Guayule is an industrial crop that can be grown for its natural rubber production and phytoremediation capability in the Western San Joaquin Valley, California

Authors: Placido, Dante; Heinitz, Claire; McMahan, Colleen; Banuelos, Gary

Submitted to: Current Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2021
Publication Date: 10/9/2021
Citation: Placido, D.F., Heinitz, C.C., McMahan, C.M., Banuelos, G.S. 2021. Guayule is an industrial crop that can be grown for its natural rubber production and phytoremediation capability in the Western San Joaquin Valley, California. Current Plant Biology. 28. Article 100223. https://doi.org/10.1016/j.cpb.2021.100223.
DOI: https://doi.org/10.1016/j.cpb.2021.100223

Interpretive Summary: California’s San Joaquin Valley (SJV) is one of the most productive agriculture regions in the world. However, groundwater transports naturally occurring salts and other toxic trace elements into cultivated soils in this region. Over time, inadequate drainage can result in the accumulation of boron (B), selenium (Se), and other unwanted salts in high concentrations, posing a challenging ecological environment for agriculture production, especially on the westside of the SJV. One strategy to solve the problem is to identify alternative crops that can grow well in this compromised environment. Guayule (Parthenium argentatum Gray), a natural rubber-producing shrub, can tolerate marginal soils, and is under development as an industrial crop in the southwestern US. Recent advances in guayule development have led to renewed interest in expanding the growing regions. Hence, the goal of the study was to evaluate several guayule accessions from the U.S. National Plant Germplasm System (NPGS) germplasm collection for their capability to grow in saline agricultural conditions that exist in the westside of SJV CA. In this greenhouse study, some guayule accessions easily tolerated selenium, boron, and salts in the irrigation water. Rubber production was actually higher under salt stress in some accessions. This study also found that guayule can tolerate, absorb, and sequester both Se and B in leaves at amounts higher than required, indicating that guayule can be considered as a gentle phytoremediation tool. Hence, guayule cultivation offers potential for growers not only in the established growing region of the southwestern U.S., but also in the westside of the SJV.

Technical Abstract: This study evaluated the growth characteristics of six guayule (Parthenium argentatum Gray) accessions irrigated with waters high in boron, selenium, and calcium and sodium salts under greenhouse conditions. The synthetic irrigation waters used in this investigation mimic the water quality used frequently for irrigation in the westside of the San Joaquin Valley, California, U.S.A. Guayule is a natural rubber-producing industrial crop that is tolerant of marginal soils and drought, and it may be grown as a profitable alternative crop with poor quality waters for this region. Among the six accessions investigated for 55 days, three of them showed increased natural rubber production under saline irrigation conditions compared to non-saline irrigation (control). Elemental analysis in the leaves revealed that guayule can also absorb and accumulate potentially toxic elements. Results from this study suggest that specific accessions of guayule can be grown under saline irrigation conditions and produce natural rubber, and exhibited potential bioremediation benefits under agronomic conditions found in the westside of the San Joaquin Valley, CA.