Phenotypic variability of guayule (Parthenium argentatum Gray) germplasm grown in Castilla-La Mancha (Spain) (I): Morphology and biomass production

Abstract

Guayule, a plant native to the Mexican deserts of Chihuahua and southern USA, has attracted interest as a substitute source of natural rubber and other bioproducts, and is a promising alternative crop for the semi-arid regions of central and eastern Spain. The trials performed on guayule production in Spain in the 1960 s need to be updated following the emergence of climate change and the development of more productive guayule accessions. Accordingly, the objective of the present study was to search for those lines that best adapt to the agro-climatic conditions of Castilla-La Mancha with respect to biomass production when the crop is industrially managed. The adaptation of 27 guayule accessions was studied by comparing their vegetative development (height, width, volume, shape, branch number and diameter). Results revealed the contribution of genetic imprinting for growth in plants up to 24 months after transplanting, after which times environmental effects were dominant in the second and third cycle after harvesting every two years. Biomass production along the three cycles simulating industrial management with biannual harvest depended on the germplasm, the harvest management and the agro-climatic conditions. The accessions with higher biomass content in branches were CAL-7 and AZ-2.