The Effect of Temperature and Polyethylene Glycol-induced Osmotic Stress on Radicle Growth of Lespedeza stipulacea, Lolium multiflorum, and Bouteloua curtipendula

Abstract

Seedlings of Lolium multiflorum Lam., Lespedeza stipulacea Maxim., and Buteloua curtipendula (Michx.) Torr. were grown for 48 hours in darkness at constant temperatures of 22°, 27°, 32°, or 37°C either in distilled water or polyethylene glycol 20,000 (PEG) solutions with osmotic potentials of −3.2, −7.7, and −9.8 bars. Redicle growth rate decreased as concentrations of polyethylene glycol increased. Radicle growth was reduced at 32° and negligible at 37° for L. multiflorum. All levels of PEG-induced osmotic stress reduced radicle growth at 22° and 32°, while at 27° only higher levels reduced growth of L. multiflorum. PEG-induced osmotic stress reduced radicle growth of B. curtipendula significantly at all temperatures except 37°, where the lowest level of PEG had an insignificant effect on radicle growth. With L. stipulacea, low levels of PEG-induced osmotic stress did not have a significant effect on radicle growth, but an osmotic stress of −9 bars reduced growth at all temperatures.