PARENT SESSION
Poster Session #33: Light Relations.
Wednesday, August 8, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
159
Effects of interactions between Na2SO4 concentrations and light levels on the growth of Helianthus paradoxus and Helianthus annuus.
MENDEZ, MONICA1, VAN AUKEN, O.1, 1
ABSTRACT- Helianthus paradoxus Heiser (the puzzle sunflower, Asteraceae) is a rare and federally threatened species found only in western Texas and several locations in New Mexico. It is a hybrid of Helianthus annuus L. (common sunflower) and H. petiolaris (plains sunflower). Helianthus paradoxus seems to be a halophyte. Yet, H. annuus, one of its parents, is a known glycophyte. The purpose of this study was to determine the effect of Na2SO4 concentrations and its interaction with light intensity on the growth of H. paradoxus and H. annuus. In a factorial field experiment, the growth of H. paradoxus and H. annuus was examined in 0, 4.1, 8.1, and 24.3 ppt of Na2SO4 under 100%, 75%, 50%, and 25% sunlight. All treatments contained four pots with five individual plants per pot. Parameters measured were height, number of leaves, basal diameter, shoot dry mass, and root dry mass. Overall, the growth of both species was inhibited under 100% sunlight, and salt tolerance seemed to decrease at higher light levels.
KEY WORDS: Helianthus paradoxus, Helianthus annuus, salt tolerance, light levels