions except for G. chiloensis 297 and 336. When biom ass production and resin content were combined for both harvests, C. c hiloensis tetraploid accessions emersed as the highest resin yielding genotypes.