Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2014
Publication Date: 4/1/2014
Citation: Sanchez, P.L., Chen, M., Pessarakli, M, Hill, H., Gore, M.A., Jenks, M.A. 2014. Effects of temperature and salinity on germination of non-pelleted and pelleted guayule (Parthenium argentatum A. Gray) seeds. Industrial Crops and Products. 55:90-96. Interpretive Summary:
Technical Abstract: Guayule (Parthenium argentatum A. Gray) is an important domestic source of natural rubber. Commercial field plots are currently established using greenhouse-grown seedlings that are hand sown as plugs. However, this practice is expensive and laborious. Direct sowing of guayule seed in the field would reduce time and cost significantly, and yet the effects of seed pelleting, temperature, salinity level, and their interactions on guayule seed germination are not well established. The objective of the study was to evaluate the effects of temperature and salinity and the performance of non-pelleted and pelleted seeds on germination and initial seedling establishment of guayule. To test the germination requirements, non-pelleted (control) and pelleted YULEX-B line seeds were planted in solutions having electrical conductivity (EC) of 0, 2, 4, 6, 8, and 10 mS/cm at 10, 20, 30, and 40 oC. After 7 days, the non-germinated seeds were transferred to distilled water plates in a 20 oC environment. Seed pelleting, temperature, salinity, and their interactions significantly affected guayule germination. The optimal conditions for seed germination (i.e., highest germination rates) were found to be 20 oC and EC 0-2 mS/cm, regardless of pelleting. Both temperature and salinity delayed germination and decreased viability. Germination was inhibited at both 10 and 40 oC. Germination percentages increased for treatments after seeds were transferred to optimal conditions. Importantly, pelleted guayule seeds exhibited higher germination than non-pelleted seeds in all treatments. Our results provide important new insights that can help guide the selection of optimal seasonal and soil conditions for field establishment with new direct seeding methods. Temperature and salinity are two of the most important factors for successful germination and seedling establishment of the high quality guayule YULEX-B Line. The results of this study were used to determine the best time to plant YULEX-B line in Maricopa, AZ. Currently an ongoing field experiment is aimed at comparing the performance of pelleted and non-pelleted seeds. Future studies will be conducted to compare the germination performance of different guayule lines.