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

Evaluating Guayule (Parthenium argentatum A. Gray) Germplasm Grown in Spain: Rubber and Resin along Three Production Cycles

“…Moreover, the expected production yield of the crop would not reach the level obtained in its original geographical location, which has been estimated at 1400 kg ha −1 year −1 in the USA [ 26 ]. As mentioned in our previous study about biomass production [ 2 ], the reason could be that the irrigation supplied was significantly lower compared with other studies. The amount of irrigation that the plantation received over 4 years (2304 mm) was less than half of what some authors consider deficit irrigation (2519 mm in 2 years) [ 27 ] and far from what is considered the optimum irrigation to achieve the maximum productive rate (3357–3573 mm in 2 years) [ 28 , 29 ].…”

“…Guayule ( Parthenium argentatum A. Gray) is a promising alternative crop for semi-arid areas with limited irrigation [ 1 , 2 ] and has the potential to replace, at least in part, the supply of natural rubber, which is currently produced exclusively from the rubber tree Hevea brasiliensis [ 3 ]. Natural rubber is used to manufacture many thousands of essential products, including molded goods such as tires and hoses, and medical products such as gloves, catheters and feeding nipples [ 4 ].…”

“…The superiority of natural rubber over synthetic forms (produced from petroleum) comes from its resilience, elasticity, abrasion resistance, efficient heat distribution, impact resistance and malleability at cold temperatures [ 5 ]. Although the industrial commercialization of guayule is presently limited, strategies for the valorization of rubber, resin and other co-products are being developed in the setting of retired land with adverse environmental conditions and irrigation [ 2 ]. Indeed, in addition to rubber, the economic viability of guayule will depend on the successful exploitation of its many co-products [ 6 , 7 , 8 ].…”

“…Previous references of traditional guayule accessions cultivated in Spain in the 1950s and 1960s, should be compared in the same cultivation area with the accessions developed later. Recently, the adaptation of 20 pure guayule accessions, traditional (9) and modern ones (11), together with seven hybrids, to the agroclimatic conditions of Castilla-La Mancha was investigated by comparing their vegetative characteristics across three sampling cycles [ 2 ], confirming that genetic imprinting remained important until plants were two years old; after this, time environmental effects were dominant in the second and, particularly, the third cycle during biannual harvesting. Also, the overall biomass production profile along the three cycles was unique to the germplasm tested, the harvest management practices and the agroclimatic conditions.…”

“…Also, the overall biomass production profile along the three cycles was unique to the germplasm tested, the harvest management practices and the agroclimatic conditions. However, in addition to biomass, the production of potentially useful co-products should be considered when selecting the best germplasm for a new growing area [ 2 ]. In this respect, the present study analyzed, for the first time, the accumulation profile of rubber and resin in the same variety of guayule germplasms (20: 9 pure traditional accessions and 11 modern pure ones), together with some modern hybrids (seven) that were adapted for growth in Santa Cruz de la Zarza (Toledo, Spain), following a schedule of 24, 48 and 60 months after planting.…”