Water use, growth, and yield of ratooned guayule under sub-surface drip and furrow irrigation in the US Southwest Desert

Authors: ELSHIKHA, DIAA ELDIN - University Of Arizona; WALLER, PETER - University Of Arizona; Hunsaker, Douglas - Doug; Thorp, Kelly; WANG, GUANGYAO - Bridgestone Americas, Inc; DIERIG, DAVID - Bridgestone Americas, Inc; CRUZ, VON - Bridgestone Americas, Inc; ATTALAH, SAID - University Of Arizona; Bautista, Eduardo; KATTERMAN, MATTHEW - University Of Arizona; Williams, Clinton; RAY, DENNIS - University Of Arizona; NORTON, RANDY - University Of Arizona; ORR, ETHAN - University Of Arizona; Wall, Gerard - Gary; OGDEN, KIM - University Of Arizona

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2023
Publication Date: 9/28/2023
Citation: Elshikha, D.M., Waller, P.M., Hunsaker, D.J., Thorp, K.R., Wang, G., Dierig, D., Cruz, V.M., Attalah, S., Bautista, E., Katterman, M.E., Williams, C.F., Ray, D.T., Norton, R., Orr, E., Wall, G.W., Ogden, K. 2023. Water use, growth, and yield of ratooned guayule under sub-surface drip and furrow irrigation in the US Southwest Desert. Water. 15(19). Article 3412. https://doi.org/10.3390/w15193412.
DOI: https://doi.org/10.3390/w15193412

Interpretive Summary: Guayule is a drought tolerant desert shrub that makes high quality natural rubber in its bark. Efforts are on-going to prompt commercial farm production of guayule in the US Southwestern desert for domestic supplies of natural rubber. After guayule is seeded, it can be harvested after two years of growth and then regrown for additional harvests made about every two years. To attain commercial rubber yields, irrigation is required but research is needed to develop efficient water use practices for guayule. ARS scientists in Maricopa, Arizona, conducted field experiments to determine optimum irrigation management for a regrown guayule crop. The research found that the highest yields and water use efficiencies were attained when irrigation application was 25% less than needed for full plant transpiration. This is because more rubber was produced in the guayule plants when plants had some water stress. It was also found that after a first harvest, a regrown guayule crop has higher rubber yield and uses less water than that for the first 2-year crop. The findings imply that commercial guayule farms will benefit by regrowing the crop for multiple harvests. The research will be of interest to the US Rubber Industry, including Tire Manufacturers, irrigation consultants, water district water managers, and other research investigators of guayule.

Technical Abstract: Guayule (Parthenium argentatum A. Gray) is a perennial desert shrub with ratoon-cropping potential for multiple harvests of its natural rubber, resin, and bagasse byproducts. However, yield expectations, water use requirements, and irrigation scheduling information for ratooned guayule are extremely limited. The objectives of this study were to evaluate dry biomass (DB), contents of rubber (R) and resin (Re) and yields of rubber (RY) and resin (ReY) responses to irrigation treatments and develop irrigation management criteria for ratooned guayule. The water productivity (WP) of the yield components were also evaluated. Guayule plants that were direct-seeded in Apr. 2018 were ratooned and regrown starting in Apr. 2020, after an initial 2-year harvest at two locations in Arizona: Maricopa and Eloy on sandy loam and clay soils, respectively. Plots were irrigated with subsurface drip irrigation (SDI) at 50, 75, and 100% replacement of crop evapotranspiration (ETc), respectively, and furrow irrigation at 100% ETc replacement, as determined by soil water balance measurements. The Eloy location did not include the 100% irrigation treatment under SDI due to unsuccessful re-growth for this specific treatment. The irrigation treatments at the locations were replicated three times in a randomized complete block design. After 21-22 months of regrowth, the guayule plants were harvested in plots. Results showed that DB increased with the amount of total water applied (TWA, irrigation plus precipitation), while R and Re were reduced at the highest TWA received at both locations. Ultimately, the SDI treatments with 75% ETc replacement resulted in the best irri-gation management in terms of maximizing RY and ReY and WP for both locations and soil types. Compared to the initial 2-year direct-seeded guayule crop, ratooned guayule required less TWA and attained higher DB, RY and ReY, as well as higher WP, with average increases of 25% in dry biomass, 33% in rubber yield, 32% in resin yield. A grower’s costs to plant the initial direct-seeded guayule crop would be offset by the additional yield revenue of the ratooned crop, which would have compara-tively small startup costs.