Guayule as an alternative crop for natural rubber production grown in B- and Se-laden soil in Central California

Authors: Banuelos, Gary; Placido, Dante; ZHU, HUI - Chinese Academy Of Agricultural Sciences; CENTOFANTI, TIZIANA - Fresno State University; ZAMBRANO, M - Fresno State University; Heinitz, Claire; LONE, TODD - Fresno State University; McMahan, Colleen

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2022
Publication Date: 10/22/2022
Citation: Banuelos, G.S., Placido, D.F., Zhu, H., Centofanti, T., Zambrano, M., Heinitz, C.C., Lone, T.A., McMahan, C.M. 2022. Guayule as an alternative crop for natural rubber production grown in B- and Se-laden soil in Central California. Industrial Crops and Products. 189. Article 115799. https://doi.org/10.1016/j.indcrop.2022.115799.
DOI: https://doi.org/10.1016/j.indcrop.2022.115799

Interpretive Summary: Guayule is a native plant in the southwestern United States and northern Mexico that is grown for natural rubber, biofuel, and terpene. Due to its drought tolerance, guayule has been considered as an alternative crop for arid and semi-arid areas. Persistent drought conditions and increased urbanization have greatly reduced the amount of good quality water available for irrigated agriculture in Central California. Consequently, other sources of water must be sought and utilized, which includes saline drainage water. However, potential crops utilizing these kinds of waters must also be salt and boron (B) tolerant. In this two-part study, we irrigated different ecotypes of guayule with simulated saline, B and selenium (Se) laden drainage water under greenhouse growing conditions. 60 days after transplanting, the most salt and B tolerant ecotypes were selected and then grown in saline and B-rich drainage sediments/soil under field conditions. In both greenhouse and field-grown plants, resin and natural rubber production were also measured. Our results indicated that sodium salinity, B, and Se levels in irrigation water and in field drainage sediment plots, did not negatively affect guayule growth, resin and natural rubber production. Hence, the promising results show that guayule is apparently a salt and B tolerant plant species. Importantly, the plant can still produce natural rubber with poor quality waters and/or growing in saline/B soils. Guayule may be an alternative crop to consider for growing in drought saline regions like the westside of Central California.

Technical Abstract: Guayule (Parthenium argentatum A. Gray), originating from southwestern United States and northern Mexico, is a promising a drought tolerant, and rubber-producing plant for arid and semiarid areas. The potential of growing guayule as an alternative crop for saline, boron- and selenium-laden soils using drainage water in the Westside of central California was evaluated in both a greenhouse and a drainage sediment field experiment. In the greenhouse experiment, salt and boron (B) tolerance and selenium (Se) accumulation were evaluated in different guayule ecotypes grown in poor quality soil and irrigated with simulated drainage water at different levels of salinity. Guayule accessions AZ1, AZ5, and AZ6 tolerated salinity and B levels better than AZ2, AZ3, and AZ4. Consequently, AZ1, AZ5, and AZ6 were planted in the field drainage sediment microplots with slight salinity and moderate B levels. In both greenhouse and microplot studies, ion (i.e., Na, B, and Se) accumulation, natural rubber and resin production were evaluated in plant tissues at harvest. Irrespective of ecotypes, guayule was able to accumulate and tolerate high tissue concentrations of B and Na. Concentrations of Se, B, and Na in the leaves ranged from 0.6-8 mg/kg DW, 20-1800 mg/kg DW, and 40-17500 mg/kg DW, respectively, in both experiments. Our results from both greenhouse and microplot sediment experiments indicated that natural rubber and resin production in stems was not affected by slight to moderate salinity, but was slightly affected at high B and saline levels in the growing medium. In both studies, concentrations of rubber and resin ranged from 4-14 w/w% in the stems and applied salt increased rubber production in some accessions. This two-phase study provides initial evidence for using guayule’s as a promising rubber-producing crop that tolerates both saline soil and irrigation with poor quality saline/B waters.