Temperature requirements for guayule seed germination

Authors: WANG, G - Bridgestone Americas Tire Operations; LYNCH, AMBER - Bridgestone Americas Tire Operations; CRUZ, VON MARK - Bridgestone Americas Tire Operations; Heinitz, Claire; DIERIG, DAVID - Bridgestone Americas Tire Operations

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2020
Publication Date: 9/21/2020
Citation: Wang, G., Lynch, A.L., Cruz, V.V., Heinitz, C.C., Dierig, D.A. 2020. Temperature requirements for guayule seed germination. Industrial Crops and Products. 157. Article 112934. https://doi.org/10.1016/j.indcrop.2020.112934.
DOI: https://doi.org/10.1016/j.indcrop.2020.112934

Interpretive Summary: Guayule is a new crop under development as an alternative source of natural rubber, but little is known about the exact requirements for optimal seed germination. We compared the germination rates of different accessions of guayule and close relatives under 10 temperature gradients. We found significant variance in temperature requirements for seed germination, with the optimal temperature ranging from 17.8 to 26.9C.

Technical Abstract: Guayule (Parthenium argentatum A. Gray) is an alternative source of natural rubber. Direct-seeding is critical to commercialization of guayule and quantifying variability in seed germination response to temperature is necessary. A thermogradient table was used to measure germination rates of the 44 most commonly available accessions of guayule, related Parthenium species, and interspecific hybrids under 10 temperature gradients. The optimal temperature for seed germination ranged from 17.8 to 26.9oC, with an average temperature of 21.8oC. The sensitivity of seed germination to temperature range varied significantly among accessions. When compared to the highest germination rate at optimal temperature, relative germination rate at 10oC and 35oC represented low and high temperature tolerance, respectively. The two accessions with >70% relative germination rate at 35oC, R1109 and P. incanum (mariola), had the optimal temperature for germination above 26.6oC. At the same time, six accessions with 70% relative germination rate at 10oC, 11591, R1110, PARL 935, CAL-3, 11605, and PARL 920, had a range of 17.8 to 21.7oC optimal temperature for germination. This study indicates that guayule and other Parthenium accessions varied significantly in temperature requirements for seed germination. These temperatures can serve as a guide to seasonal timing for direct seeded field planting.