Germination Characteristics of Helianthus maximilianai Schrad. and Simsia calva (Engelm. and Gray) Gray

Germination characteristics of Maximilian sunflower (Helianthus maximiliana Schrad.) and awnless bushsunflower {Simsia calva Engelm. & Gray) Gray were evaluated at water potentials of 0, -.25, -0.50, -0.75, and -1.0 MPa under alternating temperature regimes of 10/20, 15/25, and 20/30 degrees C in controlled environmental chambers. Cumulative germination was greatest for both species at water potentials of 0 and -0.25 MPa in the 15/25 degrees C temperature regime. Germination total and rate were depressed for both species in the 10/20 degrees C regime. The 20/30 degrees regime depressed total germination but increased germination rate. The adverse effects of more negative water potentials (-0.75 and -1.0 MPa) were more pronounced at low temperatures for awnless bushsunflower and high temperatures for Maximilian sunflower.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.Migrated from OJS platform August 202